2nd Annual Symposium of IGCP-581
“Evolution of Asian River Systems: Tectonics and Climates”
June 11-14, 2011, Hokkaido University, Sapporo, Japan
Program with abstracts
Faculty of Environmental Earth Science, Hokkaido University
2nd Annual Symposium of IGCP-581
“Evolution of Asian River Systems: Tectonics and Climates”
June 11-14, 2011, Hokkaido University, Sapporo, Japan
I. PLACE
Faculty of Environmental Earth Science, Hokkaido University, N10W5, Kita-ku,
Sapporo 060-0810, Japan
II. DATES
June 11-14, 2011
III. ORGANIZERS
IGCP-581 Local Organization Committee
Dr. Masanobu Yamamoto, Hokkaido University
Dr. Tomohisa Irino, Hokkaido University
Dr. Hitoshi Hasegawa, Hokkaido University
Prof. Hongbo Zheng, Nanjing University
Prof. Ryuji Tada, The University of Tokyo
IV. SPONSORS
• UNESCO-IGCP
• IFES-GCOE Global COE Program "Establishment of Center for Integrated Field
Environmental Science" Graduate School of Environmental Science & Division of
Environmental Resources, Graduate School of Agriculture, Hokkaido University
• Tokyo Geographical Society
• Japan Drilling Earth Science Consortium
V. SCIENTIFIC COMMITTE
Prof. Hongbo Zheng (Nanjing University, China)
Prof. Ryuji Tada (University of Tokyo, Japan)
Prof. Peter Clift (University of Aberdeen, UK)
Dr. Masood Ahmed (National Geophysical Research Institute, India)
Prof. Zhengxiang Li (Curtin University of Technology, Australia)
VI. Sessions
The 2nd Annual symposium of IGCP Project-581 will comprise presentations of
scientific results, discussion on future cooperation and a field trip. The presentation
part will last for two days (June 11-12, 2011) during which we will have following
three sessions.
S1. Modern processes and geochemical cycles in Asian river systems:
In this session, we will summarize our current knowledge about processes and
geochemical cycles in modern Asian river systems, both large and small, involving
weathering, erosion, transportation and sedimentation, and their controlling factors
such as climate, vegetation, and geography from multi-disciplinary perspectives.
S2: River system response to Asian monsoon variability and its impact on
marginal seas: terrestrial and marine records: Seek for new potential drilling
proposals: In this session, we will explore the impact of the Asian monsoon on river
processes, geochemical cycles, and the environment of marginal seas (e.g., East China
Sea) at orbital to millennial time-scales.
1
S3. Asian river–continental shelf systems linked to the Cenozoic tectonic and
climatic evolution: Seek for new potential drilling proposals: In this session, we
will discuss the evolution of Asian river drainage systems and continental shelf
systems (e.g., Yangtze River and East China Sea) and their proposed linkage with the
Cenozoic tectonic evolution (e.g., the uplift of Himalaya-Tibet plateau), Asian
monsoon, and glacio-eustatic sea-level changes associated with Northern Hemisphere
glaciation.
Session schedule
June 11 (Day 1)
8:10-9:00
Registration
9:00-9:10
Opening remark
9:10-10:20
General session
10:20-11:30
Oral session 1: Modern processes and geochemical cycles in
Asian river systems
11:30-12:15
One minute talk by poster presenters
12:15-13:30
Lunch
13:30-15:00
Poster session
15:00-16:30
Oral session 1 continue
16:50-17:30
Oral session 2: River system response to Asian monsoon
variability and its impact on marginal seas: terrestrial and
marine records (Seek for new potential drilling proposals)
18:00-20:00
Reception
June 12 (Day 2)
8:30-12:00
Oral session 2 continue
12:00-13:10
Lunch
13:10-14:00
Poster session
14:00-15:30
Oral session 3: Asian river–continental shelf systems linked to
the Cenozoic tectonic and climatic evolution (Seek for new
potential drilling proposals)
16:00-16:50
Discussions
16:50-17:00
Closing
2
PROGRAM
June 11 (Day 1)
8:10-9:00
Registration
9:00-9:10
Opening remark
9:10-9:45
Keynote
G-1
General session
Hongbo ZHENG (Nanjing University), Juntao JIA, Mengying
HE, Ling LI, Xiaochun WEI, Yuliang CHEN, Ping WANG
A Miocene Age Yangtze River: Evidence from Finger-printing
Sediments
9:45-10:20
Keynote
G-2
Peter CLIFT (University of Aberdeen), Liviu GIOSAN, Andrew
CARTER, Anwar ALIZAI, Ali R. TABREZ and Tom STEVENS
Sediment source to sink transport in the Indus River system:
Effects of reworking and drainage capture on sand
compositions
Oral session 1: Modern processes and geochemical cycles in
Asian river systems
10:20-10:50 Seiya NAGAO (Kanazawa University), Takafumi ARAMAKI,
Keynote
Takayuki TANAKA, Osamu SEKI, Yu MIKAMI, Masao
UCHIDA, Yasuyuki SHIBATA, and Masayoshi YAMAMOTO
S1-1
Transport behavior of particulate organic matter in the Ishikari
River system
10:50-10:10 Weihua WU (Nanjing Univ.), Hongbo ZHENG, Jianhua CAO,
Chao LUO, Bin ZHOU
S1-2
Sr isotopic characteristics in two small watersheds draining
typical silicate and carbonate rocks: implications for the studies
on seawater 87Sr/86Sr evolution
10:10-10:30 Jayaraju NADIMIKERI (Yogi Vemana University), Sundara
Raja Reddy. B. C
S1-3
Impact of Climate Change on some key rivers : An Indian
scenario
10:30-10:50
Coffee Break
10:50-11:10 Subodh SHARMA (Kathmandu University) and Otto MOOG
S1-4
Development of a Reference-based Himalayan River Typology
for the HKH region
3
11:10-11:30 Tomohisa IRINO (Hokkaido Unv.), Ken IKEHARA and Seiya
NAGAO
S1-5
Localized source and event driven feature of suspension
transport by small rapid river: Example from 2003 August
event in the Saru River, Hokkaido, Japan
11:30-12:15
S1-10
One minute talk by poster presenters
Poster session 1: Modern processes and geochemical cycles
in Asian river systems
Shin TOYODA (Okayama Univ. of Science), Masashi
TAKADA, and Aiko SHIMADA
Physical properties of quartz as indicators of provenance and
transportation of river sediments: Applications of electron spin
resonance, thermoluminescence and optically stimulated
luminescence
S1-11
Osamu SEKI (Hokkaido University) , Masato MIKAMI, Seiya
NAGAO, Tomohisa IRINO, Masanobu YAMAMOTO
Seasonal changes in lignin phenol compositions of suspended
particles in Hokkaido major rivers
S1-12
Kotaro Kamada (Hirosaki University)
Initial Development of a Braided River System: Situated on a
Devastated Ignimbrite Plateau
S1-13
Yuliang CHEN ( Nanjing University), Hongbo ZHENG,
Mengying HE
Implication for Provenance of Muscovite and the Component
of Light Minerals of the Yangzte and Tributaries
S1-14
Takuya MANAKA (University of Tokyo), Hiroyuki USHIE,
Daisuke ARAOKA, Atsushi SUZUKI, H. M. Zakir HOSSAIN,
and Hodaka KAWAHATA
The influence of the Ganges, Brahmaputra and Meghna Rivers
on regional and global carbon cycle
S1-15
Shinya TAKANO (Hokkaido Univ.), Go IWAHANA, Trofim
MAXIMOV, Atsuko SUGIMOTO
Stable isotopes of surface water on permafrost in Eastern
Siberia
S1-16
Yuta TSUZUKI (Hokkaido University) and Atsuko SUGIMOTO
4
Observation on water isotopic compositions for Hokkaido
water isotope map and its application
S1-17
Keita SAITO (University of Tokyo), Ryuji TADA, Takuya ITAKI
Provenance of surface sediments to the west of Okinawa Island
based on mineral assemblage
S1-18
Ken IKEHARA (Geological Survey of Japan, AIST), Hajime
KATAYAMA, Tsumoru SAGAYAMA, Kazuya SUGA, Tomohisa
IRINO, and Akiko OMURA
Long distance transport of terrigenous materials from river to
deep-sea basin by hyperpycnal flows: An example from the
2003 Hokkaido Hidaka Flood
S1-20
Shinya OCHIAI (Kanazawa University), Seiya NAGAO, Koyo
YONEBAYASHI, Taijiro FUKUYAMA, Masayoshi
YAMAMOTO, Koji NAKAMURA, and Kenji KASHIWAYA
Catchment environmental changes inferred from small
reservoir sediments in Noto Peninsula, Japan
S1-21
Shadananan NAIR (Nansen Environmental Research Centre
–India)
Erosion and sedimentation in the river basins of Kerala: impact
of climate change and anthropogenic activities
S2-10
Poster session 2: River system response to Asian monsoon
variability and its impact on marginal seas: terrestrial and
marine records (Seek for new potential drilling proposals)
Ke Wang (University of Tokyo), Hongbo Zheng, Ryuji Tada,
Yan Zheng
High-resolution paleoenvironmental and paleoclimatic record
of core MD06-3040 from East China Sea during the Holocene
S2-12
Jae Hwa JIN (Korea Institute of Geoscience and Mineral
Resources), Jun Ho KIM, and Min Jun KIM
Computer Tomography - its applicability for estimating
depositional orientation and internal structures of coastal
sediment bodies
S2-13
Taku AJIOKA, Masanobu YAMAMOTO, Tatsufumi OKINO
(Hokkaido University), Keiji TAEMURA (Kyoto University),
Akira HAYASHIDA (Doshisha University)
Branched glycerol dialkyl glycerol tetraethers as a paleoclimate
proxy: Application in Lake Biwa study
5
S2-14
J. HEO, B.K. KHIM (Pusan Univ.), C. SHIMADA,M.
UCHIDA, K. IKEHARA, Ryuji TADA
Geochemical properties and diatom assemblages from a core
KR07-04 PC3 in the southeastern East Sea/Japan Sea:
Variation of East Asian summer monsoon during the last
glacial and deglacial periods
S2-15
Yu-Hyeon PARK (Graduate School of Environmental Science,
Hokkaido University, Japan), Masanobu YAMAMOTO and
Leonid POLYAK
Terrestrial biomarkers in Alaskan margin sediments in the
Arctic Ocean
S2-16
Masanobu YAMAMOTO (Hokkaido University), Masaki
INAGAKI, Yutaka ICHIKAWA, Toshinori INAGAKI, Midori
KISHIZAKI, Tomoya SHINTANI, Hirotoka SAI, Liang-Jian
SHIAU, Min-Te CHEN, Tadamichi OBA, and Ken IKEHARA
Climate and sea level controls on terrestrial organic matter
discharge into marginal seas along the northwestern Pacific
margin since the last glacial maximum
S2-17
Yasuto YAMAMOTO, Masanobu YAMAMOTO, Tomohisa
IRINO, Taku AJIOKA (Hokkaido University), and Keiji
TAKEMURA (Kyoto University)
Paleotemperature estimation over the past 10000 years by the
application of GDGT-based proxy in soil sequences from the
Ono River Basin, Oita, Japan
S2-18
Sangmin HYUN (Korea Ocean Research and Development
Institute), Hi-Il YI
Terrestrial records in shelf sediment in East/Japan Sea and
Yellow Sea: a speculation on major river supply from the
Korean Peninsula
S3-5
Poster session 3: Asian river–continental shelf systems
linked to the Cenozoic tectonic and climatic evolution (Seek
for new potential drilling proposals)
Jianguang ZHANG (Technische Universität Darmstadt), Jens
HORNUNG, Weihua BIAN, Matthias HINDERER and Pujun
WANG
Influence of Climate and Tectonics on Progradation of a River
Delta in a Mega-Lake System (Upper Triassic, Junggar-Basin,
NW-China)
6
S3-6
Hitoshi HASEGAWA (Hokkaido University) and Noriyuki
SUZUKI
Eocene coal-bearing deposits (Ishikari Group) in central
Hokkaido: possible link to the widespread deposition of oil
source rock during the Eocene “greenhouse” condition
S3-7
Takuto ANDO (Hokkaido Univ.) , Ken SAWADA , Kazuki
OKANO, Hiroshi NISHI , and Reishi TAKASHIMA
Enhanced primary productivity triggered by excess terrestrial
input in the mid-Cretaceous Oceanic Anoxic Event 1b (the
Paquier) in the Vocontian basin, SE France
S3-8
Satoshi FUROTA, Ken SAWADA (Fac. Sci., Hokkaido Univ.)
and Gentaro KAWAKAMI (Geological Survey of Hokkaido,
HRO)
Sedimentary and geochemical records of possible large floods
occurred in the Miocene northeastern margin of Paleo-Japan
Sea
S3-9
Takeshi INOUE (Hokkaido University), Noriyuki SUZUKI,
Hitoshi HASEGAWA, Hiroyuki SAITO
Fractionation and deposition of terrestrial biomarkers in the
middle Eocene fluvial environment, Hokkaido, Japan
S3-10
U.de S. Jayawardena (University of Peradeniya)
Geological changes around Sri Lanka during Quaternary period
S3-11
Akinori KARASUDA (University of Tokyo), Ryuji TADA,
ZHENG Hongbo, Yuko ISOZAKI, Shin TOYODA, Hitoshi
HASEGAWA, Tomohiro YOSHIDA, Naomi SUGIURA
Changes in the source areas of the river sediments in the
southwestern margin of the Tarim Basin during the last 8 m.y.:
Comparison between Aertashi and Yecheng sections
S3-12
WEI Xiaochun(Nanjing Unv.), ZHENG Hongbo(Nanjing Unv.),
LI Ling(Nanjing Unv.), HE Mengying (Tongji Unv.)
Detrital zircon U-Pb ages and provenance study of Cretaceous
sediments near Nanjing
S3-13
Tian Xin (Chendu University of Technology)，Xiang Fang
Provenance of magenetites in Quaternary Sediments in
Yichang Area and Its Significance to Formation of
7
YangtzeThree Gorges
S3-14
XIANG Fang (Chendu University of Technology), TIAN Xin, LI
ZhiHong and LU Lai
LA-ICP-MS U-Pb geochronology of zircons in the Quaternary
sediments from the Yichang area of Hubei Province and its
provenance significance
S3-15
Hideto NAKAMURA (Hokkaido Univ), Ken SAWADA, Reishi
TAKASHIMA
Terrestrial biomarker analysis and its significance for the
reconstruction of paleovegetation and paleoclimate in the
Cretaceous Yezo Group, Hokkaido, Japan
S3-16
Lalan P. Singh
Evolution of Pennar River System of Peninsular India: A
review
Lunch
12:15-13:30
Poster session
13:30-15:00
Oral session 1 continue
15:00-15:30 David L. DETTMAN (University of Arizona), Xiaomin FANG
Keynote
S1-6
Quantifying monsoon intensity using stable isotopes in fluvial
and terrestrial biogenic carbonates
15:30-15:50 Mengying He (Nanjing University), Hongbo Zheng, Juntao
Jia
S1-7
Detrital Zircon U-Pb Ages of the Surface Sediments in the
Yangtze River Drainage and Their Implications for Provenance
15:50-16:10 Chao LUO (Nanjing University), Hongbo ZHENG, Weihua
WU, Cheng ZHU
S1-8
Sr-Nd Isotopic Tracing of Suspended Matter in the Lower
Reaches of the Yangtze River
16:10-16:30 U.de S. JAYAWARDENA (University of Peradeniya)
S1-9
Recognition of the head of submarine canyon at the base of
Mahaweli river delta, Sri Lanka
8
16:30-16:50
Coffee Break
Oral session 2: River system response to Asian monsoon
variability and its impact on marginal seas: terrestrial and
marine records (Seek for new potential drilling proposals)
16:50-17:10 Boo-Keun KHIM (Pusan National University), Ryuji TADA,
and Takuya ITAKI
S2-1
Composite depth profiles of cores KR07-04 PC5 and PC8 from
the Yamato Ridge in the East Sea/Japan Sea: preliminary
results and preparation for IODP Exp. 605
17:10-17:30 Noriyuki SUZUKI(Hokkaido University) and Toru KIKUCHI
S2-2
Higher plant D/H ratio and a possible fungal biomarker
showing ultra-humid climate in mid-latitude East Asian Pacific
rim during the Eocene
Reception
18:00-20:00
June 12 (Day 2)
Oral session 2: River system response to Asian monsoon
variability and its impact on marginal seas: terrestrial and
marine records (Seek for new potential drilling proposals)
continue
8:30-9:00 Min-Te CHEN (National Taiwan Ocean University), Yuan-Pin
Keynote
CHANG, Xiaopei LIN
S2-3
Dynamic responses of the East Asian monsoon and Kuroshio
over orbital to millennial timescales: East China Sea evidence
9:00-9:20
S2-4
9:20-9:40
S2-5
9:40-10:00
Takuya SAGAWA (Ehime University), Michinobu KUWAE,
Masao UCHIDA, Ken IKEHARA, Masafumi MURAYAMA, Kei
OKAMURA, Ryuji TADA
Millennial-scale surface water property change in the Japan
Sea during the Marine Isotope Stage 3
Bin ZHOU (Nanjing University), Hongbo ZHENG, David
TAYLOR, Yuehan LU
Vegetation variations since the LGM recorded by n-alkanes
from core MD05-2905, northern South China Sea
Vimal SINGH (University of Delhi) and Rahul DEVRANI
9
S2-6
Response of NW Himalayan rivers to the Late Pleistocene and
Holocene climate change
10:00-10:20
Coffee break
10:20-10:40 S. Masood AHMAD (National Geophysical Research Institute,
Hyderabad), Waseem RAZA, Tabish RAZA and G. SESEELA
S2-7
Influence of riverine fluxes on the chemical characteristics of
water masses and sediments in the Bay of Bengal
10:40-11:00 Shouye YANG (Tongji University), Quan WANG
S2-8
Deciphering the Holocene monsoon evolution in the
Changjiang drainage basin by using clay mineralogical and
geochemical compositions of the fluvial sediments
11:00-11:20 Junwu SHU (Nanjing Institute of Geology and Palaeontology,
Chinese Academy of Sciences; Kyoto Prefectural Uni.),
Weiming WANG, Leping JIANG Zhejiang
S2-9
Neolithic Cultures in Response to Monsoonal Environment in
the Lower Yangtze River, East China: a Palynological Case
Study
11:20-11:40 Ken IKEHARA (Geological Survey of Japan, AIST), Juichiro
Ashi, Kazuko USAMI, and Tomohisa IRINO
S1-19
Rapid and thick deposition of turbidite mud: A depositional
process and comparison with hemipelagic mud
11:40-12:00 Yoshimi KUBOTA (University of Tokyo), Katsunori KIMOTO,
Ryuji TADA, Uchida Masao UCHIDA
S2-11
Millennial-scale variations in East Asian summer monsoon in
the East China Sea during MIS 3 and the last deglaciation:
comparison with Chinese stalagmites' records
12:00-13:10
13:10-14:00
Lunch
Poster session
Oral session 3: Asian river–continental shelf systems linked
to the Cenozoic tectonic and climatic evolution (Seek for
new potential drilling proposals)
14:00-14:30 Ryuji TADA (University of Tokyo), Hongbo ZHENG, Yuko
Keynote
ISOZAKI, Naomi SUGIURA, Tomohiro YOSHIDA, Ke WANG,
and Akinori KARASUDA, Youbin SUN, Hitoshi HASEGAWA,
Wengang YANG, and Shin TOYODA
10
S3-1
Tectonic control on long term dust emission: a new view from
the Tarim Basin
14:30-14:50 Ping WANG (Nanjing University)
S3-2
Capture and Reversal of the Middle Yangtze River: New
evidence from DEM (Digital Elevation Model) analysis
14:50-15:10 Ken SAWADA (Hokkaido Univ.)
S3-3
Impact of terrestrial input on marine productivity in neritic area
of the Neogene paleo-Japan Sea
15:10-15:30 Hitoshi HASEGAWA (Hokkaido University), Hisao ANDO,
Takashi HASEGAWA, Toru OHTA, Masanobu YAMAMOTO,
Noriko HASEBE , Gang LI, Niiden ICHINNOROV
S3-4
Reconstructing the origin of rhythmical beddings in the
mid-Cretaceous lacustrine deposits in southeast Mongolia:
Implication for terrestrial humidity changes at the OAE interval
15:30-15:50
Coffee Break
16:00-16:50
Discussions
16:50-17:00
Closing
17:00-18:00 Co-leaders and LOC meeting
11
G-1: A Miocene Age Yangtze River: Evidence from Finger-printing
Sediments
Hongbo ZHENG1, Juntao JIA2, Mengying HE1, Ling LI1, Xiaochun WEI1, Yuliang
CHEN1, Ping WANG1
School of Earth Science and Engineering, Nanjing University, Nanjing 210093, China
The evolutionary history of the Yangtze River system has been the subject of
great interest and debate, because it bears great significance for understanding the
uplift history of the Tibetan Plateau and other regional tectonic and climatic evolution.
Key issues identified by previous researchers include: 1) timing of the capture of the
Jinsha Jiang (the upmost fragment of the Yangtze) at the First Bend; 2) timing of the
incision of the Three Gorges. A predominant view claimed that the Three Gorges
were not incised, and that the Jinsha Jiang did not drain to the east through the First
Bend until Pleistocene (e.g. Li, et al., 2001). Others proposed scenarios implying that
the formation of the Yangtze River system was completed by Miocene (Clark, et al.,
2004), even as early as Eocene (Richardson, et al., 2010).
Based on systematic finger-printing (such as mineralogy, geochemistry, isotope,
detrital zircon ages) of both surface sediments in the Yangtze River drainage, and
Cenozoic sediments preserved in the lower Yangtze basins, this study suggests that
the Yangtze River came into its present form in early Miocene.
1) Jianghan Basin, just downstream of the Three Gorges, begun rifting in the late
Cretaceous, and came into a stage of full development of graben-type basin during
Paleogene, with vast deposition of lacustrine and evaporitic sequences. Facies
analysis of Paleogene sediments does not show any major trunk streams with a
comparable size of the Yangtze River running through.
2) At the end of Paleogene, Jianghan Basin went through a period of adjustment,
being characterized with uplift, folding and erosion, and eventually turned into a
generally subsiding system (Dai, 1997). Neogene sediments overly unconformably
the Paleogene, and cap up the whole basin. Facies analysis indicates that Neogene
sediments are mainly of fluvial nature, being formed under the influence of large river
systems.
3) Fluvial sediments of early to mid Miocene age exposed near Nanjing indicate
that the lower reaches of the Yangtze River basin was prevailed by large river systems,
the provenance of which resembled to the modern Yangtze.
4) Provenance of the core sediments of Pliocene age from Yangtze Delta Basin
and Jianghan Basin also indicates that the river has been running through from the
upper to the lower reaches since early Pliocene.
In conclusion, the incision of the Three Gorges occurred most likely around
Oligocene/Miocene boundary, as part of the process of regional tectonic adjustment
during which basin development all over eastern China went through important
evolution from graben-type to general subsiding, and associated drainage networks
would also be adapted to a new tectonic regime.
12
G-2: Sediment source to sink transport in the Indus River system:
Effects of reworking and drainage capture on sand compositions
Peter CLIFT (University of Aberdeen), Liviu GIOSAN (Woods Hole Oceanographic
Institution), Andrew CARTER (Birkbeck-UCL, London), Anwar ALIZAI
(Geological Survey of Pakistan), Ali R. TABREZ (National Institute of
Oceanography, Pakistan) and Tom STEVENS (Royal Holloway London)
The Indus River has changed significantly in the last 50 ky under the influence of an
evolving monsoon climate. Periods of strong summer monsoon around 30 ka and
since 11 ka resulted in landsliding and damming in the upper catchment, buffering
large volumes of sediment, which were then suddenly released when the dam is
breached. The sediment stored is equivalent to >50% of the total sediment flux to the
ocean since 5 ka. Strong summer monsoons in the Early Holocene increased the
erosional flux to the ocean and focused mass wasting in the frontal ranges of the
Himalaya. Subsequent weakening of the monsoon has resulted in a renewed
dominance of sediment flux from the glaciated Karakoram along the main trunk Indus
stream. The flood plain was entirely accretionary prior to 10 ka, after which time the
proximal northern half of the flood plain began to be cannibalized as the rivers dug
channels, ~15 m deep and ~30–60 km across, sufficient to account of >80% of the
sediment flux to the ocean since 5 ka. Reworking has dominated the sediment flux
since ~8 ka. At the same time the river has experienced major headwater capture. The
Yamuna River, now flowing east into the Ganges was connected to the Indus, but was
lost between 50 and 10 ka. The huge number of zircon grains dated at ~1800 Ma by
U-Pb methods found in sands from the modern delta is inconsistent with the modern
discharge from the mountains, which is dominated by <300 Ma grains and suggests
both a long transport time for zircon grains in the river (>10 ky) and that the Yamuna,
which is rich in 1800 Ma grains, may be required to account for the sediment budget.
The Sutlej and Beas Rivers formerly flowed further apart and further to the southeast
compared to the present day. In doing so they brought water to the edge of the Thar
Desert in Cholistan. There, together with the Ghaggar-Hakra River, they provided
water to the Indus Valley, Harappan civilization. The subsequent rerouting of the
rivers to the north contributed to the collapse of the Harappan urban centres. Chemical
weathering increased in the flood plains of Cholistan after ~4.5 ka when the last
significant fluvial sediments were deposited. In contrast, clays in the delta indicate
reduced chemical weathering on a basin-wide scale after the mid Holocene, as the
summer monsoon weakened. Although the climate of the Indus basin is dominantly
arid flooding in the Indus Basin is now a serious geo-hazard. A high-resolution core
from the delta indicates correlation of strong monsoon periods and heavy sediment
discharge, with 4–5 major floods in ~200 years and one particularly large event over a
~100 year period. While the 2010 floods may be another such event their frequency
may increase in the context of a warming global climate.
13
S1-1: Transport behavior of particulate organic matter in the
Ishikari River system
Seiya NAGAO (Kanazawa Univ.), Takafumi ARAMAKI (NIES), Takayuki
TANAKA (JAEA), Osamu SEKI, Yu MIKAMI (Hokkaido Unv.), Masao UCHIDA,
Yasuyuki SHIBATA (NIES), and Masayoshi YAMAMOTO (Kanazawa Univ.)
Dynamics of bulk particulate organic carbon (POC) discharged from rivers is
important to understand the role of rivers in global biogeochemical cycles. The
discharge of POC from river watersheds is one of main sources to continental margins,
which are recognized as the dominant reservoir for organic carbon burial in marine
environment. However, last land-use change and river channelization have affected
discharge of suspended solids and nutrients. Climate changes have resulted in an
increase in particulate organic matter flux from terrestrial areas to the oceans due to
heavy rainfalls and changes in particulate organic matter characteristics. Therefore, it
is important to understand the origin, forms, and fate of POC in river systems.
A variety of geochemical approaches have been employed to define the
characteristics and transport behavior of organic matter, including C/N ratio, d13C and
lignin biomarker. Radiocarbon abundances are an additional indicator of terrestrial
sources because nuclear weapon testing injected large quantities of 14C into the
atmosphere. Therefore, simultaneous use of !14C and d13C values can serve as a
convenient tool for tracing and identifying the fate of bulk POM that is discharged
from rivers.
This study reports the variations in !14C and d13C values of POC at three
observation sites (Osamunai, Iwamizawa and Ishikari-Kako) from the upper to lower
Ishikari River, together with monitoring data in two major tributaries (Uryuu River
and Sorachi River) during spring to autumn in 2006. The Ishikari River system is
located in the central part of Hokkaido, Japan. It is 268 km long from the source to
mouth and a drainage basin of 14330 km2. The Ishikari River has two peaks of water
discharge at spring snowmelt and autumn rain events. Riverine suspended particles
were collected with a single-bowl continuous-flow centrifuge from the river waters
collected at five sites. The organic 14C measurements were performed by accelerator
mass spectrometry at the Aomori Research Center of Japan Atomic Energy Agency
(JAEA) and the National Institute for Environmental Studies (NIES).
Variations in !14C values of riverine POC are different from each station. In the
lower and middle Ishikari sites, the !14C values were –380 and –273 ‰ for the spring
snowmelt season, respectively and –227 ~ –131 ‰ and –181 ~ –130 ‰ for the normal
flow condition. The situation is similar with the tributaries. On the other hand, POC of
the upper site shows opposite variation trend. The POC had !14C of –124 ‰ and –154
~ –135 ‰ at the spring snowmelt and low water discharge, respectively. The variation
range of !14C value is in the order of the upper " middle < lower sites during spring to
autumn. Averaged values for !14C, d13C and C/N ratio are as follows: the upper site,
–25.4 ± 0.6‰, –120 ± 38‰ and 10.4 ± 2.3; the middle site, –26.4 ± 0.4‰, –188 ± 45‰
and 8.9 ± 1.0; the lower site, –27.5 ± 1.3‰, –235 ± 80‰ and 8.2 ± 1.9. The !14C and
d13C values decrease and C/N ratios increase at the flow direction. These results
suggest that the sources and supply processes of POC from watershed are different
from the upper, middle and lower Ishikari River.
14
S1-2: Sr isotopic characteristics in two small watersheds draining
typical silicate and carbonate rocks: implications for the studies on
seawater 87Sr/86Sr evolution
Weihua WU (Nanjing Univ.), Hongbo ZHENG (Nanjing Univ.), Jianhua CAO
(Institute of Karst Geology, Chinese Academy of Geological Sciences), Chao LUO
(Nanjing Univ.), Bin ZHOU (Nanjing Univ.)
We detailedly studied the geochemistry of two small watersheds draining typical
silicate and carbonate rocks (the Xishui River — a tributary of the Yangtze River; the
Guijiang River — a tributary of the Pearl River). The Xishui River flows across the
Dabie Proterozoic metamorphic zone which consists of abundant felsic gneisses,
leptynites, amphibolites and small amounts of mafic rocks, granites and marbles. The
Guijiang River catchment comprises largely Paleozoic carbonate rocks except
headwater catchments of it and its some tributaries which are covered with Paleozoic
granitoids. By analyzing major ion contents and 87Sr/86Sr ratios of river water and
rain/snow water, we discussed the Sr isotopic characteristics of the two rivers and
revealed the implication for the seawater Sr isotope evolution.
In the Xishui River, Sr concentration is from 1.30 to 3.17 µmol/l and 87Sr/86Sr
ranges from 0.708515 to 0.709305, which does not show the characteristics of low Sr
concentration and high 87Sr/86Sr ratio of typical silicate weathering. Previous studies
showed that rocks in the Dabie Mountains, even Precambrian high-grade
metamorphic rocks and Cenozoic granites, had low 87Sr/86Sr ratios. In comparison,
Precambrian high-grade metamorphic rocks exposed in the Himalaya also with an
intense tectonism had extremely high 87Sr/86Sr ratios. In this sense, while using the
increase of seawater 87Sr/86Sr ratios to index intensification of the continental silicate
weathering, differences of background 87Sr/86Sr ratios of silicate rocks in catchments
must be considered. Sr concentration in the Guijiang River is 0.124-1.60 µmol/l and
87
Sr/86Sr ratio is from 0.709849 to 0.724605, which also does not show the
characteristics of high Sr concentration and low 87Sr/86Sr ratio of typical carbonate
weathering. 87Sr/86Sr ratio in the main channel of the Guijiang River is
0.710558-0.715973 and has a trend of high in the headwaters, low in the middle
reaches and high in the lower reaches. The source area Maoershan Mountain consists
of Paleozoic-Cenozoic granites with very high 87Sr/86Sr ratios, which results in higher
87
Sr/86Sr ratios in the main channel of the Guijiang River than other rivers draining
typical carbonate rocks. That is, granites accounted for below 5 % of the drainage area
have very important influence on the Sr isotopic compositions of the Guijiang River.
Recent years, there were extensive controversies about the source of highly
radioactive Sr in the rivers draining the Himalaya: silicate rocks or carbonate rocks
which have high 87Sr/86Sr owing to the alteration of their Sr isotopic compositions
during metamorphism. It is significant to use the increase of seawater 87Sr/86Sr ratios
to indicate the enhanced continental silicate weathering. Our study shows that the
contributions of silicate and carbonate weathering to the seawater Sr isotope evolution
are complex. The silicate weathering may also generate low radioactive Sr, and trace
silicate rocks in the river catchments draining typical carbonate rocks may largely
raise the 87Sr/86Sr ratios in these rivers. Therefore, different background Sr isotopic
compositions of rocks in river catchments must be considered in future works.
15
0.73
Guijiang
R
87Sr/86Sr
0.725
0.72
0.715
0.71
0.705
0.1
1
10
1/Sr
Fig.1. Sr concentration inverses vs. 87Sr/86Sr ratios of the Guijiang River draining
largely carbonate rocks and Xishui River flowing on silicate rocks, which shows
opposite characteristics with the typical silicate and carbonate weathering
end-members.
16
S1-3: Impact of Climate Change on some key rivers : An Indian
scenario
Jayaraju. N*., Sundara Raja Reddy. B. C**
*Department of Geoinformatics,Yogi Vemana University, Kadapa – 516 003, India
**
Department of Geology, Sri Venkateswara University, Tirupati – 517 502, India
The warming of the global climate caused by green house effect can induce essential
changes in the river system at different time regimes over the world. The International
Panel on Climate Change (IPCC) estimates that the global average sea level will rise
between 0.6 and 2 feet (0.18 to 0.59 meters) in the next century The IPCC suggests
that by 2080, sea level rise could convert as much as 33 percent of the world’s coastal
wetlands to open water. Sea level is rising along most of the Indian coasts
http://www.epa.gov/climatechange/science/recentslc.html, and around the world. In
the last century, sea level rose 5 to 6 inches. Indian coastline stretches about 5700 kms
on the mainland and about 7500 kms including the two island territories and exhibits
most of the known geomorphological features of coastal zones. Observations suggest
that the sea level has risen at a rate of 2.5 mm year -1 along the Indian coastline since
1950s. A mean sea level rise of between 15 and 38 cm is projected by the mid- 21 st
century along India’s coast. Managing river basins has become intricate matter under
a changing climate across the globe. Demand for water has been steadily increasing in
the domestic, agricultural, industrial and power sectors. But the availability of water
has been phenomenally decreasing due to the climate abnormalities. India is one of
the countries highly vulnerable to the impact of climate change. Extremes like floods
and droughts have become common in the key river basins like Krisha River,
Godavari River, TungaBhadra River, Kaveri River etc. Water shortage in river basins
leads to socio-economic issues such as disputes over Tran boundary rivers, migration,
pricing of water, sets backs in tourism and loss of biodiversity. Large investments will
be required in adaptation and mitigation programs. Economic growth is likely to be
hampered. Results show that the water availability will be drastically reduced in
most of the river basins. Of late, India has developed a water policy and climate
policy. Several initiates have been planned and in the water sector such as the action
plans to protect rivers. Unfortunately, these policies and strategies are inefficient and
their implementation mechanism is rather weak. India urgently needs to develop an
appropriate strategies for river basin management and climate change adaptations.
This paper attempts to survey the impact of climate change on some important rivers
in south India with a special reference to the socio-economic growth.
17
S1-4: Development of a Reference-based Himalayan River Typology
for the HKH region
Subodh SHARMA1 and Otto MOOG2
1
Aquatic Ecology Centre, School of Science, Kathmandu University
2
University of Natural Resources & Applied Life Sciences (BOKU), Vienna, Austria
The longitudinal zonation approach and catchment based approach are two common
approaches in use for the classification of rivers worldwide. The regional (geographic
and physiographic) approach is comparatively a new approach extensively used these
days in regional classification of rivers. It is a trans-disciplinary way of River
Typology based on integrated geological, geographical, biological and hydrological
sciences. An attempt was made lately with support from European Commission
(Contract No. INCO-CT-2005-003659) to classify the streams in
Ganges-Brahmaputra and Indus System based on regional approach leading to the
development of a simple and operative classification system called as stream typology
for the Hindu-Kush Himalayan (HKH) Rivers. For developing assessment system, a
reference state criterion for streams was developed based on already existing system
in the partner countries (Bhutan, Bangladesh, Nepal, Pakistan, India). Based on our
study, the HKH region was divided into four different eco-regions and ten bio-regions
which serve as a basis for the development of a reference based Himalayan River
Typology for the HKH Region.
18
S1-5: Localized source and event driven feature of suspension
transport by small rapid river: Example from 2003 August event in
the Saru River, Hokkaido, Japan
Tomohisa IRINO (Hokkaido Unv.), Ken IKEHARA (Geological Survey of Japan,
AIST) and Seiya NAGAO (Kanazawa Univ.)
Supply of detrital material from river can affect the continuity, sedimentation rate,
and composition of marine sediments deposited in front of the river system, which is
controlled by the relief, weathering rate, and precipitation of the hinterland. In spite of
the small drainage area, the small rapid rivers in the island arc located under warm
humid climatic condition supply a huge amount of detrital materials to the
surrounding seas. In addition, sediment transports tend to be concentrated during
flooding events. In order to understand the depositional history and utilized it for
paleo-climate reconstruction, it is necessary to study a mechanism of suspension
generation and controlling factor of its composition.
We conducted a field survey during 2005 – 2007 in the Hidaka area in Hokkaido,
Japan, to evaluate the influence of the flooding mud to marine sediments, promoted
by the typhoon precipitation in August, 2003. We selected the Saru, Atsubetsu,
Niikappu, and Shizunai Rivers as our target, and conducted the river water sampling
and turbidity measurements at the river mouths and their branches. Water samples
were taken from the surface of flow center of each stream and stored in plastic bottles.
The collected water was filtered through Millipore® filter with 0.4 #m opening and
the suspended particles were collected and weighed in the laboratory. Major element
composition of the collected suspended materials on the filter was measured using an
energy dispersion spectrometry X-ray fluorescence analysis (EDS-XRF) with an
external calibration curve method.
Distribution of the turbidity in the Saru River drainage shows that high turbid
water is localized only to one branch called the Nukabira River and others are
relatively clear. The turbidity seems to be supplied only from one local source. Major
element compositions of the four targeted rivers (Saru, Atsubetsu, Niikappu, and
Shizunai) shows general trend that high Mg/Al is associated with low Ti/Al, K/Al,
and Ca/Al. This trend is interpreted as grain size variability because a mixture of
Mg-rich clay and silt grains consisting of K-Ca-rich feldspars and Ti-rich heavy
minerals can well explain such a compositional variation. The Nukabira River, branch
of the Saru River, only shows a relatively higher Mg/Al than general trend.
We also examined the major element composition of marine surface sediments
supplied as flood mud during the typhoon event in August, 2003 (Katayama et al.,
2007). Similar compositional trend such as low Mg/Al associated with low Ti/Al,
K/Al, and Ca/Al is also recognized for these marine sediments indicating their grain
size variability. However, Mg/Al level of the clay size end-member is similar to that
of the Nukabira River. These results suggest that the major part of marine sediments
off Hidaka region has not been supplied uniformly from wide drainage of this area but
supplied only from highly localized site on one branch (the Nukabira River).
Reference
Katayama, H., Ikehara, K., Suga, K., Sagayama T., Irino, T., TuZino, T., and Inoue, T.
(2007), Distribution of surface sediments after the 2003 flood on the shelf off
Hidaka, southern Hokkaido. Bull. Geol. Surv. Japan, 58, 189-199.
19
S1-6: Quantifying monsoon intensity using stable isotopes in fluvial
and terrestrial biogenic carbonates
David L. DETTMAN (University of Arizona), Xiaomin FANG (Chinese Academy of
Sciences)
Non-marine carbonates have been a target for the geochemical study of terrestrial
paleo-climate for decades. Recent work in this field has opened new lines of inquiry
focused on isotope paleo-hydrology and seasonal variability in the environment.
Attempting to quantify paleo-temperature in surface waters using the oxygen isotope
ratios of biogenic carbonates has proven very difficult due to two major uncertainties:
1) uncertainty surrounding the isotopic composition of the water in which the shell
was produced; and 2) the poor correlation between mean annual temperature and the
average !18O of local rainfall. By inverting the research question, however, it is
possible to use shell material to precisely quantify the isotopic composition of ancient
surface waters at both the multi-year and sub-annual level. An empirical comparison
of bulk unionid shell !18O and average growing-season river water !18O leads to a
linear correlation:
water !18OVSMOW = 1.10(shell !18OVPDB) – 0.92 (R2=0.983, n=27)
This relationship should be applicable in temperate seasonal climates across a broad
range of mean annual temperatures. Note that this relationship is limited to unionid
bivalves, which have a restricted range of growth temperature. The calculated water
!18O value is only valid for temperatures above ~12°C.
Although monsoon intensity is often discussed in terms of how much rainfall
takes place in the wet season, an equally valid measure is the aridity of the dry season.
The latter creates a strong oxygen isotope response in bodies of water (hydrologic or
biologic) that have residence times roughly equal to the wet-dry seasonal cycle. Some
bodies of water undergo significant seasonal change in response to the wet-dry
seasonal cycle, and have been used to demonstrate the presence of a strong monsoon.
However, many river systems in the monsoon environment do not undergo a large
cycle in oxygen isotope ratios because of the very short residence time of water in
active river systems or because of the very long residence time of groundwater
supported rivers.
Because of the uncertainty surrounding river water residence time in ancient
systems, we have turned to “biological bodies of water” that are independent of rivers
or lakes: land snails. Terrestrial mollusk shell shows a strong oxygen isotope response
to the monsoon dry season. A comparison of seasonal !18O cycles of unionid bivalves
or other fully aquatic mollusks with that of land-snails across a range of climates
demonstrates that the monsoon climate creates a unique and identifiable signature.
The monsoon alternation of arid and wet seasons creates a very large amplitude in the
!18O of shell grown across the seasons. In both monsoon climates and perennially
humid climates, the minimum !18O value in land snail shell is within the range of
!18O values from contemporary aquatic mollusk shells. The maximum value, however,
is very different. In humid climates (Texas, Japan, tropics) the maximum !18O value
is within 2‰ of the associated aquatic shell maximum. In contrast, shells from a
monsoon system (India, central China) have maxima that are offset by 7 to 9‰. The
magnitude of this offset is related to monsoon intensity. Land snails from deserts and
from Mediterranean climates may also have unique !18O ranges relative to nearby
aquatic mollusks.
20
S1-7: Detrital Zircon U-Pb Ages of the Surface Sediments in the
Yangtze River Drainage and Their Implications for Provenance
Mengying HE 1
Hongbo ZHENG 1
Juntao JIA 2
(1. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093;
2. School of Earth Science ＆ Technology, China University of Petroleum, Qingdao,
266555)
This paper systematically reports the detrital zircon age distribution of the sediments
along the modern Yangtze River and discusses its sedimentology and tectonic
implication. Twenty-five samples were selected from the upstream to downstream
along the Yangtze River and more than 2400 concordant zircon U-Pb ages were
obtained by LA-ICP-MS. The result shows that most zircon grains have a source of
igneous rocks according to their high Th/U ratios (above 0.3). Zircon age distributions
of all of the samples display three major peaks (200-300Ma, 750-850Ma and
1800-2000Ma), which represent Late Permian Emeishan Large Igneous Province,
Neoproterozoic Rodinia Continent break-up, and Paleo-proterozoic Columbia
Continent break-up respectively. 0-100Ma, 400-600Ma, and 2400-2500Ma are minor
peaks which might be related to other igneous events. Zircon age distributions also
show the provenance differences among the upstream, midstream and downstream of
Yangtze River. Cenozoic zircon grains existence is considered as the most unique
feature of the upstream which implies that the Tibet Plateau is one of the provenances
for the upstream. However, the percentage content of the Cenozoic zircons is quite
low (2%) comparing with the Yarlung Zangbo River (50%) which suggests that
orogenic belts round the Tibet Plateau plays a more important role in provenance of
the upstream. The unique feature of the midstream are Paleo-Proterozoic to
Meso-Proterozoic and Early Paleozoic peaks which suggest that the provenance
changes from the orogenic belts round the Tibet Plateau to Qinling-Dabie orogen and
Yangtze Craton. Finally, the zircon age distribution of the downstream displays a
similar multiple peak pattern with the whole drainage ， representing that the
downstream inherits all the sediment age signatures from the Yangtze River drainage.
Overall, the study on detrital zircon of the Yangtze River reveals regional thermal
events and gives a chance for understanding the provenance contributions.
21
S1-8: Temporal variations of silicate
consumption rates in the Yangzte River
weathering
and
CO2
Chao LUO, Hongbo ZHENG, Weihua WU, Cheng ZHU
Institute of Surficial Geochemistry, Nanjing University, Nanjing 210093, China
Silicate weathering is the only inorganic sink of atmospheric CO2 and regulates
the earth’s climate on geologic time scales. In order to understand the silicate
weathering processes and associated CO2 consumption, temporal variations in
chemical compositions of the dissolved load in the Yangtze River were measured
for the first time by analyzing biweekly samples collected over a period of about a
year (05/06/2010-04/11/2011) at the DaTong Hydrological monitoring Station.
Ca2+，Mg2+，HCO3- dominates the major ion compositions of the river waters.
Our results show that the concentrations of major ions dilute during monsoon period
compared with the non-monsoon period. However, the extent of dilution is less than
the magnitude of increase in water discharge because of the higher erosion rates
during monsoon period. Besides, Ca2++Mg2+ has a good correlation with HCO3-,
which implies that carbonate weathering dominates weathering reaction. What’s more,
the correlation coefficient between Ca2++Mg2+ and HCO3-+SO42- is better than that
between Ca2++Mg2+ and HCO3-, which may due to partly involved of sulfuric acid in
the weathering reaction.
Si/(K*+Na*) was used as an indicator of silicate weathering intensity. In this
research，the values of Si/(K*+Na*) are decreasing from monsoon to non-monsoon
period, indicating the decreasing of silicate weathering intensity during the same time.
Meanwhile, silicate weathering rate has the same trend as silicate weathering intensity.
The fraction of cation contributions from the silicates ranges from 5.25% to 13.9%
and fall to the lowest at 24th July, 2010. This may due to more contributions from
carbonate weathering. The fluxes of CO2 consumed by silicate weathering, vary from
108$109 mol/a in December to 460$109 mol/a in June, 2010, with higher
consumption rate in monsoon period. The average CO2 consumption fluxes by silicate
is estimated to be 218$109 mol/a, which is similar to the value reported by B. Chetelat
et al. (2008).
[1] Kump et al(2000) Annu. Rev. Earth Planet. Sci. 28, 611–67.
[2] Gaillardet et al(2008) Science 320, 1727-1728.
[3] Chetelat et al(2008) Geochimica et Cosmochimica Acta 72, 4254–4277
22
S1-9: Recognition of the head of submarine canyon at the base of
Mahaweli river delta, Sri Lanka
U.de S. JAYAWARDENA, Department of Civil Engineering, Faculty of Engineering,
University of Peradeniya, Peradeniya, Sri Lanka.
Sri Lanka is an Island of the Indian Ocean. The continental shelf around Sri Lanka is
narrower, shallower and has less surface relief than the average for the world. It is
believed that the origin of the continental slope around Sri Lanka is a rupture of
Gondwanaland and the northward drift of India and Sri Lanka together. The
continental shelf, continental slope and the coastal region around Sri Lanka have been
subjected to considerable changes since Pleistocene and one remarkable observation
is the occurrence of submarine canyons in eight places in western, southwestern and
eastern parts of the Island. The valleys across the continental slope are usually steep
walled cut in hard metamorphic rocks. The largest canyon has 1350 meters high walls
extending 60 km seaward and 3350 meters downward. The literature says that the
head of this largest canyon at Trincomalee is situated 200 meters from the shore, at
the outfall of the longest river in Sri Lanka, Mahaweli. The origin of the submarine
canyons in the continental slope of Sri Lanka is not very clear and there may be
various reasons. The major reason may be the erosion due to the fluctuation of sea
waves during glaciation and de-glaciation periods along the structurally weak planes
and fault planes. The objective of this paper is to highlight the extension of the canyon
structure by studying the recent geotechnical investigations around the Mahaweli
delta.
A number of boreholes were constructed for groundwater investigations around the
Mahaweli river floodplains and the other boreholes were constructed to determine the
depth to the bedrock for a bridge foundation at the river outfall. All overburden
materials are clay, silt and sand with little amount of gravels and organic sediments
like peat. Broken sea shells were observed at the deep subsurface sediments of river
outfalls. The depth to the bedrock at the river outfall is more than 75 meters and
decreases towards upstream. The shape of the bedrock below the thick fluvial
sediments in the studied area indicates the head of canyon should be marked more
than 30 kilometers from the shore towards inland. It is obvious that the submarine
canyon at Trincomalee is only a part of a very large canyon. The thick fluvial
sedimentary deposit over this canyon within the land is a result of erosion of bedrock
along a shear zone or fault and then the rise of sea level in recent times.
23
S1-10: Physical properties of quartz as indicators of provenance and
transportation of river sediments: Applications of electron spin
resonance,
thermoluminescence
and
optically
stimulated
luminescence
Shin TOYODA (Okayama Univ. of Science), Masashi TAKADA (Nara Women’s
Univ.), and Aiko SHIMADA (JEOL Ltd.)
The origins of sediments which form plains, plateaus, and hills would give
important information on the erosion processes, uprift of the mountains and so on,
then, which would indicate the environments at the time of sediment transportation.
Mineral compositions and isotopes have been use to investigate this issue. We
propose in this paper that the lattice defects in quartz are useful for these studies.
Parmagnetic defects in minerals are detected by electron spin resonance (ESR).
Based on the fact that these defects are created by natural radiation, ESR dating
method has been developed. Recently, it was found that the number of the oxygen
vacancies, measured as the E1’ center (an unpaired electron at an oxygen vacancy), in
quartz is a useful proxy of environmental change in East Asia, which indicates the
origin of aeolian dust. Thermoluminescence and optically stimulated luminescence
are also being used as dating methods, where the techniques detect the electrons
created by natural radiation and trapped at lattice defects. It was found that the color
of thremoluminescence of quartz indicates the rock type of original rock from which
quartz grains have been originated.
Sediment samples were taken from the 1400 m core from Lake Biwa between
300 and 600 m deep, provided by Prof. Takemura at Kyoto University. The samples
were sieved to grain size fractions of 250 to 500µm. Quartz grains were extracted by
chemicals, by heavy liquid, and by magnetic separation. The quartz samples were
heated at 400ºC for 1 h to erase the existent ESR signals. They were subsequently
irradiated by gamma rays up to 2500 Gy. ESR measurements were done for these
samples with respective radiation doses to detect the signals of the Al center (an
electronic hole trapped at the bond between
oxygen and Al which replaces Si), the
Ti-Li center (an electron trapped at Ti
which replaces Si, with accompanying Li
ion), and the Ge center (an electron trapped
at Ti which replaces Si, with
accompanying Li ion). The signal of the E1’
center were measured after heating the
sample at 300ºC for 15 minutes which
corresponds to the number of oxygen
vacancies. The slopes of the dose response,
possibly corresponding to the impurity
concentrations in quartz, were taken as the
efficiencies of signal formation for Al,
Ti-Li, and Ge centers. The values were
Fig. 1 Formation efficiencies of Al, Tiplotted as a function of depth of sampling Li,and Ge centers and number of oxygen
location in the core as shown in Fig. 1. The vacancies as a function of depth.
formation efficiencies of Al, Ti-Li, and Ge
centers correlate with one another while
the number of oxygen vacancies seems negatively correlated. These results would be
24
explained by two sources of sediments, one with higher Al, Ti, and Ge impurities and
lower oxygen vacancies and the other with lower Al, Ti, and Ge and higher oxygen
vacancies.
25
S1-11: Seasonal changes in lignin phenol compositions of suspended
particles in Hokkaido major rivers
Osamu SEKI1, Masato MIKAMI2, Seiya NAGAO3, Tomohisa IRINO2, Masanobu
YAMAMOTO2
1
Institute of Low Temperature Science, Hokkaido University
2
Earth and Environmental Science, Hokkaido University
3
Low Level Radioactivity Laboratory, Kanazawa University
Lignin phenol, a typical biomarker of vascular plants, are measured in suspended
particles collected at major rives in Hokkaido Island, northern Japan (Ishikari River,
Tokachi River, Teshio River, Saru River, Kushiro River and Bekanbeushi River) in
order to better understand source and delivery of riverine organic matter. In general,
results from all the rivers show large seasonal variation of lignin concentrations with
higher and lower in summer and winter, respectively. This suggests that an increase in
relative contribution of terrestrial organic matter in suspended particles in summer
time is a common characteristic of Hokkaido major catchments. Compositions of
lignin (S/V and C/V ratios) in Ishikari, Tokachi, Teshio and Saru Rivers also show
large seasonal variation, suggesting significant seasonal changes in source of
terrestrial organic matter. In contract, seasonal variation of S/V and C/V in wetland
rivers (Kushiro and Bekanbeushi Rivers) are smaller than other rivers with relatively
higher values. This suggests that riverine particulate organic matter in the wetland
river originates from peat deposit. Our study also shows that compositions of lignin
phenols generally consistent with vegetations in catchments. In addition to providing
information on contemporary processes, this study also provides a base for future
paleoclimatological work in coastal sediments.
26
S1-12: Initial Development of a Braided River System:
a Devastated Ignimbrite Plateau
Situated on
Kotaro KAMADA (Hirosaki University)
Caldera forming large-scale eruptions cause voluminous ash-fall and pyroclastic
flow deposits and they have a tremendous impact on the people in the vicinity.
Especially large volumes of pyroclastic flow deposits form low-relief landforms
called a pyroclastic flow plateaus or an ignimbrite plateaus around calderas.
After three large-scale eruptions of Towada Volcano which is located in the
northern part of the Northeast Honshu Arc, a gigantic crater lake was formed. A
tephra, which formed during the third eruption, is composed of ash-fall and
pyroclastic flow deposits, and is called Towada-Hachinohe Tephra (To-H). This
tephra is distributed thickly and widely. So a complete eruption episode during the
15Ka is recorded in this tephra and decoded as a lahar process from supra-ignimbrite
deposits.
Deep gully structures filled by debris flow and stream flow deposits with slump
block and wide channel structures filled by debris flow and stream flow deposits are
observed above the ignimbrite. These deposits are covered by hyper-concentrated
flow deposits (sheet flood deposits) and fluvial deposits, and they are characterized by
a braided river system. Braided river deposits are composed of large-scale channeled
pumiceous gravel beds in the early stages and small-scale channeled and
cross-stratified pumiceous gravel and sand in the later stages. These rithostratigraphic
changes of the supra-ignimbrite deposits indicate that the braided river system
occurred as a final event during a lahar process that occurred just after emplacement
of pyroclastic flow deposits. In an initial stage of the lahar process, conspicuous
erosion and slope failure have dominantly taken place and resedimentation of
pyroclastic flow deposits are common on the ignimbrite plateau. Later, the
resedimentaion provided low-relief topography in the lower reaches on the ignimbrite
plateau. This time series model will reveal the appearance of a braided river system
on the ignimbrite plateau.
27
S1-13: Implication for Provenance of Muscovite and the Component
of Light Minerals of the Yangzte and Tributaries
Yuliang CHEN (Nanjing University, School of Earth Sciences and Engineering,
China), Hongbo ZHENG (Nanjing University, School of Earth Sciences and
Engineering, China), Mengying HE (Nanjing University, School of Earth Sciences
and Engineering, China)
The big river systems draining the Tibetan Plateau are the major transfer of
terrigenous masses to the ocean, playing significant roles in global geochemical
cycles. As the Yangzte is the largest river originating from the Tibetan Plateau
entering the East China Sea with great amount of water discharge, sediments and
associated chemicals, recognition of the changes of the Yangtze River deposition area
and discussing the process of sediments from “source to sink” transport pattern has
great significance.
Our study utilizes the XRD and EPMA analyzing method to process the common
minerals and especially the Muscovite in the sediments samples, which including its
main tributaries. Although muscovite is much less than quartz and feldspar in quantity,
it’s variable in mineral component and crystal texture which makes it an important
and sensitive indicator of provenance from different aspects.
By processing the XRD and EPMA data we find that:
1. The sediments mainly consist of quartz, plagioclase, orthoclase, muscovite,
dolomite, calcite, chlorite, hornblende and pyroxene. The quantity of quartz
gradually increases from upper reaches to lower reaches, coinciding with its
resistance to weathering and erosion. The dolomite in a high level in upper
reaches and resulting in high quantity in middle reaches indicates a great
contribution of upper reaches. And the relatively low quantity of hornblende and
pyroxene in Jialing Jiang, Wujiang and Dongting Lake having influence the
confluence sample composition suggests that these tributaries provides limited
masses.
2. In the Mg-(Fe+Mn)-(R3+Ti) Ternary Diagram, the Muscovites in the Yangzte
sediments mainly scatter in two regions: one is the relatively high Mg and Fe
muscovite (Mg:5%-15%; Fe+Mn:5%-15%) of which is the Jinsha Jiang muscovite
and Min Jiang muscovite, the other is low Mg muscovite (Mg:<5%; Fe+Mn<10%)
of which is the Dadu He muscovite and the lower reaches.
3. As the loess are widely distributed in the origin area of Jialing Jiang and
sedimentary rock are broadly distributed in its lower reaches, the scatters in the
diagram cover a large span.
4. Especially, the Xiang Jiang muscovite covers a special area (Mg: ~5%;
Fe+Mn10%-20%) and the Mn atomicity of muscovite composition is 10 times
larger than others resulting from the manganese ore nearby.
5. Different scatters coverage between the tributaries and confluence indicates that
Lower reaches including Yuan Jiang, Xiang Jiang and Gan Jiang don’t make
prominent contributions in provenance due to the precipitating action of Dongting
Lake and Poyang Lake. The relatively high Mg-Fe muscovite found in all samples
along the Yangzte indicates the upper reaches like Jinsha Jiang contribute the
main materials.
In conclusion, the upper reaches provide main materials into the Yangzte than the
lower ones as Dongting Lake and Poyang Lake as a precipitating pool. And we can
tell the Muscovite from which tributary according to the Ternary Diagram scatters.
28
References:
[1] Yang Shouye. Advances in sedimentary geochemistry and tracing applications of
Asian rivers [J].Advances In Earth Science, 2006,21(6):648-655
[2] Jia J T, Zheng H B, Huang X T, et al. Detrital zircon U-Pb ages of late Cenozoic
sediments from the Yangtze delta: Implication for the evolution of theYangtze
River. Chinese Sci Bull, 2010, 55
[3] SUN Tao, CHEN Peirong, ZHOU Xinmin, et al. Strong Peraluminous Granites in
East Nanling Mountains, China: Study on Muscovites [J].GEOLOGICAL
REVIEW, 2002,48(5):518-525
[4] DENG Miao, WANG Ling, LIN Jinhui. Characteristics Of Micro-Crystal
Muscovite In West Sichuan, China: An X-Ray Powder Differaction Analysis [J].
ACI'A MINERALOGICA SINICA, 2006, 26(2):131-136
[5] SONG Gongbao, PENG Tongjiang, LIU Fusheng, et al. Mineralogical
Characteristics of Main Muscovites in China [J]. Acta Mineralogica Sinica. 2005,
25(2):123-130
29
S1-14: The influence of the Ganges, Brahmaputra and Meghna
Rivers on regional and global carbon cycle
Takuya MANAKA, Hiroyuki USHIE, Daisuke ARAOKA (Univ. of Tokyo), Atsushi
SUZUKI (Geological Survey of Japan, AIST), H. M. Zakir HOSSAIN (Jessore
Science and Technology Univ.), and Hodaka KAWAHATA (Univ. of Tokyo)
In the perspective of global biogeochemical cycles, continental rivers are an important
path transporting vast amounts of solids and solutes from land to ocean. The
composition of river water is largely controlled by chemical reactions with minerals
(chemical weathering) and chemical reactions of nutrients via biological activities in
the river (photosynthesis). These reactions are likely to have great impacts on carbon
cycle in terrestrial water. In this study, we focused on the possible relationship
between carbon cycle, chemical weathering, and photosynthesis in continental rivers
water. We investigated three continental rivers in Bangladesh: the Ganges,
Brahmaputra River, and Meghna River. The sampling survey was conducted on 9-20
January 2011 (dry season). We took 12 samples from the surface of the rivers (Fig.1).
We measured water temperature, pH, and total alkalinity and calculated pCO2 from
pH and total alkalinity. All river water samples in this study showed higher pH,
ranging between 7.3-8.6 (Fig.2). The values of total alkalinity varied between
800-3,000 µmol/kg, which indicate active and varying chemical weathering.
Calculated pCO2 values were above 550 ppm, higher than atmospheric pCO2 (380
ppm). The river water is a source of pCO2 to the atmosphere. The values of total
alkalinity and pH were smallest in Meghna River, followed by those of Brahmaputra
River, and the Ganges. This may reflect the difference of soil distribution in
watersheds and also the slope of the river, which has an inverse relationship to
duration of contact between river water and soils. In all rivers in this study, pH in
river water showed an increasing trend along river flow. On the contrary the values of
total alkalinity and pCO2 were lower in lower streams. These rivers have abundant
tributaries, which make the river water in lower stream diluted. In addition, river
water in dry season flows slowly. This may make it possible for phytoplankton in the
river to photosynthesize and utilize CO2 in the river during the river flowing down.
In the continental rivers, chemical weathering and photosynthesis both had significant
impacts on riverine carbon cycle. We are going to analyze other compositions of the
water and also revisit these rivers in rainy season to investigate the seasonality in
carbon cycle in these large rivers.
30
Fig. 1 Location of the Ganges, Brahmaputra River, and Meghna River.
Fig. 2 Variations of pCO2 relative to pH.
31
S1-15: Stable isotopes of surface water on permafrost in Eastern
Siberia
Shinya TAKANO (Hokkaido Univ.), Go IWAHANA (Hokkaido Univ.), Trofim
MAXIMOV (Institute for Biological Problems of Cryolithozone, SBRAS, Yakutsk,
Russia), Atsuko SUGIMOTO (Hokkaido Univ.)
Isotopic composition of water is powerful tool for investigation of hydrological
processes. We conducted the observations on the isotopic compositions of surface
water at two regions, near Yakutsk and Chokurdakh, Russia, in Eastern Siberia, to
investigate the characteristics of water cycles in each region.
Eastern Siberia is covered by permafrost, which is the largest and the deepest in
the world, and permafrost plays an important role for hydrologic cycles in the area.
Degradation of permafrost system, therefore, may have a great impact on the
hydrologic regime, consequently, on the material cycling including greenhouse gas
emission, through vegetation changes. Lena and Indigirka rivers, soil moisture and
permafrost ice, and ground water at Yakutsk city were sampled, in order to know the
hydrological processes and identify specific characteristics of rivers in both areas.
Lena river water and groundwater (well water) showed the same variation during
the period from 2003-2005, whereas they showed the different trend in 2006 and 2007.
This may have been caused by heavy rainfall in the summer of 2006. This means that
runoff from this occurred during winter after heavy rainfall, although runoff from this
area is usually not significant because of dry climate and permafrost condition.
Chokurdakh is a boundary area between taiga and tundra. Surface water and ice in
hallow layer of permafrost showed evaporative isotope signature depending on the
surface vegetation. Indigirka river basin locates in higher latitude than Lena river
basin, and vast area in middle and lower basin is lowland and surface water there may
have higher possibility for evaporation. Due to this geographical feature, Indigirka
river water showed lower %D and %&!O and more evaporative isotope signature than
Lena river water.
32
S1-16: Observation on water isotopic compositions for Hokkaido
water isotope map and its application
Yuta TSUZUKI (Hokkaido Univ.) and Atsuko SUGIMOTO (Hokkaido Univ.)
Stable isotope ratios of water can be used as tracer and powerful tool for
investigation of water cycle (i.e. source of water vapor, process of precipitation,
resource of river water and ground water and route of flow). We are planning to make
Hokkaido water isotope map that contributes for better understanding of water cycle.
We observed stable isotopes of precipitation, river water and ground water in 4
regions in Hokkaido (Sapporo, Tomakomai, Teshio and Memuro) to know the
temporal variations which are essential to complete Hokkaido water isotope map.
In Tomakomai, we also observed isotope ratios of soil water to investigate the
mechanism to form run off water to a stream in a small catchment. In the basin of
Teshio river, tributaries including many small catchment, water samples were taken
for isotope analysis. Isotope ratios of river water at Tomakomai showed no change
and %D and %18O were similar to those of Shikotsu lake water. This result suggests
that river water originates aquifer which connects to Shikotsu lake.
Precipitation sampled every week at 4 sites in Hokkaido showed seasonal variation
with amount effect and temperature effect and d-excess of precipitation was high in
winter, while seasonal variations in %D and %18O of river water were not so clear.
However, d-excess of river water showed clear seasonal variation as well as that of
precipitation with a time lag of 2 or 3 months behind.
The %D and %18O values of main stream of Teshio river increased downstream. This
was caused by inflow from tributaries of which %D and %18O were higher than those in
main stream.
The %D - %18O plots of precipitation, river water and ground water, sampled in each
region showed characteristic distribution on the plot, reflecting the precipitation
process in each region.
33
S1-17: Provenance of surface sediments to the west of Okinawa
Island based on mineral assemblage
Keita SAITO, Ryuji TADA (Univ. of Tokyo), Takuya ITAKI (AIST)
A large amount of clastic particles are carried into the East China Sea. Their
provenance is various, such as Changjiang (Yangtze), Huanghe (Yellow), Taiwan
Island, Okinawa islands and inland deserts. Since the relative contribution of each
sediment sources can be affected by changes in river discharges, ocean currents and
intensity of wind, changes in provenance of marine clastic sediments should have
recorded temporal changes in paleo-environment in the surrounding areas. Therefore,
by analyzing the terrigenous component of sediment core samples from the East
China Sea, we can reconstruct the past changes in environment around the East China
Sea. To interpret the temporal variations in grain size and mineral assemblage of the
sediments from marine cores, it is necessary to know the sources and processes of
present particle transport in the East China Sea. Thus, the objectives of this study are
to determine the provenance of surface sediments collected from the central part of
the East China Sea to the west of Okinawa Islands and to explore what kind of
paleo-environmental information the core samples preserve.
Six selected surface sediment samples from the East China Sea to the west of
Okinawa Islands, twenty-four subsamples taken from a gravity core (GH10-2008),
and four riverbed sediment samples from the main Okinawa Islands were used in this
study. The surface sediments and the gravity core GH10-2008 were recovered from
the east part of Okinawa trough to the upper slope area to the west of the main
Okinawa Islands during GH10 cruise. Riverbed sediments were collected from the
mouths of major rivers draining to the west side of the main Okinawa Island. All the
samples were decalcifed with acetic acid, then treated with hydrogen peroxide to
remove organic matter, and fractionated the fine fraction (smaller than 16 micro
meter), the medium fraction (16-63 micro meter) and the coarse fraction (larger than
63 micrometer) using 63 micrometer sieve and the settling method exploiting Stoke’s
Law. After fractionated, samples were dried in an oven at 60C and weights were
measured. In order to investigate the spatial and temporal variations in mineral
composition, the sediments were analyzed by X-ray diffraction (XRD).
In the coarse fraction of the surface and riverbed samples, the ratio of plagioclase
and quartz (plg/Qtz) varies significantly in space, and the coarse fraction of surface
sediments can be classified into three groups based on the ratio. Since clastic particles
of this size are thought to be transported by saltation and bottom traction, their source
areas are expected to be closer from the sampling sites. So we compared mineral
compositions of the coarse fraction with the geology of Okinawa Island and the
surrounding area. The result supports our idea that the provenance of the coarse
fraction basically reflects local source(s).
In contrast, the fine fractions of the surface samples have more or less constant
ratios of plg/Qtz, which are close to the riverbed sediments derived from the
Kunigami Formation exposed mainly the northern part of the Okinawa Island.
The coarse fractions of the core sediment subsamples have nearly constant plg/Qtz
ratio, which is slightly lower than that of theKunigami Formation and characterized
by the presence of clay minerals that are not contained in the coarse fractions of the
surface sediments.
The fine fractions in subsamples of core sediments also have lower plg/Qtz ratio than
that of the Kunigami Formation, and the ratio of each clay minerals are constant and
close to that of the Kunigami Formation. On the other hand, quartz has weak
34
correlation with these minerals, while plagioclase has correlation with clay minerals.
So, it is estimated that these samples are composed of two different components. One
is rich in quartz and the other is rich in both plagioclase and clay minerals, resembling
to the mineral composition of the Kunigami Formation. The component rich in
quartz could represent eolian dust source although further study is necessary.
35
S1-18: Long distance transport of terrigenous materials from river to
deep-sea basin by hyperpycnal flows: An example from the 2003
Hokkaido Hidaka Flood
Ken IKEHARA (Geological Survey of Japan, AIST), Hajime KATAYAMA
(Geological Survey of Japan, AIST), Tsumoru SAGAYAMA (Geological Survey of
Hokkaido), Kazuya SUGA (Geological Survey of Hokkaido), Tomohisa IRINO
(Hokkaido Unv.), and Akiko OMURA (Atmosphere and Ocean Research Institute,
Univ. Tokyo)
Terrigenous material is an important component of marine sediments. Large
discharge of terrigenous materials to ocean is thought to have occurred at the flood
events. Although there are several researches on material transport from river to ocean,
mode and volume of transport might be controlled by climate, hinterland geology and
topography, river type and so on. Therefore, it is important to understand the mode of
transport and deposition in the particular regions. In August 2003, hard rain by a
typhoon occurred at a narrow area in Hidaka region, Hokkaido, Japan. Several
landslides occurred by the hard rain, and large amount of terrigenous sand and mud
supplied to ocean through rivers. Local government of Hokkaido investigated
nearshore areas after the flood, and reported 20-40 cm thick flood mud deposition at
offshore of river mouths. Our surveys in 2005 to 2007 indicated that the occurrence of
two types of mud deposition related to different inner shelf topography, which
controls mode of flood mud transport, especially on maintenance the energy (density)
of the flood flow from the river. At the flat inner shelves off Niikappu-gawa and
Shizunai-gawa rivers, flood mud might deposit near the river mouths due to rapid
decreasing of flow energy, and became increasing mud contents. On the contrary,
clear flood mud found only in the small and shallow depressions, which are the buried
incised valleys of the glacial Saru-gawa and Atsubetsu-gawa rivers. Carbon isotope of
sedimentary organic matters, C/N ratio, and content of freshwater diatoms indicated
that mud is flood origin. Upward-coarsening reversely graded structure was observed
in some sand layers intercalated in the flood mud, and well-sorted very fine sand with
low mud content and parallel to wavy lamination occurred below the flood mud.
Furthermore, 3D bedforms were observed in the depressions. These facts indicated
that hyperpycnal flows occurred in the depressions. Contour-normal mud distribution
was found in the outer shelf along the extension of the shallow depressions. Mud had
high carbon isotope and C/N ratio suggesting the terrigenous origin. Furthermore, a
thin and terrigeous mud rich event layer was recovered from the basin slope with the
water depth of around 600 m at further extension of outer shelf mud belt. These facts
indicated the long-distance transport of terrigenous materials by hyperpycnal flows
from river to deep-sea basin.
36
S1-19: Rapid and thick deposition of turbidite mud: A depositional
process and comparison with hemipelagic mud
Ken IKEHARA (Geological Survey of Japan, AIST), Juichiro Ashi (Atmosphere and
Ocean Research Institute, Univ. Tokyo), Kazuko USAMI (Geological Survey of
Japan, AIST), and Tomohisa IRINO (Hokkaido Unv.)
Earthquake is a triggering mechanism of submarine slope failure. Failure of
muddy submarine slope might form muddy turbidite or turbidite mud above turbidite
sand. Actually, a few meters thick turbidite mud was collected along Sumatra Trench
after the 2007 off Sumatra Earthquake, and 10 cm thick turbidite mud was reported by
the 1993 Hokkaido-nansei-oki Earthquake from the northeastern Japan Sea. These
event beds have higher sedimentation rate than normal hemipelagic mud. Therefore, it
is important to distinguish these event beds in the sediment sequences, and to
understand the depositional mechanisms for material cycles in marine environments.
In September 2004, the Kii-hanto-oki Earthquake with its magnitude of 7.4 was
occurred off Kumano. We conducted sea-floor observations and sediment samplings 2
weeks after the earthquake mainshock using ROV NSS of AORI, Univ. Tokyo. As the
results, the turbid deep-water was observed around the epicenter. Furthermore, in a
small slope basin near the epicenter, we found out very highly turbid bottom water. In
August 2010, we revisited the site, but the turbid deep- and bottom-water was
disappeared. Based on comparison of the repeated measurements of water depths
using ROV mounted pressure sensor and altimeter, thickness of highly turbid bottom
water was inferred as around 2.4 m. Surface mud failures by the earthquake made
surface mud resuspension. Mud was dispersed by bottom currents, and formed the
turbid deep water around the epicenter. Surface failures also generated turbidity
currents, which flowed downward along the slope. Large amount of suspended fine
particles flowed into the small slope basin by the turbidity currents, and formed highly
turbid bottom water, which might be under fluid mud condition. Thick turbidite mud
was recovered from the peripheral part of the small basin. The turbidite mud has
higher sedimentation rate than the underlaid hemipelagic mud, and showed better
sorting than the hemipelagic mud. Similar better-sorted character of turbidite mud
than hemipelagic mud was also found in off Sumatra slope basin and trench, and the
deepest part of Beppu Bay. Bathymetric depression may play an important role to
form a pond of highly turbid bottom water, and to keep the fluid mud condition, and
further to deposit the thick turbidite mud.
37
S1-20: Catchment environmental changes inferred from small
reservoir sediments in Noto Peninsula, Japan
Shinya OCHIAI (Kanazawa Univ.), Seiya NAGAO (Kanazawa Univ.),
Koyo YONEBAYASHI (Ishikawa Prefectural Univ.), Taijiro FUKUYAMA (Shinshu
Univ.), Masayoshi YAMAMOTO (Kanazawa Univ.), Koji NAKAMURA (Kanazawa
Univ.), and Kenji KASHIWAYA (Kanazawa Univ.)
This study aims to reveal the sedimentation records and the transport processes of
organic matter and sediment in the reservoir-catchment systems in Noto Peninsula,
Japan. This area confronts the catchment environmental changes (vegetation and land
use changes, etc.) related to change in human activities (population decrease and
ageing, etc.) expected to affect the material transport. Small reservoir-catchment
system is suitable for clarifying material transport processes and responses to the
natural and artificial environmental changes because of its sensitivity.
Study sites are two small reservoirs (Bishaguso-ike and Shin-ike) located in Noto
Peninsula in the central Japan. Surface sediment cores were collected from these
reservoirs using a HR type core sampler (Rigo, Japan) in October 2009. The lengths
of these cores were 26 cm and 31 cm, respectively. The contents of total organic
carbon (TOC) and total nitrogen (TN), carbon and nitrogen isotope ratios (d13C and
d15N), and physical properties (water content and grain size) were analyzed for 1 cm
interval. Vertical profiles of radionuclide (210Pb and 137Cs) were also measured to
estimate sedimentation rate and age of these cores.
In Bishaguso-ike, the inferred age of the core ranges around 40 years based on
the 210Pb dating method. It also suggests that sedimentation rate of the reservoir
decreased to 25 % of previous value in 1980s. The C/N ratio of reservoir sediment
decreased from 13 to 10 corresponding to the change in sedimentation rate. The d13C
and d15N and the grain size also decrease since 1980s. These changes in organic and
physical properties suggest that the inflow of organic matter and sediment from the
catchment decreased since 1980s. This result implies that environmental changes
which decrease sediment erosion and transport occurred in the Bishaguso-ike
catchment.
In Shin-ike, the C/N ratio is about 9 and it is smaller than that of Bishaguso-ike. It
implies that autochthonous source is more dominant. The d13C and d15N values range
from -28 to -34 ‰ and 0 to 2.5 ‰ with some fluctuations. The grain size also
fluctuates corresponding to these organic properties. These fluctuations found in C/N
ratio, carbon and nitrogen isotope ratios, and grain size of two reservoirs imply that
environmental change affecting sediment transport in the reservoir-catchment system.
38
S1-21 Erosion and sedimentation in the river basins of Kerala:
impact of climate change and anthropogenic activities
Shadananan NAIR (Nansen Environmental Research Centre –India)
Changing climate together with the human impact on the environment and leads to
erosion and sedimentation, creating water crisis and leading to water related social
issues even in heavy rainfall zones, such as Kerala State in the Peninsular part of India
adjoining to the Western Ghats Mountain. Encroachment, deforestation and plantation
agriculture in the Western Ghats Mountains where the rivers originate, sand quarrying
from riverbeds and watersheds, riverbank agriculture and unscientific construction of
dams release tremendous sediment load into the rivers. Forty one out of the forty three
rivers flow fast westwards to the Arabian Sea through steep slopes, carrying
tremendous sediment loads during monsoon season. Rainfall over Kerala is becoming
highly seasonal and intense. Deep convection produces convective clouds with large
raindrops that denude the hills where forests are already cleared. Seasonal floods and
droughts hit the region in almost every year. Sedimentation made some of the once
perennial rivers seasonal in the last few decades. This has affected the life of
thousands of poor fishermen and marginal farmers. Country boats, the cheapest way
of transportation of goods, which provided jobs to many poor became part of the
history. Water rich regions now starve for water in non-rainy months. Conflicts over
water allocation are worsening. Government is forced to divert money allotted for
other development projects to find alternate sources for water, its deliveries and
control of floods and droughts. With the current rate of erosion and sedimentation, six
major rivers may disappear in the next few years. The widening and deepening of
canals for inland navigation and the proposed highway may have severe consequences
in near future. Issues are likely to worsen with the increasing population through the
attempts for more food production and new settlements. Globalisation and associated
urbanization and encroachment into water bodies are the new threats. Promotion
tourism encourages more encroachment into the forests and river shores for the
construction of resorts. Possible changes in rainfall intensity and runoff associated
with global anomalies will have added effect on erosion. This paper is a
comprehensive study of the factors affecting erosion and sedimentation in the west
flowing rivers of Peninsular India under a changing climate and environment.
Hydrological conditions and sedimentation in selected rivers have been analysed.
Results warn an increasing stress on reliable water, if the current rate of erosion
continues. Suggestions for the control of erosion and efficient and sustainable
management of river basins have been provided, taking into consideration the
environmental, social, economic and political situations.
39
S2-1: Composite depth profiles of cores KR07-04 PC5 and PC8 from
the Yamato Ridge in the East Sea/Japan Sea: preliminary results and
preparation for IODP Exp. 605
Boo-Keun KHIM (Pusan National University), Ryuji TADA (University of Tokyo),
and Takuya ITAKI (Geological Survey of Japan, AIST)
A piston core 17.8-m long PC-05 (39o29.5’N, 134o26.5’E, 1,917 m WD) and
another piston core 9.4-m long PC-08 (39o29.4’N, 134o26.6’E, 1917 m)) were
collected from the same area on the Tsushima Ridge during the KR07-12 cruise in the
East Sea/Japan Sea. Because some intervals in the upper part of core PC-05 were
disturbed, core PC-08 was replaced to make up the complete section based on the
profiles of magnetic susceptibility and L* values, resulting in the achievement of a
composite core. A variety of geochemical properties (biogenic opal, CaCO3, and TOC)
were measured to obtain the composite depth profiles, which indicate the variations of
surface-water conditions. Age estimate of a composite core was conducted indirectly
to correlate L* values with a well-dated core MD01-2407, resulting in approximately
570 ka. Biogenic opal contents show a series of orbital cycles; high during the
interglacials and low during the glacials. Variations of TOC contents seem to follow
the changes of the lithologic properties such as L* values as well as the
glacial-interglacial cycles. However, CaCO3 contents show an abrupt increase up to
70% in the lower part of core. Based on the previous results from core 96EBP3 in the
South Korea Plateau, the major constituents of these CaCO3 are coccoliths derived
from calcareous nannoplankton. Thus, the high coccolith dump in the East Sea/Japan
Sea indicates that the present-day silica ocean was not permanent condition in the
past.
40
S2-2: Higher plant D/H ratio and a possible fungal biomarker
showing ultra-humid climate in mid-latitude East Asian Pacific rim
during the Eocene
Noriyuki SUZUKI and Toru KIKUCHI (Hokkaido Univ.)
Introduction
The Eocene non-marine sedimentary rocks rich in coal seams are well distributed
in mid-latitude East Asia. Many petroleum deposits with oil and gas derived from
these non-marine source rocks have been also found in this region. The extremely
high abundance of terrestrial organic matter in the mid-latitude East Asian continent
suggests that higher primary production and the efficient carbon burial took place on
and around land during the Eocene. The formation of organic-rich sediments is also
related to the long-term global carbon cycle and climate change through the carbon
sink on land. However, the evaluation of the primary production on land in the
geologic past is not necessarily easy. The primary production on land is principally
related to local hydrology and temperature, although it is a function of many factors.
The primary production on land, therefore, can be indirectly estimated by
reconstructing the paleo-hydrology and climatic temperature.
Paleo-hydrological elements such as precipitation, humidity, and evaporation,
have been estimated based on sedimentary lithofacies, occurrences of evaporite and
calcrete, and paleontological information from various types of fossils. Some
geochemical proxies for the paleo-hydrology such as oxygen isotope ratio of
authigenic oxide minerals and carbon isotope ratio and Mg/Ca ratio of carbonate
minerals have also been proposed. Compared to various proxies for climatic
temperature, the proxies for paleohydrological elements have not been well
established. The hydrogen isotope ratio (%D) of higher land plant biomarkers is
recently suggested to be a useful proxy for the hydrology on land. The %D of
long-chain n-alkane in mature sedimentary rocks still can be a useful and good
time-resolution proxy for the paleo-hydrology in the geologic past1). Sedimentary
biomarkers derived from mold or fungi can be another useful proxy for the
paleo-hydrology, since they grow in humid and warm places. Perylene, a pentacyclic
aromatic hydrocarbon, in sediments has long been considered to be formed through
diagenetic alteration of natural precursors under anaerobic conditions. Recent studies
on carbon isotope compositions of perylene in Paleogene sediments strongly suggest
the fungal origin of perylene2).
In order to understand the impact of primary production on land to the long-term
global carbon cycle and climate change, the change in paleohydrology and
paleohumidity on land during the Eocene is investigated based on %D of higher plant
wax and a possible fungal biomarker distribution in sediments from MITI Sanriku-oki
borehole drilled at off-Sanriku (the northwest Pacific off northeast Japan).
Samples and Methods
The samples, geological setting of MITI Sanriku-oki borehole, and detailed
experimental procedure have been described elsewhere1), 2). The geological age,
lithology, fossil assemblage, paleoevironmental record and extent of maturation of the
sediments from MITI Sanriku-oki have been extensively investigated. The cutting
samples from the borehole were analyzed for both fungal biomarker and %D of higher
plant wax (long chain n-alkanes).
41
Result and Discussion
Analytical result for the aromatic fractions of about 50 samples from the MITI
Sanriku-oki borehole shows the presence of perylene, a possible fungal biomarker, in
sediments of Late Cretaceous to Early Miocene age. The occurrence of perylene in the
samples is not maturity dependent. Its relative abundance varies with age, lithology,
depositional environment, and organic matter content. It is remarkably abundant in
sediments of Eocene age, suggesting moist and humid continental climatic
environment where fungi probably flourished.
The %D values of higher plant wax in the Eocene mudstones from the same
borehole are in the range from -220 to -200‰ being 30 to 50‰ depleted in deuterium
compared to those in other sediments in MITI Sanriku-oki. The hydrogen isotope
ratio of Eocene higher plant wax is remarkably lower than those of the present-day
higher plant wax in mid-latitude. All the samples from MITI Sanriku-oki are at the
maturity level before the main phase of oil generation as indicated by vitrinite
reflectance less than 0.6%. In this maturity level, hydrogen exchange between long
chain n-alkanes (higher plant wax) and porewater rich in deuterium does not proceed
significantly. The lower %D value of higher plant wax in Eocene sediments shows a
lower %D value of the environmental water, which is attributed to active precipitation
and inactive evaporation on land. The remarkably low %D values of higher plant wax
are consistent well with the abundant fungal biomarker, showing ultra-humid
continental climate in the mid latitude East Asian Pacific rim during the Eocene.
The vast alluvial plains, deltas, and huge lakes were formed during the Eocene
due to a lowering of global sea level, tectonic uplift/erosion, and active water
circulation. The remarkable vegetation induced by active precipitation accelerated the
evolution of herbaceous plants and the expansion of grasslands during the Eocene.
The formation of enormous amounts of oil shale indicates the higher algal production
in the lacustrine environment during the Eocene. The higher primary production and
carbon fixation on land resulted in the formation of huge amounts of coal, terrestrial
petroleum source rock, and oil shale. The increased carbon fixation on land during the
Eocene suggests a possible biological forcing to be the dominant mechanism of
geologically long-term global cooling during the Eocene.
References
1) Kikuchi, T., Suzuki, N., and Saito, H. (2010) Change of hydrogen stable isotope
ratios of n-alkanes, pristane, phytane, and aromatic hydrocarbons in Miocene
siliceous mudstones with increasing maturity. Org. Geochem. 41, 940-946.
2) Suzuki, N., Yessalina, S., and Kikuchi, T. (2010) Probable fungal origin of
perylene in Late Cretaceous to Paleogene terrestrial sedimentary rocks of
northeastern Japan as indicated from stable carbon isotopes. Org. Geochem. 41,
234-241.
42
S2-3: Dynamic responses of the East Asian monsoon and Kuroshio
over orbital to millennial timescales: East China Sea evidence
Min-Te CHEN (National Taiwan Ocean University), Yuan-Pin CHANG (National
Sun Yat-sen University), Xiaopei LIN (China Ocean University)
East Asian monsoon and the Kuroshio are two main ocean-climate components that
modulate East Asian and western Pacific climate. Both components are sensitive to
seasonal and latitudinal gradient changes in incoming solar insolation so they must
respond solar insolation changes induced by precession and obliquity cycles. On the
other hand, ice cores’ polar temperatures and greenhouse gases records present
persistent millennial-scale oscillations in global climate during the past million years.
Stalagmite oxygen isotope and marine sediment temperature records suggest the
reduction or shutdown of thermohaline Circulation (THC) in the North Atlantic
Ocean may induce the abrupt millennial-scale cooling in the northern hemisphere. It
is important to know whether the sea surface temperature is cooling or warming in the
Northwestern Pacific Ocean during the short-term northern hemisphere cooling event
since the strong western boundary warm current, the Kuroshio, advects heat to high
latitudes and competes with the atmospheric cooling. We will report a detailed study
conducting based on an IMAGES core MD012404 (retrieved from the East China
Sea) that foraminifer Mg/Ca SST, oxygen isotope, and biogenic, productivity-related
components have been measured with a high-precision AMS 14C control. Our results
imply (1) a time-varied orbital responses of monsoon and the Kuroshio; (2)
“Antarctic-like” and “Greenland-type” of timing of climate changes have existed in
the same record that suggests such two types of climate phasing relationship could
occur in a small spatial scale; and (3) a rapid ocean adjustment processes that link the
change of heat and salt fluxes in the Kuroshio is important in determining the timing
of NW Pacific climate. We will compare the paleoceanographic records to a
high-resolution GCM results, with particular focusing on the ocean response to North
Hemisphere cooling events during THC shutdown.
43
S2-4: Millennial-scale surface water property change in the Japan
Sea during the Marine Isotope Stage 3
Takuya SAGAWA, Michinobu KUWAE (Ehime Univ.), Masao UCHIDA (NIES),
Ken IKEHARA (GSJ, AIST), Masafumi MURAYAMA, Kei OKAMURA (Kochi
Univ.), Ryuji TADA (U. Tokyo)
The deep sea environment in the glacial Japan Sea was more sensitive to
surface climate change than today because of semi-closed situation due to sea-level
low stands. The hemipelagic sediments in the sea are characterized by alternations of
bioturbated, organic-poor light layers and finely laminated, organic-rich thin dark
layers during the Marine Isotope Stage (MIS) 3. Such sedimentological evidence
indicates drastic changes in bottom oxygen level during MIS3. Two possible
mechanisms for dark layer deposition are suggested, i.e. enhanced productivity due to
upwelling and weakened ventilation due to density stratification. These should be
quite different situations in terms of surface water density structure. However, there
are few surface water property records at this time.
Here we conducted %18O analyses of benthic and planktonic foraminifera and
Mg/Ca analyses of planktonic foraminifera for sediment core KR07-12 PC3, which is
taken from intermediate depth (329 m) of the southern Japan Sea. We first
reconstructed sea surface temperature (SST) and %18O of seawater (%18Osw) to reveal
variations of surface water property and its relationship with dark layer depositions.
The results clearly showed millennial-scale surface environmental change during the
MIS3. Variations of SST and %18Osw were positively correlated (r = 0.77). This
relationship can be considered as mixing of two distinct water mass of high SST,
%18Osw and low SST, %18Osw. Such variations are similar to surface water
environmental change in the East China Sea (ECS) deduced from planktonic
foraminiferal assemblage, indicating that the surface water property change in the
Japan Sea is related to change in the ECS.
As compared with brightness of core MD01-2407 from the Oki Ridge,
periods of warm and salty surface water correspond to dark layer depositions at the
deep seafloor. When we compute salinity variation using modern Salinity-%18Osw
relationship, 0.5‰ change in %18Osw is equivalent to 2.5 change of salinity unit. Such
a great salinity change probably induces collapse of upper water column density
stratification in warm intervals. Our results suggest that the enhanced productivity due
to strong vertical mixing generates low oxygen condition in the bottom water.
44
S2-5: Vegetation variations since the LGM recorded by n-alkanes
from core MD05-2905, northern South China Sea
Bin ZHOU,1* Hongbo ZHENG,1 David TAYLOR,2 Yuehan LU3
(1Institute of Surficial Geochemistry, School of earth science and engineering,
Nanjing University, Nanjing 210093, China; 2 School of Natural Sciences, Trinity
College, University of Dublin, Dublin 2, Ireland; 3 Department of Geological Sciences,
the University of Alabama, Tuscaloosa, AL 35487, USA)
Variations in stable C isotopic compositions of n-alkanes (%13Calk) and the ratios
between C31 and C27 n-alkane (C31/C27) from the same core provide evidence of
biological responses on adjacent land areas in the form of changes in terrestrial
vegetation and the provenance of the remains of land plants since the LGM.
Decreased values of the C31/C27 n-alkane and %13Calk over the last 28 ka mark the
transition from glacial to interglacial conditions and indicate a greater extent of
herbaceous vegetation at the LGM than present and an increased abundance in woody
vegetation during the Holocene. Reconstructed sea surface temperatures (SST), based
on U37K' data from core MD05-2905 (20°08.17'N, l17°21.6'E) in the northern South
China Sea (SCS), reveal temperatures ca. 3 °C lower than present at times during the
last glacial maximum (LGM), with abrupt variations both during LGM and the
Holocene. At the LGM, lower temperature and sea level and greater aridity relative to
present resulted in an expansion of herbaceous vegetation over an enlarged extent of
exposed continental shelf. Rapid fluctuations in C31/C27 ratio values occurred over
millennial scales, with lower values associated with cold stages. These low values
indicate increased input of woody plant material, possibly enhanced by reduced
barriers to transportation between the source and depositional sites. More positive
%13Calk values at the LGM indicate that organic matter in the sediment core was not
only from C3 plants (e.g. Artemisia) growing on proximate parts of the exposed
continental shelf, but also from sub-tropical C4 plants most likely located in
southeastern China and on Taiwan Island.
Keywords: northern South China Sea, LGM, n-alkanes, Carbon isotopic compositions,
Rapid vegetation and climate changes, C3 and C4 plants
45
S2-6: Response of NW Himalayan rivers to the Late Pleistocene and
Holocene climate change
Vimal SINGH and Rahul DEVRANI
Department of Geology, University of Delhi, Delhi - 110007
Studies of fluvial landforms in tectonically active areas have increased in last two
decades with main focus revolving around (i) understanding the coupling of tectonics
and climate, and (ii) understanding the river response pattern to the complex coupling.
These studies are important because response of rivers in the upstream segments have
strong control on the downstream parts, which needs to be understood in depth.
In spite of several studies investigating this issue, not enough data is available to
develop a model for entire length of any Himalayan river. Most of the studies carried
out on the river systems in the north-western Himalayan region are either local river
specific (e.g. Suresh et al., 2002, 2007; Singh et al., 2001) and discuss impact of
climate change at a stretch of few tens of kilometres, or tries to be regional by
discussing sparse data spread across a large river. Often these studies ignore the local
processes such as landslides, a major contributor of sediments in these areas (e.g. Ray
and Srivastava, 2010). Further, most of the previous studies are fraught with
negligence of different morphotectonic settings within the tectonically active areas
(e.g. Juyal et al., 2010; Ray and Srivastava, 2010). Hence, the models presented so far
for the north-western Himalayan rivers response to the past climatic shifts are
debatable.
This study classifies the NW Himalayan region in to various morphotectonic settings
and demonstrates variation in river response to climatic shift within similar
morphotectonic setting. Three large rivers of the NW Himalaya namely Ganga,
Yamuna, and Sutlej are chosen for this purpose and compared for their response to
climatic shifts. All these rivers before debouching in Indo-Gangetic plains flow
through the intermontane valley. In these intermontane valley, large rivers are joined
by their smaller tributaries originating from the hanging wall of the Main Boundary
thrust (in the case of Ganga and Yamuna rivers) and the Barsar Thrust (in the case of
Sutlej river). These small streams have deposited considerable amount of sediments in
the intermontane valley which allows us to study the impact of large rivers on their
tributaries during the climatic shifts.
Results of the present study shows that signals of incision at "11 ka i.e. during
Intensive Monsoon Precipitation (IMP), are strong in the case of Ganga and Yamuna
rivers where as the Sutlej River shows incision since LGM onwards but do not record
any change at IMP. This out of phase behavioural response is attributed to two
factors: (i) Dominance of glacier and snow melt fraction in the case of the Sutlej
River whereas Ganga and Yamuna rivers witness the monsoonal precipitation as the
main fraction, and (ii) stream power of the Sutlej River is relatively more than the
Ganga and Yamuna rivers. Another result shows that there is a time lag of ~ 5 ka in
responding to the LGM between a large river and its tributary.
It was concluded that in order to develop a model for entire river length, it is first
important to classify the entire river length in to different morphotectonic and climatic
setting, followed by analysis of each of these zones and then finally integrate all these
data to establish the connectivity and propose a single model for a river.
46
Acknowledgements: This work is benefited from discussions with Dr. Vikrant Jain.
References
Juyal N., Sundriyal Y., Rana N., Chaudhary S., and Singhvi AK., 2010. Late
Quaternary fluvial aggradation and incision in the monsoon-dominated Alaknanda
valley, Central Himalaya, Uttarakhand, India. Journal of Quaternary Science 25;
1293-1304.
Ray Y., and Srivastava P., 2010. Widespread aggradation in the mountainous
catchment of the Alaknanda-Ganga River System: timescales and implications to
Hinterland-foreland relationships. Quaternary Science Reviews 29; 2238-2260.
Singh A.K., Parkash B., Mohindra R., Thomas J.V., and Singhvi A.K., 2001.
Quaternary alluvial fan sedimentation in the Dehradun valley piggyback basin, NW
Himalaya: tectonic and palaeoclimatic implications. Basin Research 13; 449-471.
Suresh N., Bagati T.N., Thakur V.C., Kumar R., and Sangode S.J., 2002. Optically
stimulated luminescence dating of alluvial fan deposits of Pinjaur Dun, NW Sub
Himalaya. Current Science 82; 1267-1274.
Suresh N., Bagati T.N., Kumar R., and Thakur V.C., 2007. Evolution of Quaternary
alluvial fans and terraces in the intramontane Pinjaur Dun, Sub-Himalaya, NW India:
interaction between tectonics and climate change. Sedimentology 54; 809-833.
47
S2-7: Influence of riverine fluxes on the chemical characteristics of
water masses and sediments in the Bay of Bengal
S. Masood AHMAD, Waseem RAZA, Tabish RAZA and G. SESEELA
[National Geophysical Research Institute (CSIR), Hyderabad – 500 007, India]
River borne fluxes from the Himalaya and Indo Burman ranges are drained
into the Bay of Bengal and Andaman Sea through several major rivers. These fluxes
have significant influence on the chemical characteristics of water masses and
sediments. We present here new stable (C & O) and radiogenic (Sr & Nd) isotopic
records from deep sea sediment cores of the Bay of Bengal and Andaman Sea. These
cores show climate related changes in their stable and radiogenic isotopes of
terrigenous components and foraminifera fossil shells. High-resolution carbon and
oxygen isotopic compositions from planktonic foraminifera show significant
variations in !18O indicating large changes in the salinity and/or temperature regimes
during the last 60 ka. A marked depletion in !18O at ~7-6 ka of near surface dwelling
planktonic foraminifera (G. ruber) at 7-6 ka in two cores from the southern Bay of
Bengal indicates low salinity surface water probably due to the strengthening of
Indian monsoon. New data from sediment cores in the northern Bay of Bengal and
Andaman Sea also show evidence of enhanced monsoonal precipitation at 7-6 ka BP.
However, monsoonal precipitation reduced considerably at ~ 5-4 ka BP.
The deep water in the Bay of Bengal and Andaman Sea also experienced
substantial changes during the last 60 ka. Comparison of the benthic foraminiferal
!18O and !13C records of the Northeast Indian Ocean (NEIO) cores with that of
Pacific cores suggest a similar deep water evolution since the last glacial maximum
(LGM). The glacial deep water !13C in the NEIO decreased by 0.6-0.7 %o compared
to 0.3-0.4%o decrease in the intermediate depth water masses. Variations in the
distribution of !13C in the deep and intermediate-depth water masses are mainly
controlled by the deep ocean circulation changes. The !13C characteristics in deep
glacial NEIO suggest reduced North Atlantic Deep Water (NADW) input.
Consequently the contribution from southern Ocean deep water during LGM may
have increased resulting in low !13C. The !13C variations during the last deglaciation
appear to have been caused by the switch ‘on’ and ‘off ’ of NADW production.
There is a systematic pattern in strontium and neodymium isotopic
compositions in sediment cores from the NEIO. Pulses of low 87Sr/86Sr and higher
radiogenic Nd values are found at an interval of ~ 5-7 ka, indicating a teleconnection
with North Atlantic Climate change (Heinrich events). It appears that isotopic
compositions of terrigenous sediments in the NEIO are controlled by the variations in
the source and pathways of sediments.
48
S2-8: Deciphering the Holocene monsoon evolution in the
Changjiang drainage basin by using clay mineralogical and
geochemical compositions of the fluvial sediments
Shouye YANG, Quan WANG
State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
The Changjiang (Yangtze River) is the largest river originated from the Tibetan
Plateau and plays an important role in marine sedimentation and biogeochemical
cycle in the East Asian marginal seas. The recognition of flux and fate of the
Changjiang-derived sediment into the East China Sea is of great significance for the
understanding of the global source-to-sink pattern of terrigenous materials into the sea
and the river-sea interactions during the late Quaternary. The Changjiang Delta as one
of the major sinks of the Changjiang-derived sediments provides important constraints
on paleoenvironmental changes and monsoon evolution in the drainage basin during
the Holocene.
Over the past decade, we have systematically investigated the tectono-climate
control on sediment production and transport in the Changjiang watershed and
delivery to the East China Sea at different temporal and spatial scales. Our work
suggests that the source rock compositions and chemical weathering intensities in the
drainage basin account for the compositional variations of the modern Changjiang
sediments. The signal of monsoon climate registered in the fine-grained fluvial
sediments can be clearly deciphered by clay mineralogy and specific geochemical
proxies. The elemental and Sr-Nd isotopic compositions and age spectrum of zircon
from the Changjiang sediments provide good constraints on sediment weathering and
recycling and evolution of weathered upper continental crust in the Yangtze Craton.
The clay mineralogy and sediment geochemistry of selected cores from the
Changjiang Delta revealed the changing provenances of fine-grained sediments and
monsoon evolution during the Holocene. Both the changing sources and sinks of the
Changjiang sediments at different time scales were recognized. It deserves more
attention to study the trapping efficiency and chemical weathering of the floodplain
and exposed continental shelf, and especially, more high-resolution core study and
reliable proxies are urgently needed to better constrain the sediment transport process.
Keywords: Changjiang River; geochemistry; delta; sediment; Holocene; monsoon
climate; paleoenvironment; clay mineral
Acknowledgement:
This work was supported by the National Natural Science Foundation of China (No.
41076018).
49
S2-9: Neolithic Cultures in Response to Monsoonal Environment in
the Lower Yangtze River, East China: a Palynological Case Study
Junwu SHU (Nanjing Institute of Geology and Palaeontology, Chinese Academy of
Sciences; Kyoto Prefectural Uni.), Weiming WANG(Nanjing Institute of Geology
and Palaeontology, Chinese Academy of Sciences), Leping JIANG
Zhejiang(Provincial Institute of Archaeology and Cultural Relics)
[Background] Yangtze River has long been regarded as the cradle of rice-based
cultures in China. The relationship between human and nature in the vulnerable
coastal plains has become an increasingly important issue in face of present global
warming.
[Aim] Our study aims to better understand early human adaptation to the dynamic
environment in the coastal Lower Yangtze.
[Result] we present a sedimentary pollen-phytolith-charcoal record from Kuahuqiao,
Zhejiang Province, to examine the relationship between humans and environment.
1) Lake phase (c.8250-7950 cal. BP), a mixed broadleaved evergreen and deciduous
forest, mainly consisting of Quercus (deciduous oak), Pinus (pine) and
Cyclobalanopsis (evergreen oak) developed at Kuahuqiao around 8300 cal. BP, It was
initially opened by the local hunters and foragers by means of fire since c.7950 cal.
BP.;
2) Culture phase (c.7950-7400 cal. BP), the disturbed forest in the lowlands
progressively
retreated
and
was
predominately
replaced
by
a
Poaceae(grass)-dominated vegetation pattern, suggesting increasingly intensified
human environmental management including rice cultivation since 7760 cal. BP. ;
3) Marine phase (post-7400 cal. BP), Kuahuqiao Culture ended in a marine
transgression since ca. 7400, suggesting cultural vulnerability to environment changes
(Fig.1).
[Acknowledgements] This research is co-funded by the Japan Society for the
Promotion of Science (No.P10102) and National Youth Science Foundation of China
(No.40901032).
50
S2-10: High-resolution paleoenvironmental and paleoclimatic record
of core MD06-3040 from East China Sea during the Holocene
Ke W()G (University of Tokyo, Graduate school of Science, Japan), Hongbo
ZHENG (Nanjing University, School of Earth Sciences and Engineering, China),
Ryuji TADA (University of Tokyo, Graduate school of Science, Japan), Yan ZHENG
(Institute of Geology and Geophysics, Chinese Academy of Science, China)
The river-dominated ocean margins play a significant role in global environment
system. One of the best examples is the epicontinental shelf of the East China Sea,
which receives a large amount of terrigenous material from two of the largest rivers in
the world, the Yangtze River and Yellow River. An elongated subaqueous mud wedge
extends from Yangtze River estuary southward off the Zhejiang and Fujian coasts [1].
It is referred to as the “mud belt deposit on the inner shelf of the East China Sea”.
Most of the sediments in the mud wedge come from the Yangtze River. The
southward flowing East China Sea Coastal Current, the northward flowing Taiwan
Warm Current, and the Kuroshio Current have played crucial roles in transporting and
trapping most of the Yangtze-derived material in the inner shelf, and that preventing
the sediments escape into the deep-sea.
IMAGES XIV 2006 Marco Polo II cruise recovered a high quality calypso
core (MD06-3040, 27.43.3663’N, 121.46.8822’E, water depth 47m, core length
19.36m) from the mud wedge. Based on high resolution AMS14C dating, the core
spans the time period from 10.6 ka to present. The grain-size compositions sensitive
to the sea-level change and sedimentary environment were taken by the analysis of
standard deviation and end-member modeling. The changes in fine population grain
size (<12µm), EM3/(EM1+EM3) (contribution of clay to fine silt fraction relative to
coarse silt fraction) and Fe/Ti ratio in the MD06-3040 core show good correlation
with 18O records of stalagmites from Dongge and Hengshan Cave in south China,
which is a measure of summer monsoon intensity[2][3] with larger fine population grain
size, lower Fe/Ti ratio, and smaller EM3 (clay to fine silt fraction) contribution and
larger EM1(coarse silt fraction) contribution. This suggest that EM3 relative to EM1
decreases, representing less fine Fe-rich minerals and detrital materials supplied from
Yangtze River be transported to ECS shelf during dry summer periods.
The East Asian Summer Monsoon and paleoclimate changes during the
Holocene are discussed with high resolution. Increases in fine population grain size,
EM3/(EM1+EM3) and Fe/Ti ratio coincide with weaker summer discharge events of
Yangtze River detected at 9.3, 8.3, 7.3, 6.0, 4.8, 3.3, 2.3, 0.7, and 0.4 ka, which also
agree well with weaker EASM precipitation events recorded in stalagmites and in
northern East China Sea [2][3][4]. This indicates that the supply of the detrital materials
to the inner shelf (MD06-3040) is strongly affected by summer monsoon intensity,
and grain size and chemical composition of MD06-3040 core have a high potential to
record EASM intensity changes during the Holocene with high resolution. The further
analyses of core sediments indicate that the Zhejiang-Fujian Coastal Current has
formed and kept stable since about 7 ka BP.
References
[1] J.P. Liu e tal, 2007. Flux and fate of Yangtze River sediment delivered to the East
China Sea. Geomorphology 85, 208–224.
[2] Carolyn A. Dykoski e tal, 2005. A high-resolution, absolute-dated Holocene and
deglacial Asian monsoon record from Dongge Cave, China. Earth and Planetary
Science Letters 233, 71– 86.
[3] C.Y. Hu e tal, 2008.Quantification of Holocene Asian monsoon rainfall from
51
spatially separated cave records, Earth Planet.Sci. Lett., 266, 221–232.
doi:10.1016/j.epsl.2008.10.015.
[4] Yoshimi Kubota e tal, 2010. Variations of East Asian summer monsoon since the
last deglaciation based on Mg/Ca and oxygen isotope of planktic foraminifera in the
northern
East
China
Sea.
Paleoceanography.
25,
4205-4220.
doi:10.1029/2009PA001891
52
S2-11: Millennial-scale variations in East Asian summer monsoon in
the East China Sea during MIS 3 and the last deglaciation:
comparison with Chinese stalagmites' records
Yoshimi KUBOTA (University of Tokyo), Katsunori KIMOTO (Japan Agency for
Marine-Earth Science and Technology), Ryuji TADA (University of Tokyo), Uchida
Masao UCHIDA (National Institute for Environmental Studies)
Oxygen isotope composition [%18O] of Chinese stalagmites has been regarded as an
useful proxy for reconstructing summer monsoonal precipitation. However,
interpretation of stalagmites’ %18O is complicated and controversial. Stalagmites’ %18O
is affected by not only summer precipitation but also ratio of summer/winter
precipitation, moisture trajectory, and moisture source. Thus, it is important to
evaluate if stalagmite’ %18O has reflected summer regional precipitation or not by
comparing with other precipitation proxy records, such as marine sea surface salinity
[SSS] records. Based on this motivation, we tried to reconstruct summer regional
precipitation in south China through evaluation of Yangtze River discharge effect on
the SSS in the northern East China Sea [ECS] in this study. Today, interannual
variability of SSS in the northern ECS is influenced strongly by the discharge of the
Yangtze River. Thus variation in %18O of seawater [%18Osw] in the northern ECS,
which is a function of SSS, reflects variation in the summer rainfall over the Yangtze
River catchment.
We reconstructed Mg/Ca-based sea surface temperature [SST] and %18Osw using
planktic foraminifera, Globigerinoides ruber, in core KR07-12-01 recovered from the
northern ECS to investigate variations in the summer regional precipitation in south
China during MIS 3. An age model of core KR07-12-01 was constructed based on 14C
dating and ash layer Aira-Tanzawa (29 ka), revealing that the core reached 42 ka.
From Mg/Ca-SST records, lower SST events are observed at 39-40, ~33, and ~29 ka,
which seem to coincide with D-O stadials #9, #6, and #5, respectively, suggesting
teleconnection between high-latitude North Atlantic and EASM regions. Heavier
shifts of %18Osw are observed at ~39 and ~30 ka, which seems to coincide with
Heinrich events #4 [H4] and #3 [H3], respectively, and maxima of stalagmites' %18O
in south China. In addition, our previous study revealed heavier shift in %18Osw in
association with Heinrich event #1 [H1]. Thus, our records are consistent with the
previous stalagmites’ study that variations in EASM precipitation in south China
decreased synchronously with millennial-scale cooling events in north Atlantic during
MIS 3. On the other hand, during the deglaciation, the reconstructed %18Osw in the
northern ECS did not change significantly in association with Younger Dryas [YD]
event. This is in contrast with stalagmites’ %18O records from eastern China, which
show a significant increase in association with YD. Other terrestrial records, such as
total organic carbon in lakes and magnetic susceptibility in loess, suggest that summer
precipitation did not change significantly during YD, which are more consistent with
our record. Thus, this discrepancy suggests that stalagmites’ %18O during the
deglaciation may have been controlled by the factors other than summer precipitation,
such as the ratio of summer/winter precipitation, moisture trajectory, and moisture
source. Consequently, stalagmites’ %18O should be interpreted carefully.
Previous studies (Nakagawa et al., 2006 and references therein) suggest that
summer monsoon front reached as north as Loess Plateau, northern China during
Bølling–Allerød [BA] period but it shifted slightly southward during the YD. Further,
they suggested that such shift in the limit of monsoon front more influenced on
53
precipitation in the area close to the monsoon front, but did not cause significant
change in precipitation in the area further south from the front. The results of this
study suggest that the summer precipitation did not change in south China in
association with YD because the monsoon front penetrated deeper to the north, but
decreased in association with H4, H3, and H1 because monsoon front during
interstadials stayed over south China. The cause of such changes in monsoon front
position between the glacial and deglacial condition needs further research.
54
S2-12: Computer Tomography - its applicability for estimating
depositional orientation and internal structures of coastal sediment
bodies
Jae Hwa JIN, Jun Ho KIM, and Min Jun KIM
Korea Institute of Geoscience and Mineral Resources
Corresponding author: [email protected]
X-ray computer tomography (CT) is a good tool to examine depositional processes of
coastal sediment bodies. When using a 160 to 225 kV X-ray tube, a sediment core, up
to 10 cm in diameter and encased within a PVC or even an aluminum pipe is
sufficiently penetrated, irrespective of its lithologic composition. When we use a
sufficiently large detector allowing us a flexible adjustment of geometrical
magnification, the CT has no problem to resolve grains smaller than very fine sand.
Throughout CT of sand cores from beach and shoreface, internal flat and cross
lamination and their boundaries are clearly distinctive. Mud cores from muddy coastal
environments are also well unveiled by the CT, thus complex biogenic traces and fine
physical structure in there are fully illustrated. The most pronounced merit of CT is its
capability to measure orientation of physical and biological sedimentary structures
within cores. In order to do that, we should mark orientation of cores immediately in
the field when we obtain those cores. The mark is necessary for giving a reference
orientation of cores while CT scanning is carried out in the laboratory. Throughout
these procedures, we ultimately get three-dimensional reconstruction of the overall
core features and any slice images to any known directions, thus we can successfully
measure depositional orientation of sedimentary structures within the cores.
55
S2-13: Branched glycerol dialkyl glycerol tetraethers
paleoclimate proxy: Application in Lake Biwa study
as
a
Taku AJIOKA, Masanobu YAMAMOTO, Tatsufumi OKINO (Hokkaido University),
Keiji TAEMURA (Kyoto University), Akira HAYASHIDA (Doshisha University)
MBT/CBT-index has been recently proposed based on distribution of branched
glycerol dialkyl glycerol tetraethers (GDGTs) derived from bacterial membrane lipids
as a paleotemperature proxy (Weijers et al., 2007, GCA). Weijers et al. (2007)
showed that the cyclyzation ratio of branched tetraethers (CBT) in soil samples
collected worldwide is correlated with soil pH, and the methylation index of branched
tetraethers (MBT) is correlated with both soil pH and mean annual air temperature
(MAAT). Branched GDGTs were subsequently detected from lake sediments, and the
MBT/CBT-index showed a different correlation with MAAT (Tierney et al., 2010,
GCA). These two calibration equations were empirically obtained, and the species of
bacteria that produce branched GDGTs and their ecology are not clear. In this study,
we analyzed branched GDGTs in soils from the watershed of Lake Biwa in central
Japan and created a calibration equation based on local soil dataset to estimate
paleo-soil pH and paleo-temperature. Branched GDGT distributions of lake sediments
were compared to those of soils to identify the source of branched GDGTs in lake
sediments. We further applied the MBT/CBT index to estimating paleotemperatures
during the last 50,000 years by analyzing core sediments retrieved from Lake Biwa.
Soil samples (0-30 cm deep at 5 cm intervals) at 25 sites in the watershed of Lake
Biwa taken in August/September 2009, and BIW07-6 sediment core (35°13’59’’N,
136°02’51’’E) taken in August 2007 were used for this study. Samples were
freeze-dried, soil samples were sieved by 2 mm mesh to remove gravels and roots and
stems of plants. Branched GDGTs were analyzed by HPLC/APCI-MS. The CBT
showed significant correlation with measured soil pH, and the MBT has correlation
with both pH and MAAT at the sampling sites. The dependency of CBT and MBT on
pH and MAAT in our sample set is however different from that in global set of soil
samples shown by Weijers et al. (2007). This difference suggests that some local
factor(s) is(are) crucial in the relationship between MBT/CBT and pH/MAAT. The
branched GDGT distributions of surface sediment in Lake Biwa were remarkably
different from those of soils in the watershed of the lake, which suggests that
branched GDGTs of the sediment were not derived from the watershed soils, but is
most likely derived from the water column and/or lake sediment surface. We applied
three different calibration equations obtained by analyzing global set of soils (Weijers
et al., 2007), by analyzing African lake sediments (Tierney et al., 2010) and by
analyzing watershed soils in this study to estimate temperature in core-top sediment of
core BIW07-6. The temperature estimated by Weijers’ equation is much lower than
MAAT and mean annual lake surface temperature. The temperature estimated by
Tierney’s equation corresponds to the mean annual temperature of surface water,
while that estimated by our equation corresponds to the mean annual temperature of
bottom water. Because the production depth of brabched GDGTs is not clear, we
cannot judge whether MBT/CBT-index indicates surface or bottom water temperature.
The variation of estimated paleotemperatures in core BIW07-06 is in harmony with
pollen records in nearby cores, suggesting that MBT/CBT index is useful for
paleotemperature estimate.
56
S2-14: Geochemical properties and diatom assemblages from a core
KR07-04 PC3 in the southeastern East Sea/Japan Sea: Variation of
East Asian summer monsoon during the last glacial and deglacial
periods
J. HEO, B.K. KHIM* (Pusan Univ.), C. SHIMADA (Mineral Industry Museum,
Akita Univ.), M. UCHIDA (Environmental Chemistry Division, National Institute for
Environmental Studies, AIST), K. IKEHARA (Geological Survey of Japan, AIST),
Ryuji TADA (Tokyo Univ.)
Geochemical properties and diatom assemblages were studied from a piston core
PC-03 collected from the continental slope of the East Sea/Japan Sea to reconstruct
the past variations of East Asian summer monsoon. AMS 14C dating on 19 horizons
from core PC-03 revealed the continuous records from 47.8 ka to 10.6 ka. CaCO3 and
TOC contents were high before 35.6 ka and deceased until ~21.5 ka as a result of the
sea level fall in East Sea/Japan Sea. Especially, Low CaCO3 contents (>1.6% in
average) were found during the Last Glacial Maximum (21.3~17.2 ka). Such low
CaCO3 contents indicate different surface-water condition uninhabitable for
planktonic foraminifera due to the freshening of the surface-water in the East
Sea/Japan Sea. At 17.2 ka, the peaks of biogenic opal content and total diatom
abundance, with an increase of a cold-water species Neodenticula seminae, seems to
be related to the entrance of cold Oyashio Current water via the Tsugaru Strait owing
to the rising sea-level. Intrusion of the Oyashio Current water was a trigger of return
to the normal salinity condition with deep convection. This is further supported by
enhancement of CaCO3, TOC contents and C/N ratio after 17.0 ka. High C/N ratios
during 16.9~12.7 ka represent an increased terrigenous input from the submerged
continental shelf with sea-level rising. Low frequency of Paralia sulcata, low-salinity
diatom, during the same period was attributed to increased salinity of surface water.
However, high frequency of P. sulcata might be due to the reworked sediments from
the northern East China Sea. Presence of Fragilariopsis doliolus, an indicator of
Tsushima Warm Current (TWC), after 10.9 ka coincides with the first entrance of the
TWC through the Korea/Tsushima Strait. The variation of opal contents shows
obvious quasi-periodic East Asian summer monsoon variability (5 ka-cycle) driving
surface-water productivity during the last glacial period. However, this correlation
should be verified further with concrete evidence.
57
S2-15: Terrestrial biomarkers in Alaskan margin sediments in the
Arctic Ocean
Yu-Hyeon PARK (Graduate School of Environmental Science, Hokkaido University,
Japan), Masanobu YAMAMOTO (Hokkaido University) and Leonid POLYAK (Byrd
Polar Research Center, Ohio State University, Columbus, OH 43210, USA)
The Arctic Ocean plays an important role in global climate changes by positive
feedbacks involving changes in sea-ice coverage, thermohaline circulation, and boreal
vegetation (Miller et al., 2010). The Pacific sector of in the Arctic Ocean is sensitive
to global climate changes and the sea ice coverage responds to changes in temperature
and the inflow of extent of input of the pacific water. The Alaska margin in western
Arctic receives considerable amount of sediment from the Yukon River and smaller
rivers in northern Alaska (Ortiz et al., 2009).
We investigated molecular distributions of branched glycerol dialkyl glycerol
tetraethers (GDGTs) as terrestrial biomarkers to explore possibilities of
paleo-temperature estimation and to reconstruct GDGT-based on temperature, the
contribution of soil organic matter (OM) and the soil pH. We discuss whether
branched GDGTs in marine sediment reflect the changes in the provenance of
terrestrial OM in Alaska margin sediments since the early Holocene. Study cores
HLY0501-JPC5 and HLY0501-JPC8 were retrieved during Leg 1 of the 2005
Healy-Oden Trans-Arctic Expedition (HOTRAX).
The mean annual air temperatures (MAAT) reconstructed using a global
calibration equation proposed by Weijers et al. (2008) in the core-top sediment show
much higher values than modern MAAT by instrumental estimation in northern
Alaska. The reconstructed temperature must be biased toward a warmer direction,
because bacterial activity depends on growth temperature and is nearly zero below the
freezing point and is higher in higher temperatures. The global calibration by Weijers
et al. (2008) does not fully cover polar region and the temperature estimate was done
by extrapolation. We thus need future effort to create a calibration equation based on
the data set in polar region to improve temperature estimates.
MAAT and pH reconstructed from each core show an increasing pattern over the
past 10 ka (MAT of JPC5: -5.3 to 5.7, JPC8: -0.6 to 7.9; pH of JPC5: 6.5 to 8.4, JPC8:
-6.8 to 7.9). In contrast, BIT value shows a decreasing pattern on both cores. In
particular, parameters from 9.5 to 7 ka show significant variation. The interval from
9.5 to 7 ka is consistent with rapid climate change observed globally and an area near
northern Alaska margin (Brachfeld et al., 2009). These trends suggest that 1) the
warming in northern Alaska began since 10 ka, 2) the contribution of marine OM
became larger, 3) changes in soil pH may have reflected changes in the provenance of
soil.
References
[1] G.H. Miller et al., 2010. Temperature and precipitation history of the Arctic.
Quaternary Science Reviews 29, 1679-1715.
[2] J. Ortiz et al., 2009. Provenance of Holocene sediment on the Chukchi-Alaskan
margin based on combined diffuse spectral reflectance and quantitative X-Ray
Diffraction analysis. Global and Planetary Change 68, 73–84.
[3] S. Brachfeld et al., 2009. Impact of diagenesis on the environmental magnetic
record from a Holocene sedimentary sequence from the Chukchi-Alaskan margin,
Arctic Ocean. Global and Planetary Change 68, 100-114.
58
S2-16: Climate and sea level controls on terrestrial organic matter
discharge into marginal seas along the northwestern Pacific margin
since the last glacial maximum
Masanobu YAMAMOTO, Masaki INAGAKI, Yutaka ICHIKAWA, Toshinori
UESHIMA, Midori KISHIZAKI, Tomoya SHINTANI, Hirotoka SAI (Hokkaido
University), Liang-Jian SHIAU, Min-Te CHEN (National Taiwan Ocean University),
Tadamichi OBA (Hokkaido University), and Ken IKEHARA (Geological Survey of
Japan, AIST)
Sediment delivery to marginal seas is governed by climate, sea level, geographic
constraints and tectonics and has possibly responded to glacial-interglacial climate
changes differently in different climate zones. In this study, we investigated the
response of the delivery of terrestrial organic matter (TOM) to sea level change since
the last glacial period and discuss how changes in sea level and climate induced
changes in TOM delivery in different settings along the northwestern Pacific margin.
We analyzed terrestrial biomarkers such as long-chain n-alkanes, long-chain
n-fatty acids, lignin and branched glycerol dialkyl glycerol tetraethers in cores from
the northwestern Pacific margin regions to evaluate TOM delivery. The cores used for
this study are GH02-1030 off Tokachi in the NW Pacific at 42°N (Inagaki et al., 2009,
JO), MD01-2421 off Kashima in the NW Pacific at 36°N (Yamamoto et al., 2005,
PPP), MD98-2195 off Kyushu in the northern Okinawa Trough at 32°N (unpublished
data), MD97-2146 off Hong Kong in the northern South China Sea at 20°N (Shintani
et al., 2011, JAES), MD97-2151 off Vietnam in the southern South China Sea at 9°N
(unpublished data), and MD05-2928 off Papua New Guinea at 11°S (Shiau et al.,
2011, GRL).
The concentration profiles of terrestrial biomarkers demonstrated that TOM
influx was higher from 19 ka to 12 ka in the sites from 32°N to 42°N. A similar
phenomenon was observed in the Sea of Okhotsk (Ternois et al., 2001, GCA).
Similarly, terrestrial soil organic matter content was higher from 16 ka to 11 ka in the
sites at 11°S. At 9°N, TOM content was high in the last glacial maximum (LGM) as
well as the last deglaciation. In contrast to these regions, TOM concentration showed
a minimum in the last deglaciation at the site of 20°N.
TOM decrease at 20°N and the corresponding increase at 11°S are attributable to
southward shift of tropical rain belt during the last deglaciation. Stronger East Asian
winter monsoon (Shintani et al., 2008, TAO) and weaker summer monsoon (Wang et
al., 2001, Nature) may have resulted in the southward shift of tropical rain belt and
caused anti-phase variation in TOM delivery to marine sites. In the tropical region,
changes in precipitation are a potential factor in regulating TOM influx into marginal
seas.
We also hypothesize that the development of alluvial fan is critical in enhancing
the discharge of TOM into marginal seas, because the suspended organic matter in the
rivers is fed mainly by riverbank erosion. The following processes may have
increased the inflow of terrestrial organic matter during the last deglaciation at the
sites north of 32°N. Fluvial deposits accumulated in the upper and middle reaches of
the rivers, and the plain was incised in the lower reaches due to low sea level stand
during the LGM. During the last deglaciation, the alluvial plain developed as a result
of sea level rise, and organic matter was efficiently fed to rivers from the bank erosion
by meandering rivers. During the Holocene, the deposition center shifted landward,
and the transportation of terrestrial organic matter to the study site decreased.
59
S2-17: Paleotemperature estimation over the past 10000 years by the
application of GDGT-based proxy in soil sequences from the Ono
River Basin, Oita, Japan
Yasuto YAMAMOTO, Masanobu YAMAMOTO, Tomohisa IRINO, Taku AJIOKA
(Hokkaido University), and Keiji TAKEMURA (Kyoto University)
MBT/CBT index based on the composition of branched Glycerol Dialkyl
Glycerol Tetraethers (GDGTs) was recently proposed as a proxy of terrestrial
paleo-air temperature (Weijers et al., 2006). In this study, we reconstructed
paleotemperature changes during the Holocene at the upstream of the Ono River
Basin by analyzing a soil sequence exposed at the flank of Mr. Kuju and a marine
sequence drilled at the mouth of the Ono River, Kyushu, Japan. The conversion of
branched GDGT composition to paleotemperature was conducted using equations
created by comparing the values in surface soils collected from the Ono River Basin
and Lake Biwa catchment basin with mean annual air temperature.
Paleotemperatures estimated in the soil sequence showed the warmest climate in
the middle Holocene, whilst they in the marine sequence showed the coolest climate
in the middle Holocene. The former reconstruction is consistent with paleoclimate
reconstruction by pollen assemblages in a nearby basin (Kuroda & Hatanaka.,1984),
suggesting that the paleotemperature estimation is reliable by using soil sequences.
Marine sequence may have a problem in the reconstruction of terrestrial environment.
Enhanced precipitation in the middle Holocene may have caused the development of
soil to higher altitudes, increasing the contribution of soil organic matter formed in
lower temperatures in the river mouth sediments. Though the marine sequence does
not show a robust record in paleotemperature, the BIT index (the ratio of branched
GDGTs to the sum of branched GDGTs and crenarchaeol) that represents the
contribution of soil organic matter was significantly lower in the period between 7.5
and 6 ka. This is consistent with the Johmon transgression in this period (Chida et al.,
1987). The BIT in the marine sequence is sensitive to sea level change and thus useful
for paleoenvironmental assessment.
60
S2-18: Terrestrial records in shelf sediment in East/Japan Sea and
Yellow Sea: a speculation on major river supply from the Korean
Peninsula
Sangmin HYUN (Ocean Satellite Remote Sensing & Observation Technology
Research Department, Korea Ocean Research and Development Institute, Korea),
Hi-Il YI (Marine Environment & Pollution Prevention Research Department)
The various rivers play a significant role in accumulation of terrestrial material in
coastal and shelf sediment. In particular, coastal and continental shelf areas adjacent
to the Korean major river system are presently receiving riverine sediments discharge
into the marine environment as a result of the recent postglacial sea-level changes. It
is suggested that the mud belt deposit on the inner shelf of the Ulleung Basin,
East/Japan Sea were mostly come from the Nakdong River, southern part of Korea [1].
The high-resolution seismic profile showed that the transparent subbottom is the most
striking feature of in these shallow sediments. The southward flowing north Korea
Current, the northward flowing East Sea coastal Current have played crucial roles in
transporting and trapping most of the river-derived material in the inner shelf [1].
In Yellow Sea, large amount of terrestrial material as well as biogenic component
such as foraminifera and organic carbon were supplied by the neighboring land area
and in situ marine environment [2]. Multi proxies of the terrestrial records indicate that
the southeastern Yellow Sea changed from an estuarine to a modern marine shelf
environment, probably due to the Yellow Sea Warm Current.
The direct observation of sediment component of those piston cores clearly shows
large amount of terrestrial material were supplied from nearby land areas [2,3]. This
data indicate that the terrigenous material fluctuates during glacial and interglacial
periods, and also suggests that the most coarse-grained sediment, derived from
terrigenous areas, at least, associated with climatic changes. In previous work [4] also
indicated that the supply of the detrital materials to the inner shelf is strongly affected
by summer monsoon intensity, thus climatic changes in East Asia area. More detailed
investigation including various bio-geochemical approaches is necessary to confirm
of terrigenous supply from major rivers in associated with eustatic sea-level changes
and climatic changes.
References
[1] Park et al, 1999. Accumulation of recent muds associated with coastal circulation,
southeastern Korea Sea (Korea Strait). Continental Shelf Research 19, 589-608.
[2] Kong et al, 2006. Late Quaternary paleoenvironmental changes in the southeastern
Yellow Sea, Korea. Quaternary International 144, 38-52.
[3] Bahk et al, 2004. Variations of terrigenous sediment supply to the southern slope
of the Ulleung Basin, East/Japan Sea since the Last Glacial Maximum. Geoscience
Journal 8, 381-390.
[4] Kubota et al, 2010. Variations of East Asian summer monsoon since the last
deglaciation based on Mg/Ca and oxygen isotope of planktic foraminifera in the
northern
East
China
Sea.
Paleoceanography.
25,
4205-4220.
doi:10.1029/2009PA001891
61
S3-1: Tectonic control on long term dust emission: a new view from
the Tarim Basin
Ryuji TADA (Univ. of Tokyo), Hongbo ZHENG (Nanjing Univ.), Yuko ISOZAKI,
Naomi SUGIURA, Tomohiro YOSHIDA, Ke WANG, and Akinori KARASUDA
(Univ. of Tokyo), Youbin SUN (Chinese Academy of Science), Hitoshi
HASEGAWA (Hokkaido Univ.), Wengang YANG (Tongji Univ.), and Shin
TOYODA (Okayama Univ. of Science)
It is generally believed that eolian dust flux reflects the extent of dry area. For
example, Rea et al. (1998) reconstructed eolian dust flux changes in the central North
Pacific during the last 12 m.y., and argued that sudden drying in central Asia occurred
at 3.6 Ma in response to the uplift of northern Tibet and consequent shutdown of the
moisture source based on the sudden increase in the dust flux at 3.6 Ma. Zheng et al.
(2004) demonstrated the sudden increase in eolian dust sedimentation rate in the
Tarim Basin at 3.6 Ma and its coincidence with the onset of conglomerate deposition,
and further argued the linkage between the tectonic uplift of northern Tibet,
consequent shutdown of the moisture source, and desertification of the Tarim Basin,
which is in line with the idea of Rea et al. (1998).
Here we investigated changes in the accumulation rates of the fluvial and/or
alluvial sediments, and the intercalated eolian sediments deposited in the northern
margin of northwestern Tibet during the last 8 m.y. and their relation with changes in
their provenance and the tectonic tilting rate. We used ESR [Electron Spin
Resonance] signal intensity and CI [crystallinity index] of quartz to examine the
provenance. ESR signal intensity of quartz reflects the age of the mother rock and is
reset at the temperature of approximately 200°C, whereas CI of quartz reflects
temperature and speed of crystallization of the mother rock and increases with the
grade of metamorphism.
The result revealed a significant increase in eolian dust accumulation rate
approximately at 4.3 Ma and the increase in eolian grain size approximately at 3.7 Ma.
On the other hand, tectonic tilting in the area started approximately at 3.8 Ma, a
significant increase in accumulation rate of conglomerate occurred at 3.6 Ma, and the
drastic change in eolian dust provenance occurred approximately at 3.5 Ma. The
drastic change in eolian dust provenance approximately at 3.5 Ma is characterized by
the significant decrease in ESR signal intensity of quartz, which probably reflects
exposure and enhanced erosion of the metamorphic and plutonic rocks in the
northwestern Tibet due to the rapid uplift of the area. These results suggest
accumulation of eolian dust in the Tarima Basin started at 4.3 Ma or earlier, which
roughly coincides with frequent occurrence of granule to pebble conglomerates,
suggesting the uplift and enhanced erosion started around this time. Tectonic tilting,
thick and extensive cobble to boulder conglomerate deposition, and exhumation of
high-grade metamorphic to plutonic rocks all started approximately 3.8 to 3.5 Ma
suggesting culmination of the uplift in the northwestern Tibet. The increase in
eolian dust grain size also occurred approximately at 3.7 Ma suggesting establishment
of stronger wind system within the Tarim Basin around this period. Since then,
accumulation rates of eolian sediments are positively correlated with the accumulation
rates of conglomerate, suggesting their close linkage.
We interpreted that the tectonic uplift of northern Tibet probably started as early
as 5 Ma and culminated at 3.6 Ma. In response to the tectonic uplift and subsequent
erosion of northwestern Tibet, large amount of detrital material was shed into the
Tarim Basin and wind-eroded, transported and accumulated as loess deposits on
62
alluvial fans developed on the northern margin of the Tibetan Plateau. Although large
amount of eolian dust was produced and accumulated within the Tarim Basin at least
since 4.3 Ma, eolian dust emission out of the basin did not start until 3.6 Ma when
northwestern Tibet uplifted high enough that wind system capable to lifting up dust to
the altitude high enough for the westerly jet to trap those dust and carry to the north
Pacific.
These results strongly suggest that production of the source material for eolian
dust by tectonic uplift and subsequent erosion, in addition to development of dry
environment, could be a major control on the dust emission. The results also suggest
that tectonic uplift and subsequent establishment of the wind system capable of lifting
up the dusts to the altitudes high enough to be entrained in the westerly jet also plays
an important role to transport dusts for long distance and spread to wider area.
63
S3-2: Capture and Reversal of the Middle Yangtze River: New
evidence from DEM (Digital Elevation Model) analysis
Ping Wang
School of Earth Science and Engineering, Nanjing University, China
The capture and reversal of the Middle Yangtze River has been proposed for
about 100 years, whereas no direct evidence supports this view. We study the
topography relief and river features using the DEM (Digital Elevation Model)
analysis, including the local relief, topographic and river profiles. The local relief of
the eastern Sichuan Basin is mostly controlled by bedrock erosion of the Middle
Yangtze river system. Lithology and original tectonic topography also influence the
distribution of the local relief. From Chongqing to Yichang, revealed by swath
profiles and river buffer profile, the Middle Yangtze stem flow reversely to the
topography gradient. Based on Hack’s law, the logarithm relationship of the drainage
area and distance suggests the continuous capture events in Middle Yangtze stem. The
confluence angle of the tributaries also suggests the main stem was captured and
reversed in upper reach of the Middle Yangtze River. Our results support the model
that the Paleo-Yangtze Fiver had two branches divide by QiYue Shan near Fengjie,
the west branch flowing westwardly and the east branch flowing eastwardly. Driving
by the increased rate of distal base-level fall of the Jianghan basin, the east branch
grew headward and captured the west branch gradually.
64
S3-3: Impact of terrestrial input on marine productivity in neritic
area of the Neogene paleo-Japan Sea
Ken SAWADA (Fac. Sci., Hokkaido Univ.)
The Neogene backarc basins formed in the paleo-Japan Sea (East Sea) regions
such as the northeastern (Tohoku) Japan have been well known as a distribution of
source rocks for petroleum and gas resources, which might have been produced by
diatom-derived organic matter (e.g. Tada, 1991; Suzuki et al., 1993). Therefore,
organic geochemical investigations have been extensively carried out for the
exploration of petroleum and gas in addition to sedimentological and paleontological
studies. Since the 1990s, Neogene paleoceanographic studies have been
systematically conducted in hemipelagic sediments in the paleo-Japan Sea region (e.g.
Tada, 1991). In addition, organic geochemical data have been used for reconstructing
paleoceanographic conditions from Miocene to Pliocene hemipelagic sediments of the
northeastern Japan areas (Stein and Stax, 1992; Yamamoto and Watanabe, 1995).
However, there have been only a few studies of paleoceanographic reconstruction in
the coastal and neritic areas in the Miocene to Pliocene paleo-Japan Sea region.
South-western Japan had presumably been connected to the Eurasian Continent
during the middle Miocene to Pliocene. Therefore, it is likely that the terrigenous
matter on the continent might have been directly transported to the paleo-Japan Sea,
and that the environmental variations in the continental areas might be closely linked
to those of the paleo-Japan Sea. Hence, it is important to reconstruct the
paleoenvironmental variations and to evaluate the sedimentology and material-cycling
system in the coastal and neritic areas of the Neogene paleo-Japan Sea.
In my (and coworkers’) study, organic petrological observations and organic
geochemical analyses have been conducted on the neritic sediments deposited at the
southern edge of the paleo-Japan Sea (Takafu syncline area, central Japan) during the
late Miocene to Pliocene (Sawada, 2006), and the Ishikari basin, where was located at
northeastern areas of the paleo-Japan Sea (Yubari area, Hokkaido, Japan) during the
middle to late Miocene (Okano and Sawada, 2008). The main objectives of these
studies were to reconstruct the variations in marine and terrestrial environments and to
evaluate the relationship between marine and terrestrial biogeochemical systems. In
particular, we focus diatom productions recorded by diatom biomarkers during the
Miocene to Pliocene.
In the southern edge of the paleo-Japan Sea, it is presumed that diatom production
increased in the naritic areas during 5-4 Ma by analysis of diatom biomarkers such as
C26 norsterane (Sawada, 2006). Furthermore, the %13C records of terrigenous kerogen
macerals suggested that paleovegetation changes from C3 to a mixture of C3 and C4
plants occurred in land areas surrounding the paleo-Japan Sea during the late Miocene
to early Pliocene. This finding coincides with the global expansion of C4 plant
ecosystems on the Eurasian Continent (e.g. Cerling et al., 1997). Interestingly, the
timing of C4 plant expansion was possibly similar to the beginning of major diatom
production in the area. Therefore, the terrestrial and shallow marine ecosystems were
possibly related to each other, as assumption by Falkowski et al. (2004). The
expansion of C4 plants was possibly associated with the high production of diatom in
the shallow-marine areas of the paleo-Japan Sea during the Neogene Period (Sawada,
2006). In recent study, the onset of increasing concentration of other diatom
biomarkers such as highly branched isoprenoid (HBI) alkanes was earlier than that of
C26 norsterane in the neritic sediments of the paleo-Japan Sea. These findings suggest
65
that production of specific diatom species in shallow areas was more efficiently
affected by variation in input of terrigenous matter.
References
Cerling, T.E., Harris, J. M., MacFadden, B.J. et al. (1997) Nature, 389, 153-158.
Falkowski, P.G., Katz, M.E., Knoll, A.H. et al. (2004) Science, 305, 354-360.
Okano, K. and Sawada, K. (2008) Geochem. J., 42, 151-162.
Sawada, K. (2006) Island Arc, 15, 517-536.
Stein, R. and Stax, R. (1992) Proc. ODP, Sci. Results, 127/128, 423-437.
Suzuki, N., Sampei, Y. and Koga, O. (1993) Geochim. Cosmochim. Acta., 57,
4539-4545.
Tada, R. (1991) J. Sedimentol. Petrol., 61, 1123-1145.
Yamamoto, M. and Watanabe, Y. (1995) J. Jap. Assoc. Petrol. Technol., 60, 27-38.
66
S3-4: Reconstructing the origin of rhythmical beddings in the
mid-Cretaceous lacustrine deposits in southeast Mongolia:
Implication for terrestrial humidity changes at the OAE interval
Hitoshi HASEGAWA (Hokkaido Univ.), Hisao ANDO (Ibaraki Univ.), Takashi
HASEGAWA (Kanazawa Univ.), Toru OHTA (Waseda Univ.), Masanobu
YAMAMOTO (Hokkaido Univ.), Noriko HASEBE (Kanazawa Univ.), Gang LI
(Nanjing Inst. Geol. Palaeont.), Niiden ICHINNOROV (Palaeont. Center, Mongolia)
The mid-Cretaceous period is characterized by an extremely warm “greenhouse”
climate, elevated atmospheric CO2 levels, and repeated occurrences of Ocean Anoxic
Events (OAEs); however, detailed processes and causal mechanisms of these marked
events, particularly the response of terrestrial climate system, have been poorly
understood. Possible causal mechanisms of OAEs in the mid-Cretaceous greenhouse
climatic conditions include following mechanism; (1) increased terrestrial humidity
and terrigenous input into the oceans, (2) enhanced ocean surface productivity, and (3)
the excess of organic burial in the oceans. Increased terrestrial humidity and chemical
weathering may have increased terrigenous input into the oceans (so called
“Weathering Hypothesis”; e.g., Weissert et al., 1998; Hasegawa, T., 2003). To
evaluate interaction between the land and the ocean during the mid-Cretaceous OAE
interval, we investigated terrestrial paleoenvironmental changes using the
mid-Cretaceous lacustrine deposits at intra-continental site in central Asia (Gobi basin,
southeast Mongolia).
The mid-Cretaceous lacustrine deposits (Shinekhudag Formation) are widely
distributed in southeastern Mongolia (Jerzykiewicz and Russell, 1991; Yamamoto et
al., 1998; Hasegawa et al., 2011). The Shinekhudag Formation, well exposed in the
Shine Khudag locality in the Shaazangiin Gobi area, is composed of dark grey paper
shale (oil shale), light grey calcareous claystone, and whitish to yellowish dolomite.
Strata are continuously exposed up to 400 m in thickness. The shale and dolomite
successions are rhythmically alternated (decimeter-, meter-, tens of meter-scale) in
Shine Khudag locality, which can be controlled by orbital cycles. Paper shale contains
micrometer-scale laminations, which are most likely of varve origin. The estimated
sedimentation rate is ca. 3-5 cm/k.y. by the varve-counting methods on thin sections.
The age of the Shinekhudag Formation is assigned as Aptian or Barremian-Aptian
based on the ostracodes, concostracans, floral and molluscan evidences (Krassilov,
1982; Jerzykiewicz and Russell, 1991; Yuan and Chen, 2005), and Ar40/Ar39 dating of
basaltic rocks in the uppermost part of the underlying Tsagantsav Formation (ca.
121-125 Ma: Graham et al., 2001).
In order to clarify the depositional environments and their controlling factors of
the rhythmically alternated lithological change in the Shinekhudag lacustrine deposits,
mineralogical and elemental analysis (C, N, S), and Rock-Eval pyrolysis were
performed on the shale and dolomite couplets. C/N values are significantly low in the
dolomite samples, while higher in the shale samples. Rock-Eval analysis shows
significantly high hydrogen index (Type I and II) with relatively high T-max values.
These results indicate that the organic matter of the Shinekhudag lacustrine deposits
were mainly of algal origin (dominant in dolomite layer) but with relative higher
contribution of terrestrial plants in shale layer. These lines of evidence suggest that
the rhythmically alternated shale and dolomite succession was formed by fluctuations
of the lake levels and associated changes in surface primary producers, which could
be controlled by orbital-scale precipitation changes during the mid-Cretaceous time.
67
References
Graham, S.A., Hendrix, M.S., Johnson, C.L., Badamgarav, D., Badarch, G., Amory, J.,
Porter, M., Barsbold, R., Webb, L.E., Hacker, B.R. (2001) Sedimentary record
and tectonic implications of Mesozoic rifting in southeast Mongolia. Geological
Society of America Bulletin, 113, 1560–1579.
Hasegawa H., Tada, R., Jiang, X., Suganuma, Y., Imsamut, S., Charusiri, P.,
Ichinnorov, N., Khand, Y. (2011) Drastic shrinking of the Hadley circulation
during the mid-Cretaceous supergreenhouse. Climate of the Past Discussions, 7,
119–151.
Hasegawa, T. (2003) Cretaceous terrestrial paleoenvironments of northeastern Asia
suggested from carbon isotope stratigraphy: Increased atmospheric
pCO2-induced climate. Journal of Asian Earth Science, 21, 849–859.
Jerzykiewicz, T., Russell, D.A. (1991) Late Mesozoic stratigraphy and vertebrates of
the Gobi Basin, Cretaceous Res., 12, 345–377.
Khand, Y., Badamgarav, D., Ariunchimeg, Y., and Barsbold, R. (2000) Cretaceous
System in Mongolia and its depositional environments, In, Okada, H. and
Mateer, N. J., Eds., Cretaceous Environments of Asia. Elsevier Science B.V.,
49–79.
Krassilov, V. (1982) Early Cretaceous flora of Mongolia. Palaeontographica B, 181,
1-43.
Weissert, H., Lini, A., Follmi, K.B., Kuhn, O. (1998) Correlation of Early Cretaceous
carbon isotope stratigraphy and platform drowning events: a possible link?
Palaeogeography, Palaeoclimatology, Palaeoecology, 137, 189–203.
Yamamoto, M., Bat-Erdene, D., Ulziikhishig, P., Watanabe, Y., Imai, N., Kajiwara,
Y., Takeda, N., Nakajima, T. (1998) Bulletin of Geological Survey of Japan, 49,
257–274.
Yuan, F., Chen, P. (2005). Early Cretaceous Crustacea (Ostracoda, Conchostraca)
from the Shine-Khudug Formation of SE Mongolia. Acta Palaeontologica
Sinica, 44, 25-35. (in Chinese, English abstract)
68
S3-5: Influence of Climate and Tectonics on Progradation of a River
Delta in a Mega-Lake System (Upper Triassic, Junggar-Basin,
NW-China)
Jianguang ZHANG1, Jens HORNUNG1, Weihua BIAN2, Matthias HINDERER1 and
Pujun WANG2
1
University of Technology, Darmstadt, Germany
2
Jillin University, Changchun, PR China
Sedimentary sequences in the central Asian Junggar basin provide a continuous
continental record of climatic and tectonic parameters during the Mesozoic. The basin
kept its paleolatitude over the whole time span, which makes it a natural laboratory
for investigation of how geodynamic processes interplay with climate and how
evolution adopts to those changes. We present a quantitative outcrop analogue study
with an exceptionally high-resolution record of a fluvial delta complex (cm to
decimetre) of the Upper Triassic at the southern margin of the Junggar Basin
(Haojiagou section, Xinjiang, China). Sedimentological logging of lithofacies and
architectural elements were combined with GR measurements and 2D mapping. The
data are analysed and interpreted in terms of depositional dynamics, cyclicity,
stacking pattern, accommodation vs. sediment supply and preservation potential.
The sedimentary inventory comprises various types of gravely channel bodies, sheet
like sandy and clayey units, as well as ferrocrete horizons and coal seams organized in
four different geosystems: Delta-slope, delta-front, delta-top and distal alluvial plain.
A four-fold cycle hierarchy was identified, which shows systematic superposition of
cycles and therefore considered to represent an external control of depositional
environments, sediment supply and accommodation space. According to preservation
of cycles and regional geodynamic data, tectonic rates did not change markedly in the
Upper Triassic (Bian et al., 2010). However, according to pollen and spores data
humidity (and its variations) changed over time and show superpositioned trends.
Depositional cycles and reorganization of sedimentary environments go along with
that observation, for example, a more humid phase coincides with less variance over
time, which results in thicker and more pronounced floodplain and sandy crevasse
units. Dryer phases seem to correlate with more frequent formation of conglomerate
filled channels. In conclusion the sedimentary record supports a strongly linked
coupling of climate with patterns of lake level fluctuations and changes in sediment
supply, possibly on a basin-wide scale. This is a unique situation for closed and partly
open lake hydrology and makes clear that only adopted or terrestrial sequence
stratigraphic concepts (e.g. stratigraphic base level) can be applied in such geosystems
(Hornung et al., In Press).
References:
Bian, W., Hornung, J., Liu, Z., Wang, P., and Hinderer, M., 2010, Sedimentary and
palaeoenvironmental evolution of the Junggar Basin, Xinjiang, Northwest
China: Palaeobiodiversity and Palaeoenvironments, v. 90, p. 175-186.
Hornung, J., Ashraf, A., Hinderer, M., Bian, W., Wang, P., Ge, S., and Mosbrugger,
V., In Press, Depositional dynamics of a coal bearing lacustrine delta: A case
study from the Junggar-Basin (NW-China, Upper Triassic): Palaeobiodiversity
and Palaeoenvironments.
69
S3-6: Eocene coal-bearing deposits (Ishikari Group) in central
Hokkaido: possible link to the widespread deposition of oil source
rock during the Eocene “greenhouse” condition
Hitoshi HASEGAWA and Noriyuki SUZUKI (Hokkaido University)
Recent exploration of oil and gas resources in East Asia revealed that there are
abundant petroleum source rocks in East Asian mid- to high-latitude, which are
derived from organic-rich lacustrine sediments and coals of the Eocene age (e.g.,
Ishida, 2005; Suzuki, 2005). Eocene coal-bearing strata are widely distributed in the
area from Sakhalin island, central Hokkaido, to off-Sanriku (the northwest Pacific off
northeast Japan) (Takano and Waseda, 2003; Honda and Nishita, 2005). Eocene coals
in central Hokkaido, such as Ishikari Group, are rich in degradenite and characterized
by comparatively high hydrogen content, showing oil-prone characteristics. The
extremely warm and humid “greenhouse” climate of the Eocene period might play an
important role for the deposition of these organic-rich sediments on land, although
their possible linkage has not yet been clarified.
The Eocene Ishikari Group mainly consists of non-marine to littoral sandstone,
siltstone, mudstone, and coal. Because of abundant coal seams in the Ishikari Group,
the Ishikari sedimentary basin has long been exploited as the Ishikari Coal Field since
late 19th century. The Ishikari Group is divided into nine lithostratigraphic formations
as the following; Noborikawa, Horokabetsu, Yubari, Wakanabe, Bibai, Akabira,
Ikushunbetsu, Hiragishi and Ashibetsu Formations in ascending order (Tanai, 1990;
Iijima, 1996; Takano and Waseda, 2003). According to the sequence stratigraphy, the
Ishikari Group consists of four million-year-order depositional sequences with a
combination of transgression and regression caused by relative sea-level changes
(Takano and Waseda, 2003). Although the Ishikari Group was previously considered
to be deposited during the middle to late Middle Eocene (ca. 46 to ca. 37 Ma) (Tanai,
1990; Iijima, 1996), unpublished data of Fission-track dating of the intercalated tuff in
the Noborikawa Formation and dinoflagellate assemblages of the Horokabetsu
Formation suggest that basal part of the Ishikari Group is deposited during the Early
Eocene age. Thus, coal-bearing succession of the Ishikari Group is thought to
represent a rare glimpse for evaluating the linkage of source rock deposition and
Earth’s climate change during the Early to Middle Eocene “greenhouse” world
(Hasegawa et al., 2009).
According to the reported FT age data and sequence stratigraphic analysis, we
correlate the 3rd order depositional sequences in the Ishikari Group with the eustatic
sea-level changes during the Early to Middle Eocene (Haq et al., 1987). Our result
suggest that the Noborikawa, Horokabetsu, and Yubari Formations are correlated with
Early Eocene age, and the Bibai, Akabira, Ikushunbetsu, Hiragishi and Ashibetsu
Formations are correlated with Middle Eocene age. If these correlations are correct,
Early Eocene Climatic Optimum (EECO) interval is possibly correlated with the
Horokabetsu Formation (lower part of the Ishikari Group). Note that the Horokabetsu
Formation is characterized by widespread lacustrine deposits in full area of Ishikari
sedimentary basins (Takano and Waseda, 2003). Thus, it is suggested that lacustrine
environments were widely distributed in central Hokkaido under the humid climate
during the extremely warm EECO interval (Zachos et al., 2008). To clarify the
possibility of widespread humid climate in Asian mid-latitude during this marked
interval, detail chronostratigraphic and geochemical studies are conducting.
References
70
Haq B.U., Hardenbol J. and Vail P.R. (1987) Chronology of Fluctuating Sea Levels
Since the Triassic. Science 235, 1156-1167.
Hasegawa H., Suzuki N. and Saito H. (2009) Coal-bearing succession of the middle
Eocene Ishikari Group in Sanbi Coal Mine, Bibai city, central Hokkaido. J. Geol.
Soc. Jap. 115, XV-XVI.
Honda, T., Nishita, H. (2005) Non-marine source rocks and hydrocarbon potential in
the southwest Sakhalin, Russia. J. Japanese Assoc. Petrol. Technol. 70, 47-55. (in
Japanese)
Iijima, A., (1996) Evolution of the Paleogene Sedimentary Basins in Hokkaido. J.
Geography, Soc. Japan. 105, 178-197.
Ishida, H. (2005) Cenozoic non-marine source rocks and sedimentary basins in China.
J. Japanese Assoc. Petrol. Technol. 70, 56-65. (in Japanese)
Suzuki, N. (2005) Summary of the Symposium on “Oil and gas from the Cenozoic
non-marine source rocks in East Asia” – A point of contact between petroleum
system and Earth system -. J. Japanese Assoc. Petrol. Technol. 70, 101-103. (in
Japanese)
Takano, O. and Waseda, A. (2003) Sequence stratigraphic architecture of a
differentially subsiding bay to fluvial basin: the Eocene Ishikari Group, Ishikari
Coal Field, Hokkaido, Japan. Sediment. Geol., 160, 131–158.
Tanai, T. (1990) Euphorbiaceae and Icacinaceae from the Paleogene of Hokkaido,
Japan. Bull. Natl. Sci. Mus., Tokyo, Ser. C 18, 91–118.
Zachos, J.C., Dickens, G.R., Zeebe, R.E. (2008) An early Cenozoic perspective on
greenhouse warming and carbon-cycle dynamics. Nature 451, 279–283.
71
S3-7: Enhanced primary productivity triggered by excess terrestrial
input in the mid-Cretaceous Oceanic Anoxic Event 1b (the Paquier)
in the Vocontian basin, SE France
Takuto ANDO, Ken SAWADA , Kazuki OKANO (Hokkaido Univ.), Hiroshi NISHI ,
and Reishi TAKASHIMA (Tohoku Univ.)
Black shales were occasionally discovered in the mid-Cretaceous formations, and
depositions of these sediments are closely associated with the expansion of
oxygen-poor water in the ocean, called the oceanic anoxic events (OAEs). In this
study, the biomarker analyses of the black shales corresponding to the OAE1b (the
Paquier level) from the Vocontian Basin of SE France are curried out in order to
reconstruct the changes of environmental systems and marine ecosystems, and to
elucidate the mechanism for expansion of anoxic waters during this OAE. The
Paquier are composed of laminated black shales, several faintly laminated layers, and
adjacent marls.
In these samples, the terrestrial higher plant biomarkers such as the retene and the
dibenzofuran are abundantly identified. The concentrations of these biomarkers are
relatively high in the middle part of the Paquier level. Moreover, the concentrations of
marine algal biomarkers such as steranes and dinosteranes are high. These trends are
similar to those of terrestrial biomarker concentrations, which indicate that the
nutrient was transported from land to ocean.
In addition, the Paquier levels, the archaeal biomarkers such as 2,6,15,19tetramethylicosane (TMI) and 2,6,10,15,19-pentamethylicosane (PMI) are detected.
Carbon isotope ratios of TMI and PMI range -35 to -20‰, suggesting that these
biomarkers are originated from methanogenic archaea. Thus, these expansions of
methanogenic archaea during the Paquier levels were possibly related to the
intensification of anoxic condition. As mentioned above, the deposition of black
shales are strongly related to terrestrial input. Furthermore, variations of dinoflagellate
and cyanobacteria productions were recorded by aromatic dinosteroids and hopanoids,
respectively. The productions of these marine primary producers tended to increase
with excess terrestrial input.
The same mechanisms are observed in modern tropical ocean areas such as the
Bismarck Sea (Papuwa New Guinea), where is characterized by strong stratification
and supply of a large amount of terrigenous materials by riverine flow system of the
Sepik River, and productivity of marine phytoplankton is high in the stratified surface
water, resulting in deposition of sediment rich in organic matter . In this study, it is
suggested that the Bismarck Sea is typical ocean model for the paleo-Tethys Sea
during the Paquier, called ‘Bismarck Sea-type OAE’.
72
S3-8: Sedimentary and geochemical records of possible large floods
occurred in the Miocene northeastern margin of Paleo-Japan Sea
Satoshi FUROTA, Ken SAWADA (Fac. Sci., Hokkaido Univ.) and Gentaro
KAWAKAMI (Geological Survey of Hokkaido, HRO)
The Neogene Kawabata Formation, which is located in Yubari area of central
Hokkaido, is characterized by turbidite facies that consist of alternations of
conglomerate, sand, and mudstones. The Ishikari Trough has been formed with N-S
direction in Central Hokkaido region during 15 Ma in the Middle to Late Miocene.
The Kawabata Formation consists of thick sediments filled with the Ishikari Trough.
We perform sedimentological and geochemical investigations of the Kawabata
Formation, in order to give understandings for transport and sedimentation of
terrigenous materials as well as material cycling in neritic to hemipelagic
environments. In this presentation, we focus organic geochemical results in the
hyperpicnite-like sedimentary sequence described in the Kawabata Formation.
We discovered a peculiar sedimentary sequence across about 50 cm thickness in
an outcrop of the Higashiyama-gawa route in Yubari. This sedimentary sequence
consists of homogenous mudstone, coarsening-upward sandstone, sandstone
intercalated thin layers of plant fragments, sandstone randomly contained plant
fragments, fining-upward sandstone, sandstone with horizontal lamination, and
homogenous mudstone, from lower to upper layers. This sequential pattern is almost
similar to that in hyperpicnite. Total organic carbon content (TOC; %) was found to
increase remarkably from sandstone layers with plant fragments to horizontal
lamination layer, which is concordant with hyperpicnite (Yoshida et al., 2009).
Organic geochemical characteristics for biomarker were followings, 1) concentrations
of coniferous biomarker were remarkably higher in homogenous mudstone below the
sandstones and coarsening-upward sandstone, 2) concentrations of degraded
biomarkers originated from angiosperm were higher in sandstone layers with plant
fragments, and 3) maturity levels were significantly lower in sandstone layers with
plant fragments. From these results, we conclude that this sedimentary sequence was
hyperpicnite.
This fact suggests that large floods happened in the Miocene central Hokkaido.
Furthermore, in a big waterfall outcrop called ‘Chidorigataki’, part of Kawabata
Formation, there are some layers like this hyperpicnite and these layers are
concentrated only about 10 m parts of a big out crop. These results suggest the
possibility that large floods happened frequently in short time scale in the Miocene
central Hokkaido, and these floods transported a lot of terrestrial materials for the
Paleo-Japan Sea.
73
S3-9: Fractionation and deposition of terrestrial biomarkers in the
middle Eocene fluvial environment, Hokkaido, Japan
Takeshi INOUE, Noriyuki SUZUKI, Hitoshi HASEGAWA, Hiroyuki SAITO
(Hokkaido Univ.)
Terrestrial sediments are rich in various types of higher plant and fungal
biomarkers, which can provide paleoenvironmental information about vegetation and
climate changes on land. Studies on terrestrial biomarkers have been conducted
mainly using the sediment samples from lacustrine and marine environments. A few
studies are available on the distribution of terrestrial biomarkers using the samples
from fluvial, floodplain, and paleosol deposits. Although understanding the
differential transportation of terrestrial organic matter is critical to reconstruct the
vegetation and climatic change on land, few studies have considered this
sedimentological factor so far. In the present study, we investigated the distribution of
higher plant and possible fungal biomarkers in the Middle Eocene fluvial to estuarine
sedimentary rocks of the Ishikari Group exposed in Bibai, Hokkaido, Japan for
understanding the differential transportation and sedimentation of terrestrial
biomarkers.
The Ishikari Group mainly consists of non-marine to littoral sandstone, siltstone,
alternating beds of sandstone and mudstone, mudstone, and coal. The Ishikari Group
is divided into nine lithostratigraphic units (formations). Total thickness of the
Ishikari Group is about 3000m. In the present study, all the sediment samples were
from the middle Eocene Bibai Formation, which is well exposed in the Sanbi Coal
Mine, central Hokkaido. Vitrinite reflectance (Ro) and other maturity parameters of
coal seams in the study area show comparatively immature level (Ro=0.44 to 0.59%)
before the main stage of oil generation. The Bibai Formation is composed of
terrestrial sedimentary rocks ranging from fluvial to estuarine deposits. The CNS
elemental compositions and aromatic biomarkers of angiosperm, gymnosperm, and
fungi in various types of terrestrial sedimentary rocks were analyzed.
The concentrations of higher plant biomarkers generally increase with increasing
TOC content, showing that sedimentary organic matter is mainly derived from higher
plant. Mudstones and siltstones poor in coaly fragments tend to be rich in angiosperm
biomarkers, whereas coal and coaly mudstones are comparatively rich in gymnosperm
biomarkers. Perylene is significantly detected in siltstones and mudstones, being
similar to the distribution of angiosperm biomarkers. Perylene is especially rich in
fine-grained floodplain deposits and poor in organic-rich swamp deposits.
Facies and lithological controls on the terrestrial biomarker distribution are
noteworthy. Diterpenoid hydrocarbons such as retene and simonellite are mainly
derived from resins of gymnosperm. Natural plant resins occur as exudates, which are
viscous and sticky. Resins, therefore, would behave with trunk, stem, and their
fragments. The Eocene Bibai coal is mainly composed of vitrinite group macerals
derived from woody plant tissues. The higher abundance of aromatic diterpenoids in
coal and coaly mudstones coincides with the expected behavior of natural plant resins
in the sedimentary environment. On the other hand, the relative abundance of
oleanoids derived from angiosperm is higher in clastic fine sediments than that in
organic-rich coal and coaly mudstones, suggesting that organic matter rich in oleanoid
precursors were transported as adsorbed on clastic particles, and/or as organic debris.
Leaves, flowers, and fruits rich in oleanoid precursors are easy to be degraded by
biodegradation and chemical degradation on and in soils. Their degradation products
74
rich in oleanoid precursors can be transported with soil particles and/or as organic
debris by winds, rainfall, runoff, and flood. Abundant distribution of oleanoid
biomarkers in fine clastic sediments associated with channel and floodplain deposits
is thus closely related to the origin of oleanoids. Perylene is also richer in fine
sediments of floodplain deposits. It would be due to that perylene is mainly derived
from fungal organic matter in soil. Reconstruction of paleoenvironment on land based
on terrestrial biomarkers requires careful consideration on the differential
transportation and sedimentation.
75
S3-10: Geological changes around Sri Lanka during Quaternary
period
U.de S. JAYAWARDENA, University of Peradeniya, Sri Lanka
The sedimentary deposits formed during last two million years of the history of the
Island Sri Lanka occur mainly within a coastal belt. Unconsolidated deposits also
occur in a number of river valleys in the interior of the country. The sediments such as
red earth beds, gravels, raised beach, nodular ironstone and dunes have been
deposited in Pliestocene Period belong to Older Group. Buried and emerged inland
coral deposits, beach rock, dune sand, lagoonal and estuarine sediments, peat and
some alluvium deposits belong to Younger Group from Holocene to present.
The occurrence of shell deposits and coral reefs in several km inland indicates
the margin of the older sea level or the upper sea level during Holocene Period.
Similarly the coral reef sediments at depth more than 50 meters from the continental
shelf of western Sri Lanka indicate the lower sea level at one time duration. Today sea
level may be a stage in between those upper and lower levels.
The continental slope around Sri Lanka is dissected by several canyons. The
valleys and gullies also indicate the erosion of continental slope around the Island. All
these features seem to be controlled by the ocean current patterns in the region.
76
S3-11: Changes in the source areas of the river sediments in the
southwestern margin of the Tarim Basin during the last 8 m.y.:
Comparison between Aertashi and Yecheng sections
Akinori KARASUDA (University of Tokyo), Ryuji TADA, ZHENG Hongbo, Yuko
ISOZAKI, Shin TOYODA, Hitoshi HASEGAWA, Tomohiro YOSHIDA, Naomi
SUGIURA
The Taklimakan Desert is the second largest sand desert in the world, and its
formation is obviously related to the desertification process of Asian interior.
However, our recent study also revealed potentially important role of sediment supply
from surrounding rivers that, in turn, is closely linked to tectonics (e.g., Tada et al.,
2010; Zheng et al., 2000). In spite of such importance, there are few researches about
palaeo river system in the Tarim Basin. This presentation focuses on terrestrial
sedimentary sequences exposed at the Aertashi and Yecheng sections in the
southwestern part of the Tarim Basin covering the last ca. 8 m.y.
At present, the Yarkand River, whose chatchment area includes the middle part of
the Karakoram Mountains, flows near the Aertashi section and a river, whose
catchment area is in the frontal mountains of the Kunkun Mountains, flows through
the Yecheng section. However, the river system in this area seems to have been
different in the past (Zheng et al., 2010).
In this research, we conducted measurements of Electron Spin Resonance (ESR)
signal intensity and crystallinity of quartz in the coarse silt fraction of the fluvial,
alluvial, and eolian sediments of these sequences in order to examine possible
changes in provenance of river sediments during the last 8 m.y. ESR is an analytical
technique to estimate the amount of oxygen vacancy in quartz formed by natural
radiation, which shows positive correlation with the age of the host rock. Crystallinity
of quartz reflects the physical conditions of formation of quartz. Therefore, these two
parameters give us information on two different characteristics about the host rocks.
Our preliminary result revealed that the ESR signal intensity of quartz in the
coarse silt fraction of fluvial sediments is about 10 between 8 to 5.9m.y in Yecheng
section, increases10 to 15 after 5.9m.y, and decreases 15 to 8 in 3 m.y. Between 8
to 4.5 m.y., the ESR signal intensity of Aertashi section is similar with Yecheng
Section, but differs after 4.5 m.y. The ESR signal intensity of Aertashi section
decreases 15 to 10 in 4.5 m.y. and decreases 10 to 1 in 3.1 m.y. From this result, river
catchment areas were the same in Aertashi and Yecheng section between 8 to 4.5 m.y.
and river’s catchment area in Aertashi section changed after 4.5 m.y. We suggest that
this change was triggered by palaeo-Yarkand river whose catchment area includes
the middle part of the Karakoram Mountains.
77
S3-12: Detrital zircon U-Pb ages and provenance study of Cretaceous
sediments near Nanjing
WEI Xiaochun (Nanjing Unv.), ZHENG Hongbo (Nanjing Unv.), LI Ling (Nanjing
Unv.), HE Mengying (Tongji Unv.)
The formation and evolution of the Yangtze River attracts much attention from
geologists. Previous evolution model proposed the ancient Yangtze River was
composed of several sections, which gradually joined as a whole with the tectonic
evolution. However, several key processes in the evolution history of Yangtze River
such as the time of the final perforation are still under debate. Existing evidence
suggests that the topography in the late Cretaceous was different from the present
topography of China，which is low in the east and high in west. Mainly reflecting in
these aspects: the Tethys Sea in Tibet was not completely closed, there might be sea
water in the Sichuan Basin, Jianghan-Dongting basin and North Jiangsu Basin is
separated by ancient Qinling-Dabie Mountains. Therefore, the source of the
sediments of Nanjing area in the Late Cretaceous might only be derived from the
highland around the basin. Source tracking from the river sediments is an important
method to research on drainage system evolution. The Late Cretaceous sediments can
provide an important background that is crucial to accurately understand the
significance of the Cenozoic sediments.
Three samples are collected from the southwestern margin of North Jiangsu Basin.
There are sandstone of Pukou Group at Yanziji, sandstone of Pukou Group at
Dianjiangtai and sandstone of Chishan group at Lingyanshan.
With the advantages of stability, strong resistance to weathering, high isotopic closure
temperature of U-Th-Pb, the study of detrital zircon age is one of the best methods to
trace provenance of the sediments. The results of the U-Pb ages of the samples
mentioned above show that the late Cretaceous sediments in three different places
have similar zircon age.
The peaks of detrital zircon U-Pb age pedigree chart of each sample are listed as
follows:
(1) Lingyanshan, 127 Ma, 289 Ma, 456 Ma, 739 Ma, 1970 Ma.
(2) Dianjiangtai, 127 Ma, 262 Ma, 425 Ma, 771 Ma, 1964 Ma.
(3) Yanziji, 123 Ma, 279 Ma, 446 Ma, 761 Ma, 1990 Ma.
The similar characters of the detrital zircon U-Pb age pedigree chart indicate that the
provenance in the Late Cretaceous is similar. The dispersive zircon ages suggest that
the sources of zircon are complex. However, the number of zircons in Late
Cretaceous is large and more concentrated, reflecting that the source is relatively
restricted. Therefore, in view of the thick conglomerate on the section, we can
conclude that the provenance of sediments possibly is the Cretaceous rocks exposed
extensively near Nanjing. As for the other zircons, they may be derived from the
ancient sedimentary rocks’ recycling.
Key words: cretaceous, detrital zircon, U-Pb age, provenance
78
S3-13: Provenance of magenetites in Quaternary Sediments in
Yichang Area and Its Significance to Formation of YangtzeThree
Gorges
Tian Xin，Xiang Fang (Institute of Sedimentary Geology，Chendu University of
Technology， Chengdu 610059， China)
The compositions of the magenetites in the Quaternary sediments found in the
Yichang area of Hubei province were analyzed by electron microprobe. On the basis
of the research data of regional geology, the provenance of the Quaternary sediments
in the Yichang area can be analyzed.
The magenetites came from the sections of 015，017，021，022，024，025，
YC02，00B and 060 in the Yichang area. Field reaseach and ESR dating results
indicate that sections of 015,021, 017,022 and 024 were from the alluvial fan and
fan-delta sediments of the Yunchi Group and Shanxiyao Group before 0.73 Ma. The
section 025 was the present riverbed sediment and the sections of 00B, YC02 were
the fourth and fifth fluvial terraces after 0.73Ma. The section 060 was the granites of
Huangling dome. We selected the magenetites from sediments with grain size of
0.063 ~ 0.125mm , and picked out some of them with different round, grain type and
size by binocular eyepiece and analyzed by electron microprobe and backscatter
images. The research analyzed 9 samples of 220 magenetites, tested 15 kinds of oxide
content: FeO、SiO2、MnO、MgO、CaO、TiO2、Al2O3、Cr2O3、V2O3、SO3、ZnO、
NiO、P2O5、Nb2O5、Ta2O5.
We classified all samples by lithology in accordance with the titanium-iron oxide
content of igneous, the result showed the provenance was complicated. The result of
cluster analysis according to the element composition of the magenetites shows that
most samples from sections of 015,017,021,022,024 and 060 were classified in the
same category. This indicates sediments from sections of 015,017,021,022,024 and
060 came from the same place, and the mother rock was mainly the granite in the
Huangling dome east. At the same time, there are some other categories in the
sections of 015,017,021,022,024. From the research data of regional geology, we can
find the provenance may be the basalt and andesite located in the Huangling dome
and Dragon Dyke area.
Some samples from the sections of 025, 00B, YC02 were classified in the same
category with secions of 015, 017, 021, 022, 024 and 060, indicating the mother rock
was mainly the granite in the Huangling. In addition, there are three categories that
did not include samples of sections of 015,017,021,022 and 024, indicating their
provenance are similar to each other but different from the Yunchi Group and
Shanxiyao Group. Compared with the element geochemistry of E’mei mountain
basalt and Panzhihua vanadic titanomagnetite ore, it can be found that they had the
similar chemical characteristics. In addition, from the backscatter images, it can be
found magenetites from the sections of 025and 00B have homogeneous structure as
well as some exsolution intergrowth structure of titanomagnetite, titanium-iron spar
and lmenite, which formed by dissolving in specific high temperature. At the same
time, the complex categories of samples from the sections of 025, YC02 suggest their
provenance was complicated. This is consistent with the fact that the sections of 025,
YC02 were the sediments from present Yangtze River.
From above discussion, a conclusion can be drawn that the compositions of the
magenetites from alluvial fan and fan-delta sediments of the Yunchi Group and
Shanxiyao Group before 0.73 Ma were different from which form the fluvial terraces
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after 0.73 Ma. This result proves that the provenance of the Quaternary sediments in
the Yichang area was different before and after 0.73Ma, which indicates there was no
the Yangtze River cutting through the Three Gorges before 0.73 Ma.
Key words: Yichang; Quaternary; magenetites; Provenance; Yangtze Three Gorges;
cutting through time
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S3-14: LA-ICP-MS U-Pb geochronology of zircons in the Quaternary
sediments from the Yichang area of Hubei Province and its
provenance significance
XIANG Fang1 TIAN Xin1 LI ZhiHong2 and LU Lai1
1
Institute of Sedimentary Geology ， Chendu University of Technology, Chengdu
610059, China
2
Xi’an Land and forestry Resources and Environment Information Engineering Co.,
Ltd., Xi’an 710075, Chian
The cutting through of Yangtze Three Gorges recently was considered as the event in
Quaternary Period, but there still has some diversity in the concrete time of cutting
through. Therefore we take the Yichang area in the west edge of Jianghan Basin as
research area, which is close to the outlet of the Three Gorges and has the entire
Quaternary strata and preferable outcrop. By the detailed research of the sedimentary
characters of Quaternary deposits, combing with the ESR dating data, a conclusion
can be drawn that Yunchi Group is sediments of alluvial fan and fan delta；the lower
part of Shanxiyao Group is sediments depositing in fan delta, but the upper part is
lacustrine sediments; thereafter Shanxiyao Group was exposed and , and laterization
took place. We select the profiles of 015, 024, 053, 00B, which respectively represent
Yunchi Group, Shanxiyao Group,the fifth level terrace and fourth level terrace of
Yangtze River, and research mineralogy characteristics and date LA-ICPMS U-Pb
ages of detrital zircons of sandy matrix in gravel layer of this four sections. According
to these researches, we found that the zircons in the older sediments of the profiles of
015 and 024 mainly derived from Huanglin Dome, Wudang Block, which lie in the
east of the Three Gorges, and little derived form Miaochuan area which in the border
between the Hubei Province and Shanxi Province, and little derived from Huarong
area in the border between the Hunan Province and the Hubei Province. These zircons
all derived from are in the east of the Three Gorges, and there was no characteristic
magmatic zircon from the E'meishan Basalt. But the zircons in sediments of the fifth
and sixth level terraces of Yangtze River contain not only the material deriving from
the east area of the Three Gorges ementioned abov, but also materials from exposed
magmatic rocks in the west of the Three Gorges: Micang Mountain-Daba Mountain
area, Longmen Mountain-Panzhihua area and Batang-Dege area in Sichuan west, as
well as some characteristic magmatic zircons from the E'meishan Basalt. Thereby, we
confirmed that the sediments represented by profiles of 015、024 are not the products
of the Yangtze River terraces as predecessors thought, and the cutting through time of
the Yangtze Three Gorges should after the end of sedimentation of the profile 024,and
before depositing of the profile 053, so the cutting through time of the Yangtze Three
Gorges should be later than 0.75Ma
Key Words Yichang area；LA-ICP MS U-Pb dating of zircons；provenance analysis；
cutting through time of the Yangtze Three Gorges
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S3-15: Terrestrial biomarker analysis and its significance for the
reconstruction of paleovegetation and paleoclimate in the Cretaceous
Yezo Group, Hokkaido, Japan
Hideto NAKAMURA, Ken SAWADA (Hokkaido Univ), Reishi TAKASHIMA
(Tohoku Univ.)
We analyze terrestrial higher plant terpenoid (HPT) biomarkers and combustion
derived polycyclic aromatic hydrocarbons in the sediments of Cretaceous Yezo Group,
to reconstruct variations in terrestrial plant community and environmental conditions
in the eastern margin of the Asian subcontinent. The HPTs such as sesqui-, di- and
triterpenoid are major constituents of plant resin, cuticle and supportive tissues. These
groups possess different taxonomic origin (i.e. gymnosperms and angiosperms), and
structural characteristics of HPTs better survive thermal maturation compared to that
of the other terrestrial plant-derived compounds, lignin and long-chain alkyl
compounds. Therefore, HPTs preserved in ancient sediments have been proposed as
useful tool for reconstruction of palaeovegetational and palaeoclimatic conditions (e.g.
[1,2]).
The sediments studied comprised 24 mudstone and 2 tuffaceous sand stone
sampled along the outcrop of the Tengu-sawa Valley in the Oyubari area, Hokkaido.
Palaeovegetation and palaeoenvironment trend through the Early- to Mid-Cretaceous
in the studied area remain largely ambiguous, because of rare occurrence of
morphologically well-preserved fossils and limited number of palynological reports.
The Early Cretaceous is an interval of the early evolution and expansion of
angiosperm. The angiosperm fossil hitherto reported from Albian in the Lower
Cretaceous of the Yezo Group. Powdered samples were ultrasonically extracted by
methanol, methanol/dichloromethane, and dichloromethane. The lipid extract was
separated by silica gel column to four fractions. Aliphatic lipid and aromatic lipid
fractions were analyzed by GC/MS.
The maturity indices show almost constant value through the studied section,
indicating the early catagenesis stage. The C27 / (C27 + C29) sterane values (approx.
0.35), high Pristane/Phytane ratio (ca. 4.0) indicate predominance of terrestrial
organic matter, which is concordant to previous reports by maceral analysis and
elemental analysis. We could identify the HPTs such as cadalene (sesquiterpenoid),
abietane type diterpenoids and oleanane type triterpenoids, as well as combustion
derived polycyclic aromatic hydrocarbons in the aromatic fraction. The angiosperm
gymnosperm index (ar-AGI) was calculated by ratio of total aromatic triterpenoids to
the sum of total aromatic angiosperm triterpenoids and total gymnosperm diterpenoids,
as molecular indicator of angiosperm /gymnosperm vegetation [2]. Higher plant
parameter (HPP) was also calculated in formula [retene / (retene + cadalene)], which is
proposed to reflect conifer vegetation [1]. The Ar-AGI values generally increase
during the Albian (0.01–0.38), which suggests that angiosperm vegetation expanded
in the hinterland, while HPP values remain high (ca. 0.8) indicating that
gymnosperms were dominant throughout the Early Cretaceous. In addition, we report
that the changes in the HPT compositions were not uniform trend, but also exhibit
significant short timescale variations. Because palaeobotanical and climatic
information are only available in much lower temporal resolution, change in the
paleo-aridity / humidity is inferred from the variation in d13Ccarbonate*wood using
previously reported carbon isotopic profiles [3]. From the result, significant variety
recorded in HPTs and PAHs in the Lower Cretaceous of the Yezo Group in this study
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suggested to reflect vegetational change under environmental variation such as
aridity/humidity.
References
[1] Hautevelle, Y., R. Michels, M., Malartre, F., Trouiller, A. (2006) Org. Geochem.,
37(5), 610-625.
[2] Nakamura, H., Sawada, K., Takahashi, M (2010) Org. Geochem., 41(9), 975-980.
[3] Takahashi, K., Hirano, H. (2003) Fossils, 74, 63-75
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