羌塘中生代海相盆地演化与后期改造及油气赋存  

Evolution and Late Modification of Mesozoic Marine Qiangtang Basin and Its Hydrocarbon Occurrence

作　　者：刘池洋[1] 郑孟林[2] 杨兴科[3] 何碧竹[4] 任战利[1] 郭佩[1] 

机构地区：[1]西北大学含油气盆地研究所,西安710069 [2]中国石油新疆油田公司勘探开发研究院,新疆克拉玛依834000 [3]长安大学地球科学与资源学院,西安710064 [4]中国地质科学院地质研究所,北京100037

出　　处：《地质学报》2016年第11期3259-3281,共23页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号91214301;40372096);西北大学大陆动力学国家重点实验室科技部专项经费;中国地质调查局项目(编号12120115026901)资助成果

摘　　要：发育在羌塘地块之上的羌塘中生代海相盆地,总体具中间地块盆地特征。盆地可划分为北羌塘坳陷、西部隆起、中部低隆起带、南羌塘坳陷和东北斜坡五个一级构造单元。盆地经历了三叠纪和侏罗纪—早白垩世初两大海相沉积期和其间晚三叠世晚期构造环境(体制)转换期三大演化阶段。三叠纪盆地演化受羌塘地块北缘拉竹龙-西金乌兰陆间洋开、合的控制,以碎屑岩、碳酸盐岩及膏盐岩和含煤碎屑岩建造为特征,盆地基底表现为南高、北低,东高、西低的特点。晚三叠世晚期,随着拉竹龙-西金乌兰洋的闭合和羌塘地块与可可西里地块的进一步汇聚,盆地整体隆升,沉积间断,形成岩溶风化壳,遂发生区域裂陷、火山活动和班公湖-丁青陆间洋裂谷新生。侏罗纪羌塘盆地再复沉降和沉积,与南邻班公湖-丁青陆间裂谷的发生发展同步,海相沉积由南向北扩展;形成了北西西向展布的多个沉积-沉降中心,以碎屑岩、碳酸盐岩和膏泥岩建造为主要特征,整体表现为西南部和东北部相对较高,南羌塘东部、北羌塘中西部沉降幅度较大的构造格局。白垩纪早期,冈底斯(拉萨)地块与羌塘地块汇聚,其间的班公湖-丁青陆间洋消亡,羌塘大型海相盆地沉积历史结束,遂进入了遭受后期改造和多个小型盆地陆相沉积时期。经早白垩世晚期—晚白垩世盆地反转和新生代进一步改造,使中生代羌塘盆地及其南北缘缝合带的原始面貌发生了较大改观,并使盆地西北部较大范围不复存在。羌塘盆地的叠合演化和改造,在中生界海相地层中发育了多套烃源岩,具有丰富的油气资源基础,构成了多层系聚集、多类型成藏的油气赋存-成藏条件。多处不同形式的油气显示和大型古油藏的发现,展示和证实了盆地所发生的油气成生、成藏过程。后期改造是影响羌塘盆地油气成藏及分布、资源规模和远�Mesozoic marine Qiangtang Basin, lying on the Qiangtang Terrane, generally has the features of median mass basin. It can be divided into five first-order tectonic units, northern Qingtang depression, western uplift, middle lower uplift, southern Qingtang depression and northeastern slope zone. Qiangtang Basin has experienced three evolution stageswhich are Triassic marine basin, Jurassic--early Early Cretaceous marine basin and late Late Triassic tectonic transition during the above two stages. The Triassic basin with its basement higher in south and east, controlled by the opening and closing of Lazhulong-Xijinwulan tectonic belt on its north side, is characterized by volcanic, clastic, carbonate, gypsum-salt rocks and coal-bearing clastic rocks. At the end of Late Triassic, responding to the closing of Lazhulong-Xiiinwulan ocean and collaging of Qiangtang Terrane and Kekexili Terrane, this marine basin uplifted as a whole and there followed a sedimentary hiatus with the formation of karst weathering crust, after which this region underwent regional rifting and volcanic activity, indicating the formation of Bangonghu-Dingqing intercontinental rift. During Jurassic, Qiangtang Basin once again subsided and received marine sediments, approximately synchronous with the development of Bangonghu-Dingqing intercontinental rift on its south side, indicative of the marine transgression from south to north. The Jurassic marine basin developed multiple NWW-trending depo-subsidence centers, with higher relief in southwest and northeast and relative subsidence centers in east part of southern Qiangtang depression and central-west part of northern Qiangtang depression. Jurassic basin was characterized by clastic, carbonate and gypsum-salt rocks. In early Cretaceous, the convergence between Gangdise （Lhasa） Terrane and Qiangtang Terrane and the closure of Bangonghu-Dingqing intercontinental ocean put an end to the marine sedimentary history of Qiangtang Terrane and since then Qiangtang Terrane stepped into continental sedi

关 键 词：羌塘盆地 叠合演化 拉竹龙-西金乌兰构造带 班公湖-丁青构造带 后期改造 油气赋存 

分 类 号：P618.13[天文地球—矿床学]