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PALEOCEANOGRAPHY, VOL. 24, PA1210, doi:10.1029/2007PA001567, 2009
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Discrimination of sources of terrigenous sediment deposited
in the central Arctic Ocean through the Cenozoic
Nahysa C. Martinez,1 Richard W. Murray,1 Gerald R. Dickens,2 and Martin Kölling3
Received 2 November 2007; revised 25 September 2008; accepted 13 October 2008; published 18 February 2009.
[1] We analyzed a suite of sediment samples recovered in the central Arctic Ocean for major, trace, and rare
earth elements in order to assess changes in terrigenous source material throughout the Cenozoic. The
terrigenous component consists of two end-members. Input from a shale-like composition dominates bulk
sediments, especially those deposited during the Paleocene and since the Miocene, and may represent sediment
supply from the eastern Laptev Sea. Therefore, even though the environment and transport mechanisms may
have varied from ice free to ice dominated, sequences of the early Paleogene and later Neogene appear to have
been influenced by a single major terrigenous source. This suggests similar transport capabilities and trajectories
for both ocean and drift currents through significant parts of the Cenozoic. Influence from a more mafic source
appears to be more important through the early Eocene to the middle Miocene and most likely represents
material from the western Laptev Sea or Kara Sea. Thus, Eocene major changes in surface water productivity
appear broadly synchronous with those in terrigenous provenance. A combination of regional sea level
variations, local shelf processes, and transport mechanisms are among the more probable causes for the observed
source changes. Although the assignment of sources using chemistry presently is constrained by a lack of data
from certain regions (e.g., eastern Siberian Sea) our results generally agree with inferences based on mineralogy
or radiogenic isotopes and shed further light on long-term reconstructions of the central Arctic Ocean.
Citation: Martinez, N. C., R. W. Murray, G. R. Dickens, and M. Kölling (2009), Discrimination of sources of terrigenous sediment
deposited in the central Arctic Ocean through the Cenozoic, Paleoceanography, 24, PA1210, doi:10.1029/2007PA001567.
1. Introduction
[2] The Arctic Ocean (Figure 1) likely drove and responded
significantly to global climate throughout the Cenozoic
[Aagaard and Carmack, 1994; Spielhagen et al., 1997;
Darby et al., 2002; Backman et al., 2004]. Because the
Arctic may sensitively respond to future global climate
change as well [Walsh, 1991; Winter et al., 1997], an
improved understanding of Arctic Ocean paleoceanography
should lead to a better definition of the role of the Arctic in
global climate and ocean dynamics.
[3] Sediments in the central Arctic Ocean, particularly
those on top of structural highs (e.g., Lomonosov Ridge)
provide records of change in the region. Many researchers
have explored the Plio-Pleistocene Arctic history by studying shallow piston cores [e.g., Winter et al., 1997; Clark et
al., 2000; Jakobsson et al., 2001; Polyak et al., 2004]. A
significant portion of this paleoceanographic research has
focused on assessing changes in the source and transport
of terrigenous material [e.g., Bischof et al., 1996; Bryce et
al., 1997; Clark et al., 2000; Darby et al., 2002; Phillips
and Grantz, 2001; Rachold, 1998; Schoster et al., 2000;
Spielhagen et al., 2004]. These chemical, mineralogical,
1
Department of Earth Sciences, Boston University, Boston, Massachusetts,
USA.
2
Department of Earth Sciences, Rice University, Houston, Texas, USA.
3
Department of Geosciences, University of Bremen, Bremen, Germany.
Copyright 2009 by the American Geophysical Union.
0883-8305/09/2007PA001567$12.00
sedimentological, and/or isotopic studies have identified
northern Siberia, northeast Siberia (including Chukchi
Sea), and northern Canada, as the three main source areas
for terrigenous supply. Discrimination between these possible sources has been used to infer changes in circum-Arctic
land and shelf processes (e.g., ice sheet history), Arctic
circulation, and their potential forcing(s) [e.g., Bischof et al.,
1996; Bryce et al., 1997; Clark et al., 2000; Darby et al.,
2002; Phillips and Grantz, 2001; Rachold, 1998; Schoster
et al., 2000; Spielhagen et al., 2004].
[4] Until recently, the pre-Quaternary history of the Arctic
Ocean remained poorly constrained because of logistical
and technological limitations that precluded drilling in
moving sea ice. Integrated Ocean Drilling Program (IODP)
Expedition 302, also known as the Arctic Coring Expedition
(ACEX), cored multiple holes on the Lomonosov Ridge. In
total, ACEX recovered significant portions of an 430 m
Holocene to Late Cretaceous record, albeit discontinuously
because of several unconformities and coring gaps. The
Cenozoic record shows the central Arctic Ocean to have
been warm, ice free, and productive during the Paleocene to
middle Eocene; cool with some ice in the middle Eocene
( 45 Ma); and following a major hiatus, cold and ice
covered from the middle Miocene to present day [Moran et
al., 2006; Stein et al., 2006]. The isotopic, sedimentologic,
and mineralogic composition of the ACEX record has also
provided new insights into provenance changes that are
being used to further explore the history of the Central
Arctic [Haley et al., 2008; Krylov et al., 2008; St. John,
2008; Darby, 2008], as will be discussed further below.
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Figure 1. Map of the Arctic Ocean and surroundings. Also shown are the Beaufort Gyre (BG), the
Transpolar Drift (TD) and the main potential terrigenous source areas. The square box shows the location
of the ACEX site. Modified from Jakobsson et al. [2000].
[5] Preliminary results from the Lomonosov Ridge,
obtained by us during the onshore portion of ACEX, show
that the chemistry of the sediments closely reflects the major
lithological changes (Figure 2) [Backman et al., 2006a]. The
distribution of various elements identify an upper siliciclastic rich Unit 1 (U1), an intermediate biosiliceous organic
rich Unit 2 (U2), an upper, organic rich part of Unit 3
(subunit 3/1 of U3), and the lower part of a siliciclastic rich
unit 3 (subunit 3/2 of U3). Major changes in detritally
associated elements through U2 and subunit 3/1 were
interpreted as recording a potential change of terrigenous
sources [Backman et al., 2006a]. Here we have measured
additional trace and REE data in a subset of the Arctic
Coring Expedition (ACEX) samples. Using both data sets,
we apply a multielemental proxy and multivariate statistical
approach in order to further characterize the inorganic
geochemistry of the sediments, and to identify the possible
source areas and/or transport pathways of terrigenous matter
in the central Arctic through the Cenozoic.
2. Background
[6] Presently, sea ice covers most of the Arctic Ocean
throughout the year, except for surrounding shelves, which
become ice free during the summer [Spielhagen et al.,
2004]. Arctic rivers deliver terrigenous material to these
shelves; sea ice entrains this sediment and transports it
across the Arctic Ocean by two main drift patterns, the
Beaufort Gyre and the Transpolar Drift (TPD) [Nürnberg et
al., 1994; Dethleff et al., 2000; Schoster et al., 2000].
Various studies have identified three broad areas for the
source of the terrigenous material deposited in the Arctic
Ocean. These are North Siberia, Northeast Siberia and
Chukchi Sea, and North Canada. Some of the diagnostic
geochemical and mineralogical characteristics of these areas
are broadly constrained (Table 1). However, there are very
few (or no) published works based on multielemental data
sets of particulates from areas such as the McKenzie River
(and/or Canadian platform), the Chukchi and North Siberian
Sea, and even for the Kara Sea (Ob or Yenisei rivers).
[7] Recent publications by ACEX participants have investigated sediment source changes during the Neogene and
the top part of the Paleogene. Haley et al. [2008], for the
relatively young part of the record (15 Ma, subunits 1/1 to
1/4), found the Sr-Nd isotopic composition of the bulk
sediments to be most similar to sediments from the Eurasian
shelf, and thus proposed predominant supplies of terrigenous material from this source area for the last 15 Ma.
Krylov et al. [2008] investigated the clay and heavy mineral
composition of sediments for the last 50 Ma (U1 and U2)
and found sediments deposited prior to 14 Ma rich in
clinopyroxene and smectite, whereas those deposited after
13– 14 Ma were rich in hornblende and illite. This was
interpreted as a switch from a western Laptev-Kara-Barent
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Figure 2. Depth profiles of major and trace elements. Gray triangles are Boston University data. Black
dots are Bremen data. Vertical dashed lines represent PAAS values. Horizontal dashed lines show the
limits of the major lithoestratigraphic units as well as subunits 1/4, 1/5, and 1/6, and the major hiatus
between 1/5 and 1/6. Horizontal gray solid line shows the bottom of the authigenic silica unit, which is
lithologically (but not chemically) different from Unit 2. Profiles for Si, S, and Cl correspond to the
Bremen data set [Backman et al., 2006a]. (right) A schematic stratigraphic column, showing the four
lithostratigraphic units is shown. Age estimates as in the paper by Backman et al. [2008]. (left) Depth of
the stratigraphic sequence.
Sea to eastern Laptev – Eastern Siberia sources during the
middle Miocene. St. John [2008], in a study of the composition and physical properties of IRD over the last 47 Ma,
agrees with an overall Russian source, without differentiating between Western and Eastern Siberian sources. Finally,
Darby [2008], using the composition of Fe oxide grains on
IRD deposited over the last 14 Ma, suggested that for this
time period shelves of both Siberia and North America
(especially, the Canadian Islands) were important sources of
sediments to Lomonosov Ridge.
3. Sites and Samples
3.1. Arctic Coring Expedition
[8] ACEX recovered sediments from five holes at four
sites on the central Lomonosov Ridge, approximately
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Table 1. Summary of Geochemical and Mineralogical Characteristics of Some Circum-Arctic Regionsa
Sea/River
E. Laptev Lena/Yana
W. Laptev Khatanga
Kara Sea
Indigirka and Kolyma
(East Siberian Sea)
Chukchi Sea
Mckenzie River
Area/Lithology
Geochemistry Mineralogy
North Siberia (Taymir Peninsula)
Siberian Platform: Cambrian/Precambrian
Shale-like and UC composition. High illite
limestones, Jurassic/Cretaceous
and chlorite, low smectite and kaolinite
terrigenous sediments, Quaternary
(compared to W. laptev)
alluvial sediments. Baikal folded region:
Proterozoic metamorphic rocks. Verhoyansk
Mountains: Paleozoic terrigenous. Triasic
and Mesozoic volcanics and granitoids
Siberian trap flood basalts (Permian/Triassic). High Cr/Al, Ti/Al, Ca/Al, clynopiroxene,
Aldan highland: Archean/Proterozoic
and smectite. Low illite and chlorite
igneous and metamorphic rocks.
(compared to E. Laptev). Enriched in
Ca, Co, Cu, Fe, Mg, Ni, Ti, and V.
Putorana Mountains (part of the Siberian
Similar to W. Laptev but more enriched
traps)
in smectite, Ni/Al, Cr/Al, Ti/Al, and
with lower values of K/Al
Kolyma-Omolon: accretionary continental
and island arc fragments. Verhoyansk
Mountains superterrrain: Paleozoic
terrigenous.
Chukotsk volcanic belt: felsic to mafic
volcanics Chukotka terrain: indistinguish
sedimentary rocks. Alaska: sedimentary
rocks and accreated volcanic terrains.
Sverdrup Basin, Mckenzie River Valley,
Coronation Gulf
Banks, Victoria, Queen Elizabeth Islands:
early Paleozoic terrain.
East Siberian
Composition similar to average shale
Basaltic-like composition. High Mg,
illite, and chlorite. Smectite content
lower than W. laptev or Kara Seas
Northern Canada
Noncarbonate clasts. Abundant kaolinite
and less smectite than North Siberia
areas
Carbonate-rich sediments
Reference
Rachold [1998], Dethleff et al.
[2000], Schoster et al. [2000],
Viscosi-Shirley et al. [2003]
Rachold [1998], Dethleff et al.
[2000], Schoster et al. [2000],
Viscosi-Shirley et al. [2003]
Schoster et al. [2000]
Viscosi-Shirley et al. [2003]
Viscosi-Shirley et al. [2003]
Bischof et al. [1996],
Spielhagen et al. [1997],
Phillips and Grantz [2001],
Viscosi-Shirley et al. [2003]
Bischof et al. [1996],
Spielhagen et al. [1997],
Phillips and Grantz [2001],
Viscosi-Shirley et al. [2003]
a
UC, upper cust.
250 km from the North Pole [Backman et al., 2006b].
Samples and data from the holes have been integrated into
a single composite sequence [Backman et al., 2006b], which
has been assigned a ‘‘revised composite depth scale’’ (rmcd)
[O’Regan et al., 2008b]. The total composite section
sequence comprises 428 m of Holocene to Upper Cretaceous
sediments and has been divided into four lithostratigraphic
units (Figure 2) [Backman et al., 2006b]. Briefly, Unit 1
(Holocene to middle Eocene; 0 – 223.56 rmcd) consists of
siliciclastic material with abundant silty clays, silty muds
and clayey silts. Numerous sandy lenses and isolated
pebbles were interpreted as fallout from IRD [Moran et
al., 2006]. Near the bottom of this unit (200 rmcd), there is a
major hiatus, represented by very slow or no deposition, or,
indeed, erosion [Moran et al., 2006; Stein et al., 2006].
Unit 2 (middle Eocene; 223.56 – 313.6 rmcd) consists of very
dark gray and black mud composed primarily of mudbearing biosiliceous ooze with abundant pyrite and elevated
total organic carbon (TOC, up to 2 – 3 wt%, compared to
TOC < 0.5 wt% for most of Unit 1). The first occurrence of
dropstones, among other observations, suggests the initiation of the transition between the ice-free (at least seasonally) and ice-covered Arctic waters [Moran et al., 2006].
Unit 3 (late Paleocene to early Eocene; 313.6 – 404.79 rmcd)
consists of clays and silty clays with variable amounts of
pyrite, siliceous material, and TOC that generally decrease
from top to bottom. The PETM (55 Ma) has been
recognized at 385 rmcd on the basis of the presence of
Apectodinium Augustum (dinocyst biomarker) and a prominent negative carbon isotope excursion [Sluijs et al., 2006].
Sea surface temperatures (at least during the summer) were
as high as 24°C, supporting ice-free conditions [Sluijs et al.,
2006]. Unit 4 (Late Cretaceous; 404.79 – 427.63 rmcd)
comprises silty clays and silty sands and is considered to
be transitional to bedrock. The top of this unit is an
unconformity.
3.2. Samples, Methods, and Data
[9] Two data sets are considered in this work. We first
analyzed 156 discrete 10 cm3 samples of bulk sediment at
the Department of Geosciences, University of Bremen,
Germany, during the ‘‘onshore’’ component of ACEX
[Backman et al., 2006c]. For these samples 48 major and
trace elements were measured by energy dispersive X-ray
fluorescence (Text S1).1 This set of samples spans the entire
sedimentary sequence at a nominal spacing of 3 m, with
some intervals at higher resolution.
1
Auxiliary materials are available in the HTML. doi:10.1029/
2007PA001567.
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We also processed and analyzed 64 discrete 10 cm3
samples of bulk sediment in the Analytical Geochemistry
Laboratory at the Department of Earth Sciences, Boston
University (Text S1). Forty elements were measured
(Table 2a – 2b) by Inductively Coupled Plasma Emission
Spectrometry (ICP-ES) and by Inductively Coupled Plasma
Mass Spectrometry (ICP-MS). These samples also span
the entire sedimentary sequence and 40 of them are exact
splits of the samples previously prepared and analyzed at
Bremen. The purpose of these analyses was to measure
additional trace elements, especially the REEs, which are
important for discriminating sedimentary provenance [e.g.,
Olivarez et al., 1991; Ziegler et al., 2007, and references
therein].
[11] The first data set (Bremen) is used in this work
mostly when exploring chemical changes through the
overall sedimentary sequence. Data tables, figures, and
further discussion regarding this data can be found in the
postcruise report [Backman et al., 2006a]. The second data
set (Boston University) is used here specifically for terrigenous source discrimination.
[10]
4. Multivariate Statistics: Q-Mode Factor
Analysis
[12] The combined geochemical data set was analyzed
using multivariate Q-mode factor analysis. We took two
approaches. First, the elements Al, Ca, Cl, Co, Mn, Ni, P,
Rb, S, Si, and Ti, which collectively represent a wide
variety of sediment components, were used to statistically
define the sedimentary components. Second, a different
suite of elements, including Al, Hf, K, La, Rb, Sc, Th, Ti,
and Zr, all of which are commonly associated with the
terrigenous component(s), were selected to investigate
potential terrigenous source changes. Factor analysis techniques are summarized in Text S1 and are very similar to
those used by Martinez et al. [2007]. Our interpretations are
based on the resultant factor scores (the weight of each
element on the discrimination of a single factor), compositional factor scores (the elemental composition of each
factor), and square factor loading (the contribution of each
factor to a single sample). In many cases care needs to be
taken when interpreting compositional factor scores, since
their actual values cannot always be matched directly to
known sources. The most important strategy when using
these composition scores is to pay attention to the relative
‘‘high’’ or ‘‘low’’ values of the elements and interelemental
ratios between the factors (e.g., knowing that Factor X has
the highest Ti/Al value of all factors is as (or, perhaps,
more) meaningful than knowing the actual value).
5. Results and Discussion
[13] A first examination of the Boston University data
confirms the main results obtained at Bremen University.
Comparing those elements analyzed at both laboratories, the
same patterns are found, although absolute values differ
slightly (Figures 2, 3, and S1). A major difference was
found when comparing some elemental ratios (e.g., Ti/Al,
K/Al, Mg/Al, Rb/Al, and Th/Al). The preliminary results
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obtained at Bremen University show the highest contents of
these detrital elemental ratios from 220– 350 rmcd. The
new data, however, do not record the same relative increase
(see Section 6.1 and Figures 3 and S1) with the exception of
La/Al, and Sc/Al (not analyzed in Bremen). We work with
the newer data set when exploring changes in source
material because the ICP-generated results are more analytically constrained. However, for understanding the entire
sequence, both data sets are considered, as this gives a better
stratigraphic resolution. We have not mixed the data sets for
statistical analysis, and for each case we have specified
which data set is used and why.
5.1. Element Profiles: Overall Sequence
[14] Unit 1 is dominated by terrigenous material (>80 wt%)
and shows a shale-like composition. Elements such as Si, Al,
Ti, K, Zr, Rb, Sc, La (and other REEs), Th, and Hf, which are
commonly associated with the detrital component, display
values similar to Post Archean Australian Shale (PAAS)
[Taylor and McLennan, 1985] (Figure 2). This is consistent
with the initial observations [Backman et al., 2006a].
[15] Unit 2 and the top of Unit 3 are generally dominated by
biosiliceous material (silica and organic matter), although the
proportions and composition vary. The terrigenous material
decreases considerably (averaging 30 wt%), because of
dilution, and most detrital elements deviate significantly
from PAAS. Si has its highest content because of the
abundance of biosiliceous material (223.56 –313.6 rmcd)
and authigenic silica (313.6 – 350 rmcd). Similarly, Cl and
Br values are elevated [Backman et al., 2006a]. The Cl
increase is consistent with the relative high halite in Unit 2
(as observed by XRD [Backman et al., 2006a]). Between
220– 350 rmcd, despite the abundance of pyrite [Backman
et al., 2006a], a relative decrease of Fe and S, with respect
to the top 20 m of Unit 2, again reflects dilution by the
biogenic and organic material. Because ratios are unaffected
by dilution, the high Fe/Al for the entire section between
200 and 350 rmcd reflects the high abundance of pyrite in
this section. The increase of P/Al in Unit 2 reflects the
common association of P and the biogenic component of
sediments. Similarly, high Ca/Al reflects the relative abundance of gypsum and to a lesser extent the rare calcite
[Backman et al., 2006a]. The major break in elemental
contents occurs at 350 rmcd and not at the boundary
between Unit 2 and Unit 3 (Figure 2).
[16] The bottom of Unit 3 (350– 404.79 rmcd) is again
dominated by terrigenous material. Most elements and
elemental ratios show contents or values similar to those
of Unit 1 (Figures 2 and 3), which is consistent with the
similarities of terrigenous abundance ( 80 wt%) and
lithology.
5.2. Q-Mode Factor Analysis: Overall Sequence
[17] To identify the broad occurrence of sedimentary
components, we chose a set of elements that proved (by
the correlation matri (Table S1) to be critical in representing
the various components present in the sediments. Thus, the
elements Al, Rb, Ti, S, Cl, Mn, P, Co, Ni, Si, and Ca were
used for the analysis. Q-mode factor analysis yielded five
factors that explain 97% of the data variability.
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Table 2a. Major and Trace Element Concentrations, Integrated Ocean Drilling Program From Arctic Coring Expedition 302
Sample
4C-01H-1W 20 – 22
4C-01H-2W 84 – 86
4C-02H-2W 64 – 66
3A-01H-4W 24 – 26
4C-03H-3W 44 – 46
2A-05X-2W 5 – 7
4C-06X-2W 56 – 58
2A-06X-2W 52 – 54
2A-07X-1W 114 – 116
2A-08X-1W 44 – 46
2A-10X-2W 070 – 72
2A-11X-2W 60 – 62
2A-12X-3W 57 – 59
2A-12X-3W 57B – 59
2A-14X-3W 44 – 46
2A-16X-2W 90 – 92
2A-17X-2W 8
2A-20X-1W 44 – 46
2A-20X-2W 25 – 27
2A-20X-3W 114 – 146
2A-22X-1W 2 – 4
2A-25X-2W 25 – 27
2A-26X-2W 44 – 46
2A-29X-2W 25 – 27
2A-30X-1W 44 – 46
2A-30X-2W 25 – 27
2A-30X-3W 44 – 46
2A-32X-2W 25 – 27
2A-32X-2W(25B)
2A-32X-4W 44 – 46
2A-33X-2 143 – 150 SQC
2A-34X-2W 44 – 46
2A-35X-2W 25 – 27
2A-35X-5W 44 – 46
2A-38X-4W 44 – 46
2A-42X-2W 62 – 64
2A-44X-2W 44 – 46
2A-48X-3 140 – 151 SQC
2A-49X-5W 44 – 46
4B-03X-2W 64 – 66
4B-03X-2W 64A – 66
2A-52X-2W 4 – 6
2A-53X-2W 80 – 82
2A-55X-2W 80 – 82
2A-56X-2W 80 – 82
2A-57X-2W 80 – 82
2A-61X-2 80 – 82
2A-62X-2 80 – 82
4A-08X-1W 4 – 6
4A-09X-1W 4 – 6
4A-15X-CC (Fine)
4A-19X-1 144 – 151 SQC
4A-19X-2W 66 – 68
4A-21X-2W 66 – 68
4A-23X-1 SQC
4A-23X-2W 66 – 68
4A-27X-2W 66 – 68
4A-28X-2W 64 – 66
4A-29X-1W 97 – 99
4A-30X-2 143 – 152 SQC
4A-34X-2 144 – 150 SQC
4A-35X-2W 75 – 77
4A-42X-1W 42 – 44
4A-42X-1W 42 – 44
Analytical
reproducibility (%)
Depth Al
Ti
Fe
Mn
Ca
Mg
Na
K
P
Ba
Sr
Cr
Ni
Sc
V
Zr
(rmcd) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)
0.20
2.36
5.62
8.52
12.41
20.83
22.01
22.77
27.02
30.82
41.52
45.29
50.84
50.84
57.70
66.55
70.34
81.39
82.71
85.10
90.97
107.21
111.89
124.70
128.39
129.71
131.40
136.20
136.20
139.41
142.70
145.69
149.27
153.98
164.78
179.36
188.68
205.86
212.24
215.14
215.14
221.32
223.95
231.78
237.66
242.16
261.60
266.54
273.80
278.80
313.35
313.43
314.15
322.93
334.50
335.23
361.02
365.40
369.27
374.70
390.41
394.91
418.48
418.48
8.34
7.56
7.84
8.58
7.46
8.49
8.82
8.60
7.59
7.89
8.71
8.47
8.76
8.07
6.32
7.90
8.74
8.71
8.84
7.57
8.68
9.34
9.04
8.20
8.11
6.34
8.21
9.47
9.37
8.91
9.28
8.35
9.52
9.01
9.58
9.25
9.48
6.38
7.31
6.04
7.08
3.78
4.51
2.75
3.96
3.39
3.25
3.29
3.28
3.66
2.54
2.83
4.21
2.36
3.74
2.26
8.35
9.30
8.72
8.80
10.45
9.89
8.41
8.33
4
0.520
0.539
0.468
0.503
0.494
0.520
0.504
0.540
0.496
0.507
0.514
0.499
0.513
0.514
0.519
0.541
0.519
0.517
0.507
0.532
0.522
0.517
0.535
0.479
0.527
0.522
0.498
0.529
0.539
0.543
0.511
0.488
0.537
0.497
0.511
0.495
0.505
0.378
0.424
0.355
0.384
0.219
0.244
0.149
0.221
0.178
0.153
0.157
0.155
0.158
0.116
0.124
0.187
0.099
0.164
0.098
0.417
0.616
0.485
0.378
0.569
0.585
0.712
0.699
2
5.34
5.75
4.67
5.06
5.06
6.21
6.16
5.59
5.59
5.38
4.84
5.35
5.03
5.07
5.54
6.40
6.22
5.06
5.16
4.95
5.30
4.63
4.58
4.39
4.53
4.82
5.51
3.86
3.71
4.76
6.28
7.43
6.20
7.26
6.19
6.03
2.82
8.62
8.14
8.10
8.06
4.80
5.77
4.80
5.08
4.76
5.35
5.22
5.30
6.22
4.87
5.75
6.94
4.18
5.36
3.54
7.09
4.80
2.39
9.05
3.76
3.53
4.41
4.21
1
0.286
0.307
0.149
0.288
0.089
0.097
0.079
0.458
0.059
0.140
0.200
0.690
0.269
0.269
0.096
0.189
0.072
0.028
1.097
0.029
0.180
0.071
0.169
0.051
0.029
0.026
0.051
0.026
0.023
0.037
0.083
1.090
0.240
0.086
0.682
1.011
0.027
0.031
0.029
0.025
0.025
0.093
0.092
0.088
0.078
0.073
0.078
0.075
0.071
0.082
0.050
0.062
0.074
0.055
0.063
0.042
0.012
0.019
0.018
0.137
0.018
0.022
0.069
0.067
1
4.04
0.50
0.46
0.50
0.42
0.40
0.40
0.52
0.46
0.46
0.47
0.46
0.46
0.43
0.33
0.37
0.37
0.36
0.43
0.32
0.38
0.33
0.31
0.35
0.29
0.26
0.30
0.27
0.27
0.27
0.27
0.77
0.29
0.32
0.30
0.32
0.30
0.19
0.25
0.22
0.20
0.56
0.38
0.36
0.43
0.53
0.36
0.39
0.44
0.61
0.55
0.31
0.36
0.30
0.39
0.28
0.51
0.41
0.41
0.53
0.48
0.41
0.55
0.55
1.71
1.48
1.13
1.17
1.15
1.13
1.22
1.19
1.12
1.13
1.04
1.00
1.04
1.05
0.92
1.17
0.97
1.03
1.05
1.01
1.03
1.00
0.90
0.81
0.95
0.81
0.95
1.00
0.98
0.95
0.99
1.07
0.97
0.88
0.98
0.95
0.81
0.82
0.93
0.84
0.87
0.57
0.68
0.47
0.58
0.53
0.54
0.59
0.66
0.71
0.52
0.52
0.89
0.41
0.69
0.40
0.92
1.06
0.95
1.03
0.85
0.86
0.68
0.67
2
6 of 17
1.86
1.85
1.70
1.85
1.84
1.74
1.69
1.89
1.87
1.86
1.85
1.84
1.69
1.68
1.68
1.55
1.65
1.72
1.44
1.56
1.75
1.68
1.71
1.59
1.58
1.53
1.59
1.64
1.66
1.74
1.48
1.45
1.55
1.58
1.55
1.64
1.57
0.69
0.96
0.98
1.06
1.48
1.58
1.52
1.38
1.70
1.38
1.42
1.39
1.40
0.37
0.80
1.11
0.97
0.92
0.89
1.35
1.21
1.36
1.02
0.93
1.08
0.82
0.94
1
2.15
2.07
1.90
2.08
2.10
1.99
1.89
1.92
2.02
2.05
2.14
2.03
1.99
2.02
1.87
1.93
2.00
1.94
1.77
1.97
2.05
2.05
2.01
1.74
1.84
1.73
1.85
2.02
2.08
2.02
1.97
1.86
2.08
1.92
1.85
2.10
2.22
1.07
1.31
1.07
1.17
0.98
1.07
0.61
0.81
0.89
0.66
0.76
0.58
0.62
0.45
0.60
0.85
0.55
0.85
0.52
2.47
2.31
2.34
2.48
2.91
2.57
1.66
2.10
2
0.085
0.084
0.075
0.093
0.093
0.127
0.120
0.107
0.108
0.099
0.093
0.115
0.066
0.070
0.104
0.086
0.149
0.073
0.064
0.075
0.098
0.068
0.074
0.078
0.064
0.082
0.094
0.043
0.045
0.078
0.107
0.239
0.121
0.193
0.117
0.119
0.045
0.033
0.034
0.025
0.027
0.090
0.032
0.026
0.057
0.085
0.035
0.049
0.054
0.132
0.109
0.030
0.030
0.036
0.043
0.021
0.077
0.038
0.031
0.086
0.099
0.074
0.103
0.096
3
542
545
609
638
618
599
562
665
712
678
725
676
658
663
558
663
645
701
664
649
646
617
629
690
693
636
693
794
771
681
731
630
678
603
782
648
2330
962
815
1294
1293
171
163
124
162
136
122
109
96
103
148
100
133
84
124
78
377
686
2506
579
521
536
1567
1468
212
146
161
173
133
154
153
185
171
171
193
185
176
170
114
146
156
165
149
140
153
152
151
162
136
99
133
142
142
140
141
157
142
141
183
192
217
90
110
84
92
86
76
62
75
81
62
65
60
68
48
51
65
48
66
46
231
159
171
115
122
118
113
110
129
91
105
93
80
111
106
137
75
79
100
121
98
83
79
90
128
82
80
81
80
100
109
89
195
78
76
132
84
80
114
70
115
70
71
93
77
78
101
78
99
52
72
41
54
48
42
43
45
49
34
26
45
18
34
19
110
84
83
77
98
104
101
109
9
84.5
107.0
52.5
48.8
44.1
49.8
52.0
51.2
45.9
43.2
42.0
42.8
40.2
42.0
47.6
49.4
42.2
43.5
40.7
48.3
41.9
42.0
43.9
37.9
44.5
40.7
42.5
44.4
46.1
40.9
46.7
39.1
45.0
40.4
69.1
111.5
191.9
91.0
69.4
64.9
65.7
44.8
39.7
33.1
36.4
37.2
38.0
33.5
43.5
42.0
32.3
29.2
38.5
23.8
42.6
27.3
107.5
58.3
33.2
56.0
45.7
49.2
55.7
54.0
3
16.4
14.9
14.1
15.3
12.4
15.5
16.8
15.7
13.6
14.2
14.7
14.3
14.8
13.7
11.5
15.5
16.0
16.5
16.9
12.9
15.1
16.4
15.3
13.8
14.3
10.7
15.3
16.8
15.4
16.5
17.4
17.0
19.6
17.2
17.3
19.4
38.3
16.7
20.2
15.7
19.4
11.2
13.4
8.4
12.2
11.1
9.7
10.2
9.3
10.7
7.9
6.6
10.5
4.7
8.9
4.8
23.3
18.5
16.0
17.0
18.1
17.9
17.7
17.7
5
176
194
156
179
179
166
187
230
189
207
202
170
221
227
234
222
193
291
251
263
234
248
148
231
232
231
258
235
242
249
189
166
225
157
266
273
280
159
236
179
189
147
201
134
186
169
162
164
154
155
129
77
121
56
108
63
287
244
197
182
262
269
156
156
167
178
158
181
160
169
165
177
164
178
173
181
184
167
185
175
189
172
172
186
182
188
186
164
172
186
171
201
175
203
193
184
203
186
181
181
229
132
157
129
136
101
116
68
98
90
71
67
62
65
51
55
83
43
76
44
170
184
176
145
199
207
262
264
4C-01H-1W 20 – 22
4C-01H-2W 84 – 86
4C-02H-2W 64 – 66
3A-01H-4W 24 – 26
4C-03H-3W 44 – 46
2A-05X-2W 5 – 7
4C-06X-2W 56 – 58
2A-06X-2W 52 – 54
2A-07X-1W 114 – 116
2A-08X-1W 44 – 46
2A-10X-2W 070 – 72
2A-11X-2W 60 – 62
2A-12X-3W 57 – 59
2A-12X-3W 57B – 59
2A-14X-3W 44 – 46
2A-16X-2W 90 – 92
2A-17X-2W 8
2A-20X-1W 44 – 46
2A-20X-2W 25 – 27
2A-20X-3W 114 – 146
2A-22X-1W 2 – 4
2A-25X-2W 25 – 27
2A-26X-2W 44 – 46
2A-29X-2W 25 – 27
2A-30X-1W 44 – 46
2A-30X-2W 25 – 27
2A-30X-3W 44 – 46
2A-32X-2W 25 – 27
2A-32X-2W(25B)
2A-32X-4W 44 – 46
2A-33X-2 143 – 150 SQC
2A-34X-2W 44 – 46
2A-35X-2W 25 – 27
2A-35X-5W 44 – 46
2A-38X-4W 44 – 46
2A-42X-2W 62 – 64
2A-44X-2W 44 – 46
2A-48X-3 140 – 151 SQC
2A-49X-5W 44 – 46
4B-03X-2W 64 – 66
4B-03X-2W 64A – 66
2A-52X-2W 4 – 6
2A-53X-2W 80 – 82
2A-55X-2W 80 – 82
2A-56X-2W 80 – 82
2A-57X-2W 80 – 82
2A-61X-2 80 – 82
2A-62X-2 80 – 82
4A-08X-1W 4 – 6
4A-09X-1W 4 – 6
Sample
65.9
70.1
53.8
64.5
64.9
78.7
75.0
67.2
75.9
79.9
69.3
68.6
69.3
69.3
68.1
72.3
69.4
75.9
74.5
96.6
85.9
90.0
91.3
74.5
98.2
85.3
85.7
118.9
93.0
118.7
106.4
79.2
103.3
92.3
143.0
162.0
125.3
48.9
58.4
49.4
47.0
21.4
26.7
15.4
23.7
18.5
18.6
19.2
18.2
21.2
70.6
92.7
35.0
52.1
16.8
31.6
31.6
28.1
25.2
24.4
23.6
25.6
20.6
18.7
28.3
26.8
23.4
21.6
18.3
26.7
21.7
20.0
21.9
18.0
19.6
18.4
16.1
18.4
20.2
18.9
21.7
26.3
26.2
26.1
48.1
69.6
170.7
128.4
78.6
86.4
84.6
25.9
28.6
26.8
26.6
24.2
23.9
22.6
26.9
26.1
62.9
66.7
38.0
34.5
29.4
39.3
22.3
22.5
17.6
23.5
26.1
22.3
25.0
25.0
20.5
25.9
29.2
27.4
26.5
24.4
24.2
25.8
16.0
24.9
36.7
23.7
27.2
29.1
29.3
27.2
18.9
25.1
27.4
60.4
39.4
61.8
118.6
111.6
139.5
90.5
106.4
57.6
61.1
51.1
66.8
69.7
64.5
53.0
61.0
61.3
138
129
105
109
120
113
119
113
107
110
145
104
100
106
123
112
105
119
111
107
120
175
102
93
102
113
109
167
161
107
113
100
125
114
116
135
297
234
429
168
159
111
100
106
107
122
109
102
132
127
124
123
110
120
116
125
126
114
126
125
121
123
118
119
84
116
125
114
106
121
117
117
114
98
111
80
91
106
119
116
118
103
117
109
113
122
128
99
111
102
100
52
58
31
50
41
37
35
36
38
30.31
26.96
24.80
26.59
20.03
27.74
25.23
25.90
23.73
24.68
23.42
27.00
22.69
21.53
18.71
27.28
27.37
25.40
31.61
23.03
25.76
23.34
26.24
23.93
22.68
17.42
20.85
23.41
21.22
24.85
24.90
39.75
30.28
27.98
29.92
34.73
52.14
24.17
34.68
22.57
21.88
30.73
15.71
10.95
20.77
27.36
14.05
18.12
16.46
29.50
8.08
7.57
6.33
7.32
7.44
7.46
7.41
6.19
6.87
6.74
6.35
6.34
6.32
6.40
6.63
6.60
7.26
6.39
6.41
6.99
6.83
6.88
6.77
5.15
6.56
6.32
6.03
7.16
7.37
6.96
6.90
5.99
7.08
6.63
7.43
7.36
8.40
6.41
7.77
6.53
6.52
3.98
4.51
2.58
4.12
3.63
3.81
3.58
3.10
3.36
42.31
39.49
35.22
37.00
30.32
39.61
37.62
37.75
40.11
39.28
41.19
40.30
37.90
39.24
23.96
40.25
38.25
41.87
38.01
39.37
40.05
42.22
40.83
40.15
39.32
22.45
34.28
38.93
39.48
39.52
40.27
38.92
40.51
40.18
45.91
46.64
63.39
31.23
36.33
30.17
29.38
33.98
28.14
15.63
33.10
31.89
19.11
22.85
19.45
29.54
97.46
115.42
74.38
79.85
66.31
89.05
83.44
83.15
88.60
85.73
89.28
87.08
82.91
84.35
59.44
92.36
82.85
101.26
90.22
90.70
90.45
98.84
85.49
96.73
94.82
54.06
85.02
94.92
92.65
89.77
93.17
89.68
94.54
97.68
129.25
130.56
266.35
66.11
78.57
62.97
60.87
67.28
55.54
33.41
64.93
63.42
40.62
44.63
41.47
60.01
10.81
8.74
7.69
8.21
6.54
9.65
9.89
9.78
9.86
8.60
10.55
10.34
8.72
10.13
5.36
10.60
8.00
11.36
10.20
9.87
10.50
11.14
9.85
10.19
9.95
5.65
8.02
9.45
10.45
8.75
10.19
10.26
11.00
10.86
11.81
12.83
18.03
6.90
10.60
7.67
6.31
7.75
6.16
3.63
7.09
7.06
4.51
4.97
4.73
6.74
37.53
35.14
31.36
33.03
28.51
35.43
34.28
34.15
36.31
35.20
36.77
36.25
33.92
35.14
23.49
37.17
34.64
40.01
35.75
36.05
36.80
38.84
35.86
35.81
36.15
22.87
33.77
36.93
36.81
36.19
37.09
36.14
38.84
38.45
44.51
47.58
72.56
29.64
38.60
29.31
28.78
32.70
24.42
14.57
29.03
30.12
18.29
20.54
19.50
29.40
7.61
7.24
6.39
6.76
5.73
7.20
7.03
6.94
7.33
7.02
7.29
7.15
6.83
7.01
4.97
7.58
7.15
8.13
7.47
7.32
7.51
7.81
7.18
7.22
7.30
5.01
7.01
7.49
7.40
7.25
7.61
7.49
8.04
7.92
9.28
9.84
16.16
6.47
8.84
6.31
6.25
7.01
4.95
3.01
5.99
6.65
3.86
4.35
4.23
6.65
1.70
1.65
1.45
1.57
1.29
1.62
1.62
1.60
1.72
1.66
1.66
1.64
1.63
1.56
1.17
1.76
1.68
1.88
1.78
1.67
1.73
1.75
1.62
1.66
1.72
1.18
1.62
1.77
1.65
1.69
1.77
1.78
1.82
1.78
2.14
2.31
4.12
1.75
2.13
1.45
1.46
1.65
1.14
0.73
1.40
1.61
0.94
1.06
1.06
1.63
0.99 6.13 5.48
0.99 5.79 5.32
0.83 5.06 4.57
0.90 5.41 4.96
0.72 4.51 3.84
0.95 5.74 5.16
0.90 5.50 4.91
0.90 5.55 5.00
0.92 5.63 4.83
0.89 5.43 4.74
0.90 5.58 4.72
0.94 5.66 5.11
0.87 5.22 4.60
0.84 5.21 4.40
0.67 4.06 3.74
0.98 6.00 5.34
0.96 5.76 5.27
1.02 6.33 5.36
1.06 6.29 6.01
0.92 5.60 4.82
0.95 5.86 5.14
0.94 5.84 4.87
0.92 5.48 4.81
0.90 5.61 4.81
0.91 5.50 4.66
0.66 4.04 3.61
0.86 5.38 4.54
0.93 5.64 4.88
0.87 5.45 4.47
0.92 5.59 4.94
0.94 5.72 4.96
1.06 6.46 6.13
1.05 6.29 5.78
1.01 6.19 5.47
1.19 7.17 6.19
1.31 8.00 7.00
2.27 13.81 12.08
0.85 5.12 4.69
1.22 7.19 6.85
0.81 4.98 4.46
0.80 4.92 4.40
1.02 6.18 5.18
0.62 3.91 2.99
0.40 2.47 2.02
0.79 4.94 3.84
0.95 5.81 4.78
0.53 3.26 2.64
0.63 3.88 3.17
0.61 3.64 3.01
1.01 6.09 5.20
1.10
1.01
0.92
0.93
0.76
0.98
0.98
0.99
0.89
0.88
0.92
1.02
0.85
0.85
0.75
1.06
1.01
1.04
1.22
0.90
1.01
0.94
0.92
0.94
0.87
0.70
0.87
0.90
0.85
0.93
0.93
1.28
1.16
1.09
1.13
1.39
2.24
0.85
1.34
0.87
0.86
1.02
0.56
0.38
0.74
0.93
0.51
0.62
0.58
1.02
3.40
3.20
2.81
3.05
2.36
3.19
3.03
3.07
2.91
2.88
2.86
3.20
2.78
2.64
2.32
3.24
3.30
3.14
3.74
2.86
3.18
2.93
3.04
2.88
2.77
2.14
2.62
2.87
2.62
3.06
3.03
4.00
3.56
3.38
3.63
4.18
6.43
2.70
3.89
2.61
2.58
3.12
1.72
1.18
2.23
2.84
1.58
1.91
1.74
3.05
0.51
0.48
0.42
0.46
0.35
0.47
0.46
0.46
0.43
0.43
0.43
0.48
0.42
0.40
0.36
0.47
0.50
0.47
0.57
0.43
0.47
0.44
0.46
0.43
0.42
0.32
0.38
0.43
0.39
0.46
0.45
0.60
0.55
0.51
0.54
0.62
0.92
0.40
0.57
0.39
0.39
0.49
0.27
0.19
0.35
0.44
0.24
0.30
0.27
0.49
3.09
3.03
2.67
2.88
2.19
2.99
2.82
2.88
2.72
2.72
2.64
3.03
2.63
2.48
2.21
2.85
3.15
2.92
3.45
2.73
2.96
2.74
2.87
2.67
2.63
1.99
2.37
2.71
2.47
2.95
2.83
3.61
3.35
3.18
3.25
3.71
5.48
2.52
3.47
2.44
2.39
2.68
1.54
1.05
1.93
2.40
1.37
1.67
1.51
2.62
0.48
0.48
0.41
0.45
0.35
0.46
0.44
0.45
0.42
0.42
0.41
0.47
0.40
0.38
0.35
0.45
0.49
0.44
0.54
0.41
0.46
0.42
0.45
0.41
0.40
0.31
0.37
0.42
0.38
0.46
0.44
0.57
0.53
0.49
0.49
0.57
0.83
0.39
0.54
0.37
0.37
0.42
0.24
0.18
0.29
0.37
0.22
0.25
0.24
0.41
4.87
5.10
4.55
4.90
4.45
4.77
4.69
4.93
4.63
5.08
4.86
5.24
5.15
4.77
5.13
5.15
5.26
4.98
4.75
5.19
5.13
5.38
5.17
4.80
5.00
5.12
4.85
5.57
5.13
5.60
5.35
4.97
5.68
5.10
5.19
5.35
7.52
3.83
4.63
3.96
3.86
2.66
2.99
1.90
2.84
2.54
2.07
2.04
1.83
1.92
30.13
38.56
19.78
19.96
23.24
20.98
13.57
23.28
9.84
23.17
61.84
14.40
22.58
14.62
8.86
15.44
93.88
31.14
26.04
37.55
21.48
19.87
8.15
17.06
9.98
11.02
8.22
21.66
24.14
30.08
12.00
9.16
13.05
13.55
30.34
28.42
29.07
32.78
37.48
45.99
29.45
15.47
18.12
10.80
13.70
12.29
14.42
11.57
11.64
13.43
17.65
13.65
10.56
11.48
9.33
11.44
14.91
11.27
12.07
11.92
12.33
11.71
11.86
12.72
6.46
12.41
12.43
13.93
12.54
12.67
12.90
13.58
11.74
10.73
12.35
5.62
10.91
12.59
13.08
12.25
12.70
11.62
17.63
13.70
14.98
18.12
19.35
13.72
20.84
13.65
16.65
7.59
8.79
5.08
7.58
7.64
5.63
5.84
6.28
5.58
2.54
2.66
2.19
2.56
2.17
2.99
2.59
2.50
2.40
2.50
3.04
2.88
2.22
2.13
1.84
2.41
4.07
4.17
5.59
2.98
3.18
3.34
2.80
2.45
2.99
1.70
2.20
6.23
6.37
2.95
2.43
5.89
3.01
3.76
2.95
2.82
8.99
11.34
27.38
8.94
8.95
6.67
5.66
4.65
8.22
10.76
6.71
8.69
8.53
12.11
65.9
70.1
53.8
64.5
64.9
78.7
75.0
67.2
75.9
79.9
69.3
68.6
69.3
69.3
68.1
72.3
69.4
75.9
74.5
96.6
85.9
90.0
91.3
74.5
98.2
85.3
85.7
118.9
93.0
118.7
106.4
79.2
103.3
92.3
143.0
162.0
125.3
48.9
58.4
49.4
47.0
21.4
26.7
15.4
23.7
18.5
18.6
19.2
18.2
21.2
Depth Li
Co
Cu
Zn
Rb
Y
Cs
La
Ce
Pr
Nd
Sm
Eu
Tb
Gd
Dy
Ho
Er
Tm Yb
Lu
Hf
Pb
Th
U
(rmcd) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)
Table 2b. Major and Trace Element Concentrations, Integrated Ocean Drilling Program From Arctic Coring Expedition 302a
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a
S and Si concentrations are those measured at Bremen University [Backman et al., 2006a]. All other elements reported in this table correspond to analysis done at Boston University. Data overspecified for
calculation purposes.
11.13
5.44
6.66
3.50
5.97
3.96
12.12
4.79
4.34
12.07
4.44
4.54
3.93
3.94
1.4
4.72
5.28
6.77
3.92
6.27
3.66
12.93
12.16
10.94
13.04
12.73
11.76
10.52
10.61
3.7
11.16
14.08
17.66
10.24
16.84
9.84
24.13
24.97
21.83
26.57
26.45
25.36
16.11
16.57
3.7
1.48
1.65
2.35
1.32
2.13
1.26
4.54
5.07
4.96
4.03
5.76
5.67
6.97
6.96
1.4
0.32
0.22
0.26
0.18
0.25
0.14
0.93
0.47
0.44
0.48
0.56
0.52
0.47
0.46
1.7
2.03
1.39
1.68
1.14
1.60
0.85
5.84
3.01
2.73
3.06
3.60
3.35
2.97
2.94
1.3
0.39
0.25
0.30
0.20
0.29
0.15
1.08
0.53
0.49
0.54
0.65
0.59
0.51
0.52
1.7
2.57
1.60
1.88
1.32
1.80
0.99
6.87
3.27
3.08
3.46
4.07
3.53
3.04
2.99
1.4
0.85
0.53
0.62
0.43
0.57
0.32
2.11
1.05
0.94
1.07
1.24
1.09
0.90
0.91
1.8
0.82 5.07 4.27
0.52 3.12 2.68
0.62 3.78 3.11
0.40 2.46 2.13
0.55 3.24 2.86
0.31 1.88 1.64
1.89 10.77 10.40
1.09 6.72 5.46
0.95 5.73 4.84
1.11 6.57 5.44
1.22 7.29 6.09
1.09 6.63 5.42
0.88 5.21 4.55
0.88 5.19 4.56
0.9
1.3
0.9
1.37
0.87
1.05
0.66
0.90
0.53
2.74
2.01
1.73
1.89
2.10
1.93
1.45
1.45
0.9
5.33
3.60
4.40
2.75
3.67
2.16
10.75
8.18
7.16
8.04
8.83
8.13
6.55
6.60
0.7
23.79
16.24
20.66
12.51
17.42
10.54
43.52
39.31
35.68
38.99
42.84
40.09
32.00
32.24
1.1
5.57
4.02
5.11
3.10
4.22
2.61
10.15
9.92
9.09
9.79
10.77
9.84
8.08
8.11
0.8
48.16
35.52
45.85
27.73
38.15
22.21
104.49
107.76
88.13
92.39
103.80
100.27
76.11
77.12
1.8
23.79
15.70
22.27
12.20
17.60
10.57
37.71
40.26
39.14
44.23
47.40
43.56
35.38
36.10
0.9
2.07
2.84
3.99
2.28
3.44
1.99
6.71
6.96
6.32
6.77
8.10
7.44
6.36
6.42
2.1
26.43
15.06
17.18
12.80
18.47
9.91
64.66
30.39
26.99
33.83
37.83
32.57
25.67
26.12
0.9
24
31
47
26
39
23
91
101
102
92
111
105
93
95
1.8
20.4 69.5 119
19.3 43.9 91
23.6 50.5 112
15.4 33.2 68
21.7 46.3 110
13.6 34.1 68
43.7 119.0 181
18.3 78.3 99
8.6 33.1 78
32.5 61.2 139
13.5 37.8 103
14.4 38.8 123
13.0 34.7 83
13.0 36.8 88
2.5
1.5
2.3
8.6
9.0
16.1
5.1
10.1
5.2
40.2
53.2
45.3
47.1
122.1
120.1
130.8
132.5
4A-15X-CC (Fine)
4A-19X-1 144 – 151 SQC
4A-19X-2W 66 – 68
4A-21X-2W 66 – 68
4A-23X-1 SQC
4A-23X-2W 66 – 68
4A-27X-2W 66 – 68
4A-28X-2W 64 – 66
4A-29X-1W 97 – 99
4A-30X-2 143 – 152 SQC
4A-34X-2 144 – 150 SQC
4A-35X-2W 75 – 77
4A-42X-1W 42 – 44
4A-42X-1W 42 – 44
Analytical
reproducibility (%)
Depth Li
Co
Cu
Zn
Rb
Y
Cs
La
Ce
Pr
Nd
Sm
Eu
Tb
Gd
Dy
Ho
Er
Tm
Yb
Lu
Hf
Pb
Th
U
(rmcd) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)
Sample
Table 2b. (continued)
8.6
9.0
16.1
5.1
10.1
5.2
40.2
53.2
45.3
47.1
122.1
120.1
130.8
132.5
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MARTINEZ ET AL.: TERRIGENOUS SOURCES OF THE ARCTIC OCEAN
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[18] Varimax factor scores (Figure 4b) and compositional
factor scores (i.e., factor concentration) (Table 3) identify
the various components, or end-members. Factor 1 explains
75 % of the data variability and possesses the highest
concentrations of Rb, Ti, Si, and Ca, as well as high scores
for these elements, representing the detrital component. The
assignment of Ca to the detrital component reflects the low
abundance of carbonate. Factor 2 explains 13% of the data
variability and represents the sulfide component (pyrite) as
S shows its highest concentration and score. Factor 3 explains
4% of the variability and is characterized by high Mn and
Ni scores, identifying a hydrogenous/authigenic component.
Factor 4 explains 3% of the data variability, has the highest
Cl contents and scores, and thus we interpret this as the
‘‘evaporitic’’ component. Silicon is also important in defining this factor. The last factor (Factor 5; not shown on
Figure 4a) accounts for only 2% of the data set variability
and does not seem to represent any major component (see
square loadings discussion, below). However, it has the
highest Co and Ni contents and shows scores with strong Ca
and P associations, so it seems to also represent a second,
minor authigenic component.
[19] The bio-siliceous components are not directly captured by this statistical treatment. One problem is that
silicon is found in opal and authigenic silica but also many
common detrital minerals, so this element has little statistical power as a quantitative discriminator. Our chemical
suite does not include enough elements that would be
associated with organic material, and therefore the organic
component was not resolved here statistically.
[20] To quantify the abundance of the various components, square loadings for each factor were plotted versus
depth (Figure 4a). The interpreted detrital component
(Factor 1) shows a depth profile very similar to those of Ti,
Al, and the other refractory elements, and suggests average
detrital contribution of 70 wt% for Unit 1, a decrease to
20% or less for Unit 2 and top of Unit 3, and higher average
contributions of 45 wt% again for the bottom of Unit 3.
These detrital contributions strongly agree with those calculated by normative methods (e.g., using PAAS), yet
constitute an alternative and independent method of quantifying this component. Importantly, it uses more than one
element and does not rely on any initial assumptions about the
composition of the chemical detrital matter. The ‘‘sulfide’’
component (Factor 2) has a depth distribution that closely
resembles the S and pyrite profiles. However, the estimated
average 55 wt% of ‘‘sulfide’’ by the factor analysis in Unit 2
and top of Unit 3 is too high because of the failure of the
analysis to resolve the siliceous biogenic component. The
authigenic/hydrogenous component (Factor 3) shows low
and homogenous contributions with the exception of a few
isolated samples in the upper 200 m. The depth profile of
this component is similar to the Mn profile and subsequently
appears to represent authigenic Mn oxides. The fourth
component (‘‘evaporite’’) contributes very little to units 1
and 3 but has average concentrations of 25 % in Unit 2. As
expected, it resembles the depth profiles of Cl and Br. The
relatively high scores of Si suggest that Factor 4 indirectly
captures the biosiliceous component. Because opal, especially diatoms, has a high porosity, this component may be
8 of 17
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Figure 3. Depth profiles of major and trace elemental ratios. Gray triangles are Boston University data.
Black dots are Bremen data. Vertical dashed lines represent PAAS values. Horizontal dashed lines show
the limits of subunits 1/4, 1/5, and 1/6, and the major hiatus between 1/5 and 1/6. Horizontal gray solid
line shows the bottom of the authigenic silica unit, which is lithologically (but not chemically) different
from Unit 2. Profiles for Si/Al, correspond to the Bremen data set [Backman et al., 2006a]. (right) A
schematic stratigraphic column, showing the four lithostratigraphic units is shown. Age estimates as in
the paper by Backman et al. [2008]. (left) Depth of the stratigraphic sequence.
linked to high amounts of pore water and, therefore, Cl. In
this way, Factor 4 might be not just a direct proxy of the
evaporitic component but also an indirect proxy of the
biosiliceous component. The fact that silica contents are
high but F4 and Cl contents are relatively low from 300 to
350 rmcd can be explained by the conversion of opal to
authigenic silica, which would decrease porosity. Factor 5
seems to be partially related to calcium phosphates since
samples with the highest contributions of this component
also show significant concentrations of fluorapatite.
6. Assessment of Terrigenous Sources to the
Lomonosov Ridge
6.1. Elemental Correlations and Depth Profiles:
Terrigenous Sources
[21] Using the 64 samples analyzed at Boston University,
we assess changes in the source of the detrital material to
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Figure 4. Results of factor analysis (sedimentary component discrimination). (a) Depth profiles of
factor analysis square loadings showing the relative contribution of each factor (interpreted here as the
detrital, sulfide, hydrogenous, and evaporitic components of the sediments). Also shown are the
estimated terrigenous abundance, pyrite content, Mn/Al, and Cl profiles. (b) The varimax factor scores
show the weight of each element on the definition of each factor. Dashed horizontal lines as in Figure 2.
the Lomonosov Ridge. A correlation matrix (Table S2)
confirms that the elements Al, Ti, K, Zr, Rb, La, and Hf
have the highest correlations among each other (r2 > 0.7).
Scandium correlates well with Al, La, and the REEs
(r2 between 0.7 and 0.9) but less so with other detrital
elements such as Ti, K, and Rb (r2 0.4). Thorium
correlations are high with Sc, Rb Cs, La, Pr, and Nd,
(r2 0.7) but low with Ti (r2 0.4), Zr (r2 0.5), and Al
(r2 0.6). As expected, all the REEs are strongly correlated
between each other (r2 between 0.7 and 1) and the middle
and heavy REEs are highly correlated with Y (0.7 < r2 < 1).
[22] These general associations are evident in depth
profiles (Figure 2). Because the biogenic component dilutes
the nonbiogenic material, we have normalized all elements
Table 3. Factor Analysis Composition Scoresa
Element
Rb
Ti
Mn
Cl
P
Co
Ni
S
Si
Ca
Percent Explained
F1
(Terrigenous)
F2
(Pyrite)
F3
(Hydrogenous)
F4
(Evaporitic)
F5
(Authigenic)
129
5339
1847
4737
1180
81
56
18
709
84
3567
b
b
3945
370
87
47
94,894
200,828
1229
13
5821
1173
71
41
24,516
262,954
3902
4
5
71
2331
14,186
232
22
97
3947
4778
6353
b
284,773
3985
75
a
b
3968
279,330
1983
3
b
103
71
21,853
263,501
1424
2
Sedimentary components discrimination. All composition scores are reported as ppm. See Backman et al. [2006a].
Information lost because of the extra positive rotation of the analysis.
b
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Figure 5. Ti/Al (g/g) versus Sc/Rb (g/g) scatterplot showing chemical discrimination between the three
lithostratigraphic units. Lena (Central Laptev Sea) and Khatanga (Western Laptev Sea) river [Holemann
et al., 1999], PAAS [Taylor and McLennan, 1985], lower-crust materials [Rudnick and Presper, 1990]
and Archean shales [Condie, 1993] are also shown as comparison.
to Al such that we can study variations within the terrigenous component. This assumes that all Al resides in the
detrital component. With such high terrigenous inventories,
any scavenged Al [Murray and Leinen, 1996; Kryc et al.,
2003] should be overwhelmed. Most detrital elemental
ratios do not record significant variation through the sediment column (as compared to the Bremen results), and are
close to those of PAAS (Figure 3). The exceptions are the
profiles of La/Al, Th/Al, and Sc/Al, which increase through
the bottom of Unit 1, Unit 2 in its entirety, and the top of
Unit 3 (only Sc/Al), and are considerably greater than PAAS
values. This suggests that terrigenous material in these
sediments may differ slightly from that in most of Units 1
and 3 (see additional discussion in Text S2). Changes in the
type of terrigenous material are also suggested by the
relationship between Ti/Al and Sc/Rb (Figure 5), which
discriminates the three units and especially separates Unit 2
from the rest.
6.2. Q-Mode Factor Analysis: Terrigenous Sources
[23] Various combinations of detritally associated elements were used in the factor analysis in order to investigate
terrigenous sources. Assessment of the elemental suite Al,
Ti, Sc, Rb, La, and Th suggests the presence of three
compositional end-members (Table 4). Factor 1 (F1)
explains 66% of the total variability and is dominated by
Al, Ti, and Rb (as seen in the varimax rotated factor scores;
Figure 6b). Factor 2 (F2) explains 29% of the variability,
with La and Th being unique in its discrimination, yet also
including Sc. Factor 3 (F3) only explains 3% of variability,
with Sc controlling its variance. The square loadings of
these factors (Figure 6a) suggest F1 is the main contributor
to most of Unit 1 (78% F1) and the bottom of Unit 3
(71% F1), while F2 contributes significantly to the bottom
of Unit 1, Unit 2, and the top of Unit 3 (45% F2). The
contribution of the third factor is smaller throughout all
units but increases in distinct intervals through Unit 2 and
Unit 3 (with minimal values in Unit 1, 9% in the
intermediate section, and 2% in the bottom of Unit 3).
When Cr is added to the elemental suite, a new factor is
produced, with Cr being the sole element dominating its
variance. However, the square loading depth profiles maintain the same overall pattern. Thus, regardless of the exact
elemental groupings, it is clear that Al, Ti, and Rb group
together and dominate Units 1 and bottom of Unit 3, and
that La, Th, Sc, with varying amounts of Cr, and Ti are
distributed between two other factors that identify Unit 2
and variability within Units 2 and 3.
[24] We have compared the factor compositions to natural
rocks, representative reference materials, and sediments that
have been suggested as potential contributors of material to
the Arctic Ocean (Figure 6c). Data and factors have been
plotted on a La-Th-Sc ternary diagram [Olivarez et al.,
1991; Weber et al., 1996; Ziegler et al., 2007]. Not all
samples plot on a simple mixing line between a felsic and a
mafic end-member. However, all samples plot on a mixing
field between the three factors and especially close to F1
and F2. When considering only La, Th, and Sc, there is no
clear discrimination between samples from one unit to
another as they all plot close to each other. The samples
are also similar in composition to PAAS and to particulates
carried by rivers draining the Laptev Sea (e.g., the Lena and
Yana Rivers).
[25] A comparison including the rest of the elements, and
paying special attention to those that are stronger in defining
each factor, show similarities between the factor compositions and some reference materials. For Factor 1, concentrations of Al, Rb and Rb/Al are similar to those of Lena and
Yana Rivers. Some of these concentrations are also comparable to NASC, PAAS [Gromet et al., 1984; Taylor and
McLennan, 1985] and Precambrian Upper crust material
from Canada [Shaw et al., 1986]. The Ti and Ti/Al values,
although slightly higher than PAAS and Yana River sediTable 4. Factor Analysis Results Aa
Element
F1
F2
F3
Al
Ti
Sc
Rb
La
Th
Percent Explained
71,659
4902
5
95
8
8
66
76,269
70,089
6452
91
35
b
51
111
211
34
29
b
9
3
a
Terrigenous source discrimination. See Boston University Data Set. All
composition scores are reported as ppm.
b
Information lost because of the extra positive rotation of the analysis.
11 of 17
MARTINEZ ET AL.: TERRIGENOUS SOURCES OF THE ARCTIC OCEAN
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Figure 6. Results of factor analysis (source discrimination). (a) Depth profiles of factor analysis square
loadings showing the relative contribution of each factor. The lithostratigraphic units are shown on the
gray column. Dashed horizontal lines as in Figure 2. (b) Varimax factor scores showing the weight of
each element on the definition of each factor. (c) Th-La-Sc Ternary diagram showing the resultant three
factors (F1, F2, and F3), samples, and various rocks, sediments, and reference materials. PAAS is from
Taylor and McLennan [1985]; Asian Loess and Kurile basalts are from Weber et al. [1996]; Archean
shales are from Condie [1993]; Canadian upper crust is from Shaw et al. [1986]; Lena, Yana, and
Khatanga River particulates are from Holemann et al. [1999]; and MORB is from Salters and Stracke
[2004]. Notice that all samples plot on a mixing field between the three factors. Lower crust is from
Rudnick and Presper [1990] and Rudnick and Fountain [1995].
ments, are too low with respect to basalts [Rudnick and
Fountain, 1995]. The Sc/Al values of Factor 1 are the
lowest of all factors and therefore more similar to those of
Lena and Yana sediments than to basalts, Western Laptev
Sea, and Kara Sea sediments. The high concentrations of
200 ppm La and 34 ppm Th for Factor 2, and 91 ppm Sc for
Factor 3 are difficult to explain. Lanthanum values greater
than 100 ppm are commonly found in slowly accumulating
sediment, usually associated with authigenic phases [Turekian
and Wedepohl, 1961; Plank and Langmuir, 1998]. The
contents of Rb and Rb/Al for Factor 2 are comparable to
average shale and materials from Lena and Yana Rivers,
however Sc/Al contents suggest a more mafic source.
Factor 3 shows the highest values of Ti, Sc, Ti/Al and
Sc/Al and therefore we suggest that either Factor 2 or
Factor 3 (or a combination of both) might indicate inputs
from a more mafic source.
[26] Although it does not seem very likely that in these
sediments La, Th, and Sc have a diagenetic/authigenic
association (Text S2), an additional set of statistical analyses
was performed using Al, Ti, K, Zr, Rb, Hf, and Cr but
avoiding La, Th, and Sc. Depending on the specific combination and number of elements used, various results were
obtained, yet a consistent pattern is observed regardless of the
precise element menu used. There are two main factors that
explain most of the data variability (Table 5 and Figures 7
and S2). One factor is dominated by Al, K, and Rb, while
the other is dominated by Ti, Zr, and Hf (Figure 7). The
square loadings show that the amount of the Ti-Zr-Hf factor
increases slightly toward the bottom of Unit 1, peaks over
Unit 2, and decreases to a minimum in the middle of Unit 3
(350 – 400 rmcd, depending on the specific analysis
(Figure S2)). The square loading profile of the Al-K-Rb
factor exhibits a pattern opposite to that of the Ti-Zr-Hf
factor. If Cr, Th or both are included in the statistical
treatment, they generate new factors (i.e., factors with very
Table 5. Factor Analysis Results Ba
Element
F1
F2
Al
Ti
K
Zr
Rb
Hf
Percent Explained
68,746
1614
23,107
82,105
10,837
b
554
61
15
47
a
105
b
52
b
Terrigenous source discrimination. See Boston University Data Set. All
composition scores are reported as ppm.
b
Information lost because of the extra positive rotation of the analysis.
Figure 7. Varimax factor scores that result from the
second set of factor analysis (not including La, Sc, and/or
Th on the variable set). The scores represent the weight of
each element on the definition of each factor.
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MARTINEZ ET AL.: TERRIGENOUS SOURCES OF THE ARCTIC OCEAN
high Cr and/or Th) with high contributions over Unit 2. The
Factor 1 compositional scores (Table 5) show that the
contents of Al, K, and Rb are similar to those from Yana
and Lena rivers, as well as to some Archean and Precambrian
shales. Titanium abundances in Factor 2 are instead comparable to those of arc basalts and MORB. The high composition scores of Zr and Hf are more difficult to explain. Some of
the highest Zr/Al values reported from the Circum Arctic
region are from the Yana River and the Kara Sea. High Zr/Al
are also common on some lower-crust granulites.
6.3. Sources of Detrital Material to Lomonosov Ridge
[27] On the basis of our multielemental approach and the
few relevant chemical data sets available, two general
statements can be made with regard to potential terrigenous
sources regions. First, there is no strong and/or clear
chemical distinction between most of Unit 1 and Unit 3
(especially the lower part of Unit 3), while the middle
portions of the recovered sequence, namely, Unit 2, the
bottom of Unit 1, and perhaps the top of Unit 3, are subtly
different. Second, the overall chemistry of the sedimentary
column mostly resembles the composition of dominant
sources to the Laptev Sea, namely the Lena, Yana, and
Khatanga rivers and associated materials.
[28] Although most of the samples from all units plot
close to each other on various ternary diagrams (e.g.,
Figures 6 and S2), there are subtle differences. The Ti/Al
versus Sc/Rb scatterplot (Figure 5) shows significant discrimination, with samples from Units 1 and 3 closer to the
average composition of Lena particulates, and Unit 2 closer
to the average composition of Khatanga material. The Sc/Al,
La/Al, and Th/Al profiles also suggest that sediments
between 170 and 184 rmcd and 313 – 350 rmcd (i.e., the
bottom of Unit 1 and through Unit 2) have a slightly
different composition, and hence, inferred origin. Moreover,
the composition of this interval is less similar to representative average shales, such as PAAS, compared to the
adjacent sediments. For Ti/Al and Sc/Al this different
composition is also observed in the top of Unit 3.
[29] Factor analysis results suggest the presence of two or
three detrital sources. The first set of results (Figure 6)
indicate a factor with compositions similar to average shale
and sediments from Lena and Yana rivers that contributes its
greatest amount over Unit 1 and through part of Unit 3.
Factor 2 presents characteristic elevated La, Th, and Sc, and
contributes significantly over Unit 2. Although difficult to
match to a specific source, the relationships between the
elements suggest this second factor represent materials from
Lena or Yana Rivers but that a small mafic component can
also be present. Factor 3, which contributes the most in the
bottom of Unit 1, Unit 2, and top of Unit 3, shows elevated
Ti, Sc, and therefore suggests a relative increase in the input
of a more mafic source over this interval. The second suite
of statistical results (Table 5 and Figures 7 and S2) supports
the presence of 2 compositional end-members. The compositional scores and loadings of this analysis suggest that
sediments of Unit 1 and Unit 3 are influenced by materials
with a shale-like composition such as those from the Lena
and Yana rivers, and that the input from sources with a more
basaltic affinity relatively increased over Unit 2, and at least
the bottom of Unit 1. The high Ti and Zr values of this
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Factor 2 are consistent with increased input from a more
basaltic source such as the Kara Sea.
[30] The second set of statistical results is also noteworthy
in that it agrees well with a factor analysis of suspended
particulate material in Siberian Rivers [Rachold, 1998].
Both our results and those of Rachold [1998] present a
Factor 1 that includes Al, K, and Rb as discriminatory
elements. In the paper by Rachold [1998], this factor
represented Lena and Yana River sediments. Moreover,
both studies also present a Factor 2 dominated by Ti, Zr,
and Hf, among other elements. Factor analysis results from
surface sediments on the Siberian-Arctic shelf [ViscosiShirley et al., 2003] also yielded a primary factor with high
Al and K factor scores (their Figure 5), which they interpreted as a shale end-member and was abundant for samples
from the eastern Laptev Sea. The fact that our second set of
results collectively propose a ‘‘clay’’ dominated factor (Al,
K, Rb), and a ‘‘high field strength element’’ factor (Ti, Zr,
Hf) may alternatively suggest that this second factor represents material derived from a different source whose composition has also been modified by grain size sorting effects,
as was suggested by Rachold [1998]. Studying such physical processes is beyond the scope of this paper because we
are dealing with bulk chemical analysis, but future studies
may wish to explore this further.
[31] Finally, the interelemental ratios V/Al, Cr/Al, Sc/Al,
and Ca/Al, found to be high on the Western Laptev or Kara
Sea, are also relatively high over Unit 2. Although Ti/Al is
not elevated, which is somewhat surprising given the
observed Ti enrichment in many basalts [Taylor and
McLennan, 1985], Ti/Al similar to those from Unit 2 have
been reported for the Kara Sea [Gordeev et al., 2004].
Nonetheless, the preponderance of the chemical data (e.g.,
chemical ratios) and the multivariate statistics suggest that
the interval defined by Unit 2, the bottom of Unit 1, and
possible the top of Unit 3 as well, is compositionally
different than the rest and could represent increased inputs
from materials with a more mafic-derived source.
7. Comparison to Other ACEX Provenance
Studies
[32] Our study supports the idea that the Eurasian margin
contributed most of the sediment to Lomonosov Ridge
during the late Neogene (most of Unit 1) and the middle
Eocene (subunit 1/6 and Unit 2) [Haley et al., 2008; Krylov
et al., 2008; St. John, 2008]. Our results also support the
suggestion of Krylov et al. [2008] regarding a source
change, within Eurasia, during the middle Miocene (at the
bottom of Unit 1). Significant changes in the chemical
composition of terrigenous material are found where their
study shows a shift of heavy and clay minerals. Although
the chemistry of the sediments does not uniquely identify
the sediment source for the middle Eocene (Unit 2), our
study is consistent with a change in the proportion of
sediment derived from sources with more mafic-derived
materials (Western Laptev or Kara Sea) to more shale-like
(Eastern Laptev Sea) materials. In contrast, our results do
not show evidence of a Canadian source to the Lomonosov
Ridge during deposition of Unit 1 [Darby, 2008].
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[33] Focusing on the Neogene section, the observed
uniformity of our chemical proxies through most of Unit
1 is consistent with recent interpretations that the present ice
drift pattern and dominant ice-based sediment transport
mechanism have operated for at least 14 Ma [Haley et al.,
2008; Krylov et al., 2008]. Because the source of the sediments deposited between 50 and 13 –14 Ma (i.e., Unit 2 and
bottom of Unit 1) is different, they may have deposited
under different paleoceanographic conditions. As suggested
by Krylov et al. [2008], this may reflect a change from
seasonal sea ice to perennial sea ice at 13– 14 Ma, so that
ice-borne material from the west became relatively less
important than material from the Eastern Laptev Sea. A
working hypothesis is that abundant sediment from distal
Eastern sources would not reach the Central Arctic until sea
ice could survive a melting season [Darby, 2008; Krylov et
al., 2008].
[34] Both the geochemistry (this study) and mineralogy
[Krylov et al., 2008] are consistent with an increase in the
input of western Laptev-Kara Sea sources of terrigenous
material for the recovered period from 50 Ma to 13 –14 Ma
(comprising all of Unit 2 and the bottom of Unit 1). There
is, of course, large unknowns with regard to the depositional
processes that occurred during the hiatus found between
18.2 – 44.4 Ma, and thus we cannot specifically document
that the proposed western source was continuously active
for the whole period from 50 Ma to 14 Ma. Moreover, our
work suggests that not only sediments from the top of Unit
1 but also those deposited before the middle Eocene (Unit 3,
or at least the bottom part thereof) came from the eastern
Laptev Sea. This suggests that (1) a similar transport path
(sea ice) was present in the Arctic during the early Paleogene, (2) another source in the past furnished material with a
similar chemistry to that entering the modern eastern Laptev
Sea, and/or (3) a different transport mechanism (e.g., ice
free) supplied fine-grained sediment from the eastern Laptev Sea to Lomonosov Ridge. Each of these three options is
discussed sequentially below.
[35] With respect to the Option 1, it is well established
that Earth in the early Paleogene was very warm, especially
at high latitudes, and probably ice free. This view is
consistent with studies of the ACEX cores, which contain
lithological, micropaleonotological and geochemical evidence for warm temperatures and ice-free conditions for
Unit 3 and much of Unit 2 [Brinkhuis et al., 2006; Moran et
al., 2006; Sluijs et al., 2006, 2008]. Although limited sea ice
may have occurred in the middle Eocene [Moran et al.,
2006], it is highly unlikely that sea ice transported terrigenous material from the Laptev Sea to Lomonosov Ridge in
the early Paleogene.
[36] Regarding Option 2, the geography of the Arctic
Basin was significantly different during the Paleocene and
Eocene, with the Lomonosov Ridge being located much
closer to the Eurasian margin and in particular to the Barent,
Kara, and Western Laptev Seas [O’Regan et al., 2008a;
Sluijs et al., 2008]. Sediments deposited at that time,
however, do not show chemical characteristics similar to
modern sediments recovered from those western regions.
There is a slight chance that the extent of chemical weathering during the ‘‘greenhouse’’ Arctic conditions of the
PA1210
early Paleogene could have modified the fingerprints of
the more basaltic western sources. In spite of this, there is
evidence that erosion and weathering has not significantly
altered the composition of ACEX sediment, at other times.
For example, the Pb isotopic composition of Neogene
sediments do not reveal major weathering changes over
the last 15 Ma, a time spans which includes the initiation of
major Northern Hemisphere glaciation at 2.7 Ma [Haley et
al., 2008]. Hence, major changes in erosion and weathering
appear to not have significantly overprinted the inorganic
chemical signatures of at least the Neogene and Pleistocene
sediments. By analogy, the contrasting composition between Unit 3 and Unit 2 is unlikely to be due to changes
in weathering of a single source (namely Barent-KaraWestern Laptev Sea). Future studies extending the Sr-Nd
and Pb isotopic studies to the Paleogene sediments would
help address this issue. Also, the fact that we are specifically
and intentionally studying refractory chemical elements well
known to be more resistant than others to alteration during
weathering and diagenesis [e.g., Taylor and McLennan,
1985], reduces the chances of sources’ compositional modification masking our provenance assessment.
[37] Assuming that proximal Paleogene sources were not
as important as the more distal the Eastern Laptev Sea
source, this may indicate a weakened or nonexistent Siberian Branch of the TPD, or reflect different continental and/
or shelf processes that prevented these proximal sources
from providing sediments to the Central Arctic. For example, Haley et al. [2008] proposed that glacier erosion could
favor the transport of sediments originally eroded form the
Putorana Basalts and temporarily deposited during interglacials on the Western Laptev Sea shelf. By analogy, sea level
changes between the early Eocene – late Paleocene and the
mid-Eocene could affect the entrapment and/or mobilization
of sediment from the Kara, Barent, or Western Laptev. For
example, a lowering of sea level during glacials may
increase marine hemipelagic deposition as rivers can more
effectively cut subaerially exposed shelf and deposit sediments further from the coast. Therefore, a scenario of sea
level rise for the time of deposition of Unit 3 would favor
sediment entrapment on the Western Laptev shelf and a sea
level decrease during deposition of Unit 2, together with the
start of seasonal sea ice, could be consistent with the
geochemical source changes. Although the global sea level
reconstructions of Miller et al. [2005] show slight increases
in sea level between 50 and 55 Ma (part of Unit 3)
compared to that from 45.5 to 50 Ma (Unit 2), we are not
certain that these are enough to produce such results, and
local variability is also likely to be important. Changes in
coastal geomorphology, which may not leave any geological record over such a long timeframe, may also play an
important role in determining transport pathways from shore
to sea.
[38] With respect to Option 3, tectonic reconstructions of
the Cenozoic evolution of the Arctic show that the distance
between the ACEX site and the Eastern Laptev Sea has not
varied significantly between the late Paleocene and the
present [O’Regan et al., 2008b, Figure 8]. Also, as derived
from Option 1, transport most likely occurred by ocean
currents instead of sea ice or iceberg rafting. Thus, we
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MARTINEZ ET AL.: TERRIGENOUS SOURCES OF THE ARCTIC OCEAN
suggest that ocean currents trajectories could have been
similar to those of the modern ice rafting (TPD) and thus
still be capable of transporting fine sediments to such distal
locations as to the Lomonosov Ridge. In the modern, both
icebergs and sea ice concentrate fine and coarse particles
(IRD), with the fines being preferentially incorporated
[St. John, 2008]. Therefore, we hypothesize that sediments
from the Eastern Laptev Sea deposited under ice rafting and
river input could carry fine grains and hence provide the
same chemical signatures, provided their loads follow the
same transport trajectories. Even if perennial sea ice is not
the only transport mechanism from the Eastern Laptev Sea,
this mode of transport could significantly enhance its
contribution and therefore our interpretation is not inconsistent with those of the studies of mineralogy [Krylov et al.,
2008] and Fe grain [Darby, 2008]. Processes related to the
hiatus comprising 26 Ma could have affected circulation
patterns for the time period of the depositional transition
between Units 1 and 2, however on the basis of our
observations we cannot resolve details at this respect.
8. Summary and Conclusions
[39] 1. Elemental contents of bulk sediments clearly
define major boundaries between lithostratigraphic units.
Moreover, as we initially observed with preliminary work
[Backman et al., 2006a], the top 40 m of Unit 3 is
chemically similar to Unit 2 such that many chemical
profiles show a major change at 350 rmcd and not at
the boundary between Units 2 and 3 (313 rmcd). This is
because the top of Unit 3 contains abundant chert, which
was presumably biogenic silica before alteration, and also
serves as a significant dilutant. The paleoceanographic
changes responsible for a switch from siliciclastic-dominated
deposition to biogenic-dominated deposition occurred
around 350 rmcd and therefore earlier than if one assumed
it happened at the Unit 2/Unit 3 boundary.
[40] 2. Factor analysis and ratios of ‘‘detrital’’ elements
suggest subtle differences in terrigenous material between
lithostratigraphic units. Unit 1 (especially subunits 1/1 to 1/4)
and Unit 3 (especially the bottom) have a shale-like composition, as shown by elemental profiles with values close
to PAAS (and other upper crustal materials) and by the
composition of Factor 1 in both of our detrital factor
analysis statistical treatments. Additionally, there are multiple pieces of evidence that suggest that Unit 2 has a subtly
different composition that could result of increased input
from materials with a more basaltic composition.
[41] 3. The provenance of the terrigenous components
cannot be definitively established because data is lacking
from some important potential source regions, notably the
East Siberian Sea, Chukchi Sea, and the Canada. Nonetheless, the overall chemistry of the terrigenous component
PA1210
sedimentary sequence appears to resemble the composition
of modern surficial sediments from the Siberian shelf (e.g.,
Laptev and Kara Sea). Furthermore, comparisons of majors
and trace elements as well as factor analysis suggest that the
eastern and central Laptev Sea (Lena and Yana Rivers
drainage area) can be a significant source of the shale-like
sediments observed over the whole ACEX sequence, but in
particular for those deposited over Unit 1 (subunits 1/1 to 1/4)
and at least the bottom portion of Unit 3. Sediment from the
Western Laptev or Kara Sea (areas drained by the Khatanga,
Ob and Yenisei River) appears to be a good candidate for
the potential ‘‘mafic’’ source that became relatively more
important during the deposition of the top of Unit 3, all of
Unit 2, and the bottom of Unit 1 (namely, from the early
Eocene to the middle Miocene, 350 rmcd to 170 rmcd).
Moreover, our results do not show evidence of a Canadian
source to the Lomonosov Ridge during deposition of Unit 1
[Darby, 2008].
[42] 4. The similarity of terrigenous sediment in Unit 1,
when there was major sea ice, and Unit 3, when there is no
evidence for sea ice, suggests different transport mechanisms from a single terrigenous source. Clearly, ice rafting
along the TPD transports fine-grained sediments from the
Eastern Laptev Sea to the Lomonosov Ridge at present.
This implies that ocean currents under ice-free conditions
could be equally capable of this type of transport. This
similarity is also unexpected since the two sedimentary
sections must have been deposited under very different
erosion and weathering regimes (precontinental and postcontinental glaciation). However, on the basis of the chemistry, the suite of refractory elements used, and the
confirmation of no significant isotopic changes due to other
major climatic transitions, we argue that the similar composition of the top of Unit 1 and the bottom of Unit 3 are not
caused by weathering.
[43] 5. That terrigenous material deposited through Unit 2
is compositionally different than the rest of the sequence,
supports the possibility of paired major changes in both the
biogenic and terrigenous system during the middle Eocene.
We suggest that regional sea level variations can be one of
the main reasons causing this paired change and that
variations in coastal geomorphology could play an important role on the entrapment and/or availability of sediments
from the Western Laptev –Kara Sea during this time period.
[44] Acknowledgments. We thank the geochemistry group at Bremen
University for their help with sample preparation and analysis for the
Bremen data set. We also thank L. Bolge and J. Sparks for their assistance
in the Analytical Geochemistry Laboratories at Boston University. N. Pisias
provided the MATLAB script used in the factor analysis. This research used
samples and data from the Integrated Ocean Drilling Program (IODP). This
research was funded by postcruise grant support by the U.S. Science
Support Program (USSSP) to R. W. Murray and N. C. Martinez at Boston
University and separately to G. R. Dickens at Rice University.
References
Aagaard, K., and E. C. Carmack (1994), The
Arctic Ocean and climate: A perspective, in
The Polar Oceans and Their Role in Shaping
the Global Environment, Geophys. Monogr.
Ser., vol. 85, edited by O. M. Johannessen,
R. D. Muench, and J. E. Overland, pp. 5 – 20,
AGU, Washington, D. C.
Backman, J., K. Moran, D. Evans, and the Expedition 302 Project Team (2004), ACEX —
Arctic Coring Expedition: ‘‘Paleoceanographic
and tectonic evolution of the central Arctic
Ocean’’, Mission Specific Platform Sci. Prospectus 1, Integrated Ocean Drill. Program
Exped., Washington, D. C.
15 of 17
Backman, J., K. Moran, D. B. McInroy, L. A.
Mayer, and the Expedition 302 Scientists
(2006a), Sites M0001 – M0004, Proc. Integrated Ocean Drill. Program., 302, 1 – 169,
doi:10.2204/iodp.proc.302.104.2006.
Backman, J., K. Moran, D. B. McInroy, L. A.
Mayer, and the Expedition 302 Scientists
PA1210
MARTINEZ ET AL.: TERRIGENOUS SOURCES OF THE ARCTIC OCEAN
(2006b), Expedition 302 summary, Proc. Integrated Ocean Drill. Program, 302, 1 – 22,
doi:10.2204/iodp.proc.302.101.2006.
Backman, J., K. Moran, D. B. McInroy, L. A.
Mayer, and the Expedition Scientists (2006c),
Methods, Proc. Integrated Ocean Drill. Program., 302, 1 – 43, doi:10.2204/iodp.proc.
302.103.2006.
Backman, J., et al. (2008), Age model and coreseismic integration for the Cenozoic Arctic
Coring Expedition sediments from the Lomonosov Ridge, Paleoceanography, 23, PA1S03,
doi:10.1029/2007PA001476.
Bischof, J., D. L. Clark, and J. Vincent (1996),
Origin of ice-rafted debris: Pleistocene paleoceanography in the western Arctic Ocean,
Paleoceanography, 11, 743 – 756, doi:10.1029/
96PA02557.
Brinkhuis, H., et al. (2006), Episodic fresh
surface waters in the Eocene Arctic Ocean,
Nature, 441, 606–609, doi:10.1038/nature04692.
Bryce, L. W., M. J. Clark, and D. L. Clark
(1997), Strontium, neodymium and lead
isotope variations of authigenic and silicate
sediment components from the late Cenozoic
Arctic Ocean: Implications for sediment provenance and the source of trace metals in seawater, Geochim. Cosmochim. Acta, 61, 4181 –
4200.
Clark, D. L., B. J. Kowallis, L. G. Medaris, and
A. L. Deino (2000), Orphan Arctic Ocean
metasediment clasts; local derivation from
Alpha Ridge or pre-2.6 Ma ice rafting, Geology,
28, 1143 – 1146, doi:10.1130/0091-7613(2000)
28<1143:OAOMCL>2.0.CO;2.
Condie, K. C. (1993), Chemical-composition and
evolution of the upper continental crust —
Contrasting results from surface samples and
shales, Chem. Geol., 104, 1 – 37, doi:10.1016/
0009-2541(93)90140-E.
Darby, D. A. (2008), Arctic perennial ice cover
over the last 14 million years, Paleoceanography, 23, PA1S07, doi:10.1029/2007PA001479.
Darby, D. A., J. F. Bischof, R. F. Spielhagen,
S. A. Marshall, and S. W. Herman (2002),
Arctic ice export events and their potential
impact on global climate during the late
Pleistocene, Paleoceanography, 17(2), 1025,
doi:10.1029/2001PA000639.
Dethleff, D., V. Rachold, M. Tintelnot, and
M. Antonow (2000), Sea-ice transport of riverine particles from the Laptev Sea to Fram Strait
based on clay mineral studies, Int. J. Earth Sci.,
89, 496 – 502, doi:10.1007/s005310000109.
Gordeev, V. V., V. Rachold, and I. E. Vlasova
(2004), Geochemical behaviour of major and
trace elements in suspended particulate material of the Irtysh River, the main tributary of the
Ob River, Siberia, Appl. Geochem., 19, 593 –
610, doi:10.1016/j.apgeochem.2003.08.004.
Gromet, L. P., et al. (1984), The ‘‘North American
shale composite’’: Its compilation, major and
trace element characteristics, Geochim. Cosmochim. Acta, 48, 2469 – 2482, doi:10.1016/00167037(84)90298-9.
Haley, B., M. Frank, R. Spielhagen, and J. Fietzke
(2008), Radiogenic isotope record of Arctic
Ocean circulation and weathering inputs of the
past 15 million years, Paleoceanography, 23,
PA1S13, doi:10.1029/2007PA001486.
Holemann, J. A., M. Schirmacher, H. Kassens,
and A. Prange (1999), Geochemistry of surficial and ice-rafted sediments from the Laptev
Sea (Siberia), Estuarine Coastal Shelf Sci., 49,
45 – 59, doi:10.1006/ecss.1999.0485.
Jakobsson, M., N. Z. Cherkis, J. Woodward,
R. Macnab, and B. Coakley (2000), New grid
of Arctic bathymetry aids scientists and
mapmakers, Eos Trans. AGU, 81(9), 89,
doi:10.1029/00EO00059.
Jakobsson, M., R. Lovlie, E. M. Arnols,
J. Backman, L. V. Polyak, J. Nutsen, and
E. Musatov (2001), Pleistocene stratigraphy
and paleoenvironmental variation from Lomonosov Ridge sediments, central Arctic Ocean,
Global Planet. Change, 31, 1 – 22, doi:10.1016/
S0921-8181(01)00110-2.
Kryc, K., R. W. Murray, and D. W. Murray
(2003), Al-to-oxide and Ti-to-organic linkages
in biogenic sediment: Relationships to paleoexport production and bulk Al/Ti, Earth Planet.
Sci. Lett., 6614, 1 – 17.
Krylov, A. A., I. A. Andreeva, C. Vogt, J. Backman,
V. V. Krupskaya, G. E. Grikurov, K. Moran, and
H. Shoji (2008), A shift in heavy and clay
mineral provenance indicates a middle Miocene
onset of a perennial sea ice cover in the Arctic
Ocean, Paleoceanography, 23, PA1S06,
doi:10.1029/2007PA001497.
Martinez, N. C., R. W. Murray, R. C. Thunell,
L. C. Peterson, F. Muller-Karger, Y. Astor, and
R. Varela (2007), Modern climate forcing of
terrigenous deposition in the tropics (Cariaco
Basin, Venezuela), Earth Planet. Sci. Lett.,
264, 438 – 451, doi:10.1016/j.epsl.2007.10.
002.
Miller, K., M. A. Kominz, J. V. Browning, J. D.
Wright, G. S. Mountain, M. E. Katz, P. J.
Sugarman, B. S. Cramer, N. Christie-Blick,
and S. F. Pekar (2005), The Phanerozoic
record of global sea-level change, Science, 310,
1293 – 1298, doi:10.1126/science.1116412.
Moran, K., et al. (2006), The Cenozoic palaeoenvironment of the Arctic Ocean, Nature, 441,
601 – 605, doi:10.1038/nature04800.
Murray, R. W., and M. Leinen (1996), Scavenged aluminum and its relationship to bulk
titanium in biogenic sediment from the central
equatorial Pacific Ocean, Geochim. Cosmochim. Acta, 60, 3869 – 3878, doi:10.1016/
0016-7037(96)00236-0.
Nürnberg, D., I. Wollenburg, D. Dethleff,
H. Eicken, H. Kassens, T. Letzig, E. Reimnitz,
and J. Thiede (1994), Sediments in Arctic seaice — Implications for entrainment, transport
and release, Mar. Geol., 119, 185 – 214,
doi:10.1016/0025-3227(94)90181-3.
Olivarez, A., R. Owen, and D. Rea (1991), Geochemistry of Eolian dust in Pacific pelagic
sediments: Implications for paleoclimatic interpretations, Geochim. Cosmochim. Acta, 55,
2147 – 2158, doi:10.1016/0016-7037(91)
90093-K.
O’Regan, M. M., et al. (2008a), Mid-Cenozoic
tectonic and paleoenvironmental setting of the
central Arctic Ocean, Paleoceanography, 23,
PA1S20, doi:10.1029/2007PA001559.
O’Regan, M., T. Sakamoto, and J. King (2008b),
Data report: Regional stratigraphic correlation
and a revised composite depth scale for IODP
Expedition 302, in Arctic Coring Expedition
(ACEX), Proc. Integrated Ocean Drill. Program, 302, 1 – 25, doi:10.2204/iodp.proc.302.
202.2008.
Phillips, R. L., and A. Grantz (2001), Regional
variations in provenance and abundance of icerafted clasts in Arctic Ocean sediments: Implications for the configuration of late Quaternary
oceanic and atmospheric circulation in the Arctic, Mar. Geol., 172, 91 – 115, doi:10.1016/
S0025-3227(00)00101-8.
Plank, T., and C. H. Langmuir (1998), The chemical composition of subducting sediment and
its consequences for the crust and mantle,
Chem. Geol., 145, 325 – 394, doi:10.1016/
S0009-2541(97)00150-2.
16 of 17
PA1210
Polyak, L. V., W. B. Curry, D. A. Darby, J. Bischof,
and T. Cronin (2004), Contrasting glacial/interglacial regimes in the western Arctic Ocean as
exemplified by a sedimentary record from the
Mendeleev Ridge, Palaeogeogr. Palaeoclimatol. Palaeoecol., 203, 73 – 93, doi:10.1016/
S0031-0182(03)00661-8.
Rachold, V. (1998), Major, trace and rare earth
element geochemistry of suspended particulate
material of east Siberian rivers draining to the
Arctic Ocean, in Land-Ocean Systems in the
Siberian Arctic: Dynamics and History, edited
by H. Kassens et al., pp. 199 – 222, Berlin
Heidelberg, New York.
Rudnick, R. L., and D. M. Fountain (1995), Nature and composition of the continental crust: A
lower crustal perspective, Rev. Geophys.,
33(3), 267 – 309, doi:10.1029/95RG01302.
Rudnick, R. L., and T. Presper (1990), Geochemistry of intermediate to high-pressure granulites, NATO ASI Ser., Ser. C, 311, 523 – 550.
Salters, V., and A. Stracke (2004), Composition
of the depleted mantle, Geochem. Geophys.
Geosyst., 5, Q05B07, doi:10.1029/
2003GC000597.
Schoster, F., M. Behrends, C. Muller, R. Stein,
and M. Wahsner (2000), Modern river discharge and pathways of supplied material in
the Eurasian Arctic Ocean: Evidence from
mineral assemblages and major and minor element distribution, Int. J. Earth Sci., 89, 486 –
495, doi:10.1007/s005310000120.
Shaw, D. M., J. J. Crame, M. D. Higgins, and
M. G. Truscott (1986), Composition of the
Canadian Precambrian shield and the continental crust of the Earth, in The Nature of the Lower
Continental Crust, edited by J. D. Dawson et
al., Geol. Soc. Spec. Publ., 24, 275 – 282.
Sluijs, A., et al. (2006), Subtropical Arctic Ocean
temperatures during the Palaeocene/Eocene
thermal maximum, Nature, 441, 610 – 613,
doi:10.1038/nature04668.
Sluijs, A., U. Röhl, S. Schouten, H.-J. Brumsack,
F. Sangiorgi, J. S. Sinninghe Damsté, and
H. Brinkhuis (2008), Arctic late Paleocene –
early Eocene paleoenvironments with special
emphasis on the Paleocene-Eocene thermal
maximum (Lomonosov Ridge, Integrated
Ocean Drilling Program Expedition 302,
Paleoceanography, 23, PA1S11, doi:10.1029/
2007PA001495.
Spielhagen, R. F., et al. (1997), Arctic Ocean
evidence for late Quaternary initiation of
northern Eurasian ice sheets, Geology, 25,
783 – 786.
Spielhagen, R. F., K. H. Baumann, H. Erlenkeuser,
N. R. Nowaczyk, N. Norgaard-Pedersen,
C. Vogt, and D. Weiel (2004), Arctic Ocean
deep-sea record of northern Eurasian ice sheet
history, Quat. Sci. Rev., 23, 1455 – 1483,
doi:10.1016/j.quascirev.2003.12.015.
Stein, R., B. Boucsein, and H. Meyer (2006),
Anoxia and high primary production in the
Paleogene central Arctic Ocean: First detailed
records from Lomonosov Ridge, Geophys. Res.
Lett., 33, L18606, doi:10.1029/2006GL026776.
St. John, K. (2008), Cenozoic ice-rafting history
of the central Arctic Ocean: Terrigenous sands
on the Lomonosov Ridge, Paleoceanography,
23, PA1S05, doi:10.1029/2007PA001483.
Taylor, S. R., and S. M. McLennan (1985), The
Continental Crust: Its Composition and Evolution, 312 pp., Blackwell Sci., Malden, Mass.
Turekian, K. K., and K. H. Wedepohl (1961),
Distribution of the elements in some major
units of the Earth’s crust, Geol. Soc. Am. Bull.,
72, 175 – 192, doi:10.1130/0016-7606(1961)
72[175:DOTEIS]2.0.CO;2.
PA1210
MARTINEZ ET AL.: TERRIGENOUS SOURCES OF THE ARCTIC OCEAN
Viscosi-Shirley, C., K. Mammone, N. Pisias, and
J. Dymond (2003), Clay mineralogy and multielement chemistry of surface sediments on the
Siberian-Arctic shelf: Implications for sediment provenance and grain size sorting, Cont.
Shelf Res., 23, 1175 – 1200, doi:10.1016/
S0278-4343(03)00091-8.
Walsh, J. E. (1991), Climate change – The Arctic
as a bellwether, N at u re, 352, 19 – 20,
doi:10.1038/352019a0.
Weber, E., II, R. M. Owen, G. R. Dickens, A. N.
Halliday, C. E. Jones, and D. K. Rea (1996),
Quantitative resolution of Eolian continental
crustal material and volcanic detritus in North
Pacific surface sediment, Paleoceanography,
11, 115 – 127, doi:10.1029/95PA02720.
Winter, B. L., et al. (1997), Strontium, neodymium, and lead isotope variations of authigenic and silicate sediment components from
the late Cenozoic Arctic Ocean: Implications
for sediment provenance and the source of
trace metals in seawater, Geochim. Cosmochim. Acta, 61, 4181 – 4200, doi:10.1016/
S0016-7037(97)00215-9.
Ziegler, C. L., R. W. Murray, S. A. Hovan, and
D. K. Rea (2007), Resolving Eolian, volcanogenic, and authigenic components in pelagic
sediment from the Pacific Ocean, Earth Planet.
17 of 17
PA1210
Sci. Lett., 254, 416 – 432, doi:10.1016/j.epsl.
2006.11.049.
G. R. Dickens, Department of Earth Sciences,
Rice University, Houston, TX 77005, USA.
([email protected])
M. Kölling, Department of Geosciences, University of Bremen, D-28359, Bremen, Germany.
([email protected])
N. C. Martinez and R. W. Murray, Department
of Earth Sciences, Boston University, Boston,
MA 02215, USA. ([email protected]; rickm@
bu.edu)