Miocene Bugasi Formation: a new lithostratic unit in Coqen area, Tibet, China
SHI He, MA Run-ze, LIU Deng-zhong, TAO Xiao-feng, HU Xin-wei(College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China)
The potassium-rich volcanic rock distributed over Jiangruola in Coqen area, Tibet, was originally assigned to the Daduo Group and the age was Paleocene-Eocene during the regional geological surveys of the (1∶1 000 000) Xigaze sheet. During the regional geological surveys of the (1∶250 000) Coqen sheet, a section of the potassium-rich volcanic rock was measured and the isotopic ages of (15.8) Ma and (15.9) Ma were obtained. Its age is Miocene. This discovery provides the occurrence of the Miocene potassium-rich magmatic activity in the northern part of the Qandise belt and provides important data for the further study of the formation and evolution of the Qinghai-Tibet Plateau. Based on the volcanic rock association, the age and the regional stratigraphical correlation, the potassium-rich volcanic rock of Miocene distributed over Jiangruola is named as Bugasi Formation.