西藏南部中白垩世黑色页岩的碳氧同位素组成及大洋缺氧事件的讨论

THE COMPOSITION OF CARBON AND OXYGEN ISOTOPE AND THE DISCUSSION ABOUT THE OCEANIC ANOXIC EVENTS IN THE MIDDLE CRETACEOUS BLACK SHALE,SOUTH TIBET

本文对西藏南部中白垩世黑色页岩中的碳氧同位素组成特征和两次大洋缺氧事件的形成、发展过程作了较为详细的分析讨论。西藏南部中白垩世期内，在仲玛期及其稍后的沉积时期存在两次大洋缺氧事件，这两次缺氧事件在时间上可与国际上的Ｃｅｎ－Ｔｕｒ和Ｃｏｎ－Ｓａｎｔ时期的全球大洋缺氧事件相对应；该区这两次大洋缺氧事件的形成、发展，是与当时全球特定的生态环境和全球性的地壳构造运动、大规模的海侵、火山喷发等重大地质灾变事件直接有关。热盐卤流体入侵只是局部、地区性因素；该地这两次大洋缺氧事件，在一定程度上受到陆源物质输入的影响，缺氧强度上有所削弱。

It is paper analysed and discussed in detail about the characteristics of isotopic composition of carbon and oxygen in the middle cretaceous black shale,South Tibet and the formed and developed processes of the two oceanic anoxic events in this paper.There were two oceanic anoxic events in Zhongmaian and the later in the middle Cretaceous,South Tibet.The two anoxic events could be in correration with the global oceanic anoxic events in the Cenomanian Turonian,Coniacian Santonian respectively.The two oceanic anoxic events in that area were bound up with the global special ecological environment and the great geological disasters,such as the global crustal tectoge nesis, the enormous transgression and the volcanic eruption,and so on at that time. The hot brine intrusion was only local factor.The two oceanic anoxic events in that area were influenced by the input of the terrigenous deposit,and the anoxic degree was limited in a certam extent.