川西龙门山北段唐王寨-仰天窝复式向斜辉绿岩脉侵位年代的限定  

Age limit of diabase dyke intrusion in Tangwangzhai-Yangtianwo compound syncline in the northern section of Longmen Mountain,western Sichuan Province

作　　者：丁啸[1] 李忠权[1,2] 李嘉宁 李洪奎[1] 陈骁[3] 刘冉[3] 杨渊宇[1,3] 应文峰[1,3] DING Xiao;LI Zhongquan;LI Jianing;LI Hongkui;CHEN Xiao;LIU Ran;YANG Yuanyu;YING Wenfeng(Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Ministry of Natural Resources,Chengdu University of Technology,Chengdu 610059,Sichuan,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,Sichuan,China;CNPC Southwest Oil and Gas Field Branch,Chengdu 610051,Sichuan,China)

机构地区：[1]自然资源部构造成矿成藏重点实验室(成都理工大学),四川成都610059 [2]油气藏地质及开发工程国家重点实验室(成都理工大学),四川成都610059 [3]中国石油西南油气田分公司,四川成都610051

出　　处：《地质通报》2022年第8期1409-1416,共8页Geological Bulletin of China

基　　金：国家自然科学基金《龙门山北段唐王寨-仰天窝向斜沉积-构造演化与动力学成因机制研究》(批准号:41672196);国家科技重大专项《四川盆地深层构造层系的晚期构造改造作用》(编号:2017ZX05008-001);四川省国土资源厅计划项目《民族地区地质遗迹成景机制与地质公园建设木事创新研究——以甘孜州八美变质岩石林为例》(编号:KJ-2019-13)。

摘　　要：唐王寨-仰天窝复式向斜是川西龙门山前山构造带中一个典型的滑覆构造,在其北东部位发育6条辉绿岩脉,限定其侵位时间有助于理解龙门山北段的构造演化。为了厘定辉绿岩脉的侵位时间,通过野外地质调查和区域构造的形成、演化、叠置、切割等关系研究,对辉绿岩脉侵位的下限年龄进行地质年代的限定。研究结果表明:①晚三叠世须家河组与侏罗系陆相碎屑岩在龙门山前山复杂断褶带中都呈平行或角度不整合覆盖于早泥盆世、石炭纪、二叠纪及早中三叠世海相地层之上,唐王寨-仰天窝复式向斜形成于中三叠世之后的印支期—燕山期;②唐王寨-仰天窝复式向斜坐落在大片志留系软弱页岩层之上,接触面上未见断层擦痕,下伏志留系的塑性流变是该向斜雏形形成的主要因素;③辉绿岩脉切割唐王寨-仰天窝复式向斜,其侵入年代应在中三叠世雷口坡组沉积之后,225~158 Ma应该是6条辉绿岩脉先后侵位年龄的分布区间。Tangwangzhai-Yangtianwo compound syncline is a typical slip nappe structure in the Longmen Mountain foreland structural belt in Western Sichuan.Six diabase dikes are developed in its northeast part,and limiting its intrusion time is helpful to understand the tectonic evolution of the northern Longmen Mountain.In order to determine the invasion time of diabase dyke,this paper defines the geological age of the lower limit of diabase dyke invasion through field geological investigation and the relationship between the formation,evolution,superposition and cutting of regional structures.The results show that:①In the complex fault fold belt in the front of Longmen Mountain,the Late Triassic Xujiahe Formation and Jurassic continental clastic rocks are in parallel or angular unconformity contact,which are superimposed on the Devonian,Carboniferous,Permian and early Middle Triassic marine strata,The Tangwangzhai-Yangtianwo compound syncline was formed in the Indosinian-Yanshanian period after the Middle Triassic;②Tangwangzhai-Yangtianwo compound syncline is located on a large area of Silurian weak shale,and no fault scratch is found on the contact surface.The plastic rheology of the underlying Silurian is the main factor for the formation of the syncline prototype;③Because diabase dykes cut the Tangwangzhai-Yangtianwo compound syncline,their intrusion age should be after the deposition of the Leikoupo Formation in the Middle Triassic.225~158 Ma should be the distribution range of intrusion age of diabase dyke.

关 键 词：复式向斜 龙门山北段 辉绿岩脉 川西 

分 类 号：P588.12[天文地球—岩石学] P542[天文地球—地质学]