川东地区二叠纪-三叠纪界线地层地质与地球化学特征  

Geological Events and Element Geochemistry Response in the PTB Section from Eastern Sichuan Area

作　　者：刘萍[1] 郑荣才[1] 常海亮 梁宁[1] 周刚[3] 

机构地区：[1]油气藏地质及开发工程国家重点实验室,成都理工大学,成都610059 [2]河南省国土资源科学研究院,郑州450003 [3]中国石油西南油气田分公司勘探开发研究院,成都610021

出　　处：《地质论评》2018年第1期29-44,共16页Geological Review

基　　金：本文为国家自然科学基金资助项目(编号：41472088)和教育部博士点基金资助项目(编号：20135122110004)的成果.

摘　　要：PTB界线是地学界长期以来讨论最热烈、最前缘的科学问题和研究热点之一。以华蓥山涧水沟和重庆尖刀山2个PTB界线地层剖面为例,按生物演化过程和沉积相特征,将剖面中的PTB界线地层划分为生物富集层、生物绝灭层和生物萧条层3个生物演替层组,从中识别出生物地层PTB(B)界线和岩石地层PTB(R)界线2种性质的PTB界线,其中位于下部的PTB(B)界线以Hindeodus parvus牙形石首现为标志,上部的PTB(R)界线以古暴露面和暴露面两侧岩性、岩相突变的沉积超覆面为标志,两者相距约4.56 m,分别为3个生物演替层的组分界线。P—T之交发生的所有海平面下降、生物绝灭、火山喷发及晚二叠世晚期正常海向早三叠世早期文石海转化等复杂地质事件,都发生在此2个不同性质的PTB界线之间。Fe、Mn、Sr微量元素和C、O、Sr稳定同位素地球化学特征的规律性变化与相关控制因素,也都出现在此2个PTB界线之间,与PTB界线地层中所出现的各种复杂地质事件有良好的对应关系和沉积学响应特征。The Permian--Triassic Boundary （PTB） is one of the hottest problems in geology, though debate for long, some is still unresolved. The profiles of Huayingshan in Siehuan province and Jiandaoshan in Chongqing city is the perfect areas for studying this problems in China. Based on detailed field investigations, petrographic examination and geological analysis, two different types and locations of biostratigraphicat and lithostratigraphicat T/P boundary are identified from Jianshuigou PTB section, according to biological evolution and sedimentary faces, which is 4.56 m distance between them, and all of complex geological events, such as sea level drops, biotic mass extinction, volcanic eruptions and the transformation from normal sea to non-normal sea with higher Sr content etc. occurred between the two T/P boundaries. The evolution curves of Fe, Mn, Sr content, 313C, 8180, and n（SVSr）/n（86Sr） are established in the PTB section at Jianshuigou. Their regular changes and related controlling factors are tightly bound with the complex geological events occurred between the two T/P boundaries. Therefore, all the complex geological events occurred at the PTB boundary, have got good response from features of element geochemistry.

关 键 词：二叠纪—三叠纪界线地层 全球海平面下降 生物大绝灭 火山活动 牙形石带 地球化学 

分 类 号：P618.13[天文地球—矿床学]