Journal of Earth Science, Onlin 2017
Printed in China
DOI: 10.1007/s12583-016-0943-6
ISSN 1674-487X
Division and Characteristics of Shale Parasequences in the
Upper Fourth Member of the Shahejie Formation, Dongying
Depression, Bohai Bay Basin, China
Jing Wu *1, 2, 3, Zaixing Jiang4, Chao Liang5
1. Petroleum Exploration and Production Research Institute of SINOPEC, Beijing 100083, China
2. State key laboratory of shale oil and gas enrichment mechanisms of SINOPEC, Beijing 100083, China
3. Sinopec Key Laboratory of shale Gas/Oil Exploration & Production, Beijing 100083, China
4. Faculty of Energy Resources, China University of Geosciences, Beijing 100083, China
5. School of Geosciences, China University of Petroleum, Qingdao 266000, China
http://orcid-org/0000-0001-9024-8680
ABSTRACT: Shale parasequence analysis is an important part of sequence stratigraphy sudies. This
paper proposed a systematic research method for analyzing shale parasequences including their delineation, division, characteristics and origins. The division method is established on the basis of lithofacies.
Multi-method analysis and mutual verification were implemented by using auxiliary indicators (such as
mineral compositions, geochemical indicators and wavelet values). A typical shale parasequence comprises a lower interval of deepening water-depth and an upper interval of shallowing water-depth [e.g.,
a shale parasequence including a high-total organic carbon (TOC) shale-low-TOC limy shale]. Abrupt
increases in pyrite content, TOC value, relative hydrocarbon generation potential [(S1+S2)/TOC], and
wavelet values are indicative of parasequence boundaries. The proposed research method was applied
to study the upper fourth member of the Shahejie Formation in the Dongying Depression, Bohai Bay
Basin. Results show that there were seven types of parasequences developed. A singular and a dual
structured parasequences were identified. Three factors controlling the development of the shale parasequences were identified including relative lake level change, terrestrial input and transgression. The
development of high-TOC (>2%) shale parasequences was mainly controlled by biological and chemical
sedimentation. The low-TOC (<2%) shale parasequences were mainly deposited by chemical sedimentation. The diversities of shale parasequences were caused by four major controlling factors including
climate, relative lake level change, terrestrial input and emergency (e.g., transgression).
KEYWORD: shale, parasequence, Dongying depression, upper fourth member of Shahejie formation.
0
INTRODUCTION
Shale oil and gas has recently become a research focus for
petroleum exploration. Shale parasequence analysis is crucial
in predicting organic richness zones, mineralogical affinity and
fracture potential of fine-grained sediments, all of which play
significant roles in controlling the porosity, permeability and
hydrocarbon generation potential (S1+S2) of shales (Singh,
2008). Such research can provide useful insights into the exploration of shale oil and gas. As shales appear to be homogeneous and do no exhibit significant vertical changes in lithofacies or sediment grain sizes, it is quite challenge to delineate
and divide shale parasequences. Most of the recent third-order
sequence (Angulo and Buatois, 2012; Smith and Bustin, 2000;
*Corresponding author: [email protected]
© China University of Geosciences and Springer-Verlag Berlin
Heidelberg 2016
Manuscript received May 29, 2016.
Manuscript accepted January 16, 2017.
Schutter, 1998), few of which are designed for parasequence
analysis. To date, there has been no systematic research method
for shale parasequence analysis available. Therefore, the study
of shale parasequences is of great importance and urgently
needed (Slatt and Rodriguez, 2012; Catuneanu, 2006).
The existing division methods only rely on one particular
aspect of geological characteristics. For example, the gamma
ray profile can be classified into the upward-increasing API
(American Petroleum Institute) intervals, upward-decreasing
API intervals, and intervals of constant API. These three kinds
of intervals are bounded by gamma ray kicks, i.e., well-log
based flooding surfaces, which can be termed as gamma ray
parasequences (Slatt and Abousleiman, 2011; Singh, 2008).
Additionally, the oil-prone shale are commonly formed by a
series of superimposed depositional TOC units (high TOC values at the base, decreasing upward) (Creaney, 1993). One TOC
unit was thought to represent a parasequence (Liu et al., 2011).
However, no single unique feature in a stratigraphic section can
be used to make an interpretation (Loucks and Rupple, 2007).
The interpretation should base on a variety of characteristics
Wu, J., Jiang, Z. X., Liang, C., et al., 2017. Division and Characteristics of Shale Parasequences in the Upper Fourth Member of the
Shahejie Formation, Dongying Depression, Bohai Bay Basin, China. Journal of Earth Science, doi: 10.1007/s12583-016-0943-6.
http://en.earth-science.net
2
indicators, especially for shale. The existing methods are not
enough. What is more, they lack the contact with third- and
fourth-order sequences providing the frame for parasequences.
To figure out these problems, this study is aim to establish
a systematic research method including division, characteristics
and origins analysis for shale parasequences. Lithofacies is the
most direct, comprehensive, and essential indicator to reflect
sequence stratigraphy change. Therefore, lithofacies characteristics and vertical superimposition patterns are chosen as the
mainline during sequence stratigraphy research. Firstly, petrologic features are analyzed. Then, multi-method analysis and
mutual verification are implemented by incorporating vertical
changes in mineral compositions and geochemical indicators to
divide third- and fourth-order sequence that lay a framework
for parasequences research. After that, a division method of
parasequences can be built. Various types of parasequences
with different characteristics can be divided in a stratigraphic
framework of third- and fourth-order sequence. Origins of different parasequences are analysed finally. Our method is verified by using the upper fourth member of the Shahejie Formation (Es4s) in the Dongying Depression, Bohai Bay Basin.
1
GEOLOGICAL SETTING
Dongying depression is a third-order tectonic unit of Bohai Bay Basin and a Mesozoic-Cenozoic fault-depression basin
Wu Jing, Zaixing Jiang, Chao Liang
(Fig. 1a, 1b). It is surrounded by four uplifts and characterized
by north-steep and south-glacis (Fig. 1c). The depression has an
exploration area of approximately 5 760 km2 (Wu et al, 2014).
It develops Paleozoic, Mesozoic, and Cenozoic strata from the
bottom to top, and the Cenozoic strata include the Palaeogene,
Neogene, and Quaternary strata. The Palaeogene strata are
generally thick and consist of Kongdian (Ek), Shahejie (Es),
and Dongying (Ed) formations. The Es formation can be divided into four members (Es1–4). The objective stratum in this
study is Es4s, the upper part of Es4.
The Es4s is developed by intense rift with fast basin expansion and large extent of subsidence. Vast semi deep-deep
water shales are distributed in the center of the depression
(Zhao, 2005), which are thicker than 1 000 m. Fan delta, nearshore subaqueous fan, and beach-bar siltstone distribute along
the margin of the depression (Yang et al, 2011; Wang, 2005;
Yan et al, 2005).
The appearance of glauconite (Wu et al, 2014), marine biohermal limestone (Qian et al., 1980), algae (e.g., Chinese
Cladosiphon and dinoflagellates), gastropods, clupeomorpha,
and Paleodictyon (Yuan, 2006; Xu et al.1997; Zhang et al.,
1985; Zhu, 1979) indicate the occurrence of transgression during Es4s in the study area. As the influence of the transgression
is paroxysmal and accidental, the study area overall is lacustrine environment.
Figure 1. The geological background of the upper fourth member of Shahejie formation in the Dongying depression, Bohai bay basin, China. (A) Dongying
depression is boarded by the Luxi uplift in the south, the Chenjiazhuang uplift in the north, the Qingtuozi uplift in the east, and the Binxian-Qingcheng uplift in
the west. During the period of the Es4s, there are Boxing, Niuzhuang, Lijin, Minfeng four sags. (B) Geological setting of Bohai Bay basin during the Palaeogene. Dongying depression is located in the south of Jiyang depression of Bohai Bay Basin. (C) N-S trending section in the study area.
Division and Characteristics of Shale Parasequences in the Upper Fourth Member of the Shahejie Formation
2 DATABASE AND METHODOLOGY
2.1 Data
A total of 835.94 m continuous cores and 1 141 samples of
shales were obtained from 7 wells (NY1, FY1, Niu38, Wang31,
Fan120, Li673, Niu872) in the target interval (Fig. 1a, Table 1).
All samples were measured in the formation laboratory of
Shengli oilfield, Shandong, China.
The relative content of each mineral composition of all
samples were measured by using X’Pert-MPD diffraction instrument (Philips Corp.): copper butt, pipe pressure 30 kV,
conduit flow 40 mA, scanning speed 2°(2θ)/min. When mineral
content is more than 40%, relative standard deviation (RSD) is
less than 10%. When it is between 20%–40%, RSD is less than
20% (Wang et al., 1996). 300 thin sections were observed to
analyze the sedimentary characteristic using an optical microscope (Axio Scope A1). 65 samples were ground to the grain of
200-mesh and subjected by inductively coupled plasma-atomic
emission spectroscopy ICP-AES (JY38S) with a focus on the
elements Ca, Al, Mg et al. Ambient temperature is between
70-75℃. Relative humidity is less than 70%. RSD is less than
1–10 ppb.
A total of 256 samples were submitted to Rock-Eval pyrolysis for determination of TOC values, the free hydrocarbons
(S1, mg HC/g rock), and the hydrocarbons cracked from kerogen (S2, mg HC/g rock). The TOC values were determined
using rock-eval-VI (Cat. No. 2-06-11) from France. Measurement technique is based on the combustion of the sample in an
oxygen atmosphere convert the total organic carbon to CO2.
With the aid of combustion calculation, the total organic carbon
content of the samples can be determined (Wu et al., 2001;
Charles and Simmons, 1986). Temperature is between 60–80℃
during the process.
For S1 and S2, the samples were heated in Helium flow. S1
were detected by using hydrogen flame ionization detector. S2
were detected by thermal conductivity detector. The absolute
standard deviation is less than or equal to 0.01 mg/g.
Well logging data have the best continuity among the geological data. However, they contain random noise component.
Cyclicity is not obvious. Wavelet is an appropriate tool transforming the signal and one of the most common methods to
study stratigraphic cycles (Liu, 2012).
Considering the self-similarity and coefficients of various
wavelets (Yan et al, 2011), daubechies wavelet (db) can represent the cyclicity of large and small depositional units in the
study area. Among the well logging series, gamma-ray logs
(GR) match the most correlation to multiscale information of
sedimentary cyclicity of source rock (Passey et al.1990). The
MATLAB software (7.0.1 version, produced from the MathWorks in American) was used to perform one-dimensional
continuous transform 11 times of GR curve with db wavelet.
Eleven wavelets represent different level of sedimentary cycle.
2.2 Methods
(1) Lithofacies association
The parasequence is a relatively conformable succession
3
of genetically related beds or bedsets bounded by lake flooding
surfaces (LFS) and their correlative surfaces indicating that
there exists evidence for sudden increase in water depth
through the surfaces. A parasequence generally comprises the
lower part indicating deepening water depth and the upper part
indicating the shallowing water depth (Van Wagoner, 1990). A
typical shale parasequence, which is different from obvious
combinations of mudstone-gravel/sandstone of coarse grained
sedimentary rocks in the shallow-water, comprises a lower
interval deepening water-depth and an upper interval of shallowing water-depth. The change from lower interval to upper
interval reflects the shallowing-upward process of water depth.
(2) Mineral compositions.
Although mineral compositions change with specific
lithofacies, some minerals can reflect the change of water depth.
For example, pyrite is proportional to the depth and reducibility
of water (Zhang and Ren, 2003; Wilkin et al., 1996; Deng,
1990; Berner, 1970). The pyrite content changes from high to
low indicating the decrease of water depth, which helps to divide parasequence.
(3) Organic geochemical indicators
The change of organic geochemical indicators including
TOC and relative hydrocarbon potential (RHP) [(S1+S2)/TOC]
levels are proportional to the water depth (Slatt et al., 2012;
Arthur and Sageman, 2004). They undergo increase followed
by decrease indicating a parasequence. The subtle changing
points of them are parasequence boundaries. The Th/U ratio is
inversely proportional to water depth (Davies and Elliot, 1996).
It undergoes decrease followed by increase indicating a parasequence.
(4) Wavelet value
Discontinuities in shales do not show obvious change and
cannot be detected by well logs directly. The wavelet analysis
can achieve better effect. Wavelet value has periodic changes
from high to low levels reflecting the shallowing upward water
bodies (Prokoph and Agterberg, 2000; Miall, 1992; Rioul and
Vetterli, 1991). It can be used to divide shale parasequence.
After wavelet transform, the change of d3 wavelet value is
consistent with the other indicators.
Table 1. Average value of major mineral compositions of shale in the upper
fourth member of Shahejie Formation in Dongying depression, Bohai Bay
Basin, China
Well
Clay
Quartz
Calcite
Dolomite
Feldspar
Pyrite
（Sample No.）
(%)
(%)
(%)
(%)
(%)
(%)
NY1(632)
22.17
21.85
35.28
13.12
4.64
2.98
FY1(378)
16.45
24.49
37.58
13.71
5.11
2.87
Niu38(50)
35
23.76
26.68
4.72
5.1
3.16
Wang31(36)
30.33
16.1
32.1
9.93
10.01
3.2
Fan120(25)
18.96
21.36
42.92
9.44
4.16
3.29
Li673(15)
16.4
29.87
31.73
12.53
6
3.47
Niu872（5）
29.6
27.2
28
6.4
6.4
2.4
Wu Jing, Zaixing Jiang, Chao Liang
4
3 RESULTS
3.1 Lithofacies Classification, Characteristics and Depositional Model
3.1.1 Lithofacies classification
The X-ray diffraction data show that, the major mineral
compositions of the Es4s shale in the Dongying depression are
calcite, clay minerals and quartz.
Other mineral compositions involve dolomite, pyrite and
feldspar. The average content of calcite is 33.47%. Its maximum can reach up to 80%. The average content of clay minerals and quartz is 24.13% and 23.51%, respectively. The organic
matter value is between 0.11%–11.4% with an average value of
2.49% (Table 2). According to the contents of various mineral
compositions and sedimentary characteristics, a total of 7 kinds
of lithofacies are identified (Table 1).
laminae. Light laminae comprise grainy calcite by a certain
degree of recrystallization. Dark laminae mainly comprise organic matter and clay minerals. Laminae are influenced by
weak water turbulence (Fig. 2d–2f). Based on the minerals
compositions and sedimentary structure, this type of lithofacies
was formed in a reducing environment of semi-deep water.
(3) Low-TOC limy shale
Carbonate content is greater than 50%. TOC value is less than
2%. The content of pyrite is low with an average content of
only 1.83 % (Fig. 2). The quartz particles with angular edge
and bioclast can be found. Laminae are developed with wave
distribution of laminae. The thickness of single laminae is
about 60–120 μm. Light laminae are dominated by micritic
calcite and dark laminae are clay minerals layers with little
organic matter (Fig. 2g,2h). This type of lithofacies was formed
in a weakly reducing environment of shallow water.
(4) Low-TOC shale
Low-TOC shale is similar with low-TOC limy shale. But
clay minerals content of low-TOC shale is greater than 50%.
Average value of TOC is less than 2% (Fig. 2). Laminae are
developed. Light laminae comprise micritic calcite and dark
laminae comprise clay minerals. This type of lithofacies was
formed in a weakly reducing environment of shallow water
(Fig. 3i, 3j).
(5) Low-TOC gypsiferous shale
Gypsums, typical products of drought condition and evaporation, with an average content of 27.75 %, distribute in light
laminae. Dark laminae comprise clay minerals. Average value
of TOC is only 0.67% (Fig. 2). This type of lithofacies was
formed in shallow water (Fig. 3k, 3l).
(6) Carbonate-bearing silty shale
Compared with oil shale or limy shale, carbonate content
of this type of shale is relatively low with an average value of
42.41%.
3.1.2 Lithofacies characteristics
(1) Oil shale
Carbonate content is greater than 50%. TOC value is greater than 4% with an average value of 4.32%. Pyrites are abundant with an average content of 3.28% and maximum of 10%
(Table 2). Smooth laminae are developed with obvious light
and dark laminae. Light laminae are dominated by columnar
calcite crystals formed by recrystallization. Dark laminae are
organic-rich clay minerals layers. Laminae are less affected by
water turbulence (Fig. 2a–2c). For the abundant of TOC and
pyrite, combined with the characteristics of sedimentary structure, this type of shale is inferred to form in a strongly reducing
environment of deep water.
(2) High-TOC limy shale
Carbonate content is greater than 50%. TOC value is commonly between 2–4% and average value is 2.7%. Pyrites are
relatively abundant with an average content of 2.22%. TOC
value and pyrites content are less than oil shale (Table. 3).
Laminae are developed with relatively pure light and dark
Table 2. Mineral compositions of different shale in the upper fourth member of Shahejie formation in Dongying depression, Bohai Bay Basin, China. The
number is presented in the form of “
a
”.
b-c
“a” is the average content, “b” is the lowest content, and “c” is the highest content.
Carbonate
Lithofacies
Clay
Quartz&Feldspar
Pyrite
TOC
Range(Ave.) wt.%
Range(Ave.) %
Oil shale
50–86（60.33）
6–25（13.22）
5–33（17.77）
1–10（3.28）
4.04–4.76（4.32）
high-TOC limy shale
50–78（60.66）
4–25（15.05）
10–35（22.17）
1–5（2.06）
2–3.98（2.7）
Low-TOC limy shale
50–89（65.04）
2–23（12.16）
5–29（19.62）
1–4（1.83）
0.58–1.98（1.55）
Low-TOC shale
4–34（18）
36–55（43.25）
26–42（33.5）
1–3（2）
0.9–2.48（1.94）
Low-TOC gypsiferous shale
3–46（26.25）
10–41（24.25）
12–23（19.75）
2（2）
0.44–0.9（0.67）
Carbonate-bearing silty shale
36–49（42.41）
11–35（22.52）
21–43（31.88）
1–6（3.17）
2–3.83（2.64）
Dolomitic-bearing silty shale
38–48（34.2）
7–34（24.64）
14–36（24.78）
2–11（3.71）
1.5–3.64（2.73）
Table 3. Origins, types and sedimentations of shale parasequences in the upper fourth member of Shahejie formation in Dongying depression, Bohai Bay Basin.
Origins
Types
Main sedimentation
oil shale-High-TOC limy shale
High-TOC limy shale-low-TOC limy shale
The relative lake level change with little terrestrial input
Biological and chemical sedimentation
High-TOC limy shale
Low-TOC shale-Low-TOC gypsiferous shale
Low-TOC limy shale
Transgression
Dolomitic-bearing silty silty shale
The relative lake level change with terrestrial input
Carbonate-bearing silty shale
Chemical sedimentation
Bio-chemi- mechanical sedimentation
Division and Characteristics of Shale Parasequences in the Upper Fourth Member of the Shahejie Formation
Mainly calcites are micritic and few are grainy calcites.
However, the content of quartz and feldspar is higher than other
shale. The average value of TOC is 2.64%. Pyrites are abundant
with an average value of 3.17% (Table. 2). Such lithofacies was
formed in a reducing environment of semi-deep water and influenced by terrigenous material (Fig. 2m, 2n).
(7) Dolomitic-bearing silty shale
Dolomite is micritic with an average value of 34.2%. TOC
value is between 1.5%–3.64% and lower than high-TOC limy
shale and carbonate-bearing silty shale. Pyrites are abundant
too with an average value of 3.71% (Table. 2). This type of
lithofacies was developed only in the early stage of Es4s with a
reducing environment of semi-deep water (Fig. 3o, 3p).
3.1.3 Lithofacies depositional model
Based on 7 kinds of lithofacies with different sedimentary
characteristics and environment, a depositional model of Es4s
5
shales proposed (Fig. 3). Organic matter and pyrite are abundant for the favourable preservation condition of strongly reducing environment of deep water. Smooth laminae are developed for almost without water turbulence. In this kind of environment, lithofacies is dominated by oil shale. TOC value is
generally between 2%–4% in reducing environment of
semi-deep water. Laminae are developed with weak water turbulence. The lithofacies are developed from the lower to upper
sections according to the water depth, including high-TOC limy
shale, carbonate-bearing silty shale and dolomitic-bearing silty
shale. TOC value and pyrite content are both low in the weakly
reducing environment of shallow water. Laminae are developed
with wave distribution as influenced by water turbulence. The
lithofacies are dominated by low-TOC shale and low-TOC limy
shale. In a drought conditions, water evaporation lead to the
formation of low-TOC gypsiferous shale and saline lake.
Figure 2. Shale characteristics of the upper fourth member of Shahejie Formation in Dongying depression, Bohai Bay Basin, China. A. well FY1, 3 324.79 m,
grey black oil shale. Arrow points to the calcite laminae with recrystallization. Strong bubble occurred after droping hydrochloric acid; b. well FY1, 3 324.79 m,
oil shale with columnar calcite crystals under cross-polarized light (+) (modified after Wu et al., 2016, arrow). Boundaries between light and dark laminae are
clear; c. well LY1, 3 662 m, field emission scanning electron microscope image of oil shale with abundant framboidal pyrite (arrow); d. well LY1, 3 662.1 m,
dark grey high-TOC limy shale with a certain degree of recrystallization (arrow); e. well LY1, 3 662.1 m, (+), high-TOC limy shale with grainy crystals (arrow).
Grainy calcite size changes large. Boundaries between light and dark laminae are relatively clear; f. well NY1, (+), 3 410.86 m, high-TOC limy shale, pyrite
content is high (arrow); g. well LY1, 3 631.5 m, light grey low-TOC limy shale. Boundaries between light and dark laminae are not smooth; h. well LY1, 3
631.5 m, (+), low-TOC limy shale, Light laminae are micritic calcite and thick (arrow); i. well NY1, 3 430.38 m, light grey low-TOC shale; j. well NY1, 3
430.38 m, (+), low-TOC shale. Dark laminae are thick comprising clay minerals and little organic matter; k. well NY1, 3498.3 m, grey white low-TOC gypsiferous shale; l. well NY1, 3 498.3 m, (+), low-TOC gypsiferous shale. Light laminae comprise gypse (arrow). Influenced by evaporation and water turbulence,
boundaries between light and dark laminae are not clear; m. well NY1, 3 373.79 m, grey carbonate-bearing silty shale; n. well NY1, 3 373.79 m, (+), carbonate-bearing silty shale comprising micritic and grainy calcites, bioclast, clay, pyrite, etc. (arrows); o. well NY1, 3 463.59 m, grey dolomitic-bearing silty
shale; p. well NY1, 3 463.59 m, (+), dolomitic-bearing silty shale. The lower laminae comprise terrigenous material and the upper laminae comprise micritic
dolomite (arrows).
Wu Jing, Zaixing Jiang, Chao Liang
6
3.2
Division and Characteristics of Third- and
Fourth-Order Sequence
One whole third order sequence including lowstand systems tract (LST), transgressive systems tract (TST) and highstand systems tract (HST) was developed in the Es4s. Well
NY1 is taken as a typical example (Fig. 4).
3.2.1 LST
The interval of 3 492–3 498.5 m (Es4s not penetrated)
mainly comprises low-TOC gypsiferous shale and Low-TOC
shale. The Th/U ratio increases upward, in contrast, the TOC
value decreases upward. These features indicate that water
continues to shallow upward. In this interval, pollen are dominated by Ephedripites, Labitricolpites, Caryapollenites, Quercoidites indicating arid climate, that formed an evaporation
environment and caused continuous decline in water depth. On
the top of this interval, there is a surface of discontinuity (gypsiferous deposition turned to limy sediments) - first flooding
surface. Based on the comprehensive analysis, this interval is
LST.
Figure 3. Shale depositional model of the upper fourth member of Shahejie Formation in the Dongying depression, Bohai Bay Basin. (modified after Wu et al.,
2016)
Figure 4. Sequence division of the upper fourth member of Shahejie Formation in well NY1, Dongying depression, Bohai Bay Basin, China.
Division and Characteristics of Shale Parasequences in the Upper Fourth Member of the Shahejie Formation
3.2.2 TST
(1) TST-1 (passive lake-level rising phase)
In the interval of 3 434–3 492 m, the lithofacies are dominated by dolomitic-bearing silty shale interbedded with
low-TOC limy shale and upward-increasing high-TOC limy
shale. In the middle segment, there is a set of turbidity deposition. TOC value and pyrite content increase upward except the
segment of turbidite depositsions. Th/U ratio undergoes opposite change. Above-mentioned characteristics indicate that the
lake level experienced continuous rise including two retrograding parasequence sets (Fig. 4, S2-3). One thing is worth to
note that four special sets of sedimentary strata (Fig. 4, ①-④)
are present with dolomite shale, with unusually high salinity
(Sr/Ba is proportion to the salinity, Jiang et al., 1994), Mg levels, TOC value and abnormally low values of trace elements
(Cr and Pb). These sets are affected by transgression responding to the geological setting of this study area. The lake level
passively rose due to the influence of four phase’s transgression,
leading to the development of TST-1.
(2) TST-2 (normal lake-level rising phase)
In the interval of 3 374–3 434 m, high-TOC limy shale
and upward-increasing oil shale are developed. TOC value
peaks in the whole well segment, i.e., 11.4% (3 374.19 m). The
values of Sr/Ba and Th/U decrease. This interval recovered to a
normal lake deposition after the transgression and composed
with three retrograding parasequence sets (Fig. 4, S4-6). In this
interval, pollen are dominated by Taxodiaceae, Ulmoideipites
indicating warm-damp climate of the study area. Water depth is
the greatest on the top of the interval influenced by the climate,
associated with the development of the maximum flooding
surface. Thus, this interval belongs to TST and is classified as
TST-2 in order to distinguish from the TST-1.
3.2.3 HST
In the interval of 3 326–3 374 m, two sets of lithofacies associations are developed and each set include carbonate-bearing silty shale and upward-increasing low-TOC
limy shale. The water depth decreases upward. These two sets
which have feature of superposition patterns (Fig. 4, S7-8).
Based on the obviously increasing Th/U ratio, sustainably decreasing TOC value and pyrite content, this interval belongs to
HST.
3.3 Division Method of Fifth-Order Sequence (Parasequence)
In this study, parasequences are divided with a combination of shale reflecting the shallowing-upward process of water
depth and verified with data of mineral compositions, geochemical indicators and wavelet in well NY1. The thickness of
parasequence within the range from 2 to 4 m.
During the division, we notice the consistency of the
lithofacies occasionally, with minor changes in mineral compositions and geochemical indicators. TOC and RHP levels undergo increase followed by decrease indistinctively. These features suggest that the deepening-shallowing change in water
depth is not significant, accounting for a lack of change in the
type of lithofacies. This kind of section also represents a parasequence with thickness of 2–3 m.
7
Seven types of parasequence are identified using the proposed method. Furthermore, they are divided into two categories, including the unitary and dual structures, according to the
amount of lithofacies type and changes of other indicators.
3.4 Characterization of parasequence
3.4.1 Dual structure
(1) Oil shale and High-TOC limy shale
This kind of parasequence is dominated by grey black oil
shale (Fig. 5a) in the lower interval (Fig. 5 blue arrows on core
picture), with dark grey high-TOC limy shale (Fig. 5b,5c) developed in the upper interval (Fig. 5 green arrows on core picture). From the lower to upper interval, TOC, S1+S2 and d3
level rise rapidly and decline slowly. These features reflect a
suddenly increase from semi-deep water to deep water through
the LFS followed by a decrease back to semi-deep water (Fig. 5
columnar section).
This kind of parasequence mainly distributes in the upper
TST-1 and lower TST-2 with upward-increasing thickness (Fig.
4). Warm-damp climate and deep water of TST afforded abundant algae and strong reducibility that helped the preservation
of organic matter in the lower interval of parasequence. The
limy depositions are formed by chemical precipitation with low
terrestrial input and recrystallized by organic acid produced by
the evolution of biological organic matters (Fig. 5c). Water
depth decreased relatively in the upper interval of parasequence.
This change reduced the preservation condition of organic
matter, which lead to the reduction of TOC value and transition
from oil shale to high-TOC limy shale.
(2) High-TOC limy shale and Low-TOC limy shale
In the lower interval of parasequence (Fig. 6 blue arrows),
low-TOC limy shale quickly tends to dark grey high-TOC limy
shale (Fig. 6a), with increasing-upward light grey low-TOC
limy shale in the upper interval (Fig. 6 green arrows, B). Pyrite
content, TOC value, S1+S2 and d3 level increase significantly
followed by decrease. The water depth deepens quickly from
shallow water to semi-deep water and then shallows slowly
back to shallow water (Fig. 6 columnar section).
This kind of parasequence mainly distributes in TST and
occasionally occurred in HST (Fig. 4). Influenced by the
warm-damp climate, deep water and a small amount of terrigenous material in TST, algae were plenty and organic matters
were preserved well. Limy deposition were formed through the
chemical precipitation, combined with high TOC value.
High-TOC limy shale was developed in the lower interval of
parasequence. When water depth decreased relatively with
decreasing reducibility in the upper interval of parasequence,
organic matters were poorly preserved and low-TOC limy shale
was developed.
(3) Low-TOC shale and low-TOC gypsiferous shale
After the development of low-TOC gypsiferous shale in
the bottom, the lower interval of parasequence is quickly dominated by light grey low-TOC shale (Fig. 7 blue arrows, A),
with increasing-upward grey white low-TOC gypsiferous shale
in the upper interval (Fig. 7 green arrows, B). At the same time,
pyrite content, TOC value, S1+S2 and d3 level obviously increase followed by decrease. These features reflect a sudden
increase through the LFS followed by decrease in water depth
8
(Fig. 8 columnar section).
This kind of parasequence only distributes in the parasequence set 1 of LST (Fig. 5) with arid climate, shallow water
and high level of salinity (Fig. 6 increasing-upward Sr/Ba).
When the terrigenous material decreased (Fig. 6 table, quartz &
feldspar), gypsiferous depositions were developed through
chemical precipitation.
3.4.2 Unitary structure
(1) Low-TOC limy shale
Wu Jing, Zaixing Jiang, Chao Liang
Lithofacies type is consistently dominated by low-TOC
limy shale (Fig. 8a, 8b) from the lower to upper interval of the
parasequence (Fig. 8 blue and green arrows). There is no significant change in mineral compositions too. But there are
some changes in the color of core (Fig. 8, core of 3 434.78m is
more black than other). TOC value, S1+S2 and d3 level slight
increase followed by decrease. Although all of these values are
low with weak changes, these still reflect an increase through
the LFS followed by decrease in water depth (Fig. 8 columnar
section).
Figure 5. Characteristics of parasequence comprising oil shale and high-TOC limy shale of the upper fourth member of Shahejie formation in well NY1,
Dongying depression, Bohai Bay Basin, China. On the core picture, the blue and green arrows respectively represent the lower and upper part of the parasequence. The numbers from 1 to 3 and the five-pointed star respectively show the location of sample in the table and thin section. LFS is lake flooding surface. A:
3432.17 m, (+), Oil shale with columnar calcite (CC, arrow); B: 3431.59 m, (+), high-TOC limy shale, abundant pyrite (P) and remains of higher plants (R,
arrows); C: 3431.59 m, (+), high-TOC limy shale, remains of higher plants with grainy calcite (GC, arrow).
Figure 6. Characteristics of parasequence comprising high-TOC limy shale and low-TOC limy shale of the upper fourth member of Shahejie Formation in well
NY1, Dongying depression, Bohai Bay Basin, China. A: 3425.98 m, high-TOC limy shale with grainy calcite under plane-polarized light (-) (GC, arrow); B: 3
424.29 m, low-TOC limy shale with micritic calcite (-) (MC, arrow).
Division and Characteristics of Shale Parasequences in the Upper Fourth Member of the Shahejie Formation
9
Figure 7. Characteristics of parasequence comprising low-TOC shale and low-TOC gypsiferous shale of the upper fourth member of Shahejie formation in well
NY1, Dongying depression, Bohai Bay Basin, China. A: 3498.3 m, (+), low-TOC shale; B: NY1 well, 3495.29 m, (+), low-TOC gypsiferous shale, gypsum (G,
arrow).
Figure 8. Characteristics of parasequence comprising low-TOC limy shale of the upper fourth member of Shahejie formation in well NY1, Dongying depression, Bohai Bay Basin, China. A: 3434.56 m, (+), low-TOC shale; B: 3434.56 m, (+), low-TOC limy shale, laminae of micritic calcite with abundant fragments
of Ostracoda and quartz (F and Q, arrows) indicate shallow water.
This kind of parasequence mainly distributes in the interval of TST-1. Climate began to warm-damp and water depth
started to deepen in TST-1 (Fig. 4). Algae were deficient.
Chemical precipitation lead to the formation of limy deposition.
(2) High-TOC limy shale
The parasequence is consistently dominated by high-TOC
limy shale from the lower to upper interval (Fig. 10 blue and
green arrows, A). The changes of TOC value and S1+S2 level
are same with the last kind of parasequence (low-TOC limy
shale) and still reflect a mildly increase through the LFS followed by decrease in water depth (Fig. 10 columnar section).
The value of d3 is steady.
This kind of parasequence mainly develops in the mid-late
stage of TST-2 and occasionally in the stage of TST-1 and HST
(Fig. 4). Rich organic matter supplied by algae and calcite deposited through chemical precipitation with semi-deep reducing
water (Fig. 9b) that composed the parasequence. TOC value
and S1+S2 level weakly decrease and indicate the upper interval of parasequence.
(3) Carbonate-bearing silty shale
Although lithofacies are consistently dominated by carbonate-bearing silty shale (Fig. 10, blue and green arrows, A),
the TOC value (generally greater than 2%), S1+S2 and d3 level
increase followed by decrease and reflect an increase through
the LFS followed by decrease in water depth (Fig. 10columnar
section). This kind of parasequence mainly develops in the
HST, gradually thinning upward and transiting to high-TOC
limy shale and low-TOC limy shale for the shallowing upward
10
water depth (Fig. 4). The compositions are varied including
calcite, remains of higher plants, clay and quartz (Fig. 11 table,
A and B). Micritic calcites were mainly formed by chemical
precipitation. Quartz particles with angular edge came from
terrigenous material and were formed by mechanical action
after erosion of parent rocks. Higher plants and algae help the
biological sedimentation.
(4) Dolomitic-bearing silty shale
This kind of parasequence mainly comprises dolomitic-bearing silty shale (Fig. 11 blue and green arrows, A). From
the lower to upper interval, TOC value and S1+S2 levels increase followed by decrease with abnormal high values of salinity (Sr/Ba) (Fig. 11 columnar section). This kind of parasequence only develops in the TST-1 affected by transgression
and comprises micritic dolomite (Fig. 11b) by chemical precipitation. Sea water offered the material basis. The overlying
strata is high-TOC limy shale for the high lake level of water
after the transgression (Fig. 4).
4
DISCUSSION
In the dual structure, there are obvious changes in the
lithofacies associations, mineral compositions, geochemical
characteristics and wavelets to divide parasequence easily. In
the unitary structure, a special or extreme form of dual structure,
lithofacies type does not change because of the minor change in
water depth during parasequence development. The lithofacies
can be developed in relatively deep water (e.g., high-TOC limy
shale) or shallow water (e.g., low-TOC limy shale). The division of shale parasequence of unitary structure most depends on
slight changes of mineral compositions and geochemical indicators.
The origins and sedimentations of shale parasequence are
diverse. Based on the characteristics of each kind of shale parasequence, geological setting and relationship with third- and
Wu Jing, Zaixing Jiang, Chao Liang
fourth-order sequence, three kinds of origins and sedimentations are summarized (Table 3). The development of high-TOC
(>2%) shale parasequence was mainly controlled by biochemical sedimentation. The development of low-TOC (<2%) shale
parasequence was mainly dominated by chemical sedimentation.
The geological conditions of the study area were complex.
The climate changed from arid -cold in LST to warm-damp in
TST and formed a large climate span. The water depth changed
from shallow water to deep water under different climate conditions and formed a large water depth span. Due to the changes of climate and water depth, the development of shale was
affected by different levels of terrestrial input. The changes of
climate and water depth also affected the biochemical condition
which influence the TOC value and pyrite content in shale.
Arid climate helped the development of gypsiferous deposition
by chemical sedimentation. In addition, The TST-1 interval
was affected by transgression. Thus, the diversities of shale
parasequences were caused by the major controlling factors
including climate, relative lake level change, terrestrial input
and emergency (transgression).
Because of limited target interval and study area in this
study, the kinds of shale parasequences may be more diverse.
However, a systematic research method and specific research
process has been established with wide applicability. For example, although the lithofacies are different under specific
geological conditions of different areas, the combination of a
lower interval deepening water-depth and an upper interval of
shallowing water-depth is applicative to divide shale parasequences. The auxiliary indicators (mineral compositions, geochemical indicators and wavelet values) can be replaced by the
other indicators in other area to divide shale parasequences.
Periodical changes of these indicators show the development of
parasequences.
Figure 9. Characteristics of parasequence comprising high-TOC limy shale of the upper fourth member of Shahejie formation in well NY1, Dongying depression, Bohai Bay Basin, China. A: 3375.87m, (+), high-TOC limy shale, laminae of grainy calcite (GC, arrow); B: 3376.85m, (+), high-TOC limy shale, laminae
of pyrite (P, arrow).
Division and Characteristics of Shale Parasequences in the Upper Fourth Member of the Shahejie Formation
11
Figure 10. Characteristics of parasequence comprising carbonate-bearing silty shale of the upper fourth member of the Shahejie formation in well NY1,
Dongying depression, Bohai Bay Basin, China. A: 3372.65 m, (+), carbonate-bearing silty shale, remains of higher plants, quartz and calcite (R, Q and C, arrow); B: 3372.65 m, (+), carbonate-bearing silty shale, calcite and remains of higher plants (C&R, arrow).
Figure 11. Characteristics of parasequence comprising dolomitic-bearing silty shale of the upper fourth member of the Shahejie formation in well NY1,
Dongying depression, Bohai Bay Basin, China. A: 3466.15 m, dolomitic-bearing silty shale; and B: 3466.15 m, (+), dolomitic-bearing silty shale with micritic
dolomite (MD, arrow).
5
CONCLUSIONS
Shale parasequence research is generally lacking
in sedimentary geology and sequence stratigraphy.
The division, characteristics and origins of shale parasequences are still poorly understood due to the absence of any systematic research methods. Our research marks a step forward in shale parasequence
research with the following key contribution:
(1) A division method with four aspects of
boundary identification for shale parasequence has
been proposed in a reasonable stratigraphic framework of third- and fourth-order sequences, which
overcomes the limitation of existing research methods
relying only on a single indicator.
(2) On the basis of division, specific characteristics and origins of shale parasequences, a systematic
research method was established. The lithofacies,
mineral compositions, geochemical characteristics, as
Wu Jing, Zaixing Jiang, Chao Liang
12
well as the wavelet features of a typical shale parasequence have been documented. Two categories including seven types caused by three origins of parasequences have been identified in consideration of the
geological setting and features of the third- and
fourth-order sequences features.
(3) The diversities of shale parasequences are
caused by a combination of controlling factors including climate, relative lake level changes, terrestrial
input and transgression.
(4) This systematic research method for shale
parasequences analysis enriches the theory of sequence stratigraphy and our understanding of shale
sedimentary geology and provides useful insight for
guiding unconventional oil and gas exploration.
Central Tarim Basin. Earth Science, 23(4): 516–528.(in Chinese with English abstract)
Liu, Z. H., 2012. Orbital Cycles Analysis and its Genesis Significance for the
Sequence Hierarchy: A Case Study of Carboniferous Karashayi Formation,
Central Tarim Basin. Journal of Earth Science, 23(4): 516–528.
doi:10.1007/s12583-012-0272-3
Loucks, R. G., Ruppel, S. C., 2007. Mississippian Barnett Shale: Lithofacies and
Depositional Setting of a Deep-Water Shale-Gas Succession in the Fort
Worth
Basin,
Texas.
AAPG
Bulletin,
91(4):
579–601.
doi:10.1306/11020606059
Miall, A. D., 1992. Exxon Global Cycle Chart: An Event for every Occasion?.
Geology,
20(9):
787–790.
doi:10.1130/0091-7613(1992)020<0787:egccae>2.3.co;2
Passey, Q. R., Creaney. S., Kulla, J. B., et al 1990. A Practical Model for Organic
Richness from Porosity and Resistivity Logs. AAPG Bulletin, 74(12):
1777-1794.doi:10.1306/0c9b25c9-1710-11d7-8645000102c1865d
REFERENCES CITED
Prokoph, A., Agterberg, F. P., 2000. Wavelet Analysis of Well-Logging Data from
Angulo, S., Buatois, L. A., 2012. Integrating Depositional Models, Ichnology, and
Sequence Stratigraphy in Reservoir Characterization: The Middle Member
Oil Source Rock, Egret Member, Offshore Eastern Canada. AAPG Bulletin,
84(10): 1617–1632. doi:10.1306/8626bf15-173b-11d7-8645000102c1865d
of the Devonian–Carboniferous Bakken Formation of Subsurface South-
Qian, K., Wang, S. M., Liu, S. F., et al., 1980. Tertiary Reef Limestone Found in
eastern Saskatchewan Revisited. AAPG Bulletin, 96(6): 1017–1043.
the Northern East China and Its Significance in Petroleum Geology. Science
doi:10.1306/11021111045
Bulletin, 24: 1140-1142 (in Chinese).
Arthur, M. A., Sageman, B .B., 2004. Sea-Level Control On Source-Rock Development: Perspectives from the Holocene Black Sea, the Mid-Cretaceous
Western Interior Basin on North America, and the Late Devonian Appalachian Basin. In: Harris, N.B. ed., The Deposition of Organic-Carbon-Rich
Sediments: Models, Mechanisms, and Consequences: SEPM Special Publication, 82: 35–59.
Rioul, O., Vetterli, M., 1991. Wavelets and Signal Processing. IEEE Signal
Processing Magazine, 8(4): 14–38. doi:10.1109/79.91217
Singh, P., 2008. Lithofacies and Sequences Stratigraphic Framework of the
Barnett Shale: [Dessertation]. University of Oklahoma, Texas.
Abouelresh, M. O., Slatt, R. M., 2012. Lithofacies and Sequence Stratigraphy of
the Barnett Shale in East-Central Fort Worth Basin, Texas. AAPG Bulletin,
Berner, R. A., 1984. Sedimentary Pyrite Formation: An Update. Geochimica et
Cosmochimica Acta, 48(4): 605–615. doi:10.1016/0016-7037(84)90089-9
Catuneanu, O., 2006. Principles of Sequence Stratigraphy. Petroleum Industry
96(1): 1–22. doi:10.1306/04261110116
Slatt, R. M., Rodriguez, N. D., 2012. Comparative Sequence Stratigraphy and
Organic Geochemistry of Gas Shales: Commonality or Coincidence?. Jour-
Press, Bei jing.Schutter, S.R., 1998. Characterization of shale deposition in
nal
relation to stratigraphic sequence systems tracts, in Schieber, J., Zimmerle,
doi:10.1016/j.jngse.2012.01.008
W., Sethi, P. eds., Shales and mudstones I. E. Schweizerhbart'sche Verlagsbuchhandlung, Stuttgart, Germany, 79–108.
of
Natural
Gas
Science
and
Engineering,
8:
68–84.
Slatt, R. M., Abousleiman, Y., 2011. Merging Sequence Stratigraphy and Geomechanics for Unconventional Gas Shales. The Leading Edge, 30(3):
Charles, M. J., Simmons, M. S., 1986. Methods for the Determination of Carbon
in Soils and Sediments——A Review. The Analyst, 111(4): 385–390.
doi:10.1039/an9861100385
274–282. doi:10.1190/1.3567258
Slatt, R. M., Philp, P. R., Abousleiman, Y., et al., 2012, Pore-to-Regional-Scale
Integrated Characterization Workflow for Unconventional Gas Shales. In
Creaney, S., Passey, Q. R., 1993. Recurring Patterns of Total Organic Carbon and
Source Rock Quality within a Sequence Stratigraphic Framework. AAPG
Bulletin,
77(3):
386–401.doi:10.1306/bdff8c18-1718-11d7-8645000102c1865d
Davies, S. J., Elliott, T., 1996. Spectral Gamma Ray Characterization of High
Resolution Sequence Stratigraphy: Examples from Upper Carboniferous
Fluvio-Deltaic Systems, County Clare, Ireland. Geological Society, London,
Breyer, J. A.,ed., Shale Reservoirs—Giant Resources for the 21st century.
AAPG Memoir, 97: 127–150.
Smith, M. G., Bustin, R. M., 2000. Late Devonian and Early Mississippian
Bakken and Exshaw Black Shale Source Rocks, Western Canada Sedimentary Basin: A Sequence Stratigraphic Interpretation. AAPG Bulletin, 84(7),
940–960. doi:10.1306/a9673b76-1738-11d7-8645000102c1865d
Van Wagoner, J. C., Mitchum, R. M., Campion, K. M., et al., 1990. Siliciclastic
Special Publications, 104(1): 25–35. doi:10.1144/gsl.sp.1996.104.01.03
Sequence Stratigraphy in Well Logs, Core, and Outcrops: Concepts for High
Deng, H. W., Qian, K., 1990. The Genetic Types and Association Evolution of
Resolution Correlation of Time and Facies. Annuaire Statistique de la So-
Deep Lacustrinefacies Mudstones. Acta SedimentoIogica Sinica, 8(3): 1–20
ciete des Nations. Societe des Nations: Service d'etudes Economiques,
(in Chinese with English abstract).
Jiang, N. Y., Jia, R. F., Wang, Z. Y., 1994.
43–62.
Permian Palaeogeography and
Wang, B., Lin, X., Bao, Y., et al., 1996. SY/T 6210-1996 Quantitative Analysis of
geochemical Environment in Lower Yangtze Region, China. Beijing: Petro-
Total Contents of Clay Minerals and Common Non-Clay Minerals in Sedi-
leum Industry Press. (in Chinese)
mentary Rocks by X-Ray Diffraction. Petroleum Industry Press, Beijing (in
Liu, Z. J., Sun, P. C., Jia, J. L., et al., 2011. Distinguishing Features and Their
Chinese).
Genetic Interpretation of Stratigraphic Sequence in Continental Deep Water
Wang, J. F., 2005. Sedimentary Facies of the Shahejie Formation of Paleogene in
Setting: A Case from Qingshankou Formation in Songliao Basin. Earth Sci-
Dongying Sag, Jiyang Depression．Journal of Palaeogeography, 7(1):45–58
ence Frontiers, 18, 171–180 (in Chinese with English abstract).
(in Chinese with English Abstract).
Liu, Z. H., 2012. Orbital Cycles Analysis and Its Genesis Significance for the
Wilkin, R. T., Barnes, H. L., Brantley, S. L., 1996. The Size Distribution of
Sequence Hierarchy: A Case Study of Carboniferous Karashayi Formation,
Framboidal Pyrite in Modern Sediments: An Indicator of Redox Conditions.
Division and Characteristics of Shale Parasequences in the Upper Fourth Member of the Shahejie Formation
Geochimica
et
Cosmochimica
Acta,
60(20):
3897–3912.
doi:10.1016/0016-7037(96)00209-8
Wu, L., Zhang, Z., Li, B., et al., 2001. GB/T 18602-2001 Rock Pyrolysis Analysis.
Standards Press of China, Beijing (in Chinese).
Wu, J., Jiang, Z.X., Qian, Kan., et al., 2014. Characteristics of Salinization
13
Chinese)
Yang, Y. Q., Qiu, L. W., Jiang, Z. X., et al., 2011. A Depositional Pattern of Beach
Bar in Continental Rift Lake Basins: A Case Study on the upper Part of the
Fourth Member of the Shahejie Formation in the Dongying Sag. Acta Petrolei Sinica, 32 (3): 417–423. (in Chinese with English Abstract)
Mechanism on the Upper Part of fourth Member of Shahejie Formation in
Liu, L., Zhu, N. H., 2013. The Characteristics of Rare Earth Elements of Red
the Dongying Sag, Shandong province. Acta Geoscientica Sinica, 35(6):
Mudstones in the Lower Part of the Fourth Member of Shahejie Formation
733–740 (in Chinese with English abstract).
in Dongying Depression and its Geological Significance. Advanced Materi-
Liu, L., Zhu, N. H., 2013. The Characteristics of Rare Earth Elements of Red
als Research, 773: 763–767. doi:10.4028/www.scientific.net/amr.773.763
Mudstones in the Lower Part of the Fourth Member of Shahejie Formation
Yuan, W. F., Chen, S. Y., Zeng, C. M., 2006. Study on Marine Transgression of
in Dongying Depression and its Geological Significance. Advanced Materi-
Paleogene Shahejie Formation in Jiyang Depression. Acta Petrolei Sinica,
als Research, 773: 763–767. doi:10.4028/www.scientific.net/amr.773.763
27(4): 40–49 (in Chinese with English abstract).
Wu, J., Jiang, Z. X., Pan, Y. W., et al., 2016. Lacustrine Fine-Grained Deposition-
Zhao, Y., 2005. The Tectonic, Sedimentary and Oil Formation Kinetics Research
al Model – A Case Study of the Upper Submember of the Fourth Member of
of the North Slope in Doying Depression: [Dissertation]. Institute of Geo-
Paleogene Shahejie Formation in Dongying Sag. Acta Petrolei Sinica, 37(9):
chemistry, Chinese Academy of Sciences, Guangzhou. (in Chinese with
1080–1089 (in Chinese with English Abstract).
English Abstract)
Xu, J. L., Pan, Z.R., Yang, Y. M., et al., 1997. Dinophyceae and Acritarchs on
Zhang, M. M., Zhou, J. J., Qin, R. D., 1985．Tertiary fish fauna from coastal
Early Tertiary in Shengli Oil Area. Shandong: University of Petroleum Press,
region of Bohai Sea. Memoirs of Institute of Vertebrate Paleontology and
1–43 (in Chinese).
Paleoanthropology, Academia Sinica, 17. Beijing: Science Press. (in Chi-
Yan, J. H., Chen, S.Y ., Jiang, Z. X., 2005. Sedimentary Characteristics of Near-
nese)
shore Subaqueous Fans in Steep Slope of Dongying Depression. Journal of
Zhang, S. Q., Ren, Y.G ., 2003. The Study of Base Level Changes of the Songliao
the University of Petroleum, China.2 9(1): 6–9. (in Chinese with English
Basin in Mesozoic. Journal of Chang’an University (Earth Science Edition),
Abstract)
25(2): 1–7 (in Chinese with English Abstract).
Yan, J. P., Sima, L. Q., Li, Y., 2011.Method of Wavelet Multiscale Analysis and
Zhu, H.R., 1979. Algae Fossil from Shahejie formation of Early Tertiary in
Its Application in Division of Sedimentation Cycle of Lake Facies Mudstone.
Binxian of Shandong. Acta Palaeontologica Sinica, 18(4): 324–341. (in
International Conference on Computational and Information Sciences. (in
Chinese with English abstract)