北山南部西山煤窑地区晚中生代陆内构造变形特征与时限约束  

Structural characteristics and time constraint of Late Mesozoic intracontinental deformation in Xishan meiyao area,south of Beishan

作　　者：韩乐乐 陈宣华[1,2] 邵兆刚[1,2] 丁伟翠[1,2] 张义平[1,2] 李冰[1,2] 徐盛林[1,2] 王叶 刘奎 杨欣茹 HAN Lele;CHEN Xuanhua;SHAO Zhaogang;DING Weicui;ZHANG Yiping;LI Bing;XU Shenglin;WANG Ye;LIU Kui;YANG Xinru(Chinese Academy of Geological Sciences,Beijing 100037,China;SinoProbe Laboratory,MNR/Chinese Academy of Geological Sciences,Beijing 100094,China)

机构地区：[1]中国地质科学院,北京100037 [2]自然资源部深地科学与探测技术实验室/中国地质科学院,北京100094

出　　处：《地质通报》2024年第11期1950-1969,共20页Geological Bulletin of China

基　　金：中国地质调查局项目《深部地质调查》(编号:DD20230008);《西北重要构造廊带深部地质调查》(编号:DD20230229)。

摘　　要：北山南部西山煤窑地区侏罗系与白垩系的构造变形记录了中亚地区晚中生代的主要构造演化过程,对揭示中亚地区的陆内变形具有重要意义。综合应用遥感影像、野外地质观测、构造解析及磷灰石(U-Th)/He(AHe)年代学方法,对北山南部西山煤窑地区的构造变形特征及时限进行了详细分析,并在此基础上探讨了动力学机制。西山煤窑地区发育逆冲推覆构造,以二叠纪花岗岩和晚石炭世辉长岩NE向逆冲至下—中侏罗统煤系地层之上为特征,上盘岩系经历剥蚀形成飞来峰,下盘发育叠瓦状逆冲断层,逆冲推覆距离约10 km。晚石炭世辉长岩的磷灰石AHe年龄显示160~130 Ma的快速冷却事件,指示该地区经历了中晚侏罗世—早白垩世早期的挤压变形,可能是亚洲南缘班公-怒江洋与北缘蒙古-鄂霍茨克洋闭合的远程效应。变形的侏罗系的AHe年龄(120~100 Ma)揭示了早白垩世晚期的隆升事件。结合区域构造事件,表明研究区经历了早白垩世晚期的伸展断陷,可能与早期地壳增厚的伸展垮塌作用有关。晚白垩世之后,正断层反转为逆冲断层,将变形的侏罗系与上覆岩系共同压覆在下白垩统之上,指示北山南部构造背景由伸展转为挤压,局部地区经历了弱挤压变形,并改造了先存挤压与伸展构造。The Xishanmeiyao area of southeastern Beishan range,presents an opportunity for investigating the intracontinental deformation history of Central Asia region during the late Mesozoic era,which is of great significance to revealing the evolutionary history of Central Asian.Here,we conducted synthesis investigation of remote sensing image interpretation,field geological observation and structural analysis,and apatite(U-Th)/He(A-He)chronology to study the deformation characteristics and time in the Xishanmeiyao area.The study area exposes the Xishanmeiyao thrusts,which is characterized by the thrusted the late Carboniferous gabbro and Permian granite to the Middle Lower Jurassic Longfengshan Formation coal-bearing strata(J1-2ln).A series of the NE direction imbricated thrust faults were developed with fault dip is 40°~50°in the footwall.The gabbro and granite klippen forming on the hang wall with the thrust nappe distance of~10 km.The AHe data of the late Carboniferous gabbro record the 160~130 Ma cooling event,it is indicated that the area experienced near NE compression deformation during the late Middle Jurassic to early stage of Early Cretaceous,which may be the coupling result of the closure of Bangong-Nujiang ocean final in the southern and the Mongolia-Okhotsk Ocean in the northern margin of Asia.The AHe data of deformed Jurassic record the 120~100 Ma cooling event related the footwall exhumation during subsequent normal faulting,which may be the caused by the collapse of thickened crust.The tectonic inversion of the near E-W normal fault causing that the deformed Jurassic and overlying rocks were overlayed to the Lower Cretaceous,indicative of the weak compressive deformation after Late Cretaceous in the southern part of Beishan and overprinted the pre-existing compressive and extensional structures.

关 键 词：北山南部 晚中生代 陆内构造变形 构造解析 磷灰石U-Th/He定年 

分 类 号：P542[天文地球—构造地质学] P534.15[天文地球—地质学]