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Sedimentation History of Neogene Lacustrine Sediments of Sueoka Bela Stena Based on Geochemical Parameters(Valjevo-Mionica Basin,Serbia) 被引量:1
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作者 Aleksandra AJNOVI Vladimir SIMI +3 位作者 Branimir JOVANIEVI Olga CVETKOVI Radovan DIMITRIJEVI Nenad GRUBIN 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2008年第6期1201-1212,共12页
Sediments of the western part of the Valjevo-Mionica basin (Serbia) were examined both geochemically and mineralogically to explain, on the basis of their sedimentologicai characteristics, the causes of changes in t... Sediments of the western part of the Valjevo-Mionica basin (Serbia) were examined both geochemically and mineralogically to explain, on the basis of their sedimentologicai characteristics, the causes of changes in their qualitative and quantitative composition. A total of 62 samples obtained from the drillhole at depths up to 400 m was investigated. Using correlation of the obtained data, six geochemical zones were defined, two of which being specially distinguished by their mineralogical, geochemical and sedimentological characteristics. The first one, upper zone A, consists of banded marlstones interbedded with clay and oil shales and is characterized by presence of analcite and searlesite. These minerals and very high contents of Na20 indicate sedimentation in alkaline conditions with increased salinity in arid climate. That provided pronounced water stratification, as well as higher bioproductivity in the basin and sedimentary organic matter preservation. Therefore, the zone A sediments are characterized by high organic matter contents of the type which provides good potential for production of liquid hydrocarbons. Another specific zone, zone F, contains sediments with very high MgO, K2O and Li concentrations. Their geochemical correlation, as well as almost complete absence of illite in this zone, indicates the presence of interstratified clay mineral type illite-saponite (lithium-bearing Mg-smectite). 展开更多
关键词 lacustrine sediments GEOCHEMISTRY searlesite statistical analysis
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Aeolian component records in lacustrine sediments and its atmospheric circulation significance for evolution of Qarhan salt lake,NE Qinghai-Tibetan Plateau
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作者 AN Fuyuan LAI Zhongping +2 位作者 FAN Qishun WEI Haichen MA Haizhou 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2014年第S1期1-2,共2页
1 Introduction The Qarhan Playa of Qaidam Basin is located at the northeastern QinghaiTibetan Plateau(QTP),in which thick lacustrine and evaporate sediments deposited since the late Pleistocene(Chen et al.,1985,1986).... 1 Introduction The Qarhan Playa of Qaidam Basin is located at the northeastern QinghaiTibetan Plateau(QTP),in which thick lacustrine and evaporate sediments deposited since the late Pleistocene(Chen et al.,1985,1986).As surrounded by capacious Gobi and yardang fields and suffered strong westerly-northwesterly wind,abundant aeolian materials were trapped in these sediment sequences in the 展开更多
关键词 Aeolian component in lacustrine sediments Atmospheric circulation East Asian winter monsoon(EAWM) evolution of Qarhan salt lake Qaidam Basin
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A Preliminary Study on the Soft–Sediment Deformation Structures in the Late Quaternary Lacustrine Sediments at Tashkorgan, Northeastern Pamir, China 被引量:11
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作者 LIANG Lianji DAI Fuchu +1 位作者 JIANG Hanchao ZHONG Ning 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2018年第4期1574-1591,共18页
This study identified soft-sediment deformation structures (SSDS) of seismic origin from lacustrine sediments in the late Quaternary paleo-dammed lake at Tashkorgan, northeastern Pamir. The observed deformation stru... This study identified soft-sediment deformation structures (SSDS) of seismic origin from lacustrine sediments in the late Quaternary paleo-dammed lake at Tashkorgan, northeastern Pamir. The observed deformation structures include sand dykes, liquefied diapir and convolute structures, gravity induced SSDS, and thixotropic pillar and tabular structures. We conducted a preliminary study on the morphology, formation and trigger mechanisms of pillar and tabular structures formed by liquefaction of underlying coarse sand and thixotropy of the upper silty clay. The regional tectonic setting and distribution of lacustrine strata indicate that the most probable trigger for the SSDS in lacustrine sediments was seismic activity, with an approximate earthquake magnitude of M〉6.0; the potential seismogenic fault is the southern part of the Kongur normal fault extensional system. AMS ^4C dating results indicate that the SSDS were formed by seismic events occurring between 26050±100 yrBP and 22710±80 yrBP, implying intense fault activity in this region during the late Pleistocene. This study provides new evidence for understanding tectonic activity and regional geodynamics in western China. 展开更多
关键词 soft-sediment deformation structures lacustrine sediment PAMIR LIQUEFACTION THIXOTROPY paleo-seismicity
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Microplastic contamination in lacustrine sediments in the Qinghai-Tibet Plateau:Current status and transfer mechanisms
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作者 Rui-ping Liu Fei Liu +3 位作者 Ying Dong Jian-gang Jiao El-Wardany RM Li-feng Zhu 《China Geology》 CAS 2022年第3期421-428,共8页
This paper aims to investigate the present situation and transfer mechanisms of microplastics in lacustrine sediments in the Qinghai-Tibet Plateau.The study surveyed the average abundance of microplastics in sediments... This paper aims to investigate the present situation and transfer mechanisms of microplastics in lacustrine sediments in the Qinghai-Tibet Plateau.The study surveyed the average abundance of microplastics in sediments.The abundance of microplastics in sediments of lakes from the Qinghai-Tibet Plateau is 17.22-2643.65 items/kg DW and 0-60.63 items/kg DW based on the data of the Qinghai Lake and the Siying Co Basin.The microplastic abundance in sediments from small and medium lakes is very high compared to that in other areas in the world.Like microplastics in other lakes of the world,those in the lakes in the Qinghai-Tibet Plateau mainly include organic polymers PA,PET,PE,and PP and are primarily in the shape of fibers and fragments.The microplastic pollution of lacustrine sediments in the Qinghai-Tibet Plateau is affected by natural changes and by human activities,and the concentration of microplastics in lacustrine ecosystems gradually increases through food chains.Furthermore,the paper suggests the relevant administrative departments of the Qinghai-Tibet Plateau strengthen waste management while developing tourism and pay much attention to the impacts of microplastics in water environments.This study provides a reference for preventing and controlling microplastic contamination in the Qinghai-Tibet Plateau. 展开更多
关键词 Microplastic pollution Environmental pollution LAKE lacustrine sediment Qinghai Lake Ecological risks Hydrogeological engineering Ecological engineering Qinghai-Tibet Plateau China
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Lacustrine sedimentary responses to earthquakes—soft-sediment deformation structures since late Pleistocene:A review of current understanding 被引量:2
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作者 Long Guo Zhongtai He Linlin Li 《Earthquake Research Advances》 CSCD 2023年第2期46-53,共8页
The traces left by earthquakes in lacustrine sediments are studied to determine the occurrence of ancient earthquakes by identifying seismically induced soft-sediment deformation structures(SSDS).Dating can help recon... The traces left by earthquakes in lacustrine sediments are studied to determine the occurrence of ancient earthquakes by identifying seismically induced soft-sediment deformation structures(SSDS).Dating can help reconstruct the relative frequency of earthquakes.Identifying seismically induced seismites,which carry abundant seismic information from numerous SSDS,is both critical and challenging.Studying the deformation mechanism of SSDS and learning about the common criteria of seismically induced SSDS improve the identification of earthquake triggers.With better research into SSDS,seismic events can be effectively captured,and temporal constraints can be carried out by 14C dating and optically stimulated luminescence(OSL)dating to identify and date the occurrence of ancient earthquakes.The present contribution primarily addresses the meaning and mechanism of SSDS and their relationship with earthquake magnitude as well as the common criteria of the SSDS induced by earthquakes. 展开更多
关键词 Soft-sediment deformation structures lacustrine sediments EARTHQUAKES LIQUEFACTION
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Uranium distribution in the lacustrine calcareous clastic-evaporite sequence in the western Qaidam Basin,and implications for U behavior in concentration of closed water
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作者 YANG Yibo FANG Xiaomin +3 位作者 LI Minghui APPEL Erwin ZHANG Weilin LIU Xiaoming 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2014年第S1期168-169,共2页
Uranium(U)provides especially useful information for reconstructing paleoredox conditions due to its unique geochemical properties and behavior in supergene environments.The proxy potential under suboxic-oxic
关键词 URANIUM Paleoredox conditions lacustrine sediments EVAPORITE Qaidam Basin
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Geochemistry of Sediments from a Subalpine Lake Sedimentary Succession in the Western Nanling Mountains,Southern China:Implications for Catchment Weathering During the Last 15400 Years
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作者 WANG Bingxiang ZHONG Wei +3 位作者 ZHU Chan OUYANG Jun WEI Zhiqiang SHANG Shengtan 《Chinese Geographical Science》 SCIE CSCD 2022年第3期537-548,共12页
In the present work,15400 yr old geochemical records of a core from the subalpine Daping swamp are presented with the aim to examine the relationship between the chemical weathering and the climatic changes in the reg... In the present work,15400 yr old geochemical records of a core from the subalpine Daping swamp are presented with the aim to examine the relationship between the chemical weathering and the climatic changes in the region of the western Nanling Mountains,China.The climate of the study region was deeply controlled by the East Asian summer monsoon.The results indicate that,in the past 15400 yrs,the values of chemical index of alteration(CIA)ranged from 73.9%to 88.2%(mean:85.3%),suggested a medium and high intensity of chemical weathering.The local exogenous clastic materials,which were derived from the weathered residues,played a key role in contributing towards the sediments.Since the climate-induced chemical weathering exerted strong influences on the geochemical features of weathered residues,the geochemical characteristics of the sediments were deeply impacted by climatic conditions.Wetter and warmer conditions would favor increased chemical weathering,resulting in more leaching of soluble and mobile elements(e.g.,Ba and Sr)and leaving the resistant and immobile elements(e.g.,Al and Ti)enriched in the weathered residues.These materials were then eroded and transported into the lake,and led to the sediments characterized by the characteristic of having depleted soluble elements.In contrast,dry and cold conditions would result in an opposite trend.In this sense,the geochemical records can serve as proxies to indicate changes of chemical weathering intensity,which were closely related to the evolution of summer monsoon. 展开更多
关键词 lacustrine sediments chemical weathering asian summer monsoon last deglacial western Nanling Mountains China
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Variation in δ^(15)N of a lacustrine sedimentary sequence in the Nanling Mountains and its potential implication for climatic conditions over the past ~16000 years
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作者 钟巍 曹家元 +1 位作者 薛积彬 欧阳军 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2013年第5期1098-1106,共9页
Although extensive studies have been performed on nitrogen isotopes in lake sediments, understanding the complexity of the δ15N variation related to past environmental and climatic conditions still remains unclear. S... Although extensive studies have been performed on nitrogen isotopes in lake sediments, understanding the complexity of the δ15N variation related to past environmental and climatic conditions still remains unclear. Supported by multi-proxy records including litho-units, organic carbon isotopes, ration of total organic carbon and total nitrogen, organic matter content, bulk dry density, the accumulation rate of organic matter, median grain size, magnetic susceptibility, and Rb/Sr and Ca/Mg ratios obtained from a sedimentary sequence in a small lake (i.e., Dahu Swamp) in the eastern Nanling Mountains in South China, we deduce that variation in the δ15N values results primarily from the sources of organic matter, which are significantly influenced by climatic conditions over the past -16 000 years. A low (or high) lake level resulting from dry (or wet) conditions would lead to more (or fewer) vascular plant remains in the sediments and stronger (or weaker) denitrification associated with hypolimnetic anoxia, resulting in lower (or higher) 615N values. In addition, dry (or wet) conditions would favor weakened (or strengthened) biogeochemical activity in the catchment, which could result in less (or more) external input of δ15N-enriched OM, thus leading to decreased (or increased) δ15N values. Our results indicate that the lake sediment δ15N record in the Nanling Mountains has the potential to provide valuable insight into past East Asian monsoon climate- driven environmental changes. 展开更多
关键词 nitrogen isotopes lacustrine sediments climate changes Nanling Mountains
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Relationship between pollen assemblages and organic geochemical proxies and the response to climate change in the Zhuye Lake sediments
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作者 Yu Li XueHua Zhou +3 位作者 ChengQi Zhang ZhuoLun Li Yue Wang NaiAng Wang 《Research in Cold and Arid Regions》 CSCD 2014年第1期37-43,共7页
This paper examines the relationship among organic geochemical proxies (TOC, C/N ratio and ~13C) and pollen assemblages in Zhuye Lake sediments since the Late Glacial. Results show that the reaction extent of organi... This paper examines the relationship among organic geochemical proxies (TOC, C/N ratio and ~13C) and pollen assemblages in Zhuye Lake sediments since the Late Glacial. Results show that the reaction extent of organic geochemical proxies and pollen as- semblages to environment changes are different. Organic geochemical proxies are sensitive to overall environmental change, while pollen assemblages indicate detailed information of environmental change. For the entire sedimentary section (except the sand layer fi'om the bottom of the section), when values of TOC, C/N ratio and total pollen concentrations are high, 813C values are low, and vice versa. The different responses of organic geochemical proxies and pollen records in Zhuye Lake are mainly due to their different sensitivity and diverse influencing factors in different environmental conditions. 展开更多
关键词 Zhuye Lake lacustrine sediments pollen assemblages geochemical proxies
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The Mid-Pleistocene Climate Transition Recorded in a 1.6 Myr-Period Lacustrine Sediment Sequence from Mazatage, Tarim Basin
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作者 LIU Jian WU Li +1 位作者 WANG Rujian ZHAO Yue 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2015年第1期312-313,共2页
The mid-Pleistocene climate transition (MPT) has been widely reported in worldwide geological events. As a key issue of the Quaternary geology, it has attracted much attention from the paleoclimate community. MPT re... The mid-Pleistocene climate transition (MPT) has been widely reported in worldwide geological events. As a key issue of the Quaternary geology, it has attracted much attention from the paleoclimate community. MPT refers to a period lasting for several hundreds of thousand years, during which the dominant climate periodicity gradually extended from 41 kyr to 100 kyr (Ruddiman et al., 1989), 展开更多
关键词 Wang Tarim Basin The Mid-Pleistocene Climate Transition Recorded in a 1.6 Myr-Period lacustrine Sediment Sequence from Mazatage
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Lacustrine high resolution sequence records from Upper Cretaceous Nenjiang Formation in Songliao Basin
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作者 GAO Youfeng JIAO Yuhui +2 位作者 WANG Pujun CHENG Rihui WANG Guodong 《Global Geology》 2020年第1期38-70,共33页
The Nenjiang Formation was continuously cored in the SK-1 borehole(China Cretaceous Continental Scientific Drilling Project-SongKe1well).Over 95.7%recovery rate,the obtained continuous core is 827.6 m in length,coveri... The Nenjiang Formation was continuously cored in the SK-1 borehole(China Cretaceous Continental Scientific Drilling Project-SongKe1well).Over 95.7%recovery rate,the obtained continuous core is 827.6 m in length,covering the geological age ranges from late Santonian to middle Campanian.This is the most complete and continuous sedimentary deposits in the Songliao basin till now.Here we systematically presented the lithological results of the observation of the cores in 2--5 cm thickness scale at the drilling spot,and the analysis on lithofacies and sedimentary sequence,cyclic stratigraphy.13 types of sedimentary rocks deposited mainly in lacustrine,delta and fluvial environments were found in the Nenjiang Fromation,and they were subdivided into 19 microfacies including dolomite,marl,argillaceous limestone,turbidite,mudstone of still water,volcanic ash,channel-lag deposit,point bar,natural levee,crevasse splay,crevasse channel,floodplain,flood lake,distributary mouth bar,subaqueous distributary channels,subaqueous natural levee,subaqueous inter-distributary bay,distal bar and adjacent shore sand bar.The whole sedimentary column is composed of 630 sixth-order depositional cycles in the meter-scale,which can be further organized in 148 fifth-order depositional cycles,38 fourth-order depositional cycles and 5 third-order depositional cycles.Meticulous depiction(centimeter level)of the whole Formation provides an approach to study its sedimentary process with high precision.The centimeter-scale description of the sequent core presented some previously unidentified dolomite and volcanic ash layers.The cyclostratigraphy of the Nenjiang Formation was controlled by Milankovitch cycled,which is helpful to discover the climatic changes of the late Santonian to the middle Campanian in Songliao Basin.In addition,the detailed description of the sequent section is significant for the upcoming oil and gas exploration in the Songliao Basin if regarding the new type of oil/gas systems. 展开更多
关键词 Upper Cretaceous Songliao Basin SK-1 lacustrine continuous sediments sedimentary facies stratigraphic cycles
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Early Holocene environment at a key location of the northwest boundary of the Asian summer monsoon: a synthesis on chronologies of Zhuye Lake, Northwest China 被引量:8
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作者 Yu LI NaiAng WANG +2 位作者 ChengQi ZHANG Yue WANG 《Journal of Arid Land》 SCIE CSCD 2014年第5期511-528,共18页
The intensified monsoon increases summer rainfall and creates wet conditions in the Asian summer monsoon region during the early Holocene. Along with millennial-scale changes of the monsoon intensity, it is still uncl... The intensified monsoon increases summer rainfall and creates wet conditions in the Asian summer monsoon region during the early Holocene. Along with millennial-scale changes of the monsoon intensity, it is still unclear whether the boundary of the monsoon region changes according to monsoon variability. Investigations into the early Holocene environment in monsoon marginal zones are crucial for understanding the monsoon boundary changes. Zhuye Lake is located at the northwest edge of the Asian summer monsoon, the northern Qilian Mountains, which are less affected by modern summer monsoon water vapor. Previous studies have reached different conclusions regarding the early Holocene climatic and environmental changes based on different dating methods(^14C and OSL(optically stimulated luminescence)) and materials(shells, carbonate, pollen concentrates and bulk organic carbon). In this study, we synthesized 102 ^14C dates and 35 OSL dates from ten Holocene sedimentary sections and ten paleo-shorelines in the lake basin. A comparison between ages from different dating methods and materials generally shows that carbon reservoir effects are relatively slight in Zhuye Lake while the disordered chronologies are mainly related to the erosion processes and reworking effects. In addition, proxy data, including lithology, pollen, total organic carbon and carbonate, were collected from different sites of Zhuye Lake. According to the new synthesis, the early Holocene environment was relatively humid, associated with high runoff and lake water levels. The result indicates that the monsoon boundary moves to the north during the period of the intensified monsoon. A typical arid-area lake was formed during the mid-Holocene when carbonate accumulation and high organic matter contents were the main features of this period. The lake retreated strongly during the late Holocene, showing a drought trend. Overall, the lake evolution is generally consistent with the Holocene Asian summer monsoon change, showing the monsoon influence to monsoon marginal zones. 展开更多
关键词 the early Holocene ^14C dating OSL dating lacustrine sediments Asian summer monsoon monsoon marginal zones
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On the Unusual Holocene Carbonate Sediment in Lake Nam Co,Central Tibet 被引量:3
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作者 LI Minghui KANG Shichang +5 位作者 ZHU Liping WANG Feiyue WANG Junbo YI Chaolu FANG Xiaomin XIE Manping 《Journal of Mountain Science》 SCIE CSCD 2009年第4期346-353,共8页
In lacustrine sediments,aragonite is a widespread mineral,whereas monohydrocalcite is a rare carbonate mineral. In the cold and high-attitude Xizang (Tibetan) Plateau,where aragonite has been commonly found in lacustr... In lacustrine sediments,aragonite is a widespread mineral,whereas monohydrocalcite is a rare carbonate mineral. In the cold and high-attitude Xizang (Tibetan) Plateau,where aragonite has been commonly found in lacustrine sediments,there is no aragonite,but low-Mg calcite,monohydrocalcite and trace dolomite. The lake receives solutes primarily from surface runoffs and remains fairly constant water chemistry for a long time. The total CaCO3 percentage in sediments could be controlled by evaporation and inflow of detrital materials. The absence of aragonite is unusual when compared to other lacustrine sediments from the Tibetan Plateau. This could be due to low Ca/Mg ratio,low salinity,low Mg and Ca concentration. Monohydrocalcite might precipitate from the lake water mediated by biological activities. Low-Mg calcite originated from minor ostracoda shell and the precipitation of lake water with biological activities. 展开更多
关键词 Carbonate minerals lacustrine sediments Environment change Nam Co TIBET
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Distribution and Significance of Methyl Steranes in Bohai Bay Basin, East China 被引量:2
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作者 Li Sumei Basin & Reservoir Research Center, University of Petroleum, Beijing 102249 《Journal of China University of Geosciences》 SCIE CSCD 2002年第4期330-337,共8页
31 samples of shales and mudstones developed in reducing hypersaline andfreshwater setting and 20 oil samples of Bamianhe oilfield, Bohai Bay basin were collected for adetailed study of petroleum system. Composition a... 31 samples of shales and mudstones developed in reducing hypersaline andfreshwater setting and 20 oil samples of Bamianhe oilfield, Bohai Bay basin were collected for adetailed study of petroleum system. Composition and distribution, especially significance ofsteroids, are discussed as a part of those. Abundant steroidal biomarkers, including C_(27-29)regular Steranes, C_(28-30) 4-methyl steranes, di-nosteranes and aromatic steranes, were detected.Results show that the composition and distribution of the steroids in samples studied are functionsof thermal maturity, organic source, paleoenvironment and lithology of potential source rocks.Alga-rich Es_4 shales (brackish water) developed in the south slope of depocenter (Niuzhuang sag)were found particularly rich in steroidal biomarkers including C_(30) 4-methyl steranes anddinosteranes. Es_3 mudstones (fresh water) were found devoid of dinosteranes. Distribution patternsof regular steranes are completely different from methyl steranes indicating different origins ofthe specific compounds of the fractioa Diagnostic distribution of steranes in rock extracts ofdiverse intervals makes the compounds to be essential indictors of source-rock tracing. Methylsteranes prove to be much more useful in oil-source rock correlation than regular steranes. Resultsalso show that alga-rich Es_4 shales located in the south slope are not likely the primary sourcerock responsible for the oils discovered based on the composition and distribution of steroids. 展开更多
关键词 biomarkers lacustrine sediments 4-methyl steranes dinosterane immature oils isom-erization oil-source correlation bohai bay basin
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Reservoir Characteristics of Fine-grained Sedimentary Rocks in Saline Lakes in the Cenozoic Upper Ganchaigou Formation,Southwestern Qaidam Basin,NW China 被引量:1
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作者 SHENG Jun LIU Jincheng +7 位作者 LI Yunlong ZOU Haiyan LONG Anlin WANG Lin LI Jiyong QI Qingshan YANG Xiaojing LI Yanan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2022年第3期1070-1081,共12页
Cenozoic fine-grained sedimentary rocks in the southwestern Qaidam Basin,as typical salinized lacustrine sediments,are significantly different from those in other freshwater lakes under the impact of the high salinity... Cenozoic fine-grained sedimentary rocks in the southwestern Qaidam Basin,as typical salinized lacustrine sediments,are significantly different from those in other freshwater lakes under the impact of the high salinity in the lake.Many fine-grained sedimentary rock samples were selected from the lower member of Neogene(N_(1))in the Gaskule Oilfield,Qaidam Basin,northwest China,with the aim to analyze and test their petrology,pore structure,and organic geochemical characteristics and determine its genesis and geological significance.Based on previous results,a new genesis of mixed sedimentary rocks is proposed.The Cenozoic lacustrine fine-grained sedimentary rocks in SW Qaidam Basin belong to mixed sedimentary rocks,which can be divided into three types,including carbonate and terrigenous clastic-bearing mudstone,carbonate-bearing to terrigenous clastic mixed sedimentary rocks,and carbonate-terrigenous clastic mixed sedimentary rocks.The geneses of mixing are quite different from that of mixed marine rocks.According to the sedimentary characteristics of the salinized lakes,three new geneses of mixed deposits are proposed:syn-sedimentary mixing,varve interbedded mixing,and biogenic mixing.The reservoir spaces of the Cenozoic lacustrine fine-grained sedimentary rocks in SW Qaidam Basin include residual intergranular pores,intercrystalline pores,microfractures,and minor dissolved pores.The reservoirs have super-low porosity and ultra-low permeability,with a porosity of 1.82%-21.04%,averaging 7.71%,and permeability of(0.0028-254.86)×10^(−3)μm^(2),averaging 2.82×10^(−3)μm^(2).The test results of total organic carbon(TOC)content show that the highest content of organic carbon reached 1.41%,and those of vitrinite reflectance show that Ro ranges from 0.525%-0.824%,with an average of 0.806%.The organic geochemical characteristics show that the fine-grained mixed sedimentary rocks of SW Qaidam Basin have the potential for self-generation and self-storage.As an unconventional reservoir,it has potential industrial value.This is the first study of fine-grained sedimentary rocks in the Qaidam Basin,which offers certain theoretical and practical values. 展开更多
关键词 energy resources unconventional reservoir sedimentary petrology organic geochemistry SALINIZATION lacustrine sediments NEOGENE
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Potential application of biogenic silica as an indicator of paleo-primary productivity in East Antarctic lakes 被引量:1
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作者 JIANG Shan LIU XiaoDong XU LiQiang SUN LiGuang 《Advances in Polar Science》 2011年第3期131-142,共12页
We collected two lake sediment cores (MC and DM) from the East Antarctic region for analysis of biogenic silica and other biogeochemical parameters (e.g., organic matter, C, N, S, H). Based on synthetically compar... We collected two lake sediment cores (MC and DM) from the East Antarctic region for analysis of biogenic silica and other biogeochemical parameters (e.g., organic matter, C, N, S, H). Based on synthetically comparative research, we focused on the potential application of biogenic silica (BSi) for the reconstruction of paleo-primary productivity in the East Antarctic lakes. Analytical results showed that a large number of diatoms were well preserved in the freshwater lake sediments, and that concentrations of biogenic silica displayed notable fluctuations over different water depths. The content of biogenic silica had a consistent profile over water depth, and this pattern changed with organic matter, reflecting their potential as eco-environmental proxies. Low lev- els of BSi and organic matter indicated reduction of lake algal production, and corresponded to decreased lake primary productivity. Due to the fragile ecosystem state and limited contribution of terrestrinl organic matter in the East Antarctic lakes, the contents of biogenic silica in the lacustrine sediments can sensitively indicate the evolutionary history of paleo-primary productivity. Overall, BSi is an ideal proxy for the reconstruction of past eeo-environmental change recorded in the lacustrine sediments on East Antarctica. 展开更多
关键词 East Antarctica lacustrine sediments BSI paleo-primary productivity organic matter
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On the Possibility of Obtaining a High Resolution Relative Paleointensity Record of the Pringle Falls Excursion at the Type Locality of Pringle Falls, Oregon, USA 被引量:1
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作者 Emilio Herrero-Bervera 《Natural Science》 2016年第3期115-124,共10页
In order to further understand the full vector excursional details of the geomagnetic field, a paleomagnetic and rock magnetic study of four sites has been conducted at the type locality of Pringle Falls, Oregon where... In order to further understand the full vector excursional details of the geomagnetic field, a paleomagnetic and rock magnetic study of four sites has been conducted at the type locality of Pringle Falls, Oregon where 827 samples were drilled and spaced along a distance of 5 km, for their detailed directional and relative paleointensity studies. The profiles have registered a high-reso- lution (>10 cm/kyr) paleomagnetic record of the excursion (ca. 211+/13 ka) as recorded by diatomaceous lacustrine sediments. Remanence as well as induced magnetization experiments to investigate the reproducibility of the signal throughout the profiles have been conducted. In addition, low-field susceptibility vs. temperature analysis was performed indicating that the main magnetic carrier is pure magnetite (Curie point 575 ℃). The magnetic grain size also has indicated Single Domain-Multi-Domain (SD-MD) magnetite. The demagnetization was done by alternating field (a.f.) experiments, and the mean directions were determined by principal component analyses. In addition, induced magnetic tests were done, such as magnetic susceptibility (x) analyses, saturation IRM, anhysteretic remanent magnetization (ARM70) as well as the normalization of J17.5 mT/ARM70 to attempt to obtain relative paleointensity records of these sediments in question. The results of the induced rock magnetic tests such as the normalization studies indicate a direct correlation between the decrease of the relative paleointensity variations (i.e. lows) with respect to the directional changes. The detailed behavior of the paleosignal is highly consistent, since they are rapidly deposited sediments providing a detailed representation of the paleofield. The dissected VGP paths in 3 different phases are highly internally consistent and are defined by clockwise and anticlockwise loops traveling from the high northern latitudes over eastern North America and the North Atlantic to South America and then to high southern latitudes. They then return to the high northern latitudes through the Pacific and over to Kamchatka. This VGP behavior defines the geomagnetic signature of the Pringle Falls excursion as recorded at the type locality. 展开更多
关键词 Pringle Falls EXCURSION lacustrine sediments Geomagnetic Signature
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Lacustrine record of 800 yr hydrological variations on the central Tibetan Plateau
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作者 Hongliang ZHANG Hucai ZHANG Yanbin LEI 《Frontiers of Earth Science》 SCIE CSCD 2023年第4期945-955,共11页
Zige Tangco is a meromictic saline lake located on the central Tibetan Plateau.Two parallel cores(ZGTC A-1 and ZGTC A-2)were collected from the lake at a water depth of 25 m during summer 2006.The chronology of core A... Zige Tangco is a meromictic saline lake located on the central Tibetan Plateau.Two parallel cores(ZGTC A-1 and ZGTC A-2)were collected from the lake at a water depth of 25 m during summer 2006.The chronology of core A-1 was reconstructed based on the Constant Initial Concentration(CIC)model of 210Pb and three accelerator mass spectrometry(AMS)ages from the chitin fragments.The hard water effect calibration of the sediment ^(14)C age showed that the reservoir effect ranged from 1655 yr at 1950 AD to 1540 yr at 1610 AD.The hydrological variation in Zige Tangco during the past 800 yr was reconstructed using multi-proxies,including organic and carbonate content,stable isotopes of fine-grained carbonate minerals(<38.5μm)and grain-size distribution of the lake sediments.Our results show that there were strong fluctuations in the lake level between 1200 and 1820 AD,and at least three dry periods were recorded between 1235 and 1315 AD,1410 and 1580 AD,and 1660 and 1720 AD characterized by high carbonate content,abrupt positive shifts of stable isotopes,and high sand content.The low-lake-level periods during the Little Ice Age(LIA)in Zige Tangco correspond to the lower δ^(18)O values in the Guliya ice core and the lower precipitation reconstructed from tree rings in Delingha.This demonstrated that the summer monsoon on the central Tibetan Plateau weakened during the dry and cold periods,whereas the winter monsoon strengthened.Relatively wetter periods or higher lake levels in Zige Tangco occurred at 1580-1650 AD and 1820-1900 AD.Negative shifts in stable isotopes were related to increased lake levels between 1800 and 1820 AD.Our results also showed that the summer monsoon precipitation on the central Tibetan Plateau was mainly controlled by solar activity during the past 800 yr. 展开更多
关键词 hydrological variation Zige Tangco stable isotopes central Tibetan Plateau lacustrine sediments LIA
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Distribution Characteristics of Effective Source Rocks and Their Control on Hydrocarbon Accumulation: A Case Study from the Dongying Sag, Eastern China 被引量:32
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作者 ZHUGuangyou JINQiang +3 位作者 ZHANGShuichang DAIJinxing ZHANGLinye LIJian 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第6期1275-1288,共14页
The exploration conducted in the Bohai Bay basin, eastern China has demonstrated that the abundant petroleum resources have close affinities to the hydrocarbon kitchen with rich organic matter. A number of oil-generat... The exploration conducted in the Bohai Bay basin, eastern China has demonstrated that the abundant petroleum resources have close affinities to the hydrocarbon kitchen with rich organic matter. A number of oil-generating associations with various characteristics of organic geochemistry and assemblages of multiple reservoir facies are developed due to the multi-center sedimentation, multi-source supply and multi-cycle evolution of filling, which have resulted in the formation of multiple oil and gas accumulation zones of various layers and trap styles. Among them the Paleogene Shahejie Formation is the most important hydrocarbon accumulation combination in the Dongying sag. Heretofore, its proved reserve has reached nearly 1.8×109t, which accounts for more than 90% of the total proved reserves of the Dongying sag. Based on previous studies, more than 600 source rock samples and 186 crude oil samples of the Shahejie Formation, collected from 30 oilfields, have been treated with organic geochemical testing. By combining the sedimentary sequence characteristics and geochemical analysis results, the source rocks of the Shahejie Formation can be divided into three genetic types, i.e. the saline lake facies (the upper ES4, brackish water deep lake facies (the lower ES3) and fresh-water lake facies (the middle ES3), which correspond to the under-filling, balanced-filling and over-filling lake types respectively and represent the three most essential genetic models for source rocks of non-marine fault basins in China. Based on a thorough oil-source correlation, the source rocks of the saline lake and brackish deep lake facies are determined to be the most contributive source rocks in the Dongying sag. Furthermore, by probing into the accumulation of organic matter and hydrocarbon migration pattern, it can be inferred that the hydrocarbons, generated from source rocks of the saline lake facies with relatively low maturity, have mainly accumulated in the uplifted parts of the basin's margin via lateral migration and the reservoirs are dominated by the buried hill and stratigraphic types, while hydrocarbons generated from source rocks of the brackish lake facies are mainly distributed in the basin's center via vertical migration and characterized by forming lithologic reservoirs. Also, the reservoirs located in the transitional belts have complex types and mostly controlled by faults, characterized by block (structural-lithologic) reservoirs, and the crude oils mainly come from source beds of Es31 and Es42 respectively. 展开更多
关键词 source rocks association characteristics fluctuation lacustrine facies sedimentation heterogeneity Dongyingsag
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Mid-Holocene Climate Variations Recorded by Palaeolake in Marginal Area of East Asian Monsoon: A Multi-proxy Study 被引量:1
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作者 LONG Hao TAN Hongbin +2 位作者 WANG Naiang TAN Liangcheng LI Yu 《Chinese Geographical Science》 SCIE CSCD 2007年第4期325-332,共8页
Traditionally, the mid-Holocene in most parts of China was thought to be warmer with higher precipitation, resulting from a strong Asian summer monsoon. However, some recent researches have proposed a mid-Holocene dro... Traditionally, the mid-Holocene in most parts of China was thought to be warmer with higher precipitation, resulting from a strong Asian summer monsoon. However, some recent researches have proposed a mid-Holocene drought interval of millennial-scale in East Asian monsoon margin areas. Thus whether mid-Holocene was dry or humid remains an open issue. Here, Zhuyeze palaeolake, the terminal lake of the Shiyang River Drainage lying in Asian monsoon marginal areas, was selected for reconstructing the details of climate variations during the Holocene, especially mid-Holocene, on the basis of a sedimentological analysis. Qingtu Lake (QTL) section of 6.92m depth was taken from Zhuyeze palaeolake. Multi-proxy analysis of QTL section, including grain size, carbonate, TOC, C/N and δ13C of organic matter, was used to document regional climatic changes during 9-3 cal ka B.P. The record shows a major environmental change at 9.0-7.8 cal ka B.P., attributed to a climate trend towards warmth and humidity. This event was followed by a typical regional drought event which occurred during 7.8-7.5 cal ka B.P. And a warm and humid climate prevailed from 7.5 to 5.0 cal ka B.P., attributed to the warm/humid Holocene Optimum in this region. After that, the climate gradually became drier. Moreover, comparison of the climate record from this paper with the summer insolation at 30°N indicates that the climate pattern reflecting the Asian monsoon changes was caused by insolation change. 展开更多
关键词 East Asian Monsoon region HOLOCENE lacustrine sediment climate change
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