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 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.
