A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province.The mineral that makes up the polymetallic layer is related to the sedimentary facies.To analyze the differ...A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province.The mineral that makes up the polymetallic layer is related to the sedimentary facies.To analyze the differentiation mechanism between polymetallic deposits(Ni-Mo and V),the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of pyrite.The results show that δ^(34)S values of pyrite vary widely from−7.8‰to 28‰in the Gezhongwu profile,while the δ^(34)S values are relatively uniform(from 27.8‰to 38.4‰)in the Haishan profile.The isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive Yangtze platform;this indicates that the δ^(34)SO_(4)^(2−)values in seawater must be differently distributed in depositional environments.The sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid,while the V layer mainly originates from seawater.Overall,the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid.展开更多
In order to figure out the redox conditions and paleo-sedimentary environment of the Middle Devonian shales in the northwest of Guizhong Depression,the trace element analysis was conducted on the Middle Devonian cores...In order to figure out the redox conditions and paleo-sedimentary environment of the Middle Devonian shales in the northwest of Guizhong Depression,the trace element analysis was conducted on the Middle Devonian cores(320.35–938.50 m)of the typical shale gas investigation well(GY-1)at a 1.50 m sampling interval through X-ray fluorescence spectroscopy(XRF)and inductively coupled plasma mass spectrometry(ICP-MS).According to the test result,the average values of V/(V+Ni),V/Cr and Ni/Co in Nabiao formation(Fm.)are larger than 0.67,4.65 and 7.71 respectively,and Nabiao Fm.is rich in biological assemblages such as tabasheer,ammonite,etc.These evidences indicate the rising sea level rose relatively in the sedimentation period of Nabiao Fm.and a deepwater shelf environment,which was favorable for the preservation of organic matters.The V/(V+Ni),V/Cr and Ni/Co in Luofu Fm.and Tangting Fm.are 0.38–0.65,0.73–4.10 and 3.70–6.72 respectively,indicating that the sea level dropped relatively in their sedimentation period,during which the water bodies became shallow,and the sedimentary environment was a weak oxidizing shallow water shelf environment.In addition,the variation of TOC has a high correlation with the enrichment degree of Ba element,indicating the favorable conditions for the enrichment and preservation of organic matters under an oxygen-deficient environment.Moreover,according to the identification of trace element indexes,the northwest of Guizhong Depression experienced the sedimentary cycle of relative rise to relative fall of sea level from bottom to top in the Middle Devonian sedimentation period.The relative sea level rose to the highest in the sedimentation period of Nabiao Fm.,in which the organic-rich shales with stable thickness and high organic content were deposited.Hence,the Nabiao Fm.could be regarded as the favorable exploration target interval in this area.展开更多
In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic a...In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic aromatic hydrocarbon(PAHs),organic carbon and nitrogen were seasonally investigated at site A(with horseshoe crab presence),sites B and C(without horseshoe crab presence)in the Crocodile Island intertidal zone in Xiamen from June 2018 to July 2019.The results showed that most of the community parameters of benthic macrofauna,population parameters of common benthic macrofauna and environmental parameters were significantly different at the sites with horseshoe crab versus non-horseshoe crab sites.A two-way ANOVA test showed that the densities of Ceratonereis erythraeensis and Sigambra hanaokai had significant site variation.Cluster and nonmetric multi-dimensional scaling(NMDS)analysis showed the community composition of benthic macrofauna was significantly different among the three sampling sites over four seasons.The mean sand content at site A(64.32%)was higher than those at site B(36.01%)and site C(18.86%).Conversely,the mean contents of silt,clay,Cr,Co,Ni,organic carbon,organic nitrogen,phenanthrene,and pyrene at site A were lower than those at site B and site C.These observations are consistent with the expected preferences of horseshoe crabs to live in areas with 60%sand content,which is associated with abundant and edible clamworms in the Crocodile Island intertidal zone,Xiamen.展开更多
Objective The distribution of rearranged hopanes in hydrocarbon source rocks is influenced by thermal maturity and original source input,and is also controlled by depositional conditions.Through comparison of lacustri...Objective The distribution of rearranged hopanes in hydrocarbon source rocks is influenced by thermal maturity and original source input,and is also controlled by depositional conditions.Through comparison of lacustrine and coal-bearing source rocks,this work attempted to analyze the composition and origin of rearranged hopanes in hydrocarbon source rocks.Taken the source rocks展开更多
The Oligocene-Miocene Asmari Formation is a thick sequence of shallow water carbonates of the Zagros Basin. Khaviz Anticline outcrop [near Behbahan city/Iran] was studied in this research in order to interpret the fac...The Oligocene-Miocene Asmari Formation is a thick sequence of shallow water carbonates of the Zagros Basin. Khaviz Anticline outcrop [near Behbahan city/Iran] was studied in this research in order to interpret the facies, depositional environment and sequence stratigraphy of the Asmari Formation succession. In this study, twelve different microfacies types have been recognized, which can be grouped into five (micro) facies associations: peritidal, lagoon, shoal, semi restricted marine and open marine. The Asmari Formation represents sedimentation on a carbonate ramp. According to the fauna data, the Asmari Formation is Oligocene (Rupelian/Chattian) to Early Miocene (Burdigalian) in age at the study area. Eight third-order depositional sequences are identified on the basis of deepening and shallowing patterns in the microfacies. The depositional sequences 0 and 1 (Rupelian-Chattian), 2, 3 and 4 (Chattian) were referred to the lower while sequences 5 and 6 (Aquitanian) were referred to the middle and sequence 7 (Burdigalian) was referred to the upper Asmari Formation. The relative sea-level curve of the Asmari basin and its matching with the global sea-level curves documented that Global eustatic phenomena affected this basin.展开更多
Dalan Formation is one of the most important gas reservoirs of south and southwest Iran which it belongs to Dehram Group and its age is Middle to Late Permian. The Dalan formation is interpreted as reflecting a major ...Dalan Formation is one of the most important gas reservoirs of south and southwest Iran which it belongs to Dehram Group and its age is Middle to Late Permian. The Dalan formation is interpreted as reflecting a major tectono-eustatic event related to the onset of rapid thermal subsidence of the early Neo-Tethys passive margin in Arabia and Iran, and the drowning of its rift shoulders. The Dalan formation consists mainly of medium to thick-bedded oolitic to micritic shallow-marine carbonate, with intercalations of evaporates. This formation overlies the Faraghan formation and extends up into the Lower Triassic kangan formation. The current paper is focused on the facies, sedimentary environment and sequence Stratigraphy study of the Middle to Upper Permian Dalan formation in the West Assaluyeh gas field the subsurface section of well ASL-A. Based on microfacies analysis and significant founa and flora, nineteen major facies in five facies associations including Tidal flat (A), Lagoon (B), Shoal (C), Open marine (D) and Mid ramp (E) were recognized in the Dalan formation. Facies analysis and those comparisons with modern and ancient environments indicated that the Dalan formation was deposited inner to mid parts of a homoclinal ramp. The sequence stratigraphy studies on the Dalan formation in this gas field led to assessment of seven main sedimentary sequences of the third-order in the Assaluyeh field, well ASL-A. The boundary between the third-order sequences with the Faraghan formation and between the Nar and Upper Dalan members are Subaerial Unconformity (SU) and the boundaries between the third-order sequences with each other and also with the Kangan formation are Correlative Conformity (CC). The main diagenetic processes in this formation are dolomitization, dissolution, anhydritization, cementation and compaction which played a significant role in improving reservoir quality. The shoal ooid grainstone facies with intergranular and oomoldic porosity comprise the main reservoir facies of the Dalan formation.展开更多
Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100...Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100~300-m-thick dark shale,mudstone and limestone encountered in the lower third member of the Eocene Shahejie Formation(Es3l member)in Zhanhua Sag,Bohai Bay Basin,eastern China,routine core analysis,thin sectioning,scanning electron microscopy(SEM),mineralogical and geochemical measurements were used to understand detailed facies characterization and paleoclimate in the member.This Es3l shale sediment includes three sedimentary cycles(C3,C2 and C1),from bottom to top,with complex sedimentary characters and spatial distribution.In terms of the composition,texture,bedding and thickness,six lithofacies are recognized in this succession.Some geochemical parameters,such as trace elements(Sr/Ba,Na/Al,V/Ni,V/(V+Ni),U/Th),carbon and oxygen isotopes(δ^(18)O,δ^(13)C),and total organic carbon content(TOC)indicate that the shales were deposited in a deep to semi-deep lake,with the water column being salty,stratified,enclosed and reductive.During cycles C3 and C2 of the middle-lower sections,the climate was arid,and the water was salty and stratified.Laminated and laminar mudstone-limestone was deposited with moderate organic matter(average TOC 1.8%)and good reservoir quality(average porosity 6.5%),which can be regarded as favorable reservoir.During the C1 cycle,a large amount of organic matter was input from outside the basin and this led to high productivity with a more humid climate.Massive calcareous mudstone was deposited,and this is characterized by high TOC(average 3.6%)and moderate porosity(average 4%),and provides favorable source rocks.展开更多
In order to reveal the sedimentary environment of carbonate rocks in Nanfen Formation of Qingbaikou System in Tonghua,Jilin Province,the mineral composition and petrochemistry of carbonate rocks in Nanfen Formation we...In order to reveal the sedimentary environment of carbonate rocks in Nanfen Formation of Qingbaikou System in Tonghua,Jilin Province,the mineral composition and petrochemistry of carbonate rocks in Nanfen Formation were analyzed.The mineral compositions of five carbonate rock samples in Nanfen Formation mainly consist of calcite,with minor clay minerals and quartz,and the rock type is siliceous marlite.The Mn/Sr va-lues range from 1.52 to 4.08,with an average of 2.64,indicating that the carbonate rocks experienced weak diagenesis;the Sr/Ba values range from 1.26 to 2.51,with an average of 1.93,indicating marine environment;the ratio of Mg/Al ranges from 35.33 to 86.34,with an average of 62.95,indicating the seawater environment,which is consistent with the result from Sr/Ba;the MgO/CaO values range from 0.01 to 0.04,with an average of 0.02,indicating humid environment;the values of V/(V+Ni)range from 0.63 to 0.73,with an average of 0.70,indicating anoxic environment.In summary,geochemical analyses show that the Nanfen Formation carbonate rocks are marine deposits,in a warm,humid,anoxic environment with poor flow of seawater,and subsequently underwent weak diagenetic alteration.展开更多
The Oligo-Miocen Asmari Formation is the most important oil reservoir in Iran. This study deals with facies associations, sedimentary environments and sequence stratigraphy of this formation in Masjed-I-Solyman oil fi...The Oligo-Miocen Asmari Formation is the most important oil reservoir in Iran. This study deals with facies associations, sedimentary environments and sequence stratigraphy of this formation in Masjed-I-Solyman oil field by using petrographical studies and statistical analysis. These findings show that studied succession belongs to the upper Asmari Formation (Bordigalian) with nine microfacies assosiations that consist of four wackestone, four packstone and one Boundstone microfacies. These microfacies were deposited in the inner and middle parts of a homoclinal carbonate ramp. Sequence stratigraphy studies express that the succession could be discriminated to four third order sedimentary sequences that would have been deposited under global sea level fluctuation (Eustasy).展开更多
Sarvak formation is one of the important hydrocarbon reservoirs in the Zagros Basin that is one of the mid-Cretaceous carbonate units in Bangestan group. This formation is located in the Kazhdomi Formation of the slop...Sarvak formation is one of the important hydrocarbon reservoirs in the Zagros Basin that is one of the mid-Cretaceous carbonate units in Bangestan group. This formation is located in the Kazhdomi Formation of the slope. Kuhmond oil field is in the southeast of Bushehr and in the north and northwestern of Fars province. In this study, sedimentology studies, stratigraphy and sedimentary environment in Sarvak Formation were studied. Based on studies, 18 main Microfacies were diagnosed in the region that have been deposited in four facies belts including open Sea, dam, lagoon and tidal zones. According to studies, the sedimentary environment of Sarvak formation in Kohmond field was diagnosed as a ramp carbonate platform (Figure 1).展开更多
Taiwan Shoal sediments are well sorted and rounded medium-coarse sands eontaining a large amount of shell and beach rock fragments and basalt gravels, and are of deltaic, coastal and eolian origin. Underwater sand wav...Taiwan Shoal sediments are well sorted and rounded medium-coarse sands eontaining a large amount of shell and beach rock fragments and basalt gravels, and are of deltaic, coastal and eolian origin. Underwater sand waves are formed by the combined tidal currents and are remolded by storm waves.展开更多
Iranian Plateau between the Lesser Caucasus-Alborz Mountains on the north and Zagros-Makran Ranges on the south has several inter-mountainous depressions which were filled by Quaternary deposits. Geologic evidence imp...Iranian Plateau between the Lesser Caucasus-Alborz Mountains on the north and Zagros-Makran Ranges on the south has several inter-mountainous depressions which were filled by Quaternary deposits. Geologic evidence implied that, the last marine conditions in some depressions such as the Dasht-e Kavir, Dasht-e Lut and Jazmourian basins, had been changed to land conditions in middle Miocene. Based on shape and elevation of the Dasht-e Kavir, Dasht-e Lut and Jazmourian plains related to sea level and geomorphology of Iranian plateau, three semi-connective artificial lakes can be constructed upon the mentioned plains by consideration of many geologic and geotechnical parameters. These artificial lakes can feed by pumping of water from Oman Sea and form a triple artificial bay which they must be connected together by two gated straits. Therefore, a possible morphotectonic idea with many advantages has suggested that it can be present as an international geotechnologic design. This design has the important environmental impacts which can be changed desert to lake sedimentary basins.展开更多
Very thick, fine-grained quartzose sandstone of the Lower Carboniferous (called the Donghe sandstone) was discovered in Donghe-1 well in the Tarim basin. Highly-productive commercial oil and gas flows were obtained wh...Very thick, fine-grained quartzose sandstone of the Lower Carboniferous (called the Donghe sandstone) was discovered in Donghe-1 well in the Tarim basin. Highly-productive commercial oil and gas flows were obtained when a well completion test was conducted. This important discovery proved that the quartzose sandstone is a prospecting target with good prospects. After that, other two paying oil and gas flows were found in the Lower Carboniferous in the Tazhong-4 and Tazhong-10 structures (Tazhong means central Tarim), equivalent to the Donghe sandstone. The Tazhong-4 structural oil field is the biggest oil field ever discovered. Therefore it is of guiding importance in oil and gas exploration to deepen the study of sedimentary and reservoir features and the sedimentary environment of the Donghe sandstone and to build a sedimentary model in order to understand the reservoir distribution pattern.展开更多
The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimula...The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimulated luminescence(OSL) dating of the strata of the section,the grain-size composition,grain-size parameters,cumulative distribution probability curve,and grain-size-sensitivity indexes(SC/D) were analyzed.The analyzed results show that the grain-size features of aeolian sand,weakly developed sandy paleosol,two-facies(aeolian and aqueous) deposits,and lagoon deposits are all different.This indicates four evolutionary phases of the sedimentary environment of the east coast of Hainan Island since 38 ka B.P.Phase I:38-22 ka B.P.;phase II:22-17 ka B.P.;phase III:17-10 ka B.P.;phase IV:10 ka B.P.-present.The climate experienced the hot-wet/hot-dry,hot-wet/hot-dry,and warm-wet/hot-wet fluctuations,and the sedimentary environment also underwent lagoon deposition,dune and interdune depression deposition,dune stabilization and soil development,shifting sand deposition,and evolutionary processes.展开更多
Sequence stratigraphic evidences have been used in this research to investigate the stratigraphic correlation of cretaceous paleogene succession in Shiraz area, Fars, SW Iran. For this purpose, 4 stratigraphic section...Sequence stratigraphic evidences have been used in this research to investigate the stratigraphic correlation of cretaceous paleogene succession in Shiraz area, Fars, SW Iran. For this purpose, 4 stratigraphic sections have been chosen and provided. According to petrographic study and field evidences, 4 depositional sequences were identified including the Tarbur, Sachun and Jahrum formations in the east and the Gurpi, Pabadeh and Asmari formations in the west of study area. After identifying the boundaries and systems tract facies, it has been found that the mentioned formations have been deposited among the continuous/discontinuous boundaries in an equivalent manner. In this case, the purple shale (between the Gurpi and Pabdeh formations) could be considered equivalent to the upper part of the Sachun formation. From the point of Paleogeography, the plat-form sedimentary environment covered almost the whole area during the Oligo-Miocene age, so that the Asmari formation would have been deposited, which is marked by sharp contact as disconformity on Jahrum formation in the east of the basin and with continuous contact (C.C) on the Pabdeh formation in the west and southwest.展开更多
The Upper Permian Xuanwei Formation widely occurs in western Guizhou,unconformably overlying the Emeishan basalts,and mainly consists of black shales.It is～170 m thick at Cuyudong Village,Weining County,West Guizhou,...The Upper Permian Xuanwei Formation widely occurs in western Guizhou,unconformably overlying the Emeishan basalts,and mainly consists of black shales.It is～170 m thick at Cuyudong Village,Weining County,West Guizhou,China,where the samples of black shale and sandy shale were collected and analyzed.The shales mainly contain SiO2,18.9%?44.1%,Al2O3,14.8%?52.8%,Fe2O3,1.0%?41.2%,LOI,3.2%?21.1%,TiO2,1.0%-6.7%,and MgO,0.2%?2.5%.The contents of all other major elements are lower than 1.0%.It is shown that the black shales have higher contents of Fe2O3 and LOI than normal shales.The siderites occurred in the black shales with higher contents of Fe2O3,which may be attributed to hydrothermal activities on seafloor.All analyzed shale samples have extremely high Ga,47.8×10-6-109.9×10-6(70.5×10-6 on average),higher than the industrial mining standard of Ga Resource Industry Standard.The total contents of rare-earth elements(REE) of 9 black shale samples vary from 213×10-6 to 1460×10-6,suggesting that these black shales are enriched in REE.The shale-normalized REE patterns display both positive and negative Ce anomalies(Ce/Ce* from 0.5 to 1.7),revealing that the Xuanwei shales were precipitated under oxic and anoxic conditions.The Rb-Sr chronological diagram of 6 shale samples in the Xuanwei Formation shows an age of 255±12 Ma.Strontium isotopic ratios(87Sr/86Sr)t0 range from 0.70635 to 0.70711,suggesting that these Xuanwei black shales might be derived from chemical weathering of the Emeishan basalts.展开更多
The southern Laizhou Bay is mainly composed of silt-sandy coasts with diverse landforms, and its marine hydrodynamic environment is sensitive to human activities. Marine hydrodynamic and sedimentary environments of th...The southern Laizhou Bay is mainly composed of silt-sandy coasts with diverse landforms, and its marine hydrodynamic environment is sensitive to human activities. Marine hydrodynamic and sedimentary environments of the study area have changed under the influence of large-scale port projects in recent years. In this paper, the evolution of hydrodynamic environment, deposition rate, and geochemical characteristics were studied based on sediment grain size, element analysis and ^(210)Pb dating of two cores, in order to analyze the influence of Weifang Port on marine environmental evolution, and provide theoretical and practical basis for protecting marine environment in developing marine resources reasonably. Results showed that sediments of the two cores were relatively coarser and mainly composed of silty sand. Sediments above 230 cm in core WF1 and 218 cm in core WF2 were deposited since 1855 when the Yellow River appeared to deposit its sediments within the modern active delta, and the average deposition rate was between 0.3 and 0.5 cm a^(-1). Implement of Weifang Port projects in 1997 and 2007 created great influence on the sedimentary environment evolution in the surrounding waters, and the deposition rate was significantly increased. The average annual deposition rates were 5.1 cm and 3.5 cm in WF1 and WF2 respectively between 1997 and 2007. Content of heavy metals in sediments showed no obvious change in the vertical, indicating that the heavy metals were less affected by human activity and there was no significant accumulation of such metals in the study area.展开更多
1.Objective The Qinglong area is located in the Eastern Yunnan- Western Guizhou uplift tectonic belt, west of the Zishui fault zone and north of the Youjiang basin. There are many sets of organic-rich shale in Longtan...1.Objective The Qinglong area is located in the Eastern Yunnan- Western Guizhou uplift tectonic belt, west of the Zishui fault zone and north of the Youjiang basin. There are many sets of organic-rich shale in Longtan Formation in Qinglong area. Many predecessors did a great deal of research on the geological features of Permian coal fields in Western Guizhou (Mei MX et al., 2004;Dou XZ et al., 2012), but lack of the research on sedimentary background and distribution characteristics of organic-rich shale in Longtan Formation. Therefore, this study focuses on the analysis of the sedimentary environment of the Upper Permian Longtan Formation in Qinglong area.展开更多
Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements ana...Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements analysis of 289 samples collected from the outcrop sections around and wells drilled in the basin and using a series of identification indexes of paleo-climate, paleo-salinity and paleo-redox conditions, such as CaO/MgO?Al2 O3, Sr/Cu, Rb/Sr, Rb/K2 O, Th/U, V/(V+Ni), the content of element B tested from the mudstone. Comprehensive analysis shows that in sedimentary period of the Chang 7, the paleo-climate was warm temperate to subtropical climate with temperature higher than 15 ?C, the water body was continental brackish water to freshwater, and the sediments were deposited under strong reduction conditions. Suitable temperature, extensively deep lake basin and strongly reductive paleo-sedimentary environment led to the blooming, enrichment and preservation of organic matter in the submember Chang 73. As a result, a set of high-quality source rock was formed, laying material foundation for large-scale accumulation of shale oil.展开更多
On the basis of measuring the magnetic parameters of sediment in Core YDZ1, combined with a grain size analysis and Carbon-14 dating, the magnetic properties of sediment and sedimentary environment in the Huanghe(Yell...On the basis of measuring the magnetic parameters of sediment in Core YDZ1, combined with a grain size analysis and Carbon-14 dating, the magnetic properties of sediment and sedimentary environment in the Huanghe(Yellow River) Delta area after the last glacial maximum have been studied. The results show that the ferrimagnetic minerals of a pseudo single domain and multi domain particles dominate the magnetic properties of sediment in Core YDZ1. The imperfect anti ferrimagnetic minerals have more contribution on sediment in a depth of 24.0–22.1 m, and more stable-single domain and pseudo single domain particles exist. The susceptibility of anhysteretic remanent magnetization and the ratio of the susceptibility of anhysteretic remanent magnetization to saturation isothermal remanent magnetization show a decrease trend below depth of 24 m, a marked increase trend in a depth of 24.0–13.5 m, and a rapid decrease at depth of 13.5 m, then a fluctuation trend upward. The above two magnetic parameters and the ratio of the susceptibility of anhysteretic remanent magnetization to the mass susceptibility can be regarded as the proxy indicators for the content of clay(<4 μm)and the fine-grained size(<32 μm). The sedimentary environment after the last glacial maximum in the Huanghe Delta area has experienced the fluvial facies, the tidal flat facies, the neritic facies, the pro delta facies, the delta front facies and the floodplain facies. Thickness of the Holocene transgression layer is 10.5 m and the depth of substrate is about 24 m according to the YDZ1 core. The sedimentary dynamic has a variation trend with strongweak-strong, which has been proved by the Flemming triangular schema.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42272103,92062221,42063009,U1812402)the Guizhou Provincial Science and Technology Projects(Grant No.Qiankehejichu–ZK[2022]common 213)the Higher Education Scientific Research Projects of the Education Department of Guizhou Province(Grant No.Qianjiaoji[2022]157).
文摘A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province.The mineral that makes up the polymetallic layer is related to the sedimentary facies.To analyze the differentiation mechanism between polymetallic deposits(Ni-Mo and V),the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of pyrite.The results show that δ^(34)S values of pyrite vary widely from−7.8‰to 28‰in the Gezhongwu profile,while the δ^(34)S values are relatively uniform(from 27.8‰to 38.4‰)in the Haishan profile.The isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive Yangtze platform;this indicates that the δ^(34)SO_(4)^(2−)values in seawater must be differently distributed in depositional environments.The sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid,while the V layer mainly originates from seawater.Overall,the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid.
基金This article was supported by project of China Geological Survey“Guizhong-Nanpanjiang Depression shale gas geological survey”(DD20190088).
文摘In order to figure out the redox conditions and paleo-sedimentary environment of the Middle Devonian shales in the northwest of Guizhong Depression,the trace element analysis was conducted on the Middle Devonian cores(320.35–938.50 m)of the typical shale gas investigation well(GY-1)at a 1.50 m sampling interval through X-ray fluorescence spectroscopy(XRF)and inductively coupled plasma mass spectrometry(ICP-MS).According to the test result,the average values of V/(V+Ni),V/Cr and Ni/Co in Nabiao formation(Fm.)are larger than 0.67,4.65 and 7.71 respectively,and Nabiao Fm.is rich in biological assemblages such as tabasheer,ammonite,etc.These evidences indicate the rising sea level rose relatively in the sedimentation period of Nabiao Fm.and a deepwater shelf environment,which was favorable for the preservation of organic matters.The V/(V+Ni),V/Cr and Ni/Co in Luofu Fm.and Tangting Fm.are 0.38–0.65,0.73–4.10 and 3.70–6.72 respectively,indicating that the sea level dropped relatively in their sedimentation period,during which the water bodies became shallow,and the sedimentary environment was a weak oxidizing shallow water shelf environment.In addition,the variation of TOC has a high correlation with the enrichment degree of Ba element,indicating the favorable conditions for the enrichment and preservation of organic matters under an oxygen-deficient environment.Moreover,according to the identification of trace element indexes,the northwest of Guizhong Depression experienced the sedimentary cycle of relative rise to relative fall of sea level from bottom to top in the Middle Devonian sedimentation period.The relative sea level rose to the highest in the sedimentation period of Nabiao Fm.,in which the organic-rich shales with stable thickness and high organic content were deposited.Hence,the Nabiao Fm.could be regarded as the favorable exploration target interval in this area.
基金the National Key Research and Development Program of China(No.2016YFC0502904)。
文摘In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic aromatic hydrocarbon(PAHs),organic carbon and nitrogen were seasonally investigated at site A(with horseshoe crab presence),sites B and C(without horseshoe crab presence)in the Crocodile Island intertidal zone in Xiamen from June 2018 to July 2019.The results showed that most of the community parameters of benthic macrofauna,population parameters of common benthic macrofauna and environmental parameters were significantly different at the sites with horseshoe crab versus non-horseshoe crab sites.A two-way ANOVA test showed that the densities of Ceratonereis erythraeensis and Sigambra hanaokai had significant site variation.Cluster and nonmetric multi-dimensional scaling(NMDS)analysis showed the community composition of benthic macrofauna was significantly different among the three sampling sites over four seasons.The mean sand content at site A(64.32%)was higher than those at site B(36.01%)and site C(18.86%).Conversely,the mean contents of silt,clay,Cr,Co,Ni,organic carbon,organic nitrogen,phenanthrene,and pyrene at site A were lower than those at site B and site C.These observations are consistent with the expected preferences of horseshoe crabs to live in areas with 60%sand content,which is associated with abundant and edible clamworms in the Crocodile Island intertidal zone,Xiamen.
基金financed by the National Science Foundation of China(grant No.41272170)the National Oil and Gas Major Project(grant No.2016ZX05007-001)
文摘Objective The distribution of rearranged hopanes in hydrocarbon source rocks is influenced by thermal maturity and original source input,and is also controlled by depositional conditions.Through comparison of lacustrine and coal-bearing source rocks,this work attempted to analyze the composition and origin of rearranged hopanes in hydrocarbon source rocks.Taken the source rocks
文摘The Oligocene-Miocene Asmari Formation is a thick sequence of shallow water carbonates of the Zagros Basin. Khaviz Anticline outcrop [near Behbahan city/Iran] was studied in this research in order to interpret the facies, depositional environment and sequence stratigraphy of the Asmari Formation succession. In this study, twelve different microfacies types have been recognized, which can be grouped into five (micro) facies associations: peritidal, lagoon, shoal, semi restricted marine and open marine. The Asmari Formation represents sedimentation on a carbonate ramp. According to the fauna data, the Asmari Formation is Oligocene (Rupelian/Chattian) to Early Miocene (Burdigalian) in age at the study area. Eight third-order depositional sequences are identified on the basis of deepening and shallowing patterns in the microfacies. The depositional sequences 0 and 1 (Rupelian-Chattian), 2, 3 and 4 (Chattian) were referred to the lower while sequences 5 and 6 (Aquitanian) were referred to the middle and sequence 7 (Burdigalian) was referred to the upper Asmari Formation. The relative sea-level curve of the Asmari basin and its matching with the global sea-level curves documented that Global eustatic phenomena affected this basin.
文摘Dalan Formation is one of the most important gas reservoirs of south and southwest Iran which it belongs to Dehram Group and its age is Middle to Late Permian. The Dalan formation is interpreted as reflecting a major tectono-eustatic event related to the onset of rapid thermal subsidence of the early Neo-Tethys passive margin in Arabia and Iran, and the drowning of its rift shoulders. The Dalan formation consists mainly of medium to thick-bedded oolitic to micritic shallow-marine carbonate, with intercalations of evaporates. This formation overlies the Faraghan formation and extends up into the Lower Triassic kangan formation. The current paper is focused on the facies, sedimentary environment and sequence Stratigraphy study of the Middle to Upper Permian Dalan formation in the West Assaluyeh gas field the subsurface section of well ASL-A. Based on microfacies analysis and significant founa and flora, nineteen major facies in five facies associations including Tidal flat (A), Lagoon (B), Shoal (C), Open marine (D) and Mid ramp (E) were recognized in the Dalan formation. Facies analysis and those comparisons with modern and ancient environments indicated that the Dalan formation was deposited inner to mid parts of a homoclinal ramp. The sequence stratigraphy studies on the Dalan formation in this gas field led to assessment of seven main sedimentary sequences of the third-order in the Assaluyeh field, well ASL-A. The boundary between the third-order sequences with the Faraghan formation and between the Nar and Upper Dalan members are Subaerial Unconformity (SU) and the boundaries between the third-order sequences with each other and also with the Kangan formation are Correlative Conformity (CC). The main diagenetic processes in this formation are dolomitization, dissolution, anhydritization, cementation and compaction which played a significant role in improving reservoir quality. The shoal ooid grainstone facies with intergranular and oomoldic porosity comprise the main reservoir facies of the Dalan formation.
基金This work is granted by the China State Lithologic Key Program(grant no.2017ZX05001-002-002).
文摘Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100~300-m-thick dark shale,mudstone and limestone encountered in the lower third member of the Eocene Shahejie Formation(Es3l member)in Zhanhua Sag,Bohai Bay Basin,eastern China,routine core analysis,thin sectioning,scanning electron microscopy(SEM),mineralogical and geochemical measurements were used to understand detailed facies characterization and paleoclimate in the member.This Es3l shale sediment includes three sedimentary cycles(C3,C2 and C1),from bottom to top,with complex sedimentary characters and spatial distribution.In terms of the composition,texture,bedding and thickness,six lithofacies are recognized in this succession.Some geochemical parameters,such as trace elements(Sr/Ba,Na/Al,V/Ni,V/(V+Ni),U/Th),carbon and oxygen isotopes(δ^(18)O,δ^(13)C),and total organic carbon content(TOC)indicate that the shales were deposited in a deep to semi-deep lake,with the water column being salty,stratified,enclosed and reductive.During cycles C3 and C2 of the middle-lower sections,the climate was arid,and the water was salty and stratified.Laminated and laminar mudstone-limestone was deposited with moderate organic matter(average TOC 1.8%)and good reservoir quality(average porosity 6.5%),which can be regarded as favorable reservoir.During the C1 cycle,a large amount of organic matter was input from outside the basin and this led to high productivity with a more humid climate.Massive calcareous mudstone was deposited,and this is characterized by high TOC(average 3.6%)and moderate porosity(average 4%),and provides favorable source rocks.
文摘In order to reveal the sedimentary environment of carbonate rocks in Nanfen Formation of Qingbaikou System in Tonghua,Jilin Province,the mineral composition and petrochemistry of carbonate rocks in Nanfen Formation were analyzed.The mineral compositions of five carbonate rock samples in Nanfen Formation mainly consist of calcite,with minor clay minerals and quartz,and the rock type is siliceous marlite.The Mn/Sr va-lues range from 1.52 to 4.08,with an average of 2.64,indicating that the carbonate rocks experienced weak diagenesis;the Sr/Ba values range from 1.26 to 2.51,with an average of 1.93,indicating marine environment;the ratio of Mg/Al ranges from 35.33 to 86.34,with an average of 62.95,indicating the seawater environment,which is consistent with the result from Sr/Ba;the MgO/CaO values range from 0.01 to 0.04,with an average of 0.02,indicating humid environment;the values of V/(V+Ni)range from 0.63 to 0.73,with an average of 0.70,indicating anoxic environment.In summary,geochemical analyses show that the Nanfen Formation carbonate rocks are marine deposits,in a warm,humid,anoxic environment with poor flow of seawater,and subsequently underwent weak diagenetic alteration.
文摘The Oligo-Miocen Asmari Formation is the most important oil reservoir in Iran. This study deals with facies associations, sedimentary environments and sequence stratigraphy of this formation in Masjed-I-Solyman oil field by using petrographical studies and statistical analysis. These findings show that studied succession belongs to the upper Asmari Formation (Bordigalian) with nine microfacies assosiations that consist of four wackestone, four packstone and one Boundstone microfacies. These microfacies were deposited in the inner and middle parts of a homoclinal carbonate ramp. Sequence stratigraphy studies express that the succession could be discriminated to four third order sedimentary sequences that would have been deposited under global sea level fluctuation (Eustasy).
文摘Sarvak formation is one of the important hydrocarbon reservoirs in the Zagros Basin that is one of the mid-Cretaceous carbonate units in Bangestan group. This formation is located in the Kazhdomi Formation of the slope. Kuhmond oil field is in the southeast of Bushehr and in the north and northwestern of Fars province. In this study, sedimentology studies, stratigraphy and sedimentary environment in Sarvak Formation were studied. Based on studies, 18 main Microfacies were diagnosed in the region that have been deposited in four facies belts including open Sea, dam, lagoon and tidal zones. According to studies, the sedimentary environment of Sarvak formation in Kohmond field was diagnosed as a ramp carbonate platform (Figure 1).
文摘Taiwan Shoal sediments are well sorted and rounded medium-coarse sands eontaining a large amount of shell and beach rock fragments and basalt gravels, and are of deltaic, coastal and eolian origin. Underwater sand waves are formed by the combined tidal currents and are remolded by storm waves.
文摘Iranian Plateau between the Lesser Caucasus-Alborz Mountains on the north and Zagros-Makran Ranges on the south has several inter-mountainous depressions which were filled by Quaternary deposits. Geologic evidence implied that, the last marine conditions in some depressions such as the Dasht-e Kavir, Dasht-e Lut and Jazmourian basins, had been changed to land conditions in middle Miocene. Based on shape and elevation of the Dasht-e Kavir, Dasht-e Lut and Jazmourian plains related to sea level and geomorphology of Iranian plateau, three semi-connective artificial lakes can be constructed upon the mentioned plains by consideration of many geologic and geotechnical parameters. These artificial lakes can feed by pumping of water from Oman Sea and form a triple artificial bay which they must be connected together by two gated straits. Therefore, a possible morphotectonic idea with many advantages has suggested that it can be present as an international geotechnologic design. This design has the important environmental impacts which can be changed desert to lake sedimentary basins.
文摘Very thick, fine-grained quartzose sandstone of the Lower Carboniferous (called the Donghe sandstone) was discovered in Donghe-1 well in the Tarim basin. Highly-productive commercial oil and gas flows were obtained when a well completion test was conducted. This important discovery proved that the quartzose sandstone is a prospecting target with good prospects. After that, other two paying oil and gas flows were found in the Lower Carboniferous in the Tazhong-4 and Tazhong-10 structures (Tazhong means central Tarim), equivalent to the Donghe sandstone. The Tazhong-4 structural oil field is the biggest oil field ever discovered. Therefore it is of guiding importance in oil and gas exploration to deepen the study of sedimentary and reservoir features and the sedimentary environment of the Donghe sandstone and to build a sedimentary model in order to understand the reservoir distribution pattern.
文摘The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimulated luminescence(OSL) dating of the strata of the section,the grain-size composition,grain-size parameters,cumulative distribution probability curve,and grain-size-sensitivity indexes(SC/D) were analyzed.The analyzed results show that the grain-size features of aeolian sand,weakly developed sandy paleosol,two-facies(aeolian and aqueous) deposits,and lagoon deposits are all different.This indicates four evolutionary phases of the sedimentary environment of the east coast of Hainan Island since 38 ka B.P.Phase I:38-22 ka B.P.;phase II:22-17 ka B.P.;phase III:17-10 ka B.P.;phase IV:10 ka B.P.-present.The climate experienced the hot-wet/hot-dry,hot-wet/hot-dry,and warm-wet/hot-wet fluctuations,and the sedimentary environment also underwent lagoon deposition,dune and interdune depression deposition,dune stabilization and soil development,shifting sand deposition,and evolutionary processes.
文摘Sequence stratigraphic evidences have been used in this research to investigate the stratigraphic correlation of cretaceous paleogene succession in Shiraz area, Fars, SW Iran. For this purpose, 4 stratigraphic sections have been chosen and provided. According to petrographic study and field evidences, 4 depositional sequences were identified including the Tarbur, Sachun and Jahrum formations in the east and the Gurpi, Pabadeh and Asmari formations in the west of study area. After identifying the boundaries and systems tract facies, it has been found that the mentioned formations have been deposited among the continuous/discontinuous boundaries in an equivalent manner. In this case, the purple shale (between the Gurpi and Pabdeh formations) could be considered equivalent to the upper part of the Sachun formation. From the point of Paleogeography, the plat-form sedimentary environment covered almost the whole area during the Oligo-Miocene age, so that the Asmari formation would have been deposited, which is marked by sharp contact as disconformity on Jahrum formation in the east of the basin and with continuous contact (C.C) on the Pabdeh formation in the west and southwest.
基金supported by the National Basic Research Program of China (2007CB411401)the National Natural Science Foundation of China (No. 40930425)
文摘The Upper Permian Xuanwei Formation widely occurs in western Guizhou,unconformably overlying the Emeishan basalts,and mainly consists of black shales.It is～170 m thick at Cuyudong Village,Weining County,West Guizhou,China,where the samples of black shale and sandy shale were collected and analyzed.The shales mainly contain SiO2,18.9%?44.1%,Al2O3,14.8%?52.8%,Fe2O3,1.0%?41.2%,LOI,3.2%?21.1%,TiO2,1.0%-6.7%,and MgO,0.2%?2.5%.The contents of all other major elements are lower than 1.0%.It is shown that the black shales have higher contents of Fe2O3 and LOI than normal shales.The siderites occurred in the black shales with higher contents of Fe2O3,which may be attributed to hydrothermal activities on seafloor.All analyzed shale samples have extremely high Ga,47.8×10-6-109.9×10-6(70.5×10-6 on average),higher than the industrial mining standard of Ga Resource Industry Standard.The total contents of rare-earth elements(REE) of 9 black shale samples vary from 213×10-6 to 1460×10-6,suggesting that these black shales are enriched in REE.The shale-normalized REE patterns display both positive and negative Ce anomalies(Ce/Ce* from 0.5 to 1.7),revealing that the Xuanwei shales were precipitated under oxic and anoxic conditions.The Rb-Sr chronological diagram of 6 shale samples in the Xuanwei Formation shows an age of 255±12 Ma.Strontium isotopic ratios(87Sr/86Sr)t0 range from 0.70635 to 0.70711,suggesting that these Xuanwei black shales might be derived from chemical weathering of the Emeishan basalts.
基金financially supported by the Marine Commonweal Scientific Research Foundation (Grant No. 201005009)the Basic Scientific Fund for National Public Research Institutes of China (Grant No. 2015G08)
文摘The southern Laizhou Bay is mainly composed of silt-sandy coasts with diverse landforms, and its marine hydrodynamic environment is sensitive to human activities. Marine hydrodynamic and sedimentary environments of the study area have changed under the influence of large-scale port projects in recent years. In this paper, the evolution of hydrodynamic environment, deposition rate, and geochemical characteristics were studied based on sediment grain size, element analysis and ^(210)Pb dating of two cores, in order to analyze the influence of Weifang Port on marine environmental evolution, and provide theoretical and practical basis for protecting marine environment in developing marine resources reasonably. Results showed that sediments of the two cores were relatively coarser and mainly composed of silty sand. Sediments above 230 cm in core WF1 and 218 cm in core WF2 were deposited since 1855 when the Yellow River appeared to deposit its sediments within the modern active delta, and the average deposition rate was between 0.3 and 0.5 cm a^(-1). Implement of Weifang Port projects in 1997 and 2007 created great influence on the sedimentary environment evolution in the surrounding waters, and the deposition rate was significantly increased. The average annual deposition rates were 5.1 cm and 3.5 cm in WF1 and WF2 respectively between 1997 and 2007. Content of heavy metals in sediments showed no obvious change in the vertical, indicating that the heavy metals were less affected by human activity and there was no significant accumulation of such metals in the study area.
文摘1.Objective The Qinglong area is located in the Eastern Yunnan- Western Guizhou uplift tectonic belt, west of the Zishui fault zone and north of the Youjiang basin. There are many sets of organic-rich shale in Longtan Formation in Qinglong area. Many predecessors did a great deal of research on the geological features of Permian coal fields in Western Guizhou (Mei MX et al., 2004;Dou XZ et al., 2012), but lack of the research on sedimentary background and distribution characteristics of organic-rich shale in Longtan Formation. Therefore, this study focuses on the analysis of the sedimentary environment of the Upper Permian Longtan Formation in Qinglong area.
基金Supported by the National Key Basic Research and Development Program(973 Project)National Science and Technology Major Project(2016ZX05050,2017ZX05001002)
文摘Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements analysis of 289 samples collected from the outcrop sections around and wells drilled in the basin and using a series of identification indexes of paleo-climate, paleo-salinity and paleo-redox conditions, such as CaO/MgO?Al2 O3, Sr/Cu, Rb/Sr, Rb/K2 O, Th/U, V/(V+Ni), the content of element B tested from the mudstone. Comprehensive analysis shows that in sedimentary period of the Chang 7, the paleo-climate was warm temperate to subtropical climate with temperature higher than 15 ?C, the water body was continental brackish water to freshwater, and the sediments were deposited under strong reduction conditions. Suitable temperature, extensively deep lake basin and strongly reductive paleo-sedimentary environment led to the blooming, enrichment and preservation of organic matter in the submember Chang 73. As a result, a set of high-quality source rock was formed, laying material foundation for large-scale accumulation of shale oil.
基金The National Natural Science Foundation of China under contract Nos 41306077 and 41501567the Major Program of University Natural Science Foundation of Jiangsu Province of China under contract No.14KJA170006the Natural Science Foundation of Shandong Province of China under contract No.ZR2013DQ025
文摘On the basis of measuring the magnetic parameters of sediment in Core YDZ1, combined with a grain size analysis and Carbon-14 dating, the magnetic properties of sediment and sedimentary environment in the Huanghe(Yellow River) Delta area after the last glacial maximum have been studied. The results show that the ferrimagnetic minerals of a pseudo single domain and multi domain particles dominate the magnetic properties of sediment in Core YDZ1. The imperfect anti ferrimagnetic minerals have more contribution on sediment in a depth of 24.0–22.1 m, and more stable-single domain and pseudo single domain particles exist. The susceptibility of anhysteretic remanent magnetization and the ratio of the susceptibility of anhysteretic remanent magnetization to saturation isothermal remanent magnetization show a decrease trend below depth of 24 m, a marked increase trend in a depth of 24.0–13.5 m, and a rapid decrease at depth of 13.5 m, then a fluctuation trend upward. The above two magnetic parameters and the ratio of the susceptibility of anhysteretic remanent magnetization to the mass susceptibility can be regarded as the proxy indicators for the content of clay(<4 μm)and the fine-grained size(<32 μm). The sedimentary environment after the last glacial maximum in the Huanghe Delta area has experienced the fluvial facies, the tidal flat facies, the neritic facies, the pro delta facies, the delta front facies and the floodplain facies. Thickness of the Holocene transgression layer is 10.5 m and the depth of substrate is about 24 m according to the YDZ1 core. The sedimentary dynamic has a variation trend with strongweak-strong, which has been proved by the Flemming triangular schema.
