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middle permian Seamount from Xiahe Area, Gansu Province, Northwest China: Zircon U-Pb Age, Biostratigraphy and Tectonic Implications

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Journal of China University of Geosciences 2009年第2期20卷 364-380页

作者：寇晓虎张克信朱云海陈中强林启祥陈奋宁黄金元 Key Laboratory of Biogeology and Environmental Geology of Ministry of Education Faulty of Earth SciencesChina University of Geosciences State Key Laboratory of Geological Processes and Mineral Resources Key Laboratory of Biogeology and Environmental Geology of Ministry of EducationChina University of Geosciences Faulty of Earth Sciences China University of Geosciences School of Earth & Environment The University of Western Australia

The well-preserved seamount buildups are documented from the northwestern Qinling （秦岭） orogenic belts, Northwest China. The study sections are located in the Ganjia （甘加） area of the Xiahe （夏河） County, Gansu （甘肃） Province. The dark basalt and overlying massive reef carbonate characterize the Xiahe seamount buildup. Basalts are dominated by the olivine type of rocks and bear distinct porphyritic textures, and fumarole and amygdaloidal structures. The basalts are dominated by SiO2 （up to 48.49 wt.%-52.29 wt.%） followed by （Na2O＋ K2O）（3.80 wt.%-4.96 wt.%） and TiO2 （2.04 wt.%-2.52 wt.%）. They are featured by considerably high content of Ti. The tholeiiteseries rocks dominate the basalts, while calc-alkali-series rocks are also present. The REE of the basalts shows the LREE-enrichment type with distinct positive Eu abnormal. The trace elements of the basalts are characterized by the lack of P and high content of Ti. These geochemical signals suggest that the Xiahe basalts were formed in an ocean-island setting. The LA ICP-MS zircon U-Pb age of the basalts is 267.6±5 Ma, which is reinforced by the presnce of the fusulinid Neoschwagerina Zone of the Wordian （middle permian） in the limestone interbeds of the basalts. Integration of petrological and geochemical studies of seamount basalts and lateral correlation of seamount buildups reveals that the Qinling-Qilian-Kunlun orogenic belts were probably the archipelagic oceans during the permian.

关键词： seamount basalt zircon U-Pb age biostratigraphy geochemistry petrology middle permian western Qinling tectonic complex Northwest China.

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Paleoecology of Oligocarpia gothanii Halle from the middle permian of Southeastern Shanxi,North China

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Acta Geologica Sinica(English Edition) 2015年第4期89卷 1063-1075页

作者： HE Xuezhi WAN Mingli YAN Mengxiao CHENG Chen WANG Shijun WANG Jun State Key Laboratory of Systematic and Evolutionary Botany (LSB) Institute of BotanyChinese Academy of Sciences LPS Nanjing Institute of Geology and PalaeontologyChinese Academy of Sciences University of Chinese Academy of Sciences

Fossil ferns are abundant and diverse in the permian Cathaysian Flora of Shanxi, North China. Although plants assemblages of the Carboniferous and permian have been extensively investigated, their palaeoecology and especially the paleoecology of ferns has not been studied in detail. Recent reinvestigation of Oligocarpia gothanii has revealed its growth habit and cloning reproduction strategy, but most previous studies lack integrated sedimentological and taphonomic data. In this study, new materials of O. gothanii have been collected from a floodplain setting in the middle permian Lower Shihhotse Formation of southeastern Shanxi. These plant fossils were found in a lenticular claystone associated with rooting structures. They are characterized by aphlebia at the base of the penultimate rachis. Sedimentological, taphonomic and morphological analyses were conducted to understand the growth habit and ecology of the fern. The result indicates that the Oligocarpia gothanii had a prostrate, ground cover growth habit, and was dominant in pioneer floras that colonized disturbed floodplains.

关键词： palaeoecology plant taphonomy middle permian Oligocarpia gothanii Halle

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Sequence Stratigraphic Model of middle permian Barakar Formation from a Marginal Gondwana Basin, India

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Journal of Earth Science 2018年第4期29卷 745-754页

作者： Joyjit Dey Souvik Sen Coal India Limited Central Mine Planning and Design Institute (CMPD1) Regional Institute-3 Jharkhand 829 103 India Geologix Limited Dynasty Building Level-4 Wing-A Andheri Kurla Road Andheri (E) Mumbai 400 059 India

Gondwana deposits are extensively found across the continents. Here we study the Mid- dle permian Barakar Formation from the marginal Gondwana Basin, eastern India, being deposited in a normal fault setting. Availability of extensive cores as well as geophysical log suites （gammaresistivity-density from drilled wells） from the study area helped us achieving high resolution interpretation. Core study identifies fluvial sedimentary architectures, which were correlated with the geophysical logs and modeled field-wide to understand vertical and horizontal facies disposition. The facies analysis has been used to establish a sequence stratigraphic model of the cyclic Barakar deposition. Four major fining upward depositional sequences were identified, each sequence comprises of low accommodation system tract （LAST） at base and high accommodation system tract （HAST） at top. LAST is characterized by vertically stacked, multistory amalgamated channel sandstone dominated facies, while floodplain dominated facies characterizes HAST, reflecting a gradual shift from braided to meandering depositional system from bottom to top of each cycle. Study reveals depocenter to be in the western part, supported by eastward thinning of sediment packets, all being deposited in a halfgraben setting.

关键词： fluvial sequence stratigraphy Gondwana sediment middle permian Barakar Formation.

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New specimens of Stenocybus acidentatus(Therapsida: Dinocephalia) from the middle permian Dashankou Fauna of China

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Acta Geologica Sinica(English Edition) 2014年第3期88卷 730-737页

作者： JIANG Shan JI Shu-an Institute of Geology Chinese Academy of Geological Sciences Key Laboratory of Stratigraphy and Paleontology Ministry of Land and Resources

The basal dinocephalian clade Stenocybusidae was known from two incomplete specimens representing one generus,Stenocybus,from Dashankou fanua in Yumen,Gansu Province of *** holotype of Stenocybus acidentatus is laterally compressed,making some characters *** we describe two new specimens of Stenocybus acidentatus from the same locality,an anterior portion of skull with articulated jaws,and a right dentary with nearly complete *** show some detailed features on the morphology of the premaxilla,maxilla,nasal,external nares and *** phylogenetic relationship between Stenocybus acidentatus and the relatively large Sinophoneus yumenensis is still difficult to determine,and needs more new complete material and further evidences.

关键词： Dinocephalia Stenocybusidae Dashankou Fauna middle permian

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Final-stage Southward Subduction of the Eastern Paleo-Asian Ocean:Evidence from the middle permian Mafic Intrusions in the Northern Margin of the North China Craton

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Acta Geologica Sinica(English Edition) 2022年第1期96卷 81-99页

作者： JING Yan GE Wenchun DONG Yu YANG Hao JI Zheng BI Junhui ZHOU Hongying XING Dehe College of Earth Sciences Jilin UniversityChangchun 130061China Key Laboratory of Mineral Resources Evaluation in Northeast Asia Ministry of Land and Resources of ChinaChangchun 130026China Tianjin Center China Geological SurveyTianjin 300170China Shenyang Center China Geological SurveyShenyang 110034China

The northern margin of the North China Craton(NCC)contains widespread permian magmatic rocks,but the origin of these rocks remains *** uncertainty hampers us from better understanding of tectonic framework and evolution of the eastern Paleo-Asian Ocean,particularly with respect to its final-stage subduction and closure *** address these questions,this study presents petrological,zircon U-Pb geochronological,whole-rock geochemical and in situ zircon Hf isotopic data for these permian mafic intrusions in the northern margin of the *** zircon U-Pb dating results indicate that these mafic intrusions were emplaced in the middle permian(ca.260 Ma).Geochemically,the studied mafic intrusions have high MgO and transition metals element contents,with high Mg^(#) values,indicating a mantle *** mafic intrusions are characterized by enrichments in large ion lithophile elements(LILEs;e.g.,Rb,Ba,and K)and light rare earth elements(LREEs),and depletions in high field strength elements(HFSEs;e.g.,Nb,Ta,and Ti)and heavy rare earth elements(HREEs),indicating that they were formed in a subduction-related *** geochemical features,together with zircon ε_(Hf)(t)values(-1.1 to+11.2),indicate that their parental magmas were derived from partial melting of heterogeneous mantle wedge metasomatized by subduction-related fluids,with the contributions of slab *** studied mafic intrusions also show wide range of major and trace elements contents,and variable Mg^(#) values,Eu and Sr anomalies,suggesting that their parental magmas had undergone variable degrees of fractional *** with the E-W trending permian continental arc along the northern margin of the NCC,we confirm that the generation of the middle permian mafic intrusions was related to southward subduction of the Paleo-Asian oceanic lithosphere beneath the NCC and the Paleo-Asian Ocean had not closed prior to the middle permian.

关键词： middle permian mafic intrusions subduction metasomatism northern margin of the North China Craton Paleo-Asian Ocean

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Evolution of sedimentary facies and fossil communities in the middle permian Maokou Formation in Zigui County, Hubei Province,South China

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Journal of Palaeogeography 2018年第1期7卷 48-57页

作者： Ke-Yu Zhu Tan Wang Zhi-Xing Yi Yong-Biao Wang State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences China University of GeosciencesWuhan

A geological event that happened at the end of the middle permian resulted in different levels of erosion in a shallow-water platform of South China, which led to diverse geological records in different sections. The Lianziya section in western Hubei Province of South China has a well-exposed stratigraphic sequence of the late middle permian rocks with abundant fossils and sedimentary facies types, providing new evidences for understanding the evolution of marine biota and environment in the late middle permian. Our study shows that four fossil communities can be recognized with the change of sedimentary facies in the late middle permian: Foraminiferal-algal community, phylloid algal community, bryozoan community and Ungdarella community. The foraminiferal-algal community is dominated by fusulinids and calcareous algae, but was soon replaced by the phylloid algal community. With an increase of terrestrial input, the phylloid algal community was again replaced by the bryozoan community. Near the end of the middle permian, with a decrease of terrestrial input, the bryozoan fossil community disappeared while the Ungdarella community became dominant. A 10 cm-thick weathered crust occurred at the top of the middle permian limestone, marking a large amplitude fall in sea-level and the beginning of a terrestrial erosion stage. The sedimentary facies and fossil community changes in the Lianziya section indicates that the middle permian crisis was a gradual process while the sea-level fall mainly occurred in the latest middle permian.

关键词： Fossil community Sedimentary facies middle permian Guadalupian Capitanian-Wuchiapingian Zigui County Hubei Province

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First record of Bystrowianid Chroniosuchians(Amphibia：Anthracosauromorpha) from the middle permian of China

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Acta Geologica Sinica(English Edition) 2017年第5期91卷 1523-1529页

作者： JIANG Shan JI Shu-an MO Jinyou natural history museum of guangxi Guangxi 530012China institute of geology chinese academy of geological scienceskey laboratory of stratigraphy and paleontologyministry of land and resourcesBeijing 100037China

Chroniosuchians are basal tetrapods owing to Anthracosauromorpha and the oldest species of chroniosuchians have been recorded in the Late permian of Russia so far. In this study, we present evidence for their existence in the middle permian of China, based on well preserved diagnostic vertebrae with associated osteoderms from the Dashankou fanua in northwestern China. The finds clearly show interosteoderm articulation pattern between the adjacent scutes in bystrowianids. The features observed in Yumenerpeton yangi may warrant the close proximity or phyletic succession of the chroniosuchid and bystrowianid types of the osteoderm design.

关键词： Bystrowianidae Chroniosuchia osteoderms middle permian China

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Characteristics of “Guangyuan-Wangcang” trough during Late middle permian and its petroleum geological significance in northern Sichuan Basin, SW China

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Petroleum Exploration and Development 2021年第3期48卷 655-669页

作者： WANG Xingzhi LI Bo YANG Xiyan WEN Long XU Liang XIE Shengyang DU Yao FENG Mingyou YANG Xuefei WANG Yaping PEI Senqi State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China School of Geoscience and Technology Southwest Petroleum UniversityChengdu 610500China Research Institute of Exploration and Development PetroChina Southwest Oil&Gasfield CompanyChengdu 610500China Exploration Division of PetroChina Southwest Oil&Gasfield Company Chengdu 610500China Northwest Sichuan Gas Mine of PetroChina Southwest Oil&Gasfield Company Jiangyou 621700China

Based on outcrop characteristics, combined with regional tectonic background, drilling and geophysical data, the sedimentary characteristics of the middle permian Maokou Formation in the northern Sichuan Basin was studied by means of macroscopic and microscopic observation, geochemical element test, total organic carbon content and vitrinite reflectance measurement. There is a set of deep-water sediments rich in organic matter in the Guangyuan-Wangcang area of northern Sichuan during the late depositional period of the middle permian Maokou Formation. The strata are distributed from northwest to southeast, with thickness of 10–30 m, mainly composed of siliceous rocks and siliceous mudstones, intercalated with gravity flow deposits. Siliceous rocks and siliceous mudstones are characterized by thin single layer, flat bedding and rich siliceous radiolarians, calthrop and brachiopod with small body and thin shell, belonging to the typical sedimentary characteristics of deep-water trough facies. The contents of Cu, Co, Mo, Ni and the ratio of Ni to Co in the geochemical tests all indicate that the siliceous rocks are products of deep-water reducing environment. The TOC value ranges from 3.21% to 8.19%, with an average of 5.53%, indicating that the siliceous rocks have good hydrocarbon generation ability. The south side of the trough is in platform margin facies with high energy, and the sediments are mainly thick massive micritic-calcsparite biogenic(clastic) limestone, which is conducive to the formation and evolution of the reservoir. During the late sedimentary period of the Maokou Formation, the northward subduction and extension of the oceanic crust at the northwestern margin of the Yangtze Plate provided the internal dynamic conditions for the formation of the "Guangyuan-Wangcang" trough. According to the location, sedimentary characteristics and formation dynamics of the trough, it is similar to the "Kaijiang-Liangping" trough during Late permian proposed by previ

关键词： Sichuan Basin Guangyuan-Wangcang trough middle permian Maokou Formation deep-water deposition siliceous rock

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Organic accumulation in the lower Chihsia Formation(middle permian) of South China:Constraints from pyrite morphology and multiple geochemical proxies

Organic accumulation in the lower Chihsia Formation(Middle P...

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中国科学院地质与地球物理研究所2012年度（第12届）学术年会

作者： Hengye Wei Daizhao Chen Jianguo Wang Hao Yu Maurice E.Tucker Key Laboratory of Petroleum Resources Research Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth Science East China Institute of Technology School of Earth Sciences University of BristolBS8 1RJEnglandUnited Kingdom

The organic-rich Chihsia Formation(middle permian) on the Yangtze platform,western Hubei,South China, is considered to he the major hydrocarbon source rock in South *** lower part of the Chihsia Formation,reported here,was deposited in an intrashelf basin and is characterised by black laminated marlstones/shales intercalated with dark-grey limestones/dolomites in which metre-scale shallowing(or cleaning)-upward cycles are *** cycle is composed of basal marlstone/shale and upper limestone. The organic matter is concentrated exclusively in the shaley bases of these cycles,and shows systematic, cyclic variations in abundance up through the *** integrated approach of pyrite morphology and multiple geochemical proxies was used to determine the mechanism of organic *** the organic-rich sediments,many redox proxies,including pyrite framboid size distribution,C-S-Fe relation-ships, iron speciation,andδS values of pyrite suggest deposition beneath the dysoxic bottom water, which evolved into a more oxic water body when the organic-poor limestones were ***, the coincidence of increased abundance of total organic carbon(TOC) with increased Ba and Mo contents indicates that organic matter accumulation was controlled mainly by primary *** data indicate that increased organic accumulation resulted mainly from higher organic carbon export with increased nutrient flux during superimposed sea-level rises of different *** in turn could have increased the oxygen consumption by respiration of microorganisms and organic matter decay,leading to the depletion of oxygen in the water ***,the rapid sedimentation rate further limited bioturbation and organic matter decomposition,facilitating the preservation of buried organic matter.

关键词： Chihsia Formation middle permian Primary productivity Redox state Organic matter Yangtze platform

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Facies Interpretation, Depositional Environment and Sequence Stratigraphy of the Sartakht Formation in the Bakhshi Section, Located in Kalmard Block, East-Central Iran

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Open Journal of Geology 2016年第5期6卷 314-329页

作者： Bibi Haniyeh Emraninasab Mohammad Hossein Adabi Mahmoodreza Majidifard Nader Kohansal Ghadimvand Department of Geology North Tehran Branch Islamic Azad University Tehran Iran Department of Geology Faculty of Earth Sciences Shahid Beheshti University Tehran Iran Research Institute for Earth Sciences Geological Survey of Iran Tehran Iran Department of Geology Islamic Azad University North Tehran Branch Tehran Iran

permian rocks in Kalmard block are recognized with Khan Group, enjoying various characteristics in different outcrops. This group is made up of three informal formations, namely Chili, Sartakht and Hermez. middle permian deposits (Sartakht formation) are composed chiefly of sandstone and carbonate rocks. This formation is composed of 58.6 m sandstone and dolomitic limestone in the Bakhshi section. Lower permian carbonate deposits (Chili formation) unconformably underlie this formation while lateritic paleosols of upper permian (Hermez formation) are depicted overlying an erosional unconformity above this formation. According to lithologic and microscopic investigations, the deposits of Sartakht formation can be divided into 2 siliciclastic petrofacies and 12 carbonate microfacies. Field observations, along with microscopic examinations, have resulted in identifying tidal flat, lagoon, shoal and open marine environments in the rocks of the studied formation. Vertical changes of microfacies and depth variation curve point to the high thickness of the microfacies of lagoon and shoal environments and low thickness of the microfacies of tidal flat and open marine environments. The carbonate-siliciclastic sequence of Sartakht formation is made up of a third-order depositional sequence, separated from carbonate depositions of lower permian (Chili formation) and lateritic paleosols of upper permian by type 1 sequence boundary (SB1). Siliciclastic deposits include LST system tract, and carbonate microfacies involve TST and HST system tracts, separated from each other by MFS. Sartakht formation rocks in Bakhshi section are deposited in a low-angle homoclinal ramp, mostly in the inner ramp, located in the south of Paleotethys Ocean. The depositional sequence identified in Sartakht formation points to the age of middle permian, conforming to middle Absaroka II supersequence. The upper erosional boundary between Sartakht and Hermez formations conforms to the global-scale sea lev

关键词： middle permian Kalmard Block Sartakht Formation Depositional Environment Sequence Stratigraphy

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