北羌塘盆地中部笙根地区索瓦组上段的孢粉型化石组合及时代

PALYNOMORPH ASSEMBLAGES AND AGE OF THE UPPER MEMBER OF THE SOWA FORMATION IN THE SHENGGEN AREA OF THE CENTRAL NORTH QIANGTANG BASIN

报道北羌塘盆地笙根地区前人划分的上侏罗统索瓦组的上部发现了具有典型意义的、代表早白垩世的Dicheiropollis花粉。表明在该地区索瓦组上部是以前未能识别的下白垩统。根据该套地层中Dicheiropollis花粉的出现及孢粉组合中大量出现的Cyathidites和Classopollis,以及较为丰富的Gonyaulacysta jurassica与多类型沟鞭藻化石组合特征,确定索瓦组上部时代归属为早白垩世早期。这不仅为北羌塘盆地笙根地区早白垩世海相地层的存在提供了依据,而且为进一步分析和完善北羌塘中生代盆地演化史提供了有意义的线索。

This study reported the finding of the representative pollen Dicheiropollis of the Early Cretaceous in the upper part of the previously defined Upper Jurassic Sowa Formation in the Shenggen area, North Qiangtang Basin. The result suggests that the upper part of the Sowa Formation in this area is the Lower Cretaceous which has not been recognized before. According to the occurrence of Dicheiropollis and the abundant Cyathidites and Classopollis, as well as the characteristics of fossil assemblages of the more abundant Gonyaulacysta jurassica and various dinoflagellate, the age of the upper Sowa Formation belongs to the early Early Cretaceous. This not only provides a basis for the existence of Early Cretaceous marine strata in Shenggen area, but also provides important clues for further analysis of the Mesozoic basin evolution history of the North Qiangtang Basin.