In order to discuss the geochemical characteristic of REEs （rare earth elements） and their geological application, we measured the contents of rare earth elements, trace elements and minerals of 29 Lopingian （Late ...In order to discuss the geochemical characteristic of REEs （rare earth elements） and their geological application, we measured the contents of rare earth elements, trace elements and minerals of 29 Lopingian （Late Permian） mudstone samples in Panxian county, carrying out ICP-MS and XRD analysis. The results show that the amount of REEs （185.56-729.46 ×10-6） is high. The ratios of w（LREE）/w（HREE） （6.84- 13.86） and W（La）N/w（Yb）N （1.01-3.02） show clear differentiation of LREEs and HREEs. ZREE has a significantly or critically positive correlation with lithophile elements Th, Nb, Ta, Ti, Ca, Sc, Cs, Zr, Hf, Sr, Be and chaicophile element Zn, a critically negative correlation with siderophile element Fe and a slightly positive correlation with illite, illite smectite mixed layers and siderite. REEs originate mainly from terrigenous minerals, in an inorganic phase, Source rocks of our samples consist of Emeishan basalt and a small part of sedimentary rocks, as suggested by the distribution patterns of REEs and w（∑REE）- w（La）/w（Yb） diagram. Moreover, abnormal surfaces near the sequence boundaries （SB2, SB3, SB4） are related wiLth the boundaries, identified by geochemical characteristics of the REEs, such as ∑REE. w（LREE）/w（HREE）, Eu/Eu＊ and Ceanom.展开更多
On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy, a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a...On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy, a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a pelagic chert section in southeast Guangxi, South China. Radiolarian Albaillella is one of the most sensitive biology to the transitional environment. The Albaillella fauna shows an ecological evolutionary process from Guadalupian to Lopingian: declined stage-recovery stage-flourishing stage. The study of characteristics of the Albaillella fauna in the transitional environment may provide more information, not only for the subdivision and correlation of a high-resolution biostratigraphy, but also for influence of radiolarian Albaillella fauna on the pre-Lopingian mass extinction.展开更多
The late Permian(Lopingian)was a crucial climate transition period from the late Paleozoic Ice Age to the early Triassic of exceptionally high temperatures.However,the origins of the third-order sea-level changes duri...The late Permian(Lopingian)was a crucial climate transition period from the late Paleozoic Ice Age to the early Triassic of exceptionally high temperatures.However,the origins of the third-order sea-level changes during the Lopingian Epoch remain unclear.Here,we presented astronomically calibrated gamma-ray(GR)log and non-U GR(computed gamma ray or CGR)curves from the clastic and carbonate successions of well GFD-1 in the Pingle Depression of South China for studying the sea-level oscillations during the Lopingian.Spectral analyses of the 405 kyr-calibrated GR and CGR time data revealed periodicities close to about 405,about 100,about 44.2,about 35.1,about 21,and about 17.5 kyr,supporting the existence of Milankovitch forcing in the sedimentary records.A high-resolution astronomical time scale and high-resolution sedimentation rate curve of the Lopingian from well GFD-1 were constructed by cyclostratigraphic analysis.The eccentricity and obliquity amplitude modulation cycles suggested long periodicities of about 2.4 and about 1.2 myr,respectively.In the Wuchiapingian greenhouse of the Lopingian,the about 2.4 myr eccentricity oscillation controlled‘weak’glacio-eustasy and/or aquifer eustatic changes related to the global third-order sea-level changes and that a lowstand(W2)was initiated by an eccentricity oscillation minimum.In contrast,during the Changhsingian,which exhibited a cooling event,an about 1.2 myr obliquity cycle was probably strong,with the sea-level records highlighting the link between the‘icehouse’sea-level lowering(C2 and C1)and the obliquity nodes.Moreover,dynamic sedimentary noise model as an indicator of sea-level showed local third-order sea-level variations,the coevolution trends in the orbital power,global and local sea-level changes,and sedimentation rate had significant implications for establishing the global nature and synchronicity of these million-year-scale eustatic records and reconstructing the temporal depositional history at a regional scale.In addition,the volcanism and tectonism that continued into the early-middle Wuchiapingian probably led to a series of climate changes that drove the hydrological cycles not paced by the Milankovitch cycles.展开更多
The Permian-Triassic transition saw extreme climatic changes that severely impacted the terrestrial ecosystem.Fossil plants,particularly fossil woods,are sensitive to climatic changes,and they,therefore,are unique mat...The Permian-Triassic transition saw extreme climatic changes that severely impacted the terrestrial ecosystem.Fossil plants,particularly fossil woods,are sensitive to climatic changes,and they,therefore,are unique materials revealing extreme environmental and climatic changes on land at that time.Abundant conifer woods were discovered in the Lopingian(Late Permian)strata of the Sunjiagou Formation in Shanxi Province,North China.The newly finding permineralized woods record the unique landscape of Lopingian North China.They represent a new conifer genus and species:Shanxiopitys zhangziensis gen.et sp.nov.Analyses of growth pattern and anatomical characteristics of the fossil woods indicate these trees grew under optimal growing conditions,and without seasonal growth cessation.However,climate signals from leaf fossils,vertebrate fossils and sedimentary evidences indicate a strongly seasonal climate in North China during the Lopingian.Thus,it is speculated that these trees likely lived in the gallery forests,which were distributed along the paleo-rivers within a seasonal landscape in the central North China block during the Lopingian.展开更多
The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic m...The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.展开更多
Within the dicynodont genus Turfanodon,there are two recognized species,T.bogdaensis and T.jiufengensis.Both species are known by relatively complete cranial materials,but the mandibles and most postcranial bones have...Within the dicynodont genus Turfanodon,there are two recognized species,T.bogdaensis and T.jiufengensis.Both species are known by relatively complete cranial materials,but the mandibles and most postcranial bones have been described only for T.jiufengensis.This paper reports new dicynodont specimens from Turpan,Xinjiang,referring them to T.bogdaensis.They can clearly be differentiated from T.jiufengensis by the flatter lateral surface of the snout region,a prominent swelling on the lateral dentary shelf,and the rounded femoral head.The diagnosis of Turfanodon is revised.The combination of a flat circumorbital rim,posterior portion of anterior pterygoid rami with converging ventral ridges,and a possible autapomorphy,a deep notch on scapula forming procoracoid foramen,are confirmed.It also differentiated from all dicynodonts other than Myosaurus,Kembawacela and Lystrosaurus by having accessory ridges lateral to the median palatal ridge.展开更多
The Permian Lopingian in the Dianqiangui Basin and its adjacent areas is marked by the coal measures of the Wuchiapingian and the carbonate strata of the Changhsingian stages. For the Lopingian of the Dianqiangui Basi...The Permian Lopingian in the Dianqiangui Basin and its adjacent areas is marked by the coal measures of the Wuchiapingian and the carbonate strata of the Changhsingian stages. For the Lopingian of the Dianqiangui Basin and its adjacent areas,the diversity of sedimentary facies and the obviousness of facies change provide an advantaged condition on a study of sequence stratigraphy. Approximately,the Wuchiapingian stage constitutes a third-order sequence and the Changhsingian stage forms an-other. For the Wuchiapingian stage in the study area,coal-measures were developed on the attached platform and,in addition,a special coal-measure that is composed of both limestone beds and coal beds was also developed in the central part of some isolated platforms. Grain-bank grainstones and packstones were formed on the margin of the attached platform as well as in the windward part of iso-lated platforms. For the Changhsingian stage in the study area,open-platform limestones were formed on the attached platform,while sponge-reef limestones were developed both on the margin of the at-tached platform and on the isolated platforms. The Lopingian Series is a set of basin-facies muddy shales with interbeds of silicalites in the inter-platform basin,which appears a set of the large-thick coarse clastic strata of molasses covering direct the deep-water strata from the Devonian to the Per-mian Yangsingian in the Qinzhou-Fangcheng region in the southern part of the study area. All of these features indicate the complexity of temporal-spatial facies-changes. Sequence-stratigraphic frame-works could be established,which would illustrate two types of facies-changing surfaces and dia-chronisms in the stratigraphic records,based on the combination of both biostratigraphic and chronostratigraphic materials and the regularity reflected by temporal evolutionary succession of sediments as well as spatial distributional patterns of sedimentary facies. Ultimately,features of sedi-mentary succession and palaeogeographical evolution of the Permian Lopingian in the study area are revealed clearly in a series of the panel diagrams of sequence-stratigraphic frameworks and the outline maps showing the sedimentary-facies and palaeogeography. The Permian Lopingian formed by two third-order sequences differs from the stratigraphy of the same era characterized by the constant re-gression along Euramerica. Most specially,if the end-Guadalupian mass-extinction event is genetically related to a regressive event represented by the unconformity of the first episode of the Dongwumovement in the study area,the mass-extinction event at the turn from the Permian to the Triassic is genetically related to a rapid transgressive event re-flected by the drowning unconformity in the study area. These phenomena might reveal a complex rela-tionship between mass-extinction events and trans-gressive-regressive events.展开更多
The Lopingian is one of the fastest rising periods of seawater strontium isotopic ratios （^87Sr/^86Sr） in earth history, and its mechanisms and increasing rates of the ^87Sr/^86Sr evolution were still disputed widel...The Lopingian is one of the fastest rising periods of seawater strontium isotopic ratios （^87Sr/^86Sr） in earth history, and its mechanisms and increasing rates of the ^87Sr/^86Sr evolution were still disputed widely. These disputations among researchers were caused mainly by timeframe selection （sections＇ thickness or data of radiometric ages）, and different stratigraphic boundaries and un-upmost dated ages. This paper examined published ^87Sr/^86Sr data of the Lopingian, and projected them on timescales based on evolutionary and age constrained conodonts fossils. ^87Sr/^86Sr evolution vs fossil constraining timescales was re-established in this period. This research suggests： （1） ^87Sr/^86Sr excursion projects on fossil zones can truly support ^87Sr/^86Sr evolutionary pattern in the period; （2） ^87Sr/^86Sr evolution provides a new approach for stratigraphic research of marine carbonate sections in lieu of biostratigraphic data; （3） ^87Sr/^86Sr stratigraphy works on marine carbonate sections of different sedimentation rates even between different basins; （4） the ^875r/^86Sr data and its shift was dependent on samples materials and chemical treatment methods; （5） the increasing rate of marine water ^875r/^86Sr in the Late Permian is suggested as 5.4× 10^-5/Ma or slightly lower; （6） sedimentation age and its ^875r/^86Sr of the Lopingian marine carbonate suggested as： Dpro=259-（Rs- 0.70695）/5.4×10^-5 （Ma）.展开更多
Two important geological issues have a long history of debate in the Xingmeng area.The first concerns the final closure of the North China plate,Siberia plate and several intermediate massifs in the area,and the other...Two important geological issues have a long history of debate in the Xingmeng area.The first concerns the final closure of the North China plate,Siberia plate and several intermediate massifs in the area,and the other concerns the folding and lifting of the Xingmeng Trough.Disagreements arise because of issues involving the tectonicpalaeogeographical environment of the Upper Permian deposits of the Linxi Formation.The Linxi Formation(Upper Permian)is generally considered to be either an exclusively continental deposit or separated into marineterrigenous facies deposited during the Lower to Middle Linxi Period and continental deposits in the Upper Linxi Period.However,in this study,large numbers of bryozoan and sponge spicule fossils were discovered for this first time in the thick limestone layers and lenses of the upper part of the Linxi Formation found in the Guandi section of Linxi county in eastern Inner Mongolia.At the same time,abundant bryozoan fossils were also found in sedimentary tuff slices that were collected from the upper part of the Taohuayingzi Formation from the Taohuayingzi section in Ar Horqin Banner,and abundant small connecting body crinoid stem fossils were found in the dark shale of the Yangjiagou Formation from the Yangjiagou section of Jiutai county,Jilin Province.These marine fossils provide the first evidence that the Xingmeng area was still a marine or mainly marine environment at the end of the late Permian.This not only provides conclusive evidence for the recognition of the above two major geological issues but also promotes changes in the approach towards research,exploration and development of oil and gas,shale gas(oil),and other mineral resources that are preserved in the late Permian layers of the Northeast-Xingmeng area.展开更多
基金supported by the Key Program of the National Natural Science Foundation of China (No. 40730422)
文摘In order to discuss the geochemical characteristic of REEs （rare earth elements） and their geological application, we measured the contents of rare earth elements, trace elements and minerals of 29 Lopingian （Late Permian） mudstone samples in Panxian county, carrying out ICP-MS and XRD analysis. The results show that the amount of REEs （185.56-729.46 ×10-6） is high. The ratios of w（LREE）/w（HREE） （6.84- 13.86） and W（La）N/w（Yb）N （1.01-3.02） show clear differentiation of LREEs and HREEs. ZREE has a significantly or critically positive correlation with lithophile elements Th, Nb, Ta, Ti, Ca, Sc, Cs, Zr, Hf, Sr, Be and chaicophile element Zn, a critically negative correlation with siderophile element Fe and a slightly positive correlation with illite, illite smectite mixed layers and siderite. REEs originate mainly from terrigenous minerals, in an inorganic phase, Source rocks of our samples consist of Emeishan basalt and a small part of sedimentary rocks, as suggested by the distribution patterns of REEs and w（∑REE）- w（La）/w（Yb） diagram. Moreover, abnormal surfaces near the sequence boundaries （SB2, SB3, SB4） are related wiLth the boundaries, identified by geochemical characteristics of the REEs, such as ∑REE. w（LREE）/w（HREE）, Eu/Eu＊ and Ceanom.
文摘On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy, a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a pelagic chert section in southeast Guangxi, South China. Radiolarian Albaillella is one of the most sensitive biology to the transitional environment. The Albaillella fauna shows an ecological evolutionary process from Guadalupian to Lopingian: declined stage-recovery stage-flourishing stage. The study of characteristics of the Albaillella fauna in the transitional environment may provide more information, not only for the subdivision and correlation of a high-resolution biostratigraphy, but also for influence of radiolarian Albaillella fauna on the pre-Lopingian mass extinction.
基金This work was supported by a National Natural Science Foundation of China(Grant No.91958210)the Government Finance Level II Project(No.DD20190083)‘the 13th Five-Year Plan’National Science and Technology Major Project(No.2016ZX05034001-003).
文摘The late Permian(Lopingian)was a crucial climate transition period from the late Paleozoic Ice Age to the early Triassic of exceptionally high temperatures.However,the origins of the third-order sea-level changes during the Lopingian Epoch remain unclear.Here,we presented astronomically calibrated gamma-ray(GR)log and non-U GR(computed gamma ray or CGR)curves from the clastic and carbonate successions of well GFD-1 in the Pingle Depression of South China for studying the sea-level oscillations during the Lopingian.Spectral analyses of the 405 kyr-calibrated GR and CGR time data revealed periodicities close to about 405,about 100,about 44.2,about 35.1,about 21,and about 17.5 kyr,supporting the existence of Milankovitch forcing in the sedimentary records.A high-resolution astronomical time scale and high-resolution sedimentation rate curve of the Lopingian from well GFD-1 were constructed by cyclostratigraphic analysis.The eccentricity and obliquity amplitude modulation cycles suggested long periodicities of about 2.4 and about 1.2 myr,respectively.In the Wuchiapingian greenhouse of the Lopingian,the about 2.4 myr eccentricity oscillation controlled‘weak’glacio-eustasy and/or aquifer eustatic changes related to the global third-order sea-level changes and that a lowstand(W2)was initiated by an eccentricity oscillation minimum.In contrast,during the Changhsingian,which exhibited a cooling event,an about 1.2 myr obliquity cycle was probably strong,with the sea-level records highlighting the link between the‘icehouse’sea-level lowering(C2 and C1)and the obliquity nodes.Moreover,dynamic sedimentary noise model as an indicator of sea-level showed local third-order sea-level variations,the coevolution trends in the orbital power,global and local sea-level changes,and sedimentation rate had significant implications for establishing the global nature and synchronicity of these million-year-scale eustatic records and reconstructing the temporal depositional history at a regional scale.In addition,the volcanism and tectonism that continued into the early-middle Wuchiapingian probably led to a series of climate changes that drove the hydrological cycles not paced by the Milankovitch cycles.
基金supported by the National Natural Sciences Foundation of China(Nos.92055201 and 31700183)。
文摘The Permian-Triassic transition saw extreme climatic changes that severely impacted the terrestrial ecosystem.Fossil plants,particularly fossil woods,are sensitive to climatic changes,and they,therefore,are unique materials revealing extreme environmental and climatic changes on land at that time.Abundant conifer woods were discovered in the Lopingian(Late Permian)strata of the Sunjiagou Formation in Shanxi Province,North China.The newly finding permineralized woods record the unique landscape of Lopingian North China.They represent a new conifer genus and species:Shanxiopitys zhangziensis gen.et sp.nov.Analyses of growth pattern and anatomical characteristics of the fossil woods indicate these trees grew under optimal growing conditions,and without seasonal growth cessation.However,climate signals from leaf fossils,vertebrate fossils and sedimentary evidences indicate a strongly seasonal climate in North China during the Lopingian.Thus,it is speculated that these trees likely lived in the gallery forests,which were distributed along the paleo-rivers within a seasonal landscape in the central North China block during the Lopingian.
基金supported by the Fundamental and Commonwealth Geological Survey of Oil and Gas of China(Grant No.DD 20221662)the National Natural Science Foundation of China(NSFC)Program(Grant No.42302124).
文摘The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.
文摘Within the dicynodont genus Turfanodon,there are two recognized species,T.bogdaensis and T.jiufengensis.Both species are known by relatively complete cranial materials,but the mandibles and most postcranial bones have been described only for T.jiufengensis.This paper reports new dicynodont specimens from Turpan,Xinjiang,referring them to T.bogdaensis.They can clearly be differentiated from T.jiufengensis by the flatter lateral surface of the snout region,a prominent swelling on the lateral dentary shelf,and the rounded femoral head.The diagnosis of Turfanodon is revised.The combination of a flat circumorbital rim,posterior portion of anterior pterygoid rami with converging ventral ridges,and a possible autapomorphy,a deep notch on scapula forming procoracoid foramen,are confirmed.It also differentiated from all dicynodonts other than Myosaurus,Kembawacela and Lystrosaurus by having accessory ridges lateral to the median palatal ridge.
基金the State Key Project of the Ministry of ScienceTechnology of China and the Project of the China Petrochemical Corporation (SINOPEC) (Grant No. NPJ-100019)
文摘The Permian Lopingian in the Dianqiangui Basin and its adjacent areas is marked by the coal measures of the Wuchiapingian and the carbonate strata of the Changhsingian stages. For the Lopingian of the Dianqiangui Basin and its adjacent areas,the diversity of sedimentary facies and the obviousness of facies change provide an advantaged condition on a study of sequence stratigraphy. Approximately,the Wuchiapingian stage constitutes a third-order sequence and the Changhsingian stage forms an-other. For the Wuchiapingian stage in the study area,coal-measures were developed on the attached platform and,in addition,a special coal-measure that is composed of both limestone beds and coal beds was also developed in the central part of some isolated platforms. Grain-bank grainstones and packstones were formed on the margin of the attached platform as well as in the windward part of iso-lated platforms. For the Changhsingian stage in the study area,open-platform limestones were formed on the attached platform,while sponge-reef limestones were developed both on the margin of the at-tached platform and on the isolated platforms. The Lopingian Series is a set of basin-facies muddy shales with interbeds of silicalites in the inter-platform basin,which appears a set of the large-thick coarse clastic strata of molasses covering direct the deep-water strata from the Devonian to the Per-mian Yangsingian in the Qinzhou-Fangcheng region in the southern part of the study area. All of these features indicate the complexity of temporal-spatial facies-changes. Sequence-stratigraphic frame-works could be established,which would illustrate two types of facies-changing surfaces and dia-chronisms in the stratigraphic records,based on the combination of both biostratigraphic and chronostratigraphic materials and the regularity reflected by temporal evolutionary succession of sediments as well as spatial distributional patterns of sedimentary facies. Ultimately,features of sedi-mentary succession and palaeogeographical evolution of the Permian Lopingian in the study area are revealed clearly in a series of the panel diagrams of sequence-stratigraphic frameworks and the outline maps showing the sedimentary-facies and palaeogeography. The Permian Lopingian formed by two third-order sequences differs from the stratigraphy of the same era characterized by the constant re-gression along Euramerica. Most specially,if the end-Guadalupian mass-extinction event is genetically related to a regressive event represented by the unconformity of the first episode of the Dongwumovement in the study area,the mass-extinction event at the turn from the Permian to the Triassic is genetically related to a rapid transgressive event re-flected by the drowning unconformity in the study area. These phenomena might reveal a complex rela-tionship between mass-extinction events and trans-gressive-regressive events.
基金This research was supported by National Basic Research Program of China （Grant No. 2011CB808905）, National Natural Science Foundation of China （Grant Nos. 41227801, 41273004, and 412003028）, Knowledge Innovation Program of the Chinese Academy of Sciences （Grant No. KZCW2-YW-Q08-4） and Instrument Developing Project of the Chinese Academy of Sciences （Grant No. YZ201433）. We thank anonymous reviewers for their generous helps to improve the manuscript, and also appreciate members of experimental paleontology research group for their stimulating discussions and constructive suggestions.
文摘The Lopingian is one of the fastest rising periods of seawater strontium isotopic ratios （^87Sr/^86Sr） in earth history, and its mechanisms and increasing rates of the ^87Sr/^86Sr evolution were still disputed widely. These disputations among researchers were caused mainly by timeframe selection （sections＇ thickness or data of radiometric ages）, and different stratigraphic boundaries and un-upmost dated ages. This paper examined published ^87Sr/^86Sr data of the Lopingian, and projected them on timescales based on evolutionary and age constrained conodonts fossils. ^87Sr/^86Sr evolution vs fossil constraining timescales was re-established in this period. This research suggests： （1） ^87Sr/^86Sr excursion projects on fossil zones can truly support ^87Sr/^86Sr evolutionary pattern in the period; （2） ^87Sr/^86Sr evolution provides a new approach for stratigraphic research of marine carbonate sections in lieu of biostratigraphic data; （3） ^87Sr/^86Sr stratigraphy works on marine carbonate sections of different sedimentation rates even between different basins; （4） the ^875r/^86Sr data and its shift was dependent on samples materials and chemical treatment methods; （5） the increasing rate of marine water ^875r/^86Sr in the Late Permian is suggested as 5.4× 10^-5/Ma or slightly lower; （6） sedimentation age and its ^875r/^86Sr of the Lopingian marine carbonate suggested as： Dpro=259-（Rs- 0.70695）/5.4×10^-5 （Ma）.
基金supported by the Chinese Geological Survey(1212011120972)the National Natural Science Foundation(41072021)the Geologic Survey Project of China(1212011121067)
文摘Two important geological issues have a long history of debate in the Xingmeng area.The first concerns the final closure of the North China plate,Siberia plate and several intermediate massifs in the area,and the other concerns the folding and lifting of the Xingmeng Trough.Disagreements arise because of issues involving the tectonicpalaeogeographical environment of the Upper Permian deposits of the Linxi Formation.The Linxi Formation(Upper Permian)is generally considered to be either an exclusively continental deposit or separated into marineterrigenous facies deposited during the Lower to Middle Linxi Period and continental deposits in the Upper Linxi Period.However,in this study,large numbers of bryozoan and sponge spicule fossils were discovered for this first time in the thick limestone layers and lenses of the upper part of the Linxi Formation found in the Guandi section of Linxi county in eastern Inner Mongolia.At the same time,abundant bryozoan fossils were also found in sedimentary tuff slices that were collected from the upper part of the Taohuayingzi Formation from the Taohuayingzi section in Ar Horqin Banner,and abundant small connecting body crinoid stem fossils were found in the dark shale of the Yangjiagou Formation from the Yangjiagou section of Jiutai county,Jilin Province.These marine fossils provide the first evidence that the Xingmeng area was still a marine or mainly marine environment at the end of the late Permian.This not only provides conclusive evidence for the recognition of the above two major geological issues but also promotes changes in the approach towards research,exploration and development of oil and gas,shale gas(oil),and other mineral resources that are preserved in the late Permian layers of the Northeast-Xingmeng area.
