川西-龙门山盆山系统走向差异演化的变形、隆升和沉积记录及关键构造变革期讨论  

Strike variation evolution of the basin-mountain system in western Sichuan Longmenshan as recorded by deformation,exhumation and deposition and discussion on the period of key structural transformation

作　　者：李智武[1] 宋天慧 王自剑[1] 童馗 武文慧[1] 冉波[1] 李金玺[1] 邓宾[1] 刘树根[1] LI Zhiwu;SONG Tianhui;WANG Zijian;TONG Kui;WU Wenhui;RAN Bo;LI Jinxi;DENG Bin;LIU Shugen(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059

出　　处：《成都理工大学学报（自然科学版）》2021年第3期257-282,共26页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：国家自然科学基金项目(41230313,41472107,41572111)。

摘　　要：综合利用露头构造解析、地震剖面解释、锆石和磷灰石裂变径迹年龄和沉降-沉积等资料,对川西-龙门山盆山系统沿走向的构造变形、差异隆升-剥蚀和沉积记录进行系统梳理,探讨龙门山冲断带和川西前陆盆地系统的走向差异演化特征及其关键构造变革期。受控于本身的地质结构差异及周缘多个构造带的多期交互作用,龙门山冲断带和川西前陆盆地在构造、隆升和沉积等方面都表现出明显的走向差异。龙门山冲断带自北向南总体上具有韧性减弱、脆性增强、构造定型时间变新的趋势,龙门山北段和盆地北部定型于燕山期,而龙门山中、南段和盆地南部定型于喜马拉雅期。中生代期间,龙门山北段隆升较快;而新生代期间,龙门山中、南段隆升较快。川西前陆盆地同样表现出南北差异隆升的特点,北部隆升较早,大约在45 Ma B.P.;而南部隆升较晚,在20~25 Ma B.P.。川西(北)前陆盆地的沉降中心经历了4次明显的迁移,即从晚三叠世的龙门山中段前缘向东北迁移,中侏罗世到大巴山-米仓山前缘,晚侏罗世-早白垩世向西迁移至米仓山-龙门山北段前缘,于晚白垩世-新生代期间再次向南迁移到龙门山中-南段前缘。龙门山冲断带和川西前陆盆地的走向差异演化表现为印支期向南递进扩展、燕山早-中期南北分异和燕山晚期-喜马拉雅期北隆南降。龙门山冲断带和川西前陆盆地经历了晚三叠世、中侏罗世、早白垩世和古近纪4个关键构造变革期。晚三叠世构造变革期包括龙门山水下隆起和海相前陆盆地(马鞍塘组上部至小塘子组)、龙门山局部隆升和海陆过渡相前陆盆地(须家河组第二至第三段)以及龙门山全面隆升和陆相前陆盆地(须家河组第四至第五段)三大阶段,主要受控于扬子构造域并受秦岭构造域的强烈影响。中侏罗世构造变革表现为扬子构造域向秦岭构造域的转变;�Based on the field outcrop structural analysis,seismic profile interpretation,zircon and apatite fission track ages and subsidence-sedimentary data,the records of tectonic deformation,differential uplift-denudation and deposition along the strike of the western Sichuan-Longmenshan basin-mountain system are systematically summarized,and the variation evolution along the strike of the basin-mountain system and crucial tectonic transitions are discussed.The NE-trending Longmenshan thrust belt and adjacent western Sichuan foreland basin have experienced a protracted Mesozoic-Cenozoic tectonic history,characterized by multi-phase interactions among multiple dynamic systems and by significant along-the-strike variations in deformation,exhumation and deposition.From north to south,the deformation of the Longmenshan thrust belt and western Sichuan foreland basin generally shows a trend of decreasing ductility,increasing brittleness and rejuvenating structural stereotyping,which occurred in late Yanshanian for the northern portion and from the Indosinian,Yanshanian to Himalayan for the central and southern portions.Analysis of zircon and apatite fission track ages shows that the northern portion of the Longmenshan cooled more rapidly than the central and southern portions during the Mesozoic,while the latter underwent more rapid exhumation during the late Cenozoic.There is a similar trend within the western Sichuan foreland basin where the onset of exhumation changes from~45 Ma B.P.in the northern portion to 20~25 Ma B.P.in the central and southern portions.The subsidence center of the western Sichuan foreland basin(northern part)underwent four significant migrations,i.e.,from the front of the central Longmenshan to the northeast during the Late Triassic,to the front of Dabashan and Micangshan during the middle Jurassic,to the front of the Micangshan and northern Longmenshan between the late Jurassic and early Cretaceous,and then to the front of the southern Longmenshan during the late Cretaceous to Cenozoic.The along-str

关 键 词：变形 隆升 沉积记录 走向差异 演化 构造变革 川西前陆盆地 龙门山冲断带 

分 类 号：P542[天文地球—构造地质学]