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Detrital Zircon Geochronology of early triassic Strata in the West Qinling Orogen:Implications for the Tectonic Evolution of the Paleo-Tethyan Ocean

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Journal of Earth Science 2024年第4期35卷 1087-1106页

作者： Zuochen Li Xianzhi Pei Liyong Wei Guobing Liang Meng Wang Ruibao Li Lei Pei Chengjun Liu Youxin Chen Feng Gao Xi’an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals School of Earth Science and ResourcesChang’an UniversityXi’an710054China Xi’an Mineral Resources Survey Center China Geological SurveyXi’an710100China School of Geology and Mining Engineering Xinjiang UniversityUrumqi830000China

The West Qinling Orogen(WQO)is located in the western part of the Qinling Orogen and in the transition zone of Qilian Orogen,Songpan-Garze Orogen and Yangtze Block,and also the key position of triassic collision orogenic *** study of the early triassic strata in the WQO is contributed to analyze the closure process of the *** conducted LA-ICP-MS U-Pb dating studies on detrital zircons to determine the provenance,depositional age,and tectonic setting of the early triassic Longwuhe Formation in the Lintan area of the *** results show that the majority of the detrital zircons in the Longwuhe Formation are mainly magmatic origin and have characteristic of crust source *** lowest limit of sedimentation of the Longwuhe Formation is constrained to the early triassic,with the youngest detrital zircon age of 253±3 *** ages can be divided into five age groups:3346–1636 Ma,with two peak ages of ca.2495 and ca.1885 Ma;1585–1010 Ma,with a peak age at ca.1084 Ma;992–554 Ma,with a peak age at ca.939 Ma;521–421 Ma,with a peak age at ca.445 Ma;418–253 Ma,with a peak age at ca.280 ***,the sources of the Longwuhe Formation include the northern margin of the WQO,the Qilian Orogen(QLO)and the basement of the southern margin of the North China Block(NCB),of which the ancient basement of the southern margin of the NCB is the main source area of the Longwuhe *** with previous studies,we propose that the Longwuhe Formation was formed in a fore-arc basin,which is related to the closure of the A’nyemaqen-Mianlüe Ocean from the early Permian to early–Middle triassic due to the northward subduction-collision of the Yangtze Block(YZB).This also indicates that the A’nyemaqen-Mianlüe Ocean has flat subduction characteristics.

关键词： West Qinling orogenic belt early triassic paleo-Tethyan Ocean geochronology zircon

There was no “Great Bank of Guizhou” in the early triassic in Guizhou Province, South China

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Journal of Palaeogeography 2015年第1期4卷 99-108页

作者： Zeng-Zhao Feng Zhi-Dong Bao Xiu-Juan Zheng Yuan Wang China University of Petroleum (Beijing)

In the 1990s, some geologists named the early triassic isolated carbonate platform in the Luodian area of southern Guizhou Province in South China as the ＂Great Bank of Guizhou＂. During the past twenty years, this term ＂Great Bank of Guizhou＂ was used in more than 300 articles in foreign countries. In the 1990s, the authors have studied the lithofacies palaeogeography of the early and Middle triassic in South China. In June 2014, we went to the Luodian area and studied the early triassic Bianyang section again. According to the geological data we acquired, in the early triassic of the Luodian area of southern Guizhou Province, there was only an isolated ＂Luodian Carbonate Platform＂, while no bank existed, not to mention the ＂Great Bank of Guizhou＂. It is worth further discussion.

关键词： early triassic Luolou Formation Ziyun Formation Great Bank of GuizhouLuodian Carbonate Platform Bianyang section South China

Western Tethyan Epeiric Ramp Setting in the early triassic： An Example from the Central Dinarides (Croatia)

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Journal of Earth Science 2018年第4期29卷 806-823页

作者： Dunja Aljinovic Micha Horacek Leopold Krystyn Sylvain Richoz Tea Kolar-Jurkovsek Duje Smircic Bogdan Jurkovsek University of Zagreb Faculty of Mining Geology and Petroleum Engineering Pierottijeva 6 Zagreb 10000 Croatia BLT Wieselburg HBLFA Francisco-Josephinum Rottenhauserstr. 1 Wieselburg 3250 Austria Institute of Paleontology Vienna University A lthanstrafle 14 Vienna 1090 Austria Lund University Lithosphere and Biosphere science Solvegatan 12 Lund 22362 Sweden Geological Survey of Slovenia Dimiceva Ulica 14 Ljubljana 1000 Slovenia

In the central part of the External Dinarides in Plavno, Croatia, near Knin, a remarkably thick （927.5 m） early triassic depositional sequence was investigated. The Plavno sequence starts in the earlyGriesbachian and ends with a continuous transition into the Anisian strata. A complete 13C isotope curve has been achieved and combined with conodonts, bivalves and ammonoids to establish and correlate stage and substage boundaries. The 613C curve is consistent with former studies. It displays a general increase from the Griesbachian to a prominent maximum beyond the ＋8%0 amplitude around the Dienerian-Smithian boundary （DSB）, followed by a steep and continuous decline to low, negative values in the Smithian. Around the Smithian-Spathian boundary （SSB） a steep rise to a second maximum occurred. It is followed by a saw-tooth shaped decline in the Spathian and a similar increase to a peak at the Spathian-Anisian boundary （SAB）. Sedimentologically, the Plavno sequence is interpreted as having been deposited on an extensive epeiric ramp under long-term transgressive conditions, sharing depositional characteristics of both the epeiric platform and the carbonate ramp. The entire Plavno sequence was deposited above the storm-wave base and was storm influenced. Three informal members are differentiated： 1） the dolostone member （early Griesbachian）; 2） the silicielastic member （red-coloured shale, siltstone, sandstone with oolitic/bioclastie grainstone intercalations）, which can be further divided into lower, middle and upper intervals （Late Griesbachian, Dienerian and Smithian）; and 3） the mudstone member （grey lime mudstones, marls and calcisiltites with common ammonoids and gastropods- Spathian）. The Plavno sequence is compared with other western Tethyan sections. Observed differences stem from local controls on deposition in the overall shallow marine environment.

关键词： early triassic Dinarides epeiric ramp 6Z3C isotope curve litho- and biostratigraphy.

Conodont Biostratigraphy and Age of the early triassic Fish-Bearing-Nodule Levels from Nanjing and Jurong, Jiangsu Province, South China

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Journal of Earth Science 2020年第1期31卷 9-22页

作者： Shuang Liu Zuoyu Sun Cheng Ji Min Zhou Dayong Jiang Laboratory of Orogenic Belt and Crustal Evolution Ministry of EducationDepartment of Geology and Geological MuseumPeking UniversityBeijing 100871China College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao 266590China CAS Key L aboratory of Economic Stratigraphy and Paleogeography Nanjing Institute of Geology and PaleontologyCenter for Excellence in Life and PaleoenvironmentChinese Academy of SciencesNanjing 21000SChina

Fish-bearing-nodules are found in early triassic marine strata in many regions, including East Greenland, East Spitsbergen, Northwest Madagascar, Canada, Angola, and South China. A new Olenekian(early triassic) conodont biostratigraphic study for stratum that contains fish-bearing-nodule levels is conducted based on the Longtan(LT) Section of Nanjing City and the Qingshan(QS) Section of Jurong County, Jiangsu Province, South China. A total of 101 samples were collected at the two sections and three conodont zones were recognized: in ascending order, they are Scythogondolella(Sc.) milleri Zone, Novispathodus(Nv.) pingdingshanensis Zone, and Triassospathodus(Tr.) aff. homeri Zone. The Scythogondolella milleri Zone is globally recognized as the uppermost conodont zone of the Smithian and the base of the Novispathodus pingdingshanensis Zone was previously suggested as the marker of the Smithian-Spathian boundary in the Yangtze region. The fish-bearing-nodule levels of Nanjing and Jurong are within the conodont Scythogondolella milleri Zone, laterally correlated well with the upper part of the Novispathodus waageni Zone in Chaohu of Anhui Province that also contains fish-bearing-nodule levels. The conodont biostratigraphic correlation confirms the early triassic fish-bearing-nodule levels in the Lower Yangtze region are coeval, with an end-Smithian in age.

关键词： early triassic conodont fish-bearing-nodule Lower Yangtze region South China

Taphonomy of early triassic fish fossils of the Vega-Phroso Siltstone Member of the Sulphur Mountain Formation near Wapiti Lake,British Columbia,Canada

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Journal of Palaeogeography 2013年第4期2卷 321-343页

作者： Karen Anderson Adam D. Woods Department of Geological Sciences California State University

Abstract The taphonomy of fishes living in lacustrine environments has been extensively studied in both the laboratory and the fossil record;the taphonomy of marine fishes,however,is poorly *** marine fishes with heavy ganoid and cosmoid scales,which provided protection from rapid taphonomic loss,offer a means to examine marine fish taphonomy in the fossil *** genera of early triassic fishes(the ray-finned actinopterygians Albertonia,Bobasatrania,Boreosomus,and the lobe-finned coelacanth(sarcopterygian),Whiteia)from the Wapiti Lake,British Columbia locality of the Lower triassic Sulphur Mountain Formation were examined in order to gain a better understanding of the taphonomy of fish in marine environments,determine ambient environmental conditions in the region during the early triassic,and ascertain the habitat and mode of life of the *** indicate that environmental conditions that contributed to the preservation of the fossil fishes of the current study included deposition in deep,quiet waters,which reduced the odds of disarticulation,colder waters under higher pressure,which slowed decay and limited postmortem floatation,and waters that were anoxic,which discouraged predators and *** addition,the thickness of the primitive ganoid and cosmoid scales of the fossil fishes also increased their preservation ***,physiological and environmental indicators suggest that Whiteia,Albertonia,and possibly Bobasatrania lived in deep,cold waters near the oxygen minimum zone,while Boreosomus lived higher in the water *** the anatomical and physiological characteristics of modern fishes will likely continue to inhibit marine taphonomy studies,examination of ancient fish,particularly those with ganoid or cosmoid scales,may provide future avenues of research to gain a better understanding of marine fish taphonomy and provide a powerful tool to examine ancient fish behavior and their environment.

关键词： taphonomy fish fossils fossil fishes early triassic

Late Olenekian Radiolarians from Bedded Chert of Ashio Terrane, Northeast Japan, and Faunal Turnovers in Western Panthalassa during early triassic

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Journal of China University of Geosciences 2002年第2期13卷 124-140,T001页

作者： NoritoshiSuzuki NatsumiAkiba 等 ResearchCenterforHigherEducationTohokuUniversity Sendai980－8578Japan DepartmentofEarth＆PlanetaryScience GraduateSchoolofSciencetheUniversityofTokyoTokyo113－0033Japan

Late Olenekian assemblages in the western Panthalassa have been recovered from bedded radiolarian chert sequences of an accretionary complex, the Ashio belt. These faunas are documented and considered in terms of radiolarian diversity and faunal turnover during the latest Permian to Middle triassic time. The fauna includes 30 radiolarians belonging to Spumellaria or Entactinaria, with two relicts from the Late Permian. This late Olenekian fauna is markedly different from Permian and Anisian faunas, respectively, and is herein named the Minowa fauna. Study of the literature indicates that radiolarian provinces were significantly disconnected between the western Panthalassa and eastern Tethys during late Olenekian time. Furthermore, 121 of 143 species disappeared during late Olenekian time, and in turn 118 new species appeared in the western Panthalassa around the Olenekian Anisian boundary. It is concluded that faunal turnover occurred at least three times between the latest Permian and Middle triassic. The first turnover is the Paleozoic type radiolarian extinction at the Permian triassic boundary, the second is the diversification of spheroidal Spumellaria and Entactinaria between early and late Olenekian time, and the third is a faunal turnover from the Minowa fauna to the true Mesozoic type radiolarian faunas that are characterized by multi segmented Nassellaria.

关键词： radiolaria early triassic Middle triassic faunal turnover mass extinction Minowa radiolarian fauna.

Paleomagnetic study on the early triassic red beds from Jiaocheng,Shanxi Province——Local rotation and tectonic significance

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Paleomagnetic study on the Early Triassic red beds from Jiao...

A new small baurioid therocephalian from the Lower triassic Jiucaiyuan Formation, Xinjiang, China

中国科学院地质与地球物理研究所2004学术年会

作者： SHI Ruiping,HUANG Baochun,ZHU Rixiang & REN Shoumai Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

Paleomagnetic and rock magnetic study has been conducted on the early triassic red beds of Liujiagou Formation from Jiaocheng,Shanxi *** was shown as the main magnetic *** eradicating an initial viscous component at room temperature to～100℃-200℃,thermal demagnetization shows that most samples contain two remanence components,intermediate-temperature remanence component at 250℃--500℃and high-temperature component at 500℃-680℃.The intermediate-temperature component has a negative fold test at the 95%confidence *** the pole position of the intermediate-temperature component in geographic coordinates is correlated with the Middle Jurassic reference pole of the North China Block(NCB) within the 95%confidence,suggesting that it might be a remagnetization component acquired during the Yanshanian *** high-temperature component contains both reversal and normal polarities with positive fold test and C-level positive reversal test at the 95%confidence level,which suggests that this high-temperature component can be regarded as primary *** of this newly obtained early triassic paleopole with the coeval mean pole of the Ordos Basin suggests that a locally relative rotation may have happened between the Ordos and the Jiaocheng area of Shanxi *** rotation may be related with two faults:one is Lishi big fault separating Ordos from Shanxi and the other is Jiaocheng big fault, which is situated in the southeast of sampling locality and was still in motion during the Cenozoic.

关键词： Jiaocheng Shanxi paleomagnetism early triassic local rotation.

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古脊椎动物学报（中英文） 2024年第3期62卷 201-224页

作者： LIU Jun Fernando ABDALA Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing 100044China College of Earth and Planetary Sciences University of Chinese Academy of Sciences Beijing 100049 Área de Paleontología Unidad Ejecutora LilloCONICETFundación Miguel Lillo Miguel Lillo 251TucumánArgentina Evolutionary Studies Institute University of the Witwatersrand Private Bag 3WITSJohannesburg2050South Africa

Several therocephalian species,mainly represented by cranial material from the late Permian,have been reported from China in recent *** we describe a tiny new baurioid therocephalian,Jiucaiyuangnathus confusus *** ***.,from the Jiucaiyuan Formation,Xinjiang,*** new taxon is represented by a partial snout with occluded partial lower jaw and two postcranial *** juvenile in stage,the new species is diagnosed by the following features:round pit in middle of lateral surface of maxilla;lacrimal contact nasal;fossa for dentary tooth on the posterior end of the premaxilla,lateral to the anterior choana;two small vertical triangular ridges extending dorsally and ventrally on the vomerine anterior portion,and bordering a thin vomerine foramen laterally;anterior projection of the lateral part of the frontal on the nasal;symphyseal region of the dentary projected anteriorly;5 upper premaxillary teeth,upper and lower canines absent,diastema between the last premaxillary upper incisor and first maxillary tooth present,no diastema separating anterior from posterior dentition in the mandible,10 maxillary teeth and 12 dentary teeth,posterior postcanine expands mesiodistally,having a main large cusps and tiny anterior and posterior accessory cusps in line;neural arches of the atlas fused by the neural spine,neural spine of the axis projected posteriorly,procoracoid foramen lies between procoracoid and *** of the dentition resembles those of the small baurioid Ericiolacerta parva from South Africa and Silphedosuchus orenburgensis from *** specimens provide the rare opportunity to know in detail the postcranial skeleton of baurioids.

关键词： Jimsar,Xinjiang early triassic Jiucaiyuan Formation Therocephalia,Baurioidea

Carbon isotope composition and comparison of Lower triassic marine carbonate rocks from Southern Longmenxia section in Guang＇an, Sichuan Basin

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Science China Earth Sciences 2017年第1期60卷 80-94页

作者： HUANG SiJing HUANG KeKe ZHONG YiJiang LI XiaoNing MAO XiaoDong HU ZuoWei LIU SiBing ZHANG Meng WU WenHui State Key Laboratory of OilGas Reservoir Geology and Exploitation Institute of Sedimentary Geology Chengdu University of Technology Chengdu 610059 China

The early triassic was a period of ecological restoration for the earth's system after the end-Permian mass *** records linked to the variations in marine ecosystems during this period have attracted the interest of geologists for many *** on petrographic analysis of samples and evaluations of their reliability as proxies for original seawater,this study investigated the carbon and oxygen isotopic compositions of 350 carbonate rock samples from the Lower triassic(and adjacent strata)in the southern Longmenxia section of Guang'an,eastern Sichuan *** results indicate that the triassic carbonate rocks from the southern Longmenxia section favorably preserved the original seawater'sδ^(13)C ***,carbon and oxygen isotopic compositions are found to be poorly correlated,with a determination coefficient as low as 0.0205 and only 44 rock samples show results of Mn/Sr>2 and/orδ^(18)0triassic is established using the data from the remaining 306 samples with Mn/Sr-6.5‰.This curve presents favorable comparability on a global scale,specifically in theδ^(13)C minima near the Permian-triassic boundary,at the top of the Jia1 and within the the Jia3,as well as in theδ^(13)C maxima at the tops of the Ye1 and Ye4,at the base of the Jia2 and at the top of the *** peaks and troughs corresponding to these maxima and minima all reflect global *** comparing these results to previous research on coeval carbon isotopic curves established within the chronostratigraphic framework,the ages of these critical evolution points are *** results show that the Ye1 roughly corresponds to the Griesbachian substage;the Ye2 through Ye4 correspond to the Dienerian substage;Jial corresponds to the Smithian substage;from the Jia2 to the lower part of the Jia4 correspond to the Spathian substage;and the middle and upper parts of the Jia4 belongs to the Aegean Substage of

关键词： Southern Longmenxia section early triassic Carbon isotopic composition Global events Smithian-Spathian boundary event