河西走廊平山湖盆地早白垩世构造变形期次及其碎屑锆石U-Pb年龄约束  

The Early Cretaceous tectonic deformation stages and detrital zircon U-Pb ages of Pingshanhu Basin in Hexi Corridor

作　　者：邵浩浩 陈宣华 张达[2] 邵兆刚 李冰 王增振 张义平 徐盛林 史建杰 苗慧心 SHAO Haohao;CHEN Xuanhua;ZHANG Da;SHAO Zhaogang;LI Bing;WANG Zengzhen;ZHANG Yiping;XU Shenglin;SHI Jianjie;MIAO Huixin(SinoProbe Center-China Deep Exploration Center,Chinese Academy of Geological Sciences&China Geological Survey,Beijing 100037,China;College of Earth Science and Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质调查局-中国地质科学院地球深部探测中心,北京100037 [2]中国地质大学地球科学与资源学院,北京100083

出　　处：《中国地质》2019年第5期1079-1093,I0001-I0018,共33页Geology in China

基　　金：中国地质调查局“祁连—天山及周缘盆山结合带深部地质调查”项目（121201101000150013）资助~~

摘　　要：河西走廊北部的平山湖盆地,被围限于龙首山、北大山和合黎山之间,是一个在早白垩世受南北两侧逆冲断层共同控制形成并发展的盆地。笔者通过研究盆地内下白垩统沉积特征、构造变形、生长地层以及碎屑锆石U-Pb年代学特征,划分了平山湖盆地在早白垩世的构造演化期次,并恢复其形成演化过程。盆地内发育一套由下向上总体变细的下白垩统庙沟群沉积序列,盆地内构造变形以NE-SW向挤压和近E-W向伸展为主,庙沟群上岩组的碎屑锆石最小年龄为(129.3±1.8)Ma,可能代表了地层沉积和同期地堑发育的最早时间。由此得出,在早白垩世早期发育挤压构造盆地,同构造生长地层为挤压盆地的形成与构造演化提供了时代约束;在早白垩世晚期发育伸展断陷盆地,由挤压到伸展的转换时间晚于129.3 Ma。Pingshanhu basin,located in the north of Hexi Corridor,is bounded by the Longshou Mountain in the south,the Beida Mountain in the north,and Heli Mountain in the west.The deposition and evolution of Pingshanhu basin were controlled by overthrust fault in the Early Cretaceous.In this paper,the authors deepened the study of the Early Cretaceous Miaogou Group,mainly about the geometry of the basin,the tectonic stress field and detrital zircon.The authors made a detail discussion on the tectonic evolution of Pingshanhu Basin.In Pingshanhu Basin,Miaogou Group exhibits an upward-fining sedimentary sequence.The tectonic deformation is dominated by NE-SW trending compression and E-W trending extension.The latest zircon age is(129.3±1.8)Ma,which may represent the earlieset time of the upper rock formation and the formation age of graben.On the basis of the sedimentary facies of Early Cretaceous Miaogou Group,the tectonic style,tectonic stress field and zircon ages of clastic rocks,the authors hold that Pingshanhu Basin was a compressional basin in the early Early Cretaceous.The growth strata restricted the compressional structure ages.It was an extensional rifted basin in late Early Cretaceous.The conversion time was posterior to 129.3Ma.

关 键 词：平山湖盆地 早白垩世 沉积特征 构造变形 生长地层 形成演化 深地探测工程 

分 类 号：P542[天文地球—构造地质学] P597[天文地球—地质学]