西藏班公湖地区竟柱山组时代及其构造意义

发布时间：2018-06-10 15:19

本文选题：竟柱山组 + 地质特征　；参考：《大地构造与成矿学》2016年04期

【摘要】：上白垩统竟柱山组呈近EW向分布于班公湖怒江缝合带内,该组以陆相磨拉石建造为特征,角度不整合在蛇绿岩及老的海相地层之上,从早到晚由河流相向湖泊相演化。本文以班公湖怒江缝合带西段的班公湖地区出露的竟柱山组为主要研究对象,对其岩性特征、沉积环境及形成时代进行了分析,认为竟柱山组为班公湖怒江特提斯洋全面闭合后的陆相山间盆地沉积,是洋陆转换全面完成之后的陆相沉积。本文首次对班公湖地区竟柱山组进行了ESR年代学、磁性地层学研究,得出了研究区竟柱山组底部砾岩的ESR年龄为92.0±9.0 Ma,古地磁测年显示该组的底界年龄约为96 Ma。班公湖地区在96 Ma左右全面完成了由洋到陆的转换,进入了陆内环境。
[Abstract]:The Upper Cretaceous Jingzhushan formation is distributed in the Nu River suture zone of Bangong Lake in the near EW direction. The formation is characterized by continental Molarasite formation, unconformable on ophiolite and the old marine strata, and evolves from river to lake facies from early to late. In this paper, the outcrop of Jingzhushan formation in the western section of the Bangong Lake Suture Zone of Bangong Lake is taken as the main research object. The lithologic characteristics, sedimentary environment and forming age of the formation are analyzed. It is considered that the Jingzhushan formation is the continental intermountain basin after the complete closure of the Tethys ocean in Bangong Lake and the continental facies after the completion of oceanic land conversion. In this paper, the ESR chronology and magnetic stratigraphy of the Jingzhushan formation in Bangong Lake area have been studied for the first time. The ESR age of the bottom conglomerate of the Jingzhushan formation is 92.0 卤9.0 Ma, and the paleomagnetic dating shows that the bottom boundary age of the formation is about 96 Ma. The Bangong Lake area completed the transition from ocean to land at about 96 Ma and entered the intracontinental environment.
【作者单位】：中国地质大学(武汉)紧缺矿产资源勘查协同创新中心;中国地质大学(武汉)资源学院;中陕核工业集团公司;中国地质调查局成都地质调查中心;
【基金】：中国地质调查局1:50000区域地质调查项目(1212011121242、1212011121246);中国地质调查局成都地质调查中心地调科研项目委托业务(121201010000150014-28、121201010000150014-29)联合资助
【分类号】：P535;P542

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