西秦岭造山带晚中生代-新生代陆内构造演化  

The Late Mesozoic-Cenozoic intracontinental evolution of the West Qinling Belt,Central China

作　　者：张逸鹏 张培震 王岳军 许斌斌 王伟涛 Yipeng Zhang;Peizhen Zhang;Yuejun Wang;Binbin Xu;Weitao Wang(Guangdong Provincial Key Laboratoryof Geodynamics and Geohazards,Schoolof Earh Seiences and Engineering,Sun Yatsen University Zhuhai 519080,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519080,China;Guangdong Earthquake Agency,Guangzhou 510070,China)

机构地区：[1]中山大学地球科学与工程学院,广东省地球动力作用与地质灾害重点实验室,珠海519080 [2]南方海洋科学与工程广东省实验室(珠海),珠海519080 [3]广东省地震局,广州510070

出　　处：《科学通报》2024年第18期2568-2586,共19页Chinese Science Bulletin

基　　金：国家自然科学基金(42030301,42302237,42272248,42272247);第二次青藏高原综合科学考察研究(2019QZKK0901);南方海洋科学与工程广东省实验室(珠海)创新团队建设项目(311023002);广东省基础与应用基础研究基金(2022A1515011895,2021A1515110288)资助。

摘　　要：晚中生代以来,东亚大陆处于太平洋和特提斯构造域多向汇聚的叠加区域,其陆内变形过程与陆缘板块的俯冲和碰撞作用紧密相连.西秦岭造山带位于中国大陆中部,是理解东亚大陆内部构造演化与动力学过程的关键区域.在对西秦岭造山带晚中生代-新生代陆内构造格架划分和主要构造形迹及其运动学特征观测的基础上,本文基于断层滑动矢量应力反演理论和方法,在露头尺度获取了1215组断层滑动矢量数据,共划分出四期古构造应力场序列,整体表现为最大主应力方向顺时针旋转的过程,表明西秦岭陆内变形受太平洋构造域的影响逐渐减弱,而相应受特提斯构造域的作用逐渐增强.西秦岭早白垩世以NW-SE向伸展应力场为主(D1,约145~105 Ma),造山带内部发育一系列断陷盆地,这与东亚同汇聚背景下的造山带伸展构造作用息息相关.之后,西秦岭以N-S向伸展与EW向弱挤压共存的应力场为主(D2,约105~65 Ma),造山带内部的构造变形幅度较弱,西秦岭向着稳定的克拉通方向逐渐发展,同时广泛的剥蚀作用使得区域开始形成准平原化的地貌.继而,西秦岭逐渐受NW-SE向和N-S向叠加的挤压应力场所影响(D3,约50~30 Ma),导致全区以广泛的收缩构造变形为主,揭示出区域受到太平洋和特提斯构造域多向汇聚作用的共同影响.最后,西秦岭以NE-SW向挤压应力为主(D4,约22~5 Ma),区域新生代盆地整体抬升,缺乏显著的收缩构造变形,这是由于青藏高原侧向生长导致高原中部至西秦岭的中-下地壳和岩石圈地幔挤出的构造作用所致.这种“伸展垮塌-剥蚀夷平-活化隆升”是陆内造山带受多个构造域控制和发展的一般规律,并且陆内变形总是受控于最为活动的构造域,其转变过程是渐变的.The East Asian continent was formed by the amalgamation of several microcontinents and overprinted by the polyphase of intracontinental reworking and reactivation under the far-field effect of subduction-collision during the Mesozoic to Cenozoic.The Qinling Belt,stretching from east to west in Central China,was formed during episodes of accretion and collision between the North China Block,South Qinling Terrane,and South China Block along the Shangdan suture in the north and the Mianlue suture in the south.The Qinling Belt transitioned from an intercontinental orogenic belt to an intracontinental orogenic belt during the late Mesozoic,whereby it did not cratonize after collision but evolved into a new tectonic regime characterized by intensive intracontinental orogenesis and regional erosion.The Qinling Belt was eventually divided into the East Qinling Belt and West Qinling Belt by the Foping Dome,which represents not only the gradient boundary layers of different lithospheric thicknesses but also the topographic transition zone between the Western and Eastern China mainland regions.Although previous studies have established the pre-Triassic evolution of the West Qinling Belt,the basic intracontinental tectonic setting and geodynamic evolution remain unclear,including whether the intracontinental setting was controlled only by the Pacific subduction system,or was more complex,involving additional tectonic domains.Paleostress inversion refers,traditionally,to mathematical or graphical inversion of the geometrical attributes of faults with the aim of quantifying the stress associated with fault activity in the geological past.In this study,we present a comprehensive paleostress inversion to obtain the intracontinental evolution of the West Qinling Belt.Paleostress inversion of 1215 fault slip vectors from outcrops,combined with defined structural levels and dating results for key lithostratigraphic units,is systematically employed to establish the paleostress fields in the West Qinling Belt during the Late Mesozoic

关 键 词：中央造山带 西秦岭造山带 陆内变形 应力反演 古构造应力场 

分 类 号：P542[天文地球—构造地质学]