From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target a...From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8―2.7 Ma). The more active Antarctic bottom sea-waters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.展开更多
Organic matter is the basis for oil and gas generation,and the depositional environment controls its enrichment.The first member of the Qingshankou Formation(K_(2)qn^(1))in Songliao Basin has a thick organic-rich shal...Organic matter is the basis for oil and gas generation,and the depositional environment controls its enrichment.The first member of the Qingshankou Formation(K_(2)qn^(1))in Songliao Basin has a thick organic-rich shale and so is an important target section for shale oil exploration and development.In the Gulong Sag,shale samples from this unit were collected over the full length of the section.The characterization of the environments of deposition(EOD)of K_(2)qn^(1)was improved by utilizing lithological characteristics,thin section observations,elemental compositions,and organic carbon concentrations.Combined with the normalization coefficients proposed in this paper,an organic matter correlation model was established to elucidate the factors that influence organic matter enrichment.From the bottom to the top of K2qn1,the lake depth gradually becomes shallower,the primary productivity first decreases and then increases,the reducing conditions become stronger and then weaker,the water salinity gradually decreases,the climate first becomes semi-humid and then warm and humid,and the input of terrigenous debris first decreases and then increases.A major marine transgression at the base of the K_(2)qn^(1)᾽s brought in nutrients to increase primary productivity,and the density-stratified reducing environment preserved and enriched organic matter.High primary productivity occurred during the middle of the deposition of the K_(2)qn^(1),while terrigenous input is low.Organic matter is preserved in reduced deep lake environments,resulting in organic matter-rich black shale.The lake became shallower,and the salinity decreased in the upper part of K_(2)qn^(1).Benthic organisms rapidly multiplied,consuming large amounts of oxygen and destroying the previously depositional environment,resulting in a reducing environment disturbed by benthic organisms with poor preservation conditions and the lowest organic matter content.展开更多
The Weihe Basin,which is known as a Cenozoic rift Basin,is special for its location where not only enrich oil,gas and water,but also is a"sweet"for environment evolution research.It sits in the transition ar...The Weihe Basin,which is known as a Cenozoic rift Basin,is special for its location where not only enrich oil,gas and water,but also is a"sweet"for environment evolution research.It sits in the transition area between the ordos basin with full of oil and gas resources in the north and the Qinling Orogenic Belt with rich mineral展开更多
The Upper Cretaceous Qingshankou Formation black shales,deposited in the late Turonian(LTB shales),are the main source rocks of the Songliao Basin.The origins of organic matter enrichment of the shales is a contentiou...The Upper Cretaceous Qingshankou Formation black shales,deposited in the late Turonian(LTB shales),are the main source rocks of the Songliao Basin.The origins of organic matter enrichment of the shales is a contentious subject fuelling many ongoing debates.This study investigates the genesis of the organic matter-rich shale by using molecular geochemistry.The LTB shales can be divided into three sections.The SectionⅠshales were deposited in saline,stratified and anoxic water conditions,which are related to seawater incursion events.At least three episodic and periodic seawater incursion events were recognized during SectionⅠshale deposition.The SectionⅡshales deposited in brackish to fresh and deep lake-level conditions with high primary productivity,which are related to lake-level transgression.The SectionⅢshales were deposited under fresh and slightly oxidized water conditions,which are related to lake-level regression.Two organic matter enrichment models for the LTB shales are identified,that is,the seawater incursion model and the maximum lake-level transgression sedimentation model,which act on different shale sections,both playing significant roles in the enrichment of organic matter.展开更多
The Quaternary sediments in the Yangtze delta are loose and lack precise stratification marks in the lithology. Moreover, due to the limitations of dating methods, it is difficult for Quaternary cores to deliver accur...The Quaternary sediments in the Yangtze delta are loose and lack precise stratification marks in the lithology. Moreover, due to the limitations of dating methods, it is difficult for Quaternary cores to deliver accurate age constraints. Thus, it is a challenge to establish the Quaternary stratigraphic framework. Gravity core LZK1 was drilled on Hengsha Island, Shanghai, in the Yangtze delta, in 2012. The core was terminated at 403.83 m below the local land surface, the uppermost 291.2 m comprising a thick sequence of Quaternary sediments. This study investigated the stratigraphic subdivision and paleoenvironmental change of the Quaternary sediments. From bottom to top, the Quaternary stratigraphic sequence can be subdivided into the lower Pleistocene Anting Formation, Middle Pleistocene Jiading Formation, Upper Pleistocene Chuansha Formation and Nanhui Formation, Holocene Loutang Formation, Shanghai Formation, and Rudong Formation. According to this study, the Hengsha Island area was dominated by a freshwater lacustrine environment during the early Pleistocene, an alternation of shallow lake and shore lake environment during the Middle Pleistocene, a delta plain to lagoonal environment during the early Upper Pleistocene, a fluvial channel to floodplain environment from the LGM(Last Glacial Maximum) to the end of the Upper Pleistocene, and a delta environment during the Holocene.展开更多
Dongyuemiao Member shale in the Sichuan Basin,China,is characterized by organic-rich shale intervals with different types of interbeds and accumulation modes.The aim of this study is to elucidate the impact of paleoen...Dongyuemiao Member shale in the Sichuan Basin,China,is characterized by organic-rich shale intervals with different types of interbeds and accumulation modes.The aim of this study is to elucidate the impact of paleoenvironmental indicators on interbed development.With this aim in mind,we established an interbed classification scheme and quantified the development of different types of interbeds and their frequencies.We categorized the shale interbeds into three types based on interbed type:silt interbeds(SIs),shell fragment interbeds(SFIs),and shell skeleton interbeds(SSIs).The SIs,SFIs,and SSIs are respectively the products of extrabasinal low-density turbidity currents,intrabasinal debris flow,and intrabasinal low-density turbidity currents.We propose that variations in paleoenvironmental conditions primarily influenced the types of interbeds that developed but had minimal impact on the frequency of their development.Models depicting the interbed development within the 1st Submember of Dongyuemiao Member indicate that during the early Dongyuemiao depositional period,under conditions of relatively aridity,weak weathering,high terrigenous input,and strong hydrodynamic activity,SSIs were well developed.In the middle depositional period,as the climate gradually transitioned to more humid conditions,and the weathering intensity and amount of terrestrial input increased,the development of SIs and SFIs significantly increased.During the late depositional period,with a continuous decrease in terrestrial inputs and sedimentation rates,the development of SIs decreased while that of SSIs increased.展开更多
The Hongzuisi Section in Lanzhou area is used to infer the paleoclimate since the late glacial epoch. Through combined analysis of organic carbon isotope and CaCO3 content, paleoenvironment evolution of Hongzuisi Sect...The Hongzuisi Section in Lanzhou area is used to infer the paleoclimate since the late glacial epoch. Through combined analysis of organic carbon isotope and CaCO3 content, paleoenvironment evolution of Hongzuisi Section since the late glacial epoch is discussed. There were changes in both dry-moist and warm-cold. Especially the climate changes can be compared with synchronous sections of other areas, which provides useful information for our future forecast.展开更多
Core ZHS-176 contains the paleoenvironmental records from the northern South China Sea （NSCS） since the Last Glacial Maximum （LGM）. A coupled approach based on clay mineral assemblages, planktonic foraminiferal ox...Core ZHS-176 contains the paleoenvironmental records from the northern South China Sea （NSCS） since the Last Glacial Maximum （LGM）. A coupled approach based on clay mineral assemblages, planktonic foraminiferal oxygen and carbon isotopes, and calcium carbonate content is used to trace the sources of the fine-grained sediment and to investigate the paleoenviornmental evolution in this area. Clay mineral assemblages are dominated by illite （average about 39%） and chlorite （about 27%）, which comes mainly from Taiwan and the East China Sea. Kaolinite, which accounts for about 13%, comes mainly from the Zhujiang （Pearl） River, and Luzon Island is the main source for smectite （about 21%）. The planktonic foraminiferal oxygen isotopic oscillations during the last glacial period are coeval with climate variations recorded in the Greenland ice core and Western Pacific sediment. These variations include the LGM, Heinrich event 1, Bφlling-Allerφd （B/A）, and Younger Dryas. For the Holocene, three periods of strong precipitation （S1-S3） and three periods of weak precipitation （W1-W3） are identified. The oxygen isotopic record exhibits corre-lation with climate records from distant regions, including the high-latitude Northern Hemisphere, providing evidence for global tele-connection among regional climate. A brief, negative planktonic foraminiferal carbon isotopic excursion during B/A reflects increased methane released from marine gas hydrate due to the rapid warming of the water. By comparing calcium carbonate content curves of the core ZHS-176 with these of other five boreholes lying above the lysocline, a remarkable low calcium carbonate event is found during the early Holocene in NSCS.展开更多
基金the Key Program of the National Natural Science Foundation of China (Grant No. 90411014)the National Natural Science Foundation of China (Grant Nos. 40576032 and 40506016).
文摘From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8―2.7 Ma). The more active Antarctic bottom sea-waters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.
基金funded by the National Natural Science Foundation of China(Grant Nos.42072147 and 41922015)the Fundamental Research Funds for the Central Universities(No.22CX07001A).
文摘Organic matter is the basis for oil and gas generation,and the depositional environment controls its enrichment.The first member of the Qingshankou Formation(K_(2)qn^(1))in Songliao Basin has a thick organic-rich shale and so is an important target section for shale oil exploration and development.In the Gulong Sag,shale samples from this unit were collected over the full length of the section.The characterization of the environments of deposition(EOD)of K_(2)qn^(1)was improved by utilizing lithological characteristics,thin section observations,elemental compositions,and organic carbon concentrations.Combined with the normalization coefficients proposed in this paper,an organic matter correlation model was established to elucidate the factors that influence organic matter enrichment.From the bottom to the top of K2qn1,the lake depth gradually becomes shallower,the primary productivity first decreases and then increases,the reducing conditions become stronger and then weaker,the water salinity gradually decreases,the climate first becomes semi-humid and then warm and humid,and the input of terrigenous debris first decreases and then increases.A major marine transgression at the base of the K_(2)qn^(1)᾽s brought in nutrients to increase primary productivity,and the density-stratified reducing environment preserved and enriched organic matter.High primary productivity occurred during the middle of the deposition of the K_(2)qn^(1),while terrigenous input is low.Organic matter is preserved in reduced deep lake environments,resulting in organic matter-rich black shale.The lake became shallower,and the salinity decreased in the upper part of K_(2)qn^(1).Benthic organisms rapidly multiplied,consuming large amounts of oxygen and destroying the previously depositional environment,resulting in a reducing environment disturbed by benthic organisms with poor preservation conditions and the lowest organic matter content.
文摘The Weihe Basin,which is known as a Cenozoic rift Basin,is special for its location where not only enrich oil,gas and water,but also is a"sweet"for environment evolution research.It sits in the transition area between the ordos basin with full of oil and gas resources in the north and the Qinling Orogenic Belt with rich mineral
基金funded by a grant from the National Natural Science Foundation of China(Grant Nos.U2244207,42102200)the China Geological Survey Foundation(Grant Nos.DD20230257,DD20242404)。
文摘The Upper Cretaceous Qingshankou Formation black shales,deposited in the late Turonian(LTB shales),are the main source rocks of the Songliao Basin.The origins of organic matter enrichment of the shales is a contentious subject fuelling many ongoing debates.This study investigates the genesis of the organic matter-rich shale by using molecular geochemistry.The LTB shales can be divided into three sections.The SectionⅠshales were deposited in saline,stratified and anoxic water conditions,which are related to seawater incursion events.At least three episodic and periodic seawater incursion events were recognized during SectionⅠshale deposition.The SectionⅡshales deposited in brackish to fresh and deep lake-level conditions with high primary productivity,which are related to lake-level transgression.The SectionⅢshales were deposited under fresh and slightly oxidized water conditions,which are related to lake-level regression.Two organic matter enrichment models for the LTB shales are identified,that is,the seawater incursion model and the maximum lake-level transgression sedimentation model,which act on different shale sections,both playing significant roles in the enrichment of organic matter.
基金funded by the Geological Survey of China(Nos.DD20190370,DD20160345-07)the National Natural Science Foundation(No.40902049)。
文摘The Quaternary sediments in the Yangtze delta are loose and lack precise stratification marks in the lithology. Moreover, due to the limitations of dating methods, it is difficult for Quaternary cores to deliver accurate age constraints. Thus, it is a challenge to establish the Quaternary stratigraphic framework. Gravity core LZK1 was drilled on Hengsha Island, Shanghai, in the Yangtze delta, in 2012. The core was terminated at 403.83 m below the local land surface, the uppermost 291.2 m comprising a thick sequence of Quaternary sediments. This study investigated the stratigraphic subdivision and paleoenvironmental change of the Quaternary sediments. From bottom to top, the Quaternary stratigraphic sequence can be subdivided into the lower Pleistocene Anting Formation, Middle Pleistocene Jiading Formation, Upper Pleistocene Chuansha Formation and Nanhui Formation, Holocene Loutang Formation, Shanghai Formation, and Rudong Formation. According to this study, the Hengsha Island area was dominated by a freshwater lacustrine environment during the early Pleistocene, an alternation of shallow lake and shore lake environment during the Middle Pleistocene, a delta plain to lagoonal environment during the early Upper Pleistocene, a fluvial channel to floodplain environment from the LGM(Last Glacial Maximum) to the end of the Upper Pleistocene, and a delta environment during the Holocene.
基金sponsored by the National Natural Science Foundation of China,China(No.42272171)National Science and Technology Major Project of China,China(No.2017ZX05036).
文摘Dongyuemiao Member shale in the Sichuan Basin,China,is characterized by organic-rich shale intervals with different types of interbeds and accumulation modes.The aim of this study is to elucidate the impact of paleoenvironmental indicators on interbed development.With this aim in mind,we established an interbed classification scheme and quantified the development of different types of interbeds and their frequencies.We categorized the shale interbeds into three types based on interbed type:silt interbeds(SIs),shell fragment interbeds(SFIs),and shell skeleton interbeds(SSIs).The SIs,SFIs,and SSIs are respectively the products of extrabasinal low-density turbidity currents,intrabasinal debris flow,and intrabasinal low-density turbidity currents.We propose that variations in paleoenvironmental conditions primarily influenced the types of interbeds that developed but had minimal impact on the frequency of their development.Models depicting the interbed development within the 1st Submember of Dongyuemiao Member indicate that during the early Dongyuemiao depositional period,under conditions of relatively aridity,weak weathering,high terrigenous input,and strong hydrodynamic activity,SSIs were well developed.In the middle depositional period,as the climate gradually transitioned to more humid conditions,and the weathering intensity and amount of terrestrial input increased,the development of SIs and SFIs significantly increased.During the late depositional period,with a continuous decrease in terrestrial inputs and sedimentation rates,the development of SIs decreased while that of SSIs increased.
文摘The Hongzuisi Section in Lanzhou area is used to infer the paleoclimate since the late glacial epoch. Through combined analysis of organic carbon isotope and CaCO3 content, paleoenvironment evolution of Hongzuisi Section since the late glacial epoch is discussed. There were changes in both dry-moist and warm-cold. Especially the climate changes can be compared with synchronous sections of other areas, which provides useful information for our future forecast.
基金The National Basic Research Program of China under contract No. 2007CB411704
文摘Core ZHS-176 contains the paleoenvironmental records from the northern South China Sea （NSCS） since the Last Glacial Maximum （LGM）. A coupled approach based on clay mineral assemblages, planktonic foraminiferal oxygen and carbon isotopes, and calcium carbonate content is used to trace the sources of the fine-grained sediment and to investigate the paleoenviornmental evolution in this area. Clay mineral assemblages are dominated by illite （average about 39%） and chlorite （about 27%）, which comes mainly from Taiwan and the East China Sea. Kaolinite, which accounts for about 13%, comes mainly from the Zhujiang （Pearl） River, and Luzon Island is the main source for smectite （about 21%）. The planktonic foraminiferal oxygen isotopic oscillations during the last glacial period are coeval with climate variations recorded in the Greenland ice core and Western Pacific sediment. These variations include the LGM, Heinrich event 1, Bφlling-Allerφd （B/A）, and Younger Dryas. For the Holocene, three periods of strong precipitation （S1-S3） and three periods of weak precipitation （W1-W3） are identified. The oxygen isotopic record exhibits corre-lation with climate records from distant regions, including the high-latitude Northern Hemisphere, providing evidence for global tele-connection among regional climate. A brief, negative planktonic foraminiferal carbon isotopic excursion during B/A reflects increased methane released from marine gas hydrate due to the rapid warming of the water. By comparing calcium carbonate content curves of the core ZHS-176 with these of other five boreholes lying above the lysocline, a remarkable low calcium carbonate event is found during the early Holocene in NSCS.
