晚第四纪以来巴塘断裂的活动特征及滑动速率  

THE LATE QUATERNARY ACTIVITY CHARACTERISTICS AND SLIP RATE OF BATANG FAULT IN SE TIBETAN PLATEAU

作　　者：黄伟亮 张家乐 项闻 杨虔灏 HUANG Wei-liang;ZHANG Jia-le;XIANG Wen;YANG Qian-hao(College of Geological Engineering and Surveying of Chang an University,Key Laboratory of Western China Mineral Resources and Geological Engineering,Xi an 710054,China;Anqing Copper Mine,Tongling Nonferrous Metals Group Holdings Co.Ltd.,Anqing 246000,China;Nuclear Industry Jinhua Exploration Design Institute Co.,Ltd.,Jinhua 321000,China)

机构地区：[1]长安大学,地质工程与测绘学院,西部矿产资源与地质工程教育部重点实验室,西安710054 [2]铜陵有色金属集团股份有限公司安庆铜矿,安庆246000 [3]核工业金华勘测设计院有限公司,金华321000

出　　处：《地震地质》2023年第6期1265-1285,共21页Seismology and Geology

基　　金：国家自然科学基金(42041006,42277152);中央高校基本科研业务专项(300102262910)共同资助。

摘　　要：青藏高原东南缘是现今陆内地壳形变最为强烈的地区之一,一系列长度和力学性质不同的活动断裂将岩石圈分割为多个活动块体。川滇块体是其中构造活动最为显著的区域之一,其西边界由多条互相平行的断裂组成,巴塘断裂是其中的一条主干断裂。了解该断裂晚第四纪以来的变形特征和速率对于认识川滇块体强震的空间分布及变形模式具有重要意义。巴塘断裂整体走向NNE,全长115km,是一条全新世右旋走滑活动断裂。该断裂基本控制了基岩山体边界,其中坡中槽、三角面、断层陡崖等地貌沿断裂呈线性分布,并在黄草坪及巴塘县城2处区域保存了丰富的晚第四纪活动证据。文中利用无人机摄影测量手段建立了黄草坪及巴塘县城分辨率达亚米级的数字地形数据,并对被断错的洪积扇、冲沟等地貌标志物进行了精确测量。在黄草坪地区,巴塘断裂活动造成的山前冲沟水平偏转量为(46±9)m,同时在巴塘县城断裂活动使莫曲河洪积扇边缘被右旋断错(40±5)m。文中利用单个砾石宇宙成因核素法及深度剖面法分别确定了黄草坪最老一级地貌面和莫曲河洪积扇的年龄,分别为(12.5±0.5)ka和(16.4+3.9/-5.6)ka,据此可以得到巴塘断裂晚第四纪以来的右旋走滑速率为2~4mm/a。该速率值占现今川滇块体西边界整体剪切变形的50%~80%,但小于利用GPS形变资料反演得到的约10mm/a的结果。这种差异表明川滇块体西边界可能呈现连续-弥散变形特征,而巴塘断裂是西边界中的一条主要变形构造。The southeastern margin of the Tibetan plateau is one of the most intensely deformed regions in the continental crust.A series of active faults with varying lengths and mechanical properties have segmented the lithosphere into multiple active blocks,with the Sichuan-Yunnan block being one of the most tectonically active regions.Its eastern boundary is characterized by secondary fault zones such as the Xianshuihe-Anninghe-Zemuhe,Xiaojiang,and Daliangshan fault zone,forming a narrow and continuous strike-slip deformation zone with a total length exceeding 1100km.The western boundary of the Sichuan-Yunnan Block is mainly composed of the Jinsha River and the Red River fault zone,with the Jinsha River fault zone consisting of more than 20 roughly parallel secondary faults,forming a complex fault zone with 30~200km width.Despite recent GNSS network observation revealing the current tectonic deformation rates in this region,there is still a lack of research on the deformation characteristics and rates of individual active faults.This limitation makes it difficult in the assessment and understanding of seismic hazards in the area,restricting the scientific understanding of the current deformation mode in the southeastern margin of the Tibetan plateau.The Batang Fault,located within the Jinsha River fault zone at the western boundary of the Sichuan-Yunnan block,is a NE-trending main fault that obliquely cuts across the Jinsha River Fault,dividing later into northern and central segments.Presently,the Batang Fault is characterized by dominant right-lateral strike-slip motion.The deformation characteristics and rates of this fault since the Late Quaternary are crucial for understanding the spatial distribution of strong earthquakes and deformation patterns in the Sichuan-Yunnan block.The Batang Fault has a total length of 115km and is a Holocene right-lateral strike-slip active fault.The fault extends along the margins of bedrock mountains on both sides of the Maqu river and Jinsha River valleys,trending NNE or NWW to SEE,w

关 键 词：川滇块体 走滑断裂 活动速率 晚更新世 河流阶地 

分 类 号：P315.2[天文地球—地震学]