“崆峒山组砾岩”形成演化的动力学机制分析  

Development and Genetic Mechanism of the Kongtongshan Formation Conglomerate

作　　者：宋立军[1,2] 赵靖舟[1] 袁炳强[1] 刘池洋[2] 吴冲龙[3] 

机构地区：[1]西安石油大学油气资源学院,陕西西安710065 [2]西北大学含油气盆地研究所,陕西西安710069 [3]中国地质大学(武汉)资源学院,湖北武汉430074

出　　处：《大地构造与成矿学》2009年第4期508-519,共12页Geotectonica et Metallogenia

基　　金：国家973计划(2002CD211706);科技支撑项目(2006BAB01B08、2006BAB01A01);西安石油大学科技创新基金项目(206103);陕西省教育厅专项科研计划项目(07JK364);陕西省自然科学基金;中国博士后基金(20080441181)资助成果

摘　　要：查明"崆峒山组砾岩"形成的动力学环境是认识鄂尔多斯盆地西南缘的盆地原型、构造属性、华北克拉通西部破坏的关键。采用野外调查、取样与室内测样分析相结合的方法,系统研究了"崆峒山组砾岩"的沉积特征、裂变径迹热史,在此基础上以盆山耦合思想为指导,结合区域及深部背景资料,认为崆峒山组砾岩形成于秦祁海槽剪刀式闭合导致的右旋走滑区域背景下,走滑使位于砾岩西侧的青铜峡-固原古断裂复活,控制了崆峒山组砾岩形成。砾岩形成的动力学过程,可分为早期(231～218Ma)走滑拉张断陷沉积阶段,晚期(231～205Ma)走滑挤压坳陷沉积阶段和末期(205～195Ma)隆升剥蚀改造阶段,其分别与裂变径迹热史重建的砾岩快速增温、缓慢降温、快速冷却三个阶段相对应。崆峒山组砾岩埋藏增温的时刻及其形成演化的动力学过程表明,崆峒山组砾岩应为晚三叠世沉积。To make sure of the dynamic environment of the Kongtongshan Formation conglomerate is the key to recognize the prototype basin, tectonic attribute, tectonic evolution and breakage of the northwestern China Craton. By means of sedimentary characteristics, structure and fission track, the regional background and dynamic mechanism of the Kongtongshan Formation conglomerate can be comprehensively analyzed on southwestern margin of the Ordos Basin. The Kongtongshan Formation conglomerate developed under a dextral strike slip environment in late Triassic, which resulted from gradually closing of the Paleo-Tethys Ocean from east to west. Under the regional dynamic environment of strike slip, the ancient Qingtongxia-Guyuan fracture reactivated, which controlled the formation of the Kongtongshan Formation conglomerate. It can be divided into three stages, which are respectively corresponding with the rapid increase, slow-lowering and rapid lowering of temperature from thermal history of fission track. The early stage was transtensional fault-sedimentation from 231 Ma to 218Ma, the middle stage was transpressional depression-sedimentation from 218Ma to 205Ma, and the late stage was denudation from 205Ma to 195Ma. It also shows the Kongtongshan Formation conglomerate developed in late triassic.

关 键 词：崆峒山组砾岩 动力学机制 晚三叠世 

分 类 号：P542[天文地球—构造地质学]