地质通报2017，Vol.36Issue(2)：181-189,9.
藏北荣玛乡亚丹地区下二叠统曲地组的厘定及大地构造意义
Redefinition of the Lower Permian Qudi Formation in Yadan area, Rongma Town, northern Tibet, and its tectonic significance
摘要
Abstract
The continuous separation of accretionary complex in central Qiangtang of Tibet is significant for defining the framework of strata from Paleozoic to Triassic and studying the evolution of Tethys. The authors measured a section of the accretionary complex in Yadan area, Rongma Town, Nyima County, Tibet, and discovered a sequence of submarine fan clasolites formed by deep-water gravity flow on the continental slope in Early Permian. The north of the strata is covered by Cenozoic red Kangtuo Formation, and the south is in faulted contact with basalt blocks. It is intercalated with sandstone lenses from the outer part to the middle fan. The in-tercalated layer of bioclastic limestone formed by collapse deposition contains a fusuline fauna and consists of ten species in four gen-era such as Parafusulina, Pseudofusulina, Schwagerina, Chalaroschwagerina, suggesting Artinskian period. The 1:250000 geological map of Rigan Peicuo defined the strata as Tunlong Gongba Formation which was mainly formed by diamictite continental shelf de-posits. Based on the lithostratigraphy and the time of the fossil assemblage, The authors redefined the submarine fan strata as Qudi For-mation. In combination with previous widely reported limestone formation containing fusuline and the continental rift background of basic dikes in central Qiangtrang from Late Carboniferous to Early Permian, the authors hold that the early Permian sedimentary for-mation represented the initial evolution of the Meso-Tethys Ocean and there existed a small ocean basin after the Kungurian Stage.关键词
西藏荣玛乡/曲地组/(蜓)类化石/早二叠世/海底扇/增生杂岩Key words
Rongma Town,Tibet/Qudi Formation/fusuline fauna/Early Permian/submarine fan/accretionary complex分类
天文与地球科学引用本文复制引用
焦鹏伟,梁晓,王根厚,高金汉,孙喜辉,冉皞,何亚东,郑艺龙..藏北荣玛乡亚丹地区下二叠统曲地组的厘定及大地构造意义[J].地质通报,2017,36(2):181-189,9.基金项目
中国地质调查局项目《西藏荣玛乡南地区1:5万四幅区域地质调查》(编号:121201103000150004)和中央高校基本科研业务费项目《西藏羌塘中部蓝岭高压变质带变质、变形作用过程及构造意义》(编号:2652014004) （编号:121201103000150004）
