洞庭拗陷下第三系沅江组碳酸盐岩沉积环境探讨

DISCUSSION ON THE SEDIMENTARY ENVIRONMENT OF THE CARBONATE OF PALEOGENE YUANJIANG FORMATION IN THE DONGTING DEPRESSION

曹淑韵

Cao Shuyun

地质矿产部中南石油地质局

Central South-China Petroleum Geology Bureau, Ministry of Geology and Minerals

洞庭拗陷位于湖南北部,东西两侧为幕阜—九岭隆起、武陵隆起,南北与雪峰、华容隆起为邻,是在古老构造的基础上,由燕山运动形成的白垩—第三纪断陷盆地。盆地内又可分成几个次级凹陷和凸起。喜山运动使整个盆地抬升,下第三系普遍遭受剥蚀。下第三系、白垩系及其更老地层,直接被第四系覆盖。

Microfossils of Ortonella,Hedstromia, Bevocastria, Cayeuxia, Sepulidea and Foraminifera and Foraminifera-like are fouad in carbonate samples from the Yuan Jiang formation of the Dongting depression for the first time. According to the characteristics of the carbonate, it is believed that sea water transgressed from the northeastern and northern parts of the Dongting depression during Paleogene. This brought the depression an environment of brackish water linking with the maritime basins. On this basis, the oil prospects of each part of the Dongting depression are discussed.

https://doi.org/10.11781/sysydz198401024