The Meishan Section of Changxing County, Zhejiang Province, China and the base of its Bed 27c,in which Hindeodus parvus first occurs, are recommended as the GSSP of Permian-Triassic boundary (PTB).The present paper in...The Meishan Section of Changxing County, Zhejiang Province, China and the base of its Bed 27c,in which Hindeodus parvus first occurs, are recommended as the GSSP of Permian-Triassic boundary (PTB).The present paper introduces a description of the section. Biostratigraphic correlation with other famous sections shows the completeness of this section and justifies choice of H. Parvus as the index fossil. Chemostratigraphic investigation provides the δ￣13C excursion and the moderate but inconsistent Ir spike as auxiliary symbols for the PTB. This boundary is closely related to transgression,anoxia,volcanism,mass extinction and possible impact events which can be correlated with those in South China and other parts of the world .展开更多
The Global boundary Stratotype Section and Point(GSSP)for the base of the Hirnantian Stage(the uppermost of the Ordovician System)is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangjiawan No...The Global boundary Stratotype Section and Point(GSSP)for the base of the Hirnantian Stage(the uppermost of the Ordovician System)is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangjiawan North section.The section is located near Wangjiawan village,42 km north of Yichang city(western Hubei,China),at 30°58′56″N and 111°25′10″E.The GSSP level coincides with the first appearance of the graptolite species Normalograptus extraordinarius(Sobolevskaya).Secondary markers include the onset of a positive carbon-isotope excursion,and a slightly earlier first appearance of Normalograptus ojsuensis(Koren and Mikhailova).The Wangjiawan North section possesses continuity of sedimentation and biozonation with completeness of exposures,abundant and well-preserved graptolites and shelly fossils,i.e.the Hirnantia-Dalmanitina shelly fauna which is a key element for recognition of the Hirnantian Stage.The Wangjiawan North,South and Riverside sections possess favorable facies and widespread correlation potential,are free from structure complication,metamorphism and other alteration,and have good accessibility.The Riverside section in particular possesses amenability to isotopic age determination.The beginning of the Hirnantian was followed by a global episode of a major extinction event,which happened in the Diceratograptus mirus Subzone.The proposal was voted by the International Subcommission on Ordovician Stratigraphy in October,2004,approved by the International Commission on Stratigraphy in February,2006,and ratified by the International Union of Geological Sciences in May,2006.展开更多
Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraph...Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between the Transpecos composite sequence (chronozone)and the UAA- 1 composite sequence (chronozone).展开更多
Following votes by the Pliensbachian Working Group,the Jurassic Subcommission and the International Commission on Stratigraphy,lUGS ratified the proposed Global Boundary Stratotype Section and Point(GSSP)for the base ...Following votes by the Pliensbachian Working Group,the Jurassic Subcommission and the International Commission on Stratigraphy,lUGS ratified the proposed Global Boundary Stratotype Section and Point(GSSP)for the base of the Pliensbachian Stage(Lower Jurassic)at the base of bed 73b in the Wine Haven section,Robin Hood's Bay,Yorkshire Coast,UK.This level contains the characteristic ammonite association Bifericeras donovani Dommergues and Meister and Apoderoceras sp.Complementary data include:a)Strontium-isotope stratigraphy,based on analysis of belemnites which yield a calcite 87Sr/^86Sr ratio for the boundary level of 0.707425 and data supporting interpretation of continuous sedimentation;b)Belemnite oxygen-isotope data indicate a significant temperature drop(-5℃)across the boundary at this locality;c)A Transgressive Systems Tract(TST)initiated in the Aplanaturn Subzone(uppermost Sinemurian)continues into the Lowermost Pliensbachian(Taylori Subzone);it forms part of a transgressive facies cycle sensu Graciansky et al.(1998);d)The Upper Sinemurian to lowermost Plensbachian at Wine Haven section has a predominantly norreal magnetic polarity,but two discrete reversed polarity magnetozones are present.The first spans much of the latest Sinemurian Aplanatum Subzone.It terminates〈0.5m below the Sinemurian-Pliensbachian boundary and may prove a valuable chronostratigraphic marker The second extends from the latest Oxynotum Subzone probably through to the lower part of the Raricostatum Subzone.展开更多
文摘The Meishan Section of Changxing County, Zhejiang Province, China and the base of its Bed 27c,in which Hindeodus parvus first occurs, are recommended as the GSSP of Permian-Triassic boundary (PTB).The present paper introduces a description of the section. Biostratigraphic correlation with other famous sections shows the completeness of this section and justifies choice of H. Parvus as the index fossil. Chemostratigraphic investigation provides the δ￣13C excursion and the moderate but inconsistent Ir spike as auxiliary symbols for the PTB. This boundary is closely related to transgression,anoxia,volcanism,mass extinction and possible impact events which can be correlated with those in South China and other parts of the world .
文摘The Global boundary Stratotype Section and Point(GSSP)for the base of the Hirnantian Stage(the uppermost of the Ordovician System)is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangjiawan North section.The section is located near Wangjiawan village,42 km north of Yichang city(western Hubei,China),at 30°58′56″N and 111°25′10″E.The GSSP level coincides with the first appearance of the graptolite species Normalograptus extraordinarius(Sobolevskaya).Secondary markers include the onset of a positive carbon-isotope excursion,and a slightly earlier first appearance of Normalograptus ojsuensis(Koren and Mikhailova).The Wangjiawan North section possesses continuity of sedimentation and biozonation with completeness of exposures,abundant and well-preserved graptolites and shelly fossils,i.e.the Hirnantia-Dalmanitina shelly fauna which is a key element for recognition of the Hirnantian Stage.The Wangjiawan North,South and Riverside sections possess favorable facies and widespread correlation potential,are free from structure complication,metamorphism and other alteration,and have good accessibility.The Riverside section in particular possesses amenability to isotopic age determination.The beginning of the Hirnantian was followed by a global episode of a major extinction event,which happened in the Diceratograptus mirus Subzone.The proposal was voted by the International Subcommission on Ordovician Stratigraphy in October,2004,approved by the International Commission on Stratigraphy in February,2006,and ratified by the International Union of Geological Sciences in May,2006.
文摘Through a detailed study of sequence boundaries, it is concluded that sequence stratigraphy is an independent regional and transitional stratigraphic system between local lithostratigraphy and global chronostratigraphy. Therefore, a new tripartite stratigraphic classification scheme has been proposed. By combining organically the concept of sequence boundaries with the GSSP, it is suggested that the GSSP should be chosen in a conformale portion of a related sequence boundary, and the boundary established in light of this concept is defined as the Best Natural Boundary (BNB). The definition of the BNB points out the working area and stratigraphic level for the GSSP. By referring to a case study of the Permian Guadalupian/Lopingian boundary, the concept of the BNB has been elaborated in detail, and it is proposed that the BNB of the Guadalupian and the Lopingian lies between the Mesogondolella granti Zone and the Ctarkina postbitteri Zone, which is also the sequence chronostratigraphic boundary between the Transpecos composite sequence (chronozone)and the UAA- 1 composite sequence (chronozone).
文摘Following votes by the Pliensbachian Working Group,the Jurassic Subcommission and the International Commission on Stratigraphy,lUGS ratified the proposed Global Boundary Stratotype Section and Point(GSSP)for the base of the Pliensbachian Stage(Lower Jurassic)at the base of bed 73b in the Wine Haven section,Robin Hood's Bay,Yorkshire Coast,UK.This level contains the characteristic ammonite association Bifericeras donovani Dommergues and Meister and Apoderoceras sp.Complementary data include:a)Strontium-isotope stratigraphy,based on analysis of belemnites which yield a calcite 87Sr/^86Sr ratio for the boundary level of 0.707425 and data supporting interpretation of continuous sedimentation;b)Belemnite oxygen-isotope data indicate a significant temperature drop(-5℃)across the boundary at this locality;c)A Transgressive Systems Tract(TST)initiated in the Aplanaturn Subzone(uppermost Sinemurian)continues into the Lowermost Pliensbachian(Taylori Subzone);it forms part of a transgressive facies cycle sensu Graciansky et al.(1998);d)The Upper Sinemurian to lowermost Plensbachian at Wine Haven section has a predominantly norreal magnetic polarity,but two discrete reversed polarity magnetozones are present.The first spans much of the latest Sinemurian Aplanatum Subzone.It terminates〈0.5m below the Sinemurian-Pliensbachian boundary and may prove a valuable chronostratigraphic marker The second extends from the latest Oxynotum Subzone probably through to the lower part of the Raricostatum Subzone.
文摘埃迪卡拉系为国际地层表新增的新元古界最上部的系级年代地层单位,层型剖面被确定为南澳大利亚弗林德斯山脉依诺拉马河剖面,其底界点位(GSSP)选定为埃拉逖那冰成杂砾岩(Elatina diamictite)之上盖帽碳酸盐岩努卡利那组(Nuccaleena Formation)的下界(Gradstein et al., 2004;Knoll et al., 2004)。我国修定后的震旦系与埃迪卡拉系完全相当,底界以南沱冰碛岩之上盖帽碳酸盐岩的下界为界。本文综合国际地层委员会新元古代地层分会以及相关国家和地区近年来在埃迪卡拉系年代地层学领域研究的新进展、存在问题以及未来发展趋势作一概要介绍,以期引起国内晚前寒武纪地层古生物学者的广泛关注。
