北山-阿拉善晚新生代变形的特征与机制  

Late Cenozoic deformation characteristics and mechanism of the Beishan-Alxa region

作　　者：张进 张北航[3] 赵衡 云龙 曲军峰[2] 王振义 杨亚琦[5] 赵硕 ZHANG Jin;ZHANG Beihang;ZHAO Heng;YUN Long;QU Junfeng;WANG Zhenyi;YANG Yaqi;ZHAO Shuo(MNR Laboratory of Deep Earth Sciences and Technology,Beijing 100037,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China;MOE Key Laboratory of Karst Georesources and Environment,College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China)

机构地区：[1]自然资源部深地科学与探测技术实验室,北京100037 [2]中国地质科学院地质研究所,北京100037 [3]中国科学院西北生态环境资源研究院,甘肃兰州730000 [4]核工业北京地质研究院,北京100029 [5]贵州大学资源与环境工程学院喀斯特地质资源与环境教育部重点实验室,贵州贵阳550025

出　　处：《地学前缘》2023年第5期334-357,共24页Earth Science Frontiers

基　　金：中国地质调查局三级项目(DD20230217,DD20221646);国家自然科学基金项目(41972224);中国地质科学院基本科研业务费专项(JKYZD202309)。

摘　　要：北山-阿拉善地区位于中亚造山带中部,新生代晚期受控于印度-欧亚板块的碰撞,发生了不同程度的陆内变形,是青藏高原与蒙古高原应力传递区,是研究印度-欧亚碰撞远程效应的关键地区。北山-阿拉善地区晚新生代变形区别于中亚造山带西段的天山以及阿尔泰地区,表现为发育一系列近东西向的左行走滑断层及其间一系列北东向的正断层及其控制的断陷(拉分)盆地。近东西向的左行走滑断层规模较大,走向延伸很长,成为北山-阿拉善新生代晚期变形的骨干构造。整体上北山-阿拉善地区之间的晚新生代变形是在北侧北东东向南蒙古—天山左行走滑断层和南侧北东东向阿尔金断层之间阶区内的变形,在这个左行-左阶的区域内,变形表现为边界走滑断层派生出的近东西向次级走滑断层(P剪切)和北东向伸展盆地(如额济纳盆地和旧井盆地)。该区域是一个左行张剪区域,使得该区成为区别于蒙古戈壁阿尔泰的右行压剪构造,而阶区内区域性的伸展导致了本区平坦的地势并成为主要的汇水盆地区。GPS速度场以及上地幔-下地壳各向异性资料表明,塔里木克拉通在青藏高原向北的扩展过程中起重要作用,青藏高原北缘上地幔-下地壳在遇到塔里木克拉通后沿着该克拉通东南边缘转向,向北东流动,而塔里木本身则继续向北北东传递应力,导致天山的崛起并挤压准噶尔盆地,进而形成了阿尔泰山北北西走向的右行剪切变形;向北东方向流动的上地幔—下地壳则导致北山-阿拉善地区以及南蒙古地区的晚新生代左行剪切变形,该地区的变形宏观上呈现弥散性特点,区别于塔里木-天山-准噶尔地区新生代变形集中天山和阿尔泰山一带的现象。The Beishan-Alxa region is located in the middle segment of the Central Asian Orogenic Belt.This region,controlled by the Indian-Eurasian collision in the Late Cenozoic,has undergone intracontinental deformation to varying degrees.It is a stress transfer area between the Qinghai-Tibetan Plateau and the Mongolian Plateau,and a key area to study the remote effects of the Indian-Eurasian collision.Differing from the Late Cenozoic deformation in the Tianshan/Altai regions in the western segment of the Central Asian Orogenic Belt,the Beishan-Alxa region developed a set of near EW-trending left-lateral strike-slip faults,and between them a series of NE-trending normal faults were developed which control faulted depression(pull-apart)basins.The much larger near EW-trending faults,with a long strike extension,become the main structure of Late Cenozoic deformation in this region.On the whole,the deformation is in the step area between the NEE-trending South Mongolian-Tianshan left-lateral strike-slip fault on the north side,and the NEE-trending Altyn Tagh fault on the south side.In this left-lateral left-step area,the deformation is manifested as nearly E-W secondary strike slip faults(P shear),derived from the boundary strike-slip faults and the NE extensional basins(such as the Ejina basin,Jiujing basin).Under sinistral transtensional setting this area develops a sinistral shear structure distinct from the dextral shear structure of the Mongolian Gobi Altai;while its flat landform,developed under regional extension within the step area,makes it the main catchment basin area in the Beishan-Alxa region.The GPS velocity field and anisotropy data of the upper mantle-lower crust indicate the Tarim Craton plays an important role in the northward expansion of the Qinghai-Tibetan Plateau.At the Tarim Craton the upper mantle-lower crust of the Qinghai-Tibetan Plateau turns northeastward along the southeastern edge of the craton while the Tarim continues to exert stress northeastward,leading to the rise of the Tianshan mountain r

关 键 词：北山-阿拉善 晚新生代 青藏高原 陆内变形 变形机制 

分 类 号：P542[天文地球—构造地质学]