里阿斯假砂园虫Pseudocylammina liasica(Hottinger,1967)在西藏班公湖—怒江缝合带西段改则的首现及其地层的厘定

Firstly Discovery and Its Stratigraphic Determination of Pseudocylammina liasica (Hottinger,1967) in the Western Part of Bangong Lake-Nujiang Suture Zone of Gaize County, Tibet

通过1∶5万区域地质调查,在西藏班公湖—怒江缝合带西段改则物玛北部布孜村地区,新发现里阿斯假砂园虫Pseudocylammina liasica Hottinger,时代为早侏罗世(Lias期)。据岩石组合特征及沉积时代,本次暂且归属该套地层为下侏罗统布孜村组。里阿斯假砂园虫的首现及其地层的厘定不仅丰富了西藏班公湖—怒江缝合带西段古生物学大有孔虫类的研究,而且为区域地层对比和格架建立增添了新资料及新认识;同时本研究为今后进一步探讨班公湖—怒江洋盆的演化提供了地质学证据,具有重要的意义。

Pseudocylammina liasica Hottinger was newly discovered in the Early Jurassic(Lias)in Buzicun,north Wumaof Gaize,western section of Bangong Lake--Nujiang suture zone,Tibet,according to 1∶50000 regional geological survey.According to the characteristics of rock assemblage and sedimentary age,this set of strata is tentatively assigned to the Buzicun Formation of the Lower Jurassic.Firstly discovery of Pseudocylammina liasica Hottinger and stratigraphic determination not only enriches the paleontological study of the macroforaminifera in the western section of the Bangonghu-Nujiang suture zone in Tibet,but also provides new information and new understanding for the regional stratigraphic correlation and the establishment of the framework.Meanwhile,this study provides the geological evidence for further study on the evolution of the Bangong Lake-Nujiang ocean basin,which is of great significance.