滇西北弥渡地区主要断裂晚新生代发育特征及其动力学机制  

Late Cenozoic development characteristics and dynamic mechanism of the main faults in the Midu area,northwestern Yunnan

作　　者：黄小龙[1,2,3] 吴中海 吴坤罡[1,2,4] HUANG Xiaolong;WU Zhonghai;WU Kungang(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Neotectonic Movement and Geohazard,Institute of Geomechanics,Beijing 100081,China;Research Center of Neotectonism and Crustal Stability,China Geological Survey,Beijing 100081,China;China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]新构造运动与地质灾害实验室,北京100081 [3]中国地质调查局新构造与地壳稳定性研究中心,北京100081 [4]中国地质大学(北京),北京100083

出　　处：《地质力学学报》2021年第6期913-927,共15页Journal of Geomechanics

基　　金：国家自然科学基金项目(41571013,U2002211);中国地质调查局项目(DD20160268,12120114002101);中国地质科学院地质力学研究所基本科研业务费项目(DZLXJK201702)。

摘　　要：弥渡地区位于滇西北断陷带东南缘,红河断裂带尾端与程海断裂交汇部位,是揭示滇西北断陷带形成机制及其与红河断裂带间运动学关系的关键区域。综合利用遥感解译及野外调查发现,区内主要发育有北东向的毛栗坡断裂,北西—北北西向的凤仪-定西岭断裂、弥渡断裂、密祉断裂、寅街断裂。对断裂错动地质、地貌体及擦痕的统计分析结果表明,毛栗坡断裂第四纪以左旋走滑活动为主兼具有正断分量;弧形的弥渡断裂及北西向的寅街断裂第四纪期间均以正断活动为主;上新世期间凤仪-定西岭断裂以右旋走滑为主,密祉断裂主要为伸展正断,二者第四纪期间均无明显活动。据弥渡地区主要断裂的几何形态、运动学特征及红河断裂带晚新生代活动性变化过程推测,控制弥渡盆地展布的弥渡断裂、寅街断裂等主要第四纪活动断裂是在继承和改造红河断裂带原有断层行迹的基础上形成的。上新世或更早,弥渡地区及滇西北断陷带的断裂活动与地壳张扭变形可能与红河断裂带尾端伸展变形作用有关,但第四纪期间,程海断裂基本上完全控制了弥渡地区主要活动断裂的发育,这一时期区内张扭变形的动力可能来自于川滇内弧带的顺时针旋转以及周缘南汀河断裂、畹町断裂与理塘断裂等左旋走滑断裂引起的区域性走滑拉分的共同作用。The Midu area is located at the southeast end of the northwestern Yunnan fault depression zone, the intersection of the Red River fault zone and the Chenghai fault. It is a key area for uncovering the formation mechanism of the Northwest Yunnan fault depression zone as well as its kinematic relationship with the Red River fault zone. Based on remote sensing interpretation and field investigation, we found five faults in the study area, namely the NE-trending Maolipo fault, NW-NNW-trending Fengyi-Dingxiling fault, Midu fault, Mizhi fault and Yinjie fault. We made statistical analysis of the fault slipping geological-landscape bodies and slickensides, and the results are produced in three aspects. Firstly, the Maolipo fault are mainly characterized by left lateral strike-slip activity with normal fault component in Quaternary. Secondly, the arc-shaped Midu fault and the NW-trending Yinjie fault are dominated by normal fault activity in Quaternary. Thirdly, during the Pliocene the Fengyi-Dingxiling fault was characterized by dextral strike-slips, while the Mizhi fault by extensional normal faults, and there was no obvious activity in both faults during the Quaternary. We inferred both from the geometry and kinematics of the main faults in the Midu area and the activity evolution of the Red River fault zone that, in the Late Cenozoic the main Quaternary active faults, such as the Midu fault and Yinjie fault, were formed on the basis of inheriting and remaking the original fault trace of the Red River fault zone. These active faults controlled the distribution of the Midu basin. The fault activity and transtensional deformation in the Midu area and the Northwest Yunnan fault depression zone during the Pliocene or even earlier could be affected by the extensional deformation at the end of the Red River fault zone. However, during the Quaternary the Chenghai fault basically controlled the development of main active faults in the Midu area. The crustal transtensional deformation in this period might be driven by the cloc

关 键 词：滇西北断陷带 程海断裂 红河断裂带 晚新生代 断块旋转 

分 类 号：P546[天文地球—构造地质学] P542[天文地球—地质学]