晋北地区口泉断裂带晚中生代分段构造特征  

Structural Features of Late Mesozoic Kouquan Fault Zone,Northern Shanxi Province

作　　者：罗晓华[1,2] 杨明慧[1,3] 贾春阳 李占元 雷志斌[1] 张少华[4] LUO Xiaohua;YANG Minghui;JIA Chunyang;LI Zhanyuan;LEI Zhibin;ZHANG Shaohua(College of Geosciences,China University of Petroleum,Beijing 102249,China;The No.2 Geological Exploration Institute,CMGB,Fuzhou,Fujian 350108,China;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China;State Key Laboratory of Continental Dynamics,Northwest University,Xi'an,Shaanxi 710069,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]中国冶金地质总局第二地质勘查院,福建福州350108 [3]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [4]西北大学大陆动力学国家重点实验室,陕西西安710069

出　　处：《现代地质》2019年第3期551-560,共10页Geoscience

基　　金：国家自然科学基金项目(41172127,41572102);国家自然科学基金重点项目(90814005);西北大学大陆动力学国家重点实验室项目(BJ081334)

摘　　要：口泉断裂带位于华北克拉通中部造山带的西侧,晚中生代具有独特的逆冲构造样式和复杂的构造演化过程。以区域地质调查资料为基础,通过野外地质考察、构造建模及磷灰石裂变径迹分析,研究了口泉断裂带晚中生代的分段构造特征及其形成机制。结果显示:(1)口泉断裂带自东南向西北逆冲推覆,沿断裂带走向的位移活动具南强北弱特点;上盘为太古宇片麻岩,下盘地层依次为寒武系—奥陶系、石炭系—二叠系及侏罗系。(2)口泉断裂带具有分段特点,主体构造样式为非典型的构造三角带,具有两套以上的滑脱层;底滑脱层自南向北从太古宇、寒武系—奥陶系升高至石炭系,被动顶板滑脱层则位于下寒武统馒头组—毛庄组或下伏的太古宇片麻岩。(3)据磷灰石裂变径迹测试模拟,口泉断裂带逆冲活动的最早年龄是(147. 1±6. 0) Ma,为晚侏罗世,其形成机制与晚侏罗世伊泽奈崎板块俯冲造成的NW向挤压大地构造背景有关。Kouquan Fault Zone is located in the western part of the Trans-North China Orogen,North China Craton,and shows a unique thrusting style and complex Late Mesozoic structural evolution. This study focuses on the Late Mesozoic structural segmentation and mechanism,based on field observation,structural modeling and apatite fission track dating. The results show that:( 1) Kouquan Fault Zone nappe thrusted from southeast to northwest,and the displacement is stronger in the south than in the north of the fault zone. The hanging-wall comprises Archaean gneiss,while the footwall comprises Cambro-Ordovician,Permo-Carboniferous and Jurassic sequences.( 2) Kouquan Fault Zone is featured by segmentation and the main structural style is a typical triangular zone with over two sets of décollement sequences. The lower décollement sequence is Archaean,CambroOrdovician and Carboniferous,but the upper décollement sequence is the Lower Cambrian Mantou-Maozhuang Group or the underlying Archaean gneiss.(3) The formation of Kouquan Fault Zone may be associated with the NW-directed compression led by the Late Jurassic subduction of the Izanagi plate. Apatite fission-track simulation suggests that the earliest thrusting of Kouquan Fault Zone occurred in the Late Jurassic to Early Cretaceous( 147. 1 ± 6. 0 Ma).

关 键 词：口泉断裂带 构造分段 构造演化 晚中生代 华北克拉通 

分 类 号：P548[天文地球—构造地质学]