古地理学报2012，Vol.14Issue(5)：583-595,13.
四川盆地上三叠统须家河组四段—六段海侵沉积记录
Transgression sedimentary records of the Members 4-6 of Upper Triassic Xujiahe Formation in Sichuan Basin
摘要
Abstract
In recent years, the controversy about whether continental facies or marine facies of the upper Triassic in Sichuan Basin is increasingly attracting attention. Correct understanding of this problem is not only the key to our interpretation of the formation and evolution of Sichuan Basin, but also the key to natural gas exploration of the Xujiahe Formation. Based on comprehensive investigation of provenance, sedimentary structures, clay minerals, boron and organic geochemical analysis of potassium and other evidence , it is believed that Member 1 , Member 2 and Member 3 of the Xujiahe Formation were deposited in marine environment, while Members 4, 5 and 6 were effected by transgression because of uplifting of the southern section of the Longmen Mountain and gradually lost contact with the open sea of Sichuan Basin. Five aspects showing transgression exists; ①Petrographic thin section analysis of 1000 wells shows that the southern section of Longmen Mountain was not lifted or not lifted completely out of water in the Late Trias-sic, and Sichuan Basin was still connected to the open sea; ② There exists a large number of plumes and bidirectional cross-bedding, double-clay layer structure, layer and fold the whole vortex structure in the Members 4-6 , indicating tidal influence during this period ; ③ After deposition of the Member 4 , kaolin-ite began to appear along with predominant presence of illite and chlorite, indicating that acidic water body has started to appear, but it was still contaminated by alkaline water body; ④Boron-potassium ratio analysis shows that the ancient water salinity decreased after depositional period of the Member 3 , but it was still significantly higher than normal salinity of freshwater lakes ( mean 0. 5%0) , which manifested there was still a lot of salt water injection during this period; ⑤ Organic geochemical analysis indicates that source rock of the-Xujiahe Formation has distinct specificities, showing obvious influence of transgression.关键词
海侵/沉积记录/双黏土层结构/四川盆地/上三叠统Key words
transgression/ sedimentary records/ double-clay layers texture/ Sichuan Basin/ Upper Triassic分类
天文与地球科学引用本文复制引用
施振生,谢武仁,马石玉,李国宪..四川盆地上三叠统须家河组四段—六段海侵沉积记录[J].古地理学报,2012,14(5):583-595,13.基金项目
国家重点基础研究发展规划(973)项目(编号:2007CB209504)资助 （973）
