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2002年  13卷  第2期

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Lower Triassic Inorganic Carbon Isotope Excursion in Chaohu, Anhui Province, China
Tong Jinnan, Qiu Haiou, Zhao Laishi, Zuo Jingxun
2002, 4(2).
摘要:
This paper reports a Lower Triassic inorganic carbon isotope profile from the North Pingdingshan Section in Chaohu, Anhui Province, China, which was situated in a deep part of the Lower Yangtze carbonate ramp. The δ (13C) excursion shows two periods from the Permian~Triassic boundary to the lower Spathian substage, corresponding to the ecosystem undergoing evolution and recovery after the end Permian mass extinction and related events. The first period starts at the δ (13C ) depletion caused by the mass extinction and evolves with a gradual δ (13C) increase resulting from the development of some disaster taxa during the Induan. The strong Smithian δ (13C) depletion in the second period might be formed by the collapse of the disaster ecosystem and the biotic recovery occurred with the explosive increase of bioproductivity in the Spathian. Thus the δ (13C) excursion in the Lower Triassic expresses patterns of biotic evolution and recovery during the erratic ecosystem that followed the great end Permian mass extinction.
Late Olenekian Radiolarians from Bedded Chert of Ashio Terrane, Northeast Japan, and Faunal Turnovers in Western Panthalassa during Early Triassic
Noritoshi Suzuki, Natsumi Akiba, Harumasa Kanoh
2002, 4(2).
摘要:
LateOlenekianassemblagesinthewesternPanthalassahavebeenrecoveredfrombeddedradiolarianchertsequencesofanaccretionarycomplex,theAshiobelt.ThesefaunasaredocumentedandconsideredintermsofradiolariandiversityandfaunalturnoverduringthelatestPermiantoMiddleTriassictime.Thefaunaincludes30radiolariansbelongingtoSpumellariaorEntactinaria,withtworelictsfromtheLatePermian.ThislateOlenekianfaunaismarkedlydifferentfromPermianandAnisianfaunas,respectively,andishereinnamedtheMinowafauna.StudyoftheliteratureindicatesthatradiolarianprovincesweresignificantlydisconnectedbetweenthewesternPanthalassaandeasternTethysduringlateOlenekiantime.Furthermore,121of143speciesdisappearedduringlateOlenekiantime,andinturn118newspeciesappearedinthewesternPanthalassaaroundtheOlenekian~Anisianboundary.ItisconcludedthatfaunalturnoveroccurredatleastthreetimesbetweenthelatestPermianandMiddleTriassic.ThefirstturnoveristhePaleozoictyperadiolarianextinctionatthePermian~Triassicboundary,thesecondisthediversificationofspheroidalSpumellariaandEntactinariabetweenearlyandlateOlenekiantime,andthethirdisafaunalturnoverfromtheMinowafaunatothetrueMesozoic~typeradiolarianfaunasthatarecharacterizedbymulti~segmentedNassellaria.
Discussion on Induan Olenekian Boundary in Chaohu, Anhui Province, China
Zhao Laishi, Tong Jinnan, Zuo Jingxun, Ming Houli
2002, 4(2).
摘要:
ThispaperproposesaschemeforthedefinitionoftheLowerTriassicInduan~Olenekianboundary(IOB)basedoninvestigationofsectionsinChaohu,AnhuiProvince,Chinaaswellasdataaccumulatedfromotherstudieselsewhere.TheconodontNeospathoduswaageniissuggestedastheindexfossiloftheboundary.AccordingtotheFADofN.waageni,theIOBisatthebaseofbed25~2oftheWestPingdingshanSectioninChaohu,42.19mabovethePermian~Triassicboundary,anditisslightlyhigherthanthebaseoftheFlemingitesEuflemingitesAmmonoidZoneatthesection.
A Proposed Area for Study of Accessory Section and Point of Terrestrial Permian Triassic Boundary
Peng Yuanqiao, Wang Shangyan, Wang Yufang, Yang Fengqing
2002, 4(2).
摘要:
After the establishment of the global stratotype section and point (GSSP) of the Permian~Triassic boundary (PTB), the definition of the accessory section and point (ASP) of the terrestrial Permian~Triassic boundary (TPTB) is now on the agenda. However, all good TPTB sections so far known have the following shortcomings: (1) the exact TPTB horizon is difficult to define paleontologically with high resolution, and (2) accurate correlation between marine and terrestrial PTBs is hard to attain. In order to enhance the understanding of the nature of the global life crisis in both the marine and terrestrial environments across the Paleozoic~Mesozoic transition, these shortcomings need to be addressed. In western Guizhou and eastern Yunnan, Southwest China, some fossiliferous PTB sections which include marine, paralic and terrestrial are well~developed, allowing bed~to~bed correlation of the PTB sequences. Fortunately, the marine PTB sequence in this area is almost the same as found at the Meishan Section, where the GSSP of the PTB is located, which may provide a reliable auxiliary marker for high~resolution demarcation of the TPTB. These features found in western Guizhou and eastern Yunnan make this area a good place to study the ASP of the TPTB, so we propose to study the ASP of the TPTB in this area.
Study on a Terrestrial Permian~Triassic Boundary Section—Zhejue Section, Weining County, Guizhou Province, China
Wang Shangyan, Peng Yuanqiao, Yin Hongfu
2002, 4(2).
摘要:
TheZhejueSectionisanexcellentterrestrialPermian~Triassicboundary(TPTB)sectionnotonlyforitsconvenientaccessibilityandgoodoutcrop,butalsoforitsabundantfossils.Inaddition,therearetwoclaystonebedsthatwereformedbyeventsacrossthePermian~Triassicboundary(PTB)atthissection.Theclaystonesprovideabridgeforhigh~resolutioncorrelationbetweenmarineandterrestrialPTBs.AnotheradvantageisthatthePTBattheZhejueSectioncanbecorrelatedwiththatoflittoralandneriticfaciesbytracingwestwards.Synthesizedstratigraphicstudies,includingbiostratigraphy,eventostratigraphy(susceptibilitiesandcarbonisotopesacrosstheTPTB,andmicrospherulesfoundintheboundaryclaystones)andsequencestratigraphy,arecarriedoutatthissection.
First Research on Marine and Nonmarine Sedimentary Sequences and Micropaleontologic Significance across Permian/Triassic Boundary in Iran (Isfahan and Abadeh)
Mehdi Yazdi, Manizheh Shirani
2002, 4(2).
摘要:
Abundantichthyoidremains,conodontsandholothuriansscleriteswererecoverednearthePermian/TriassicboundaryfromasectionsouthofIsfahan.Recoveredichthyoidremainsincludesharkmicroteethandscales.TheichthyolithmaterialissimilartoaFasanianichthyolithfromtheZakazaneareaintheSlovakkarstoftheWesternCarpathians,whichrepresentsasubspeciesofAcodinatriassica.Conodontspeciesaremostlyneogondolellids.Thisfaunaindicatesthatthesedimentaryenvironmentwasmarine,whiletothenorthoflocalitiesnearIsfahanandZagross,terrestrialdepositionwasdominantatthattime.AluminasilicateandkaolinarepresentinacontinentalunitinDopolanrefractorymain(ShahidNilchianmine)andasectionsouthofChahrisehVillage,northofIsfahan.Pisolitie,ironstonefaciesandbauxiteclayarecommonnearthePermian/TriassicboundaryintheChahrisehregion
Alkane Biomarkers in Permian~Triassic Boundary Strata at Meishan Section, Changxing, Zhejiang Province
Lu Liqiang, Tong Jinnan
2002, 4(2).
摘要:
MeishanSectionDinChangxingCounty,ZhejiangProvince,ChinahasbeenselectedastheglobalstratotypeofthePermian~Triassicboundaryandvariousstudieshavebeendoneattheboundary,butthegaschromatographic~massspectrographicanalysisofalkanebiomarkershasnotbeeninvestigated.ThispaperpresentstheresultsofastudyofthebiomarkersanalyzedinaseriesofsamplesacrossthePermian~TriassicboundaryatbothMeishanSectionAandSectionD.TheresultsshowthattheoverallconcentrationofalkanebiomarkersinthePermian~TriassicboundarystrataishighinBed26whileitislowinBed27.Avarietyofbiomarkerparametersdemonstratethatthemainsourcesoforganicmatterinthesedimentarealgaeandbacteriaandthatthedepositionalenvironmentvariedfromweaklyoxidizingtoreducingduringthestudiedinterval
Research on Ecostratigraphy of Changhsingian at Meishan Section D, Changxing, Zhejiang Province
Liu Jinhua, Zhang Kexin, He Weihong, Wu Shunbao
2002, 4(2).
摘要:
On the basis of researches over several years on biostratigraphy of Changhsingian at Meishan Section D in Changxing County, the abundant materials were accumulated. This paper studies the ecostratigraphy and establishes 7 community zones (CZ), in ascending order, Sinoplatysomus~Geinitzina~Clarkina subcarinata, Tapashanites~Nodosaria~Clarkina subcarinata, Crurithyris~Geinitzina~Clarkina subcarinata, Glomospira~Clarkina changxingensis, Colaniella~Clarkina changxingensis, Rotodiscoceras~Palaeofusulina~Hindeodus typicalis, Clarkina meishanensis~Hypophiceras.The habitat type (HT) is different from upper shallow sea to the lower part of the lower shallow sea.
Analyses of Sequence Stratigraphy and Environments across Permian~Triassic Boundary in Liaotian, Northwestern Jiangxi Province
Cai Xiongfei, Gu Yansheng, Wang Dehui, Zhang Zejun, Chen Bing
2002, 4(2).
摘要:
Based on the study of lithology, sedimentology and paleontology at the Permian~Triassic boundary in Liaotian, Northwestern Jiangxi Province, the sequence stratigraphy and depositional environments across the boundary are reconstructed. The top part of the Upper Permian Changxing Formation is composed of very thick~bedded light~colored dolomitic limestone formed in high deposition rate on carbonate ramp, which indacates a transgression systems tract (TST). The Lower Triassic Qinglong Formation shows continuous deposition with the underlying Upper Permian. The lower member of Qinglong Formation consists of calcareous shale, shelly limestome and dolomitic limestone with abundant bivalves (Claraia sp.) and trace fossils (Chondrites). The calcareous shale at the bottom of Lower Triassic indicates a calm deep water environment to form the condensed section (CS). The shelly limestome and dolomitic limestone with shell fossils, intraclast, algal ooide show clean but turbulent environment of carbonate ramp, which produce the deposition of highstand systems tract (TST).
Research on Outcrop Sequence Stratigraphy of Permian in Middle~Lower Yangtze Region
Zhang Kexin, Liu Jinhua, He Weihong, Wu Shunbao
2002, 4(2).
摘要:
According to the latest International Chronostratigraphic Scheme (ICS, 2000), the Permian in the Middle~Lower Yangtze region of South China can be divided into three series and nine stages relevant to the traditional six stages of South China. From Assellian to Changxingian of Permian, 44 Ma in age range, the strata are composed of 14 third~order sequences, each of which is 3.14 Ma in average age range. There is one third~order sequence of Zisongian, equivalent to middle and upper Chuanshan Formation or equal to Asselian and two thirds of Sakmarian. There are two third~order sequences, corresponding to Liang~shan Formation or Zhenjiang Formation and upper Chuanshan Formation, which are assigned to Longlingian, coinciding with Artinskian and one third of Sakmarian. In addition, three third~order sequences, equal to Qixia Formation, are attributed to Chihsian, corresponding to Kubergandian and one third of Roadian. Four third~order sequences, comprising Gufeng, Maokou, Yanqiao, Yinping and Wuxue formations, are assigned to Maokouan, equivalent to two thirds of Roadian, Wordian and Capitanian. Two third~order sequences, equal to Longtan Formation or Wujiaping Formation, are included in Wuchiapingian. Other two third~order sequences, corresponding to Changxing Formation or Dalong Formation, are assigned to Changhsingian. In brief, these above third~order sequences can be incorporated into 4 sequences sets.