青海省橡皮山地区石炭、三叠纪地层沉积相及对宗务隆构造带的演化响应

Sedimentary facies analysis of the Carboniferous and Triassic strata in the Xiangpishan area of Qinghai Province and its response to the Zongwulong tectonic belt evolution

青海省橡皮山地区位于柴北缘构造带和南祁连构造带之间的宗务隆裂陷槽内,经历了复杂的地质演化过程。本文在野外地质调查的基础上,以沉积学基本思想为指导,从岩石特征、原生沉积构造特征、古生物特征等方面对该区出露石炭纪至中二叠世的甘家组和早-中三叠世的隆务河组进行综合分析,认为橡皮山地区在石炭纪发生裂陷作用,形成宗务隆裂陷槽,甘家组开始沉积,形成了一套远端变陡的缓坡型碳酸盐台地沉积,二叠纪后本区闭合,发生褶皱隆升,地质作用由沉积变为剥蚀,在三叠纪早期,本区再次经历拉张作用,转变为沉积盆地,隆务河组形成了一套典型的陆坡浊流沉积地层,三叠纪中晚期再次闭合,沉积彻底结束。

The Xiangpishan area in Qinghai province is located in the tectonic ridge of the Qaidamian tectonic belt and the southern Qilian tectonic belt,which has undergone complicated geological evolution.In this paper,on the basis of field geological survey,using the basin theory sedimentology,we analyze the formation of the Carboniferous-Permian Ganjia Formation and the Early-Middle Triassic Longwuhe Formation from the aspects of rock characteristics,primary sedimentary facies,palaeontological features and so on.It was believed that the eruption occurred in the Carboniferous area in the Carboniferous,and the sediments were formed.The Ganjia Formation began to deposit and formed a set of steeply slow gentle carbonate platform.After the Permian,the area was closed and folds uplifted,and the geological effect was changed from sedimentation to denudation.In the early Triassic,the area was subjected to stretching again and transformed into sedimentary basins.Longwuhe Formation formed a typical continental shelf turbidite sedimentary strata.In the late of Triassic,the area closed again,and the deposition was completely over.