藏南雅鲁藏布江南带古近纪早期放射虫化石的发现与蹬岗组地层特征

Discovery of Early Paleogene Radiolarian Fossils in the Southern Area of Yarlung Zangbo,Zangnan and Its Stratigraphic Characteristics

在藏南雅鲁藏布江南带地层分区中通过1:25万区域地质调查,从原划晚三叠世修康群等地层中解体出一套以砂岩、泥(页)岩、硅质岩为主夹有玄武岩等的地层,整合于晚白垩世桑单林组与始新世郭雅拉组之间,命名为蹬岗组;并于硅质岩中先后发现了大量古近纪早期(古新世早期-始新世早期)放射虫化石,计有3个组合185属206种。大量放射虫化石的发现对蹬岗组地层时代的准确厘定起了重要作用,进一步丰富了地层研究的基础资料。

In the stratigraphic division of the Yarlung Zangbo Jiangnan belt, Zangnan, through the 1 ： 25 million regional geological survey, a set of strata with sandstone, mud （page） rock and siliceous rocks dominated by basalt was disintegrated from the late three fold strata of the qeckang group, which was integrated between the late Cretaceous sangmonin group and the Eocene Kuo Jala group. In the siliceous rocks, a large number of early Paleogene （early Paleocene Eocene） radiolarian fossils have been found in the siliceous rocks. There are 3 assemblages and 185 genera and 206 species. The discovery of a large number of radiolarian fossils has played an important role in the accurate determination of the age of the formation of the formation of the formation and further enriched the basic data of stratigraphie research.