Geological Journal of China Universities

New Thinking, Method and Calculated Examples of High Temperature Thermochronology of Granite Plutons

2013, 19(3): 385.

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Using least squares regression procedure, a best regression equation (t _Zr=1.0005×t _Rb+0.493041) with high correlation
coefficient (R =0.997) is fitted for 723 pairs of zircon U-Pb ages (t _Zr) and whole rock Rb-Sr ages (t _Rb) of granite plutons. The
frequency analysis of 723 individual values of differences between t _Zr and t _Rb (Δt _Zr-Rb) for granites shows symmetrical normal
distribution (skewness C _SK=0.193; kutrocess C _KU=6.722) with the Mean of 0.624 Ma and the Mode of 1.0 Ma. These statistical
characteristics indicate that for the granites as a whole, both the zircon U-Pb dating ages and the whole-rock Rb-Sr isochron ages
are consistent within permissible errors. However, because of a time difference between emplacement age and crystallizationsolidification
age, this isotope thermochronological method can be applicable only for the stage after their crystallizationsolidification.
Based on the differences between zircon U-Pb ages and whole-rock Rb-Sr isochron ages and the closure temperatures
of corresponding isotopic systems, previous researchers studied the cooling rates (CR _Zr-Rb) and thermal evolution history of 10
granite plutons, but these cooling rates are incorrelate to the volume change of granite plutons and contrary to the basic law of
thermophysics, i.e., the cooling rate of a larger hot body should be slower compared with a smaller one. In this paper, based on the
theory of thermal conductivity and using the concept of time difference between emplacement age and crystallization-consolidation
age, developed by present authors (2010), we come to a conclusion that, at the same thermo-physical conditions, the volume scale is the most important parameter that controls cooling rate of the granite plutons. On the example of existing 10 granites, and for
the high temperature thermal stage from magma emplacement to magma crystallization-consolidation, we derived a power function
regression equation to describe the relationship of cooling rate with volume parameter D: CR _ECTD=7544.7×D -2.1686. The calculated
results are obviously more reasonable and evidently conformable to the basic law of thermophysics.

Zircon U-Pb Dating and Hf Isotopes of the Granites Related to Yuchiling Mo Deposit in Songxian County and Their Constraints on the Metallogenetic Age

2013, 19(3): 403.

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The Yuchiling porphyry-type Mo deposit is located at the northwestern part of the Heyu granitic batholith along the
southern margin of the North China Craton. Zircon LA-ICP-MS U-Pb dating yields an age of 135.2±2.4 Ma for the ore-bearing
parent rock (granite porphyry), and of 138.2±2.3 Ma for the country rock (the unit. 3 intrusion of the Heyu granitic batholith),
indicating that they were all the products of the mid-Early Cretaceous magmatism, and the formation of the Yuchiling Mo deposit should not be older than~135 Ma. The zircon Hf isotope compositions of the Yuchiling ore-bearing granitic porphyry and the
granite country rocks vary greatly. The 176Hf/177Hf values of the former are from 0.281364 to 0.282420 with the εHf(t ) values ranging
from -9.6 to -46.9, and those of the latter are from 0.281774 to 0.282337 with the εHf(t ) values ranging from -12.5 to -32.8,
suggesting that these rocks have undergone a significant magmatic mixing during the crystallization. Also, the mature end-member
is likely to be the Neoarchean-Paleoproterozoic Taihua Group basement and the immature end-member should be the Yanshanian
upwelling and underplating mantle-derived materials or the lower crust reworking of the preexisting mantle-derived constitutes. The
Yuchiling porphyry-type Mo deposit was formed when the Paleo-Pacific regime superposed, destroyed, and transformed the Paleo-
Tethys tectonic systems comprehensively. The intense thinning of the crust induced the underplating or intraplating of the basaltic
magma, leading to partial melting of ancient crustal rocks with higher Mo background, contaminating a small amount of mantlederived
constitutes or juvenile crust materials on different degrees. This Mo-rich magmatic system had experienced a high degree
of differentiation and subsequently ascended to the shallow level of crust and emplaced as granitic porphyry. As the country rock is
granite, the crannies of the porphyry exocontact are few. And for this reason molybdenum mineralization of the ore-bearing porphyry
body have taken place in varying degrees and shown a characteristic of whole-rock mineralization.

Investigation of the Genesis of Granite in the Hardat Tolgoi Pb-Zn Ore Deposit, Inner Mongolia

2013, 19(3): 415.

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The Hardat Tolgoi Pb-Zn deposit is a medium-sized Pb-Zn deposit recently found in Erenhot-Dongwuqi polymetallic
ore belt along the suture zone between the North China plate and the Siberia plate. The granite relevant to the Pb-Zn mineralization
in the orefield is a concealed pluton. The LA-ICP-MS zircon U-Pb dating indicates that the granite was emplaced at 125±4.3
Ma and thus was the products of“ Yanshanian” magmatism. Detailed geochemical data show that the granite is composed of
weakly peraluminous (A/CNK= 0.99-1.08) rocks with low iron, high silicon, and high alkali contents (mostly Na<K). The granite
is enriched in large-ion lithophile elements (LILEs, such as Rb and K), Nd and Ta, but is depleted in high-field strength elements
(HFSEs, such as Nb and Ti), Ba and Sr. The chondrite-normalized REE pattern shows M type with tetrad effect and strong Eu
depletion (δEu=0.003~0.013). These results suggest that the alkaline feldspar granite belongs to alkalinity A type granite and was
formed in a post-orogenic tectonic environment. Nd-Pb isotopic compositions show that the alkaline feldspar granite was derived
from partial melting of the Mesoproterozoic upper crust.

Recent Advances in Skarn Forming Models and the Yamansu Skarn Related Deposits

2013, 19(3): 425.

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Skarn has been scientifically recognized as a distinct class of rock for more than 100 years. However, the definition
of skarn is loose. Recently, mineralogy was proposed to be the key to define a skarn: a mineral assemblage including a wide
variety of calc-silicate and associated minerals, but is usually dominated by garnet and pyroxene; it was formed in almost all ages
and a variety of tectonic settings. This pure“ descriptive” definition is not genetic and does not account for processes such as
“metasomatism” and “ replacement”. As for the genetic aspect, diverse models have been proposed: from a general dictionary
definition of contact metamorphic-metasomatic interactions with intruding granitic magma in early times to interactions with maficultramafic
magma and high temperature magmatic skarn in recent years. It seems that genetic geological domain of skarn could be
controversial and is also expanding with time. Melt inclusion in skarn minerals and assimilation experiments studies provides new
insight on the skarn. Skarn-related iron deposits are of the most abundant types among the others, which may reach 5000 Mt with
a grade of 45%. Skarn-related iron deposits are mostly associated with mafic-ultramafic magmatism, alkaline alteration extensively
developed, and were low in Au compared to IOCG. These deposits of Precambrian age are rare. This paper also summarizes some
features of skarn-related iron deposits which promote our understanding of different iron ore deposits. In addition, the skarnization
processes in Yamansu skarn deposit were illustrated.

Three Dimensional Evolution of Etch Pits on Crystal Olivine and Insights into Understanding Petrofabrics

2013, 19(3): 437.

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Chemical etching with 20% HF (HF+distilled water, volume rate) at room temperature was studied on seven sections
of olivine crystals, i.e., parallel twin (100), (010), (001), rhombic prism (110), (011), (101) and rhombic dipyramid (111) sections.
AFM (Atomic Force Microscopy) and DIC (Differential Interference Contrast Microscope) methods were used to analyze these
etched sections . With a fixed shape and angle, etch figures were different in each case, but all are elongated to [010] and
shortened to [100]. The face indices and the crystallographic orientation of a single crystal were only determined by the specific
etch figures, also in rocks. Meanwhile, the etch figure symmetry displayed the point group mmm of olivine. Measured by a
specific shape in DIC 200×, the reaction rate of the seven sections was v (010)>v (110)>v (100)>v (111)>v (101)>v (001)>v (011). Classified the
etched random grain section indices identified by typical etch figure, the crystallographic preferred orientation of olivine grains in
peridotites from Bixiling in Dabieshan areas, was defined as having strong maxima of [100]， subnormal to the foliation， and strong
maxima of [010]， subparallel to the lineation. These observations may suggest that specific tectonic events affected the peridotites
at the localities.

Assessment on the New Pressure-Volume-Temperature (PVT ) Data of Supercritical Water

2013, 19(3): 447.

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Since 1990, the PVT data of supercritical water from experiments and molecular dynamics simulations are extended to
very high temperatures and pressures. These data are assessed in detail in this work. The equation of state for water developed by
the International Association for the Properties of Water and Steam (IAPWS95) is chosen as a reliable basis for the assessment,
which is also aided by appropriate extrapolation of the equation. The results suggest that the simulated data of Zhang and Duan
(2005) and those of Abramson and Brown (2004) derived from sound velocity measurements agree well with those of the most
accurate data of water at present, but the latter has small systematic deviations. The data in the other groups have obvious
systematic deviations or uncertainties. The simulated data of Belonoshko and Saxena (1991) have a large P -T range, but they also
have large uncertainties and obvious systematic deviations. The simulated data of Brodholt and Wood (1993) also have notable
systematic deviations. As pressure increases, the volume deviations of these two groups of simulated data vary from positive to
negative, where the deviations in the latter group are particularly obvious, and show very strong pressure dependence features at
high pressures, so they are easy to correct. The experimental data of Withers et al. (2000), Brodholt and Wood (1994) and Frost and Wood (1997) have obvious positive deviations, and can be corrected in principle, where the deviations of the first group are small,
but those of the latter two are much bigger. Overall, the experimental data of Larrieu and Ayers (1997) have large uncertainties,
where small deviations are only limited to the data at specific temperature and pressure, and the deviations of the other data have
no obvious regularity. These results should be helpful in the correct use of and further refinement of the above data.

Molecular Dynamics Study of Self-Diffusion of Silica and Oxygen in Silica Melt

2013, 19(3): 456.

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The diffusivity of elements in mineral controls the processes of ion exchange, isotope fractionation, and phase
transition. As one of the most important components of silicate melts, SiO2 plays a very important role in the earth mantle structure
and the dynamics process. This paper focuses on the ion diffusion mechanism in silica melt and the corresponding pressure when
the self-diffusion coefficient reaches its maximum value. We calculated the changing process of Si and O ions, self-diffusion
coefficient at temperatures of 3000 K by using the molecular dynamics (MD) simulation which contains 4500 ions in the silica
melt with Morse stretch potential. Calculations show that both Si and O self-diffusion coefficients increase at initial compression
and reach maximum values at 17.5 GPa. Self-diffusion coefficients for O are slightly greater than that for Si. The Si and O ions,
diffusion feature is caused by a defect-controlled transport mechanism and the five-fold coordination structure of Si ion is the main
reason for the rise of the diffusion coefficients in accord with the increasing pressure. The fact that the diffusion coefficient reaches
its maximum value means the change in the formation of five-fold Si in the liquid silica. This paper also calculated the relationship
between the average volume of [SiO2] unit and the pressure, which agrees well with the results of our experiment.

The Development Characteristics of the Fault System and Basin Structures of the Bodong Sag, East China

2013, 19(3): 463.

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Based on the detailed description of fault system, this paper established different types of fault structure patterns
and analyzed the distribution characteristics of faults in the study area of Bodong by using abundant seismic data and combined
analyses of sections and time slice characteristics. Furthermore, we carried out studies of the controlling role that fault system
played on basin structures. It is concluded that the development characteristics of fault system in Cenozoic age was in accordance
with the right lateral stress-field of Tanlu fault which is expressed as NNE-trending strike-slip faults for main branches, NEtrending
tensional faults for secondary ones and near EW-trending faults for the least abundant ones. Also, faults can be
subdivided into slip typed, tensional-slip, slip-tensional, and tensional types. Besides, different types of faults have different
structures due to the effects of property and activity intensity. Fault system in different ages showed tremendous differences
because of stress transition of Tanlu fault from left lateral to right lateral and intensity transition between tension and slip.
According to the dominant impact that fault acted on basin structures, Cenozoic basin can be classified into four revolutionary
stages, i.e., transitional stage from left lateral to right lateral, slip-tension faulted stage, tension-slip faulted stage, and slipdepression
stage. Therefore, the identification of temporal and spatial differences of faults could be used as an important guideline
for the oil and gas exploration in Dodong area.

Lithostratigraphical Correlation of the Volcanic Rock Series in Hongshanzi Basin in Great Hingan Range

2013, 19(3): 472.

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Because of the large time span and the age overlap of the lithostratigraphic units of Mesozoic volcanic rocks in southern
Great Hingan Range, we have chosen volcanic rocks from Hongshanzi Basin to measure the SHRIMP zircon U-Pb age, together
with the zircon U-Pb age of the volcanic rocks from adjacent area and the characteristics of rock associations to correlate the
volcanic rock series . The zircon in two alkaline rhyolite samples (sample numbers HS505, HS102) and one high-k calc-alkaline
rhyolite samples (sample numbers HS601) from Hongshanzi Basin has obvious oscillatory ring, high Th/U ratio, and they belong
to typical magma genesis. The results of zircon U-Pb dating indicate that the ²⁰⁶Pb/²³⁸U age range of 10 analysis points of sample
HS601 is 150~160 Ma with the weighted average of 156.5±1.6 Ma and MSWD of 1.11. Eleven analysis points of sample
HS102 is 153~159 Ma with the weighted average of 154.7±1.7 Ma and MSWD of 0.77. Fourteen analysis points of samples
HS505 is 151~160 Ma with the weighted average of 156.5±1.4 Ma and MSWD of 1.16. The age range of the volcanic rocks
from Hongshanzi Basin is 157~155 Ma, which belongs to the early Late Jurassic. The volcanic rocks in Hongshanzi Basin show characteristics of high-k calc-alkaline rhyolite-alkaline rhyolite associations, which are similar to those of the Xinmin Formation.
The volcanic rocks are also stratigraphically correlatable. Therefore, the volcanic rocks should belong to the Xinmin Formation.
The Late Jurassic felsic volcanic rocks in southern Great Hingan Range, which was previously assigned to Manketouerbo
Formation and Manitu Formation, should belong to the Xinmin Formation, and the age of the revised Xinmin Formation is similar
to that of mafic volcanic rocks of Tiaojishan Formation or Lanqi Formation in northern Hebei-western Liaoning and Tamulan
Formation in northern Great Hingan Range, showing two zones, northerly and southerly, of rock association of the Late Jurassic
volcanic rock in Northeast China.

Geological Characteristics of Mud Volcanoes and Geochemical Significance of the Associated Oil Seepages in the Southern Junggar Basin

2013, 19(3): 484.

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This paper analyzes the tectonic background of the Sikeshu and Dushanzi mud volcanoes, and points out that under
the effect of water pressure difference caused by the terrain of Meso-Cenozoic sediments in the northern Tianshan, the rich
groundwater rises along the fault zone developed at the anticline top and meets with clay rocks around the passage. Then the
mud is formed and erupts to the surface as the mud volcanoes. The paper also studies chromatogram of oil and biomarkers of the
associated oil seepages in Sikeshu and Dushanzi mud volcanoes. Comparing with the geochemical characteristics of potential
source rocks and the previous results, we suggest that all samples are mature and probably are the mixed production of Jurassic
and Tertiary oil sources. This study provides important clues to the oil and gas exploration in southern Junggar Basin.

Geological Features, Ages, and Tectonic Implications of the Wenquan Group in NW Chinese Tianshan

2013, 19(3): 491.

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The metamorphic rocks of the Wenquan Group in the Northern Chinese Tianshan have been regarded as
Paleoproterozoic in age. According to our field observations and zircon SHRIMP U-Pb dating, the Wenquan Group can be
subdivided into three lithotectonic units: (1) pre-Early Neoproterozoic meta-volcanic and meta-sedimentary rocks, including
amphibolite, micaschist, quartz schist, biotite gneiss and marble; (2) Early Neoproterozoic migmatite and orthogneiss; and (3)
undeformed Early Paleozoic gabbro and diorite. All these three units were intruded by two-mica granite or dykes. Migmatite and
granitic gneiss collected from the south of Wenquan City yielded zircon SHRIMP U-Pb ages of 926±12 Ma and 907±11 Ma,
respectively. These ages are close to those of Neoproterozoic granitoids occurring in the Chinese Tianshan. Previous results of
a Nd isotopic study on orthogneiss indicate an origin of partial melting of continental crust, and the occurrences of synchronous
migmatite support a thickening and partial melting of continental crust. Gabbro and diorite intruded in the granitc gneiss and
amphibolite of the Wenquan Group. A diorite yields a zircon SHRIMP U-Pb age of 452±7 Ma, and contains inherited zircons
with older ages of 1.1 Ga and 1.4 Ga. According to the previous studies, the gabbro and diorite have geochemical features of arc-related magmatism, the early Paleozoic arc-type magmatic rocks of the study area were likely formed during subduction of
the Junggar-Balkhash Oceanic lithosphere, and the subsequent accretion between the Northern Yili block and the Kazakhstan
continent that induced the metamorphism and deformation of the Precambrian metamorphic and magmatic rocks of the Wenquan
Group.

The Crustal Velocity Structure of the Ordos Block and its Southern Edge Revealed from the Ambient Seismic Noise Extraction

2013, 19(3): 504.

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Using the dispersion curves of Rayleigh waves that were extracted from the seismic noise of 53 broad-band stations
recorded in the Ordos Block and its southern Edge by two seismic stations cross correlation, we have obtained the average
dispersion curve of the Fen-Wei graben system, the Northern edge of Qinling, the Ordos Block and the Liupan Mountains, and
extracted the crustal and upper mantle structures of the four regions. The results show that the depth of the crust in the Fen-Wei
graben system, the northern edge of Qinling and the Ordos Block, and the Liupan Mountains is 34 km, ~40 km, and 49~50 km,
respectively. The velocity of S wave in the uppermost mantle of the corresponding region is 4.20 km/s, 4.25 km/s, 4.30 km/s, and
4.15 km/s. The most obvious difference of velocity structure appears in the upper crust. The Liupan Mountains has a low velocity
in the middle crust. The characteristics of velocity are almost the same for the lower crust.

Microfacies and Depositional Environment Evolution of the Middle-Upper Triassic Zhuganpo Formation in Zhenfeng, Southwestern Guizhou

2013, 19(3): 513.

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Aiming at understanding the Middle-Late Triassic drowning of the Yangtze carbonate platform, this paper analyzes
the microfacies of the Middle-Upper Triassic Zhuganpo Formation in Zhenfeng area, Southwestern Guizhou and discusses its
depositional environment evolution. Using standard microfacies type methods of Flügel, nine microfacies including laminated
bindstone, peloidal packstone, micritic limestone, bioclastic wackestone, encrinite packstone, intraclastic-ooid-bioclastic
grainstone, lump-bioclastic wackestone, bioclastic wackestone-pelagic, and micritic limestone-pelagic are recognized. The ordered
combination and stratigraphic distribution of these 9 microfacies show that they were formed during the rapid transition from tidal
flat to carbonate platform margin environments, and the prolonged deep shelf and basin environments. The analysis of sea-level
changes of the Zhuganpo Formation indicates that they were different from the main part of Yangtze Platform, but their third-order
cycles and second-order cycles were briefly concordant with global sea-level changes.

Characterization of Tempestite Sediments of the Neoproterozoic Zhaowei Formation in Xuzhou Area, Jiangsu Province

2013, 19(3): 520.

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The Neoproterozoic Zhaowei Formation in Xuzhou consists of 4 units, i.e., oolitic unit, tempestite unit，stromatolitic
unit and dolomite unit. The stromatolitic unit was subdivided into A and B parts. The tempestites, which abate from early to later
stages, alternate with non-tempestites in the vertical section. Some typical sedimentary symbols of tempestite sediments were
developed in this zone such as hummocky cross stratification(HCS), flush-filling structure, cut structure, organic reef-cutting
structures, calcrudites, graded bed and so on. Four kinds of tempestites sequences were summarized according to the vertical
sequence types, structures and sediment characteristics. The distribution of tempestites was also summarized. The discovery of
tempestites is helpful to interpret the sedimentary environment. According to the distribution of tempestites and the lithologic
characteristics, the authors suggest that the sedimentary environments the Zhaowei Formation were successively shoals- landward
shallow subtidal zone- open carbonate platform- restricted carbonate platform- tidal flat or lagoon and the climate during the
deposition was warm and arid. Frequent storms occurred due to the relatively low palaeolatitude during the deposition.

Research of the Tight Oil Reservoir in the Lucaogou Formation in Jimusar Sag: Analysis of Lithology and Porosity Characteristics

2013, 19(3): 529.

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Petrology and pore characteristics of the tight oil reservoir in the Lucaogou Formation, Jimusar Sag, were carefully
studied by core observation, thin section identification, and EMPA analyses, with reference to outcrop profiles, and logging and
seismic data. It was found that the reservoir section was heterogeneous and mainly consisted of rhythmically interbedded dolomite/
siltstone and mudstone, with 3~5 rhythms in one section. Rock types identified include dolomitic siltstone, silty dolomite, dolarenite,
and dolomicrite, of which the former two were most widely distributed and served as the main reservoir rocks of the upper
and lower reservoir segments ‘( sweet points’) of the Lucaogou Formation; while dol-arenite was distributed only in the upper
segment and dolomicrite occurred as thin interlayers in both segments. Observations of EMPA showed that dissolved pores, which
could be subdivided into intragranular pores, intergranular pores and cracks, were the main pore type, and their diameter ranges
from several μm to 30μm. The minerals dissolved were mainly albite, followed by dolomite. As to the composition of the rocks,
dolomitic siltstone and silty dolomite mainly consisted of albite, dolomite, and some potassium feldspar. Dol-arenite was composed
of microcrystalline dolomite and some albite, and dolomicrite mainly consisted of microcrystalline dolomite and some quartz,
albite and other minerals.

The Sequence Architecture and Characteristics of Sandbody
Distribution of the First Member of the Dainan Formation in Jinnan-Yaotan Block of Jinhu Depreesion

2013, 19(3): 536.

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By using the high resolution sequence stratigraphy theory, the sequence stratigraphy for the first member of Dainan
Formation in Jinnan-Yaotan block of Jinhu Depression is analyzed together with comprehensive research of seismic, core and well
logging data. Two kinds of transitional surface, sequence boundary, and flooding surface are recognized. And the aimed segment is
divided into one long-term cycle, two to three intermediate term cycles and four to seven short-term cycles. The main types of the
short and intermediate term are upward-deepening, and upward-deepening then to upward-shallowing. The long term is upwarddeepening
then to upward-shallowing. Based on the principle of isochronic correlation, the sequence stratigraphic framework of
the first member of Dainan Formation is established, and the sandbodies of intermediate term cycles are tracked and correlated.
The result shows that the upside of Shigang Fault and the Lvzhuang tectonic zone are loss of the MSC3, the sandbodies are mainly
distributed in the west of Jinnan area and the downside of Shigang Fault， the character of stratigraphic onlap is apparent. This
kind of sandbody is a very favorable target for subtle reservoir exploration.

Seismic Facies Research of the Jiufotang Formation and Shahai Formation
in Ludong Depression, Kailu Basin

2013, 19(3): 544.

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Ludong Depression is the peripheral exploratory area of Liaohe Oilfield Company. Based on the seismic reflection
termination relationship and the regional geological background, the Jiufotang Formation and Shahai Formation in Ludong
Depression can be divided into two seismic sequences, i.e., the Jiufotang sequence and shahai sequence. According to the internal
reflection texture and external geometric configuration and in combination with the parameters of amplitude and continuity, six
seismic facies are identified in the target sequences of the study area, including parallel sheet, sub-parallel sheet, wedge shaped,
foreset, unorganized and lenticular seismic facies. And their characteristics are described in detail. These seismic facies show
variations in horizontal distribution and are successive and evolutionary vertically. Seismic facies are correlated to sedimentary
facies through a comprehensive interpretation. The seismic-sedimentary facies model of each sequence is established according to
the lacustrine sedimentary theory. The results show that the sedimentary facies of fan delta, nearshore submarine fan, turbidite fan
and lake was developed in the target sequences.

Hydrocarbon Accumulation Model in Gucheng Oil Field of Biyang Depression

2013, 19(3): 552.

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The oil resource, hydrocarbon accumulation period, hydrocarbon accumulation process and hydrocarbon accumulation
model for Gucheng oil field in Biyang depression were studied using the data of the seismic, geological well measurement, DST,
fluid inclusion of reservoir and analysis of petroleum geochemistry. The results show that the source rocks of the upper member
and lower member of Eh3 southeast depression provide oil and gas to respective formations, along southwest that is tectonic uplift
direction in Gucheng oil field. There are two periods of hydrocarbon accumulation. One key period is in the end of liaozhuang
group. At the end of Eh1, the source rock of the lower member of Eh3 southeast depression reached the peak of hydrocarbon
generation, and hydrocarbon migrated from southeast depression into structural nose of Gucheng oil field along deltatic sand
body, can form a certain scale of fossil oil accumulation. At the end of liaozhuang group, fossil oil accumulation suffered from
some degree of destruction due to tectonic uplift and fault activity, and that the source rock of the upper member of Eh3 southeast
depression reached the peak of hydrocarbon. Large mature hydrocarbon crossed fault along delta sand body, forming convergent
stepladder type of hydrocarbon accumulation model.

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