华南早三叠世缺硅事件研究

二叠纪末发生了生物史最大的一次灭绝事件。因此，人们认为P/T大灭绝引起的生态系的坍塌造成了早三叠世缺硅事件。近年来，在泛大洋地区的新西兰和以及日本等地深水剖面报道了早三叠世硅质岩的存在。广布于华南地区大隆组硅质岩沉积被归于晚二叠世晚期。因此普遍认为华南地区早三叠世缺乏硅质沉积。近年来，本研究组在贵州改毛剖面大隆组上午发现早三叠世早期典型分子Isarcicella isarcica 和 Isaricicella staeschei。因此，新的证据使得我们必须重新检验大隆组上部的时代。本项目拟通过对华南关键地区大隆组顶部地层的牙形石、放射虫以及沉积微相、生物分异度、地球化学等研究，建立精细年代地层序列，厘定"早三叠世的硅质岩"的确切时代及沉积环境，在此基础上研究"早三叠世缺硅事件"的古地理响应，可进一步帮助我们深入了解二叠纪-三叠纪之交这一史上最大生物大绝灭事件。

The end-Permian saw the largest mass extinction in life's history. Numerous extinction mechanisms have been suggested to explain the causes of the end Permian biotic extinction with ocean anoxia proposed as one of the most important causes.The spread of anoxia coincides with the disappearance of chert deposition in many sections around the world. Thus, collapse of ecosystem during the Permian-Triassic mass extinction led to an Early Triassic 'chert gap'. Recently. in Panthalassa, there are some chert deposition which across the PTB transition have been found in the pelagic sections in Arrow Rocks and Waiheke Island in New Zealand and Japan.The chert deposition of Dalong Formation widespread in South China. The age of Dalong Formation was assigned to Latest Permian.Hence, it is common accepted there was an Early Triassic chert gap in South China. During past few years, based on the conondont study,the research team found some typical Early Triassic conodont species Isarcicella isarcica and Isaricicella staeschei from the upper part of Dalong Formation at the Gaimao section in Guiyang, Guizhou Provice. There maybe also radiolaria-bearing chert deposition extended to Early Triassic at Xinmin section in Anshun, Guizhou Province. The new evidence push us to re-check the age of Dalong Fromation. This project will mainly focus on studying conodont and radiolarian biostratigraphy, microfacies, biotic diversity as well as geochemistry on Dalong Formation in some key areas in South China. Based above study, this project try to establish high-resolution chronological sequence of Dalong Formation, to define the age and palaeoenvironments of "Early Triassic chert". Furthermore, this peoject will also study the palaeogeograpgical background of the Early Triassic chert deposition. This study is of important sigificance for better understanding the Permian-Triassic mass extinction.