西藏色龙西山二叠系-三叠系界线剖面稳定碳同位素特征

Stable Carbon Isotope Characteristics of Permian-Triassic Boundary at the Selong Xishan Section

古生代-中生代之交的生物灭绝过程和原因一直是科学家关注和致力解决的关键古生物学问题之一.色龙西山剖面的牙形石分带工作取得了重要进展,为认识该地区地层序列和沉积历史提供了新的证据.全岩碳同位素分析表明,在长兴阶与印度阶附近该剖面存在着碳同位素负偏,可以同我国华南多个剖面进行对比,揭示了古生代-中生代之交的碳同位素变化和生物灭绝模式具有全球对比性.新识别出的奥伦尼克阶底部(Neospathodus waageni带底部)碳同位素值大幅度负偏及之后的正偏,与华南等地的变化规律一致,反映了二叠纪末期到早三叠世长期的、复杂的生物和环境变化过程.

The process and cause about the mass extinction event across the Paleozoic-Mesozoic transition have always been one of the key paleontological issues in the past few decades.The conodont zoning of the Selong Xishan section has made important progress,providing new evidence for understanding the stratigraphic sequence and sedimentary history of the area.Carbon isotope analyses of bulk samples in this study indicate that there are negative shifts across the Changshingian-Induan Boundary,which are comparable to South China.Newly identified carbon isotope negative shift at earliest Olenekian,base of Neospathodus waageni zone and the following positive shift coincide with the pattern recognized in South China and other places,implying the multi-phase extinction-recovery processes in Early Triassic.