The Global Stratotype Section and Point （GSSP） for the boundary between the Capitanian and Wuchiapingian stages, also the boundary between the Guadalupian and Lopingian Series is defined at the First Appearance Dat...The Global Stratotype Section and Point （GSSP） for the boundary between the Capitanian and Wuchiapingian stages, also the boundary between the Guadalupian and Lopingian Series is defined at the First Appearance Datum （FAD） of the conodont Clarkina postbitteri postbitteri at the base of Bed 6k in the Penglaitan Section along the Hongshui River in Guangxi Province, South China. This point is within a chronomorphocline from Clarkina postbitteri hongshuiensis to C. dukouensis and nearly coincides with the Middle-Upper Absaroka Megasequence boundary and as such is documented within a continuously deposited carbonate lowstand succession with deep-water facies of the Maokou Formation below and deep-water facies of the Heshan Formation above. Furthermore, this point also coincides with a major extinction of various Permian fossils including corals, fusulinaceans, ammonoids and brachiopods. The proximity to an apparently global major sequence boundary and extinction event will serve as a means of correlation of this GSSP into other regions in which the defining taxon is not present because of profound provincialism during the Middle and Upper Permian. Carbon isotopic trends and magnetostratigraphic signatures are also provided to help correlate this GSSP into other regions, including those with continental facies successions. The Tieqiao Section near the county town of Laibin is also described as a supplementary reference section.展开更多
The Cretaceous/Paleogene （K/Pg） Working Group, after many years of studies, voted to define the Global Stratotype Section and Point （GSSP） for the base of the Danian Stage at the base of the boundary clay at a sec...The Cretaceous/Paleogene （K/Pg） Working Group, after many years of studies, voted to define the Global Stratotype Section and Point （GSSP） for the base of the Danian Stage at the base of the boundary clay at a section near El Kef Tunisia. The GSSP was approved by the International Commission on Stratigraphy （ICS） and ratified by the International Union of Geological Sciences （IUGS） in 1991. Nevertheless, the GSSP was not officially published, although some papers dealing with geological aspects of the K/Pg boundary at El Kef have been published and this is quite well known. In April 2006, the GSSP was revisited, a marker was put in place and protection of the site was requested. Many correlation criteria are present at the GSSP of which the most useful are the meteorite impact evidence （iridium anomaly, Ni-rich spinel, etc.） and the mass extinction of planktic micro- and nannofossils. This event coincides with the GSSP, allowing us to propose that the K/Pg boundary is marked exactly by the moment of the meteorite impact, which implies that all the sediments generated by the impact belong to the Danian. This definition solves problems of correlation in the Yucatan peninsula （Mexico） and its surroundings.展开更多
文摘The Global Stratotype Section and Point （GSSP） for the boundary between the Capitanian and Wuchiapingian stages, also the boundary between the Guadalupian and Lopingian Series is defined at the First Appearance Datum （FAD） of the conodont Clarkina postbitteri postbitteri at the base of Bed 6k in the Penglaitan Section along the Hongshui River in Guangxi Province, South China. This point is within a chronomorphocline from Clarkina postbitteri hongshuiensis to C. dukouensis and nearly coincides with the Middle-Upper Absaroka Megasequence boundary and as such is documented within a continuously deposited carbonate lowstand succession with deep-water facies of the Maokou Formation below and deep-water facies of the Heshan Formation above. Furthermore, this point also coincides with a major extinction of various Permian fossils including corals, fusulinaceans, ammonoids and brachiopods. The proximity to an apparently global major sequence boundary and extinction event will serve as a means of correlation of this GSSP into other regions in which the defining taxon is not present because of profound provincialism during the Middle and Upper Permian. Carbon isotopic trends and magnetostratigraphic signatures are also provided to help correlate this GSSP into other regions, including those with continental facies successions. The Tieqiao Section near the county town of Laibin is also described as a supplementary reference section.
文摘The Cretaceous/Paleogene （K/Pg） Working Group, after many years of studies, voted to define the Global Stratotype Section and Point （GSSP） for the base of the Danian Stage at the base of the boundary clay at a section near El Kef Tunisia. The GSSP was approved by the International Commission on Stratigraphy （ICS） and ratified by the International Union of Geological Sciences （IUGS） in 1991. Nevertheless, the GSSP was not officially published, although some papers dealing with geological aspects of the K/Pg boundary at El Kef have been published and this is quite well known. In April 2006, the GSSP was revisited, a marker was put in place and protection of the site was requested. Many correlation criteria are present at the GSSP of which the most useful are the meteorite impact evidence （iridium anomaly, Ni-rich spinel, etc.） and the mass extinction of planktic micro- and nannofossils. This event coincides with the GSSP, allowing us to propose that the K/Pg boundary is marked exactly by the moment of the meteorite impact, which implies that all the sediments generated by the impact belong to the Danian. This definition solves problems of correlation in the Yucatan peninsula （Mexico） and its surroundings.
