湖南慈利礁相二叠系-三叠系界线地层及其对大灭绝事件的启示

Reef Facies Strata of Permian-Triassic Boundary in Kangjiaping Section,Cili Area,Hunan Province and Its Implications for Biological Mega-deracination

湖南慈利康家坪长兴组礁相地层上直接覆以大冶组"错时相"钙质微生物岩、鲕状灰岩、蠕虫状灰岩等沉积物。岩相、生物地层和碳同位素演变表明大灭绝事件处地层连续;剖面上长兴期末的化石分布呈现一种单幕式灭绝型式和过程;占据大灭绝后浅水碳酸盐相的是一种以微生物主导的"异常生态系"。

The reef facies of the Changxing Formation is overlaid by the ＂anachronistic facies＂ such as calcimicrobialite,oolitic limestone and vermicular limestone of the Daye Formation at Kajiaping section,Cili area,Hunan Province.The lithology,biostratigraphy and carbon isotope excursion of those reef facies indicate that the sequence is continuous across the mass extinction boundary.The distribution of fossils in the latest Changhsingian at the section shows a single-episode pattern and process of mass extinction.The shallow carbonate facies was occupied by a ＂abnormal ecosystem＂ dominated by microbes in the aftermath of mass extinction.