接收函数成像揭示东昆仑断裂带及其周缘地壳结构  

Receiving function imaging reveals the crustal structure of the East Kunlun fault zone and surrounding areas

作　　者：仝霄飞 徐啸 郭晓玉 李春森 向波 余嘉豪 罗旭聪 袁梓昭 林燕琪 时宏城 TONG Xiaofei;XU Xiao;GUO Xiaoyu;LI Chunsen;XIANG Bo;YU Jiahao;LUO Xucong;YUAN Zizhao;LIN Yanqi;SHI Hongcheng(School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,China)

机构地区：[1]中山大学地球科学与工程学院,广东珠海519802 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519802

出　　处：《地学前缘》2023年第4期270-282,共13页Earth Science Frontiers

基　　金：国家自然科学基金项目(41974097,42274120,41874102);科学技术部第二次青藏高原科学考察项目(2019QZKK0701)。

摘　　要：前人的研究结果表明,自中新世以来青藏高原持续进行着穿时性的向东逃逸,而东昆仑断裂的左旋走滑运动正是这种变形的表现。正确地厘定断裂的位置与地壳结构,对于更加深入地认识高原的变形、应力传递和物质运输起着至关重要的作用。有大地测量学和地貌学研究指出,东昆仑断裂沿走向向东的滑移速率逐渐递减,在被第四纪沉积物所覆盖的若尔盖盆地内尤为明显。然而,该盆地分布有广袤的高山草甸、低洼沼泽,使得通过地表追踪断裂的地貌学迹象研究尤为困难。因此,东昆仑断裂带在若尔盖盆地内的位置无法确认。本次研究采用了由167个间隔约1 km的短周期地震仪站组成的密集阵列以及9个宽频带台站,对若尔盖盆地内东昆仑断裂的地壳结构进行成像。通过比较地壳中地层的不连续性和莫霍面的深度变化,确定了东昆仑断裂在若尔盖盆地内继续向东延伸。此外,塔藏断裂和东昆仑断层在地壳结构上的相似性说明它们之间存在继承关系。高分辨率的接收函数结构为高原的向外生长提供了新的证据。Previous studies have suggested that the Tibetan Plateau continues to undergo eastward extrusion since the Miocene,and the observed sinistral strike-slip deformation in eastern Kunlun is strong evidence of such movement.To gain a better understanding of the land deformation,stress transfer,and material transport on the Tibetan Plateau,it is crucial to correctly identify the location of faults and the regional crustal structure.Geodetic and geomorphic evidence have indicated an eastward decrease of slip rate along the eastern Kunlun fault,particularly in the Roergai Basin covered with a variety of Quaternary sediments.However,due to basin’s alpine herbaceous swamp nature,it is particularly challenging to identify fault traces in the basin;as a result,the location of the eastern Kunlun fault within the Roergai Basin is unclear.In this contribution,a dense array of 167 seismic stations(spaced at~1-km intervals)and 9 broadband stations were used to investigate the crustal structure beneath the eastern Kunlun fault in the Ruoergai Basin.Through basin-wide comparisons of discontinuities in crustal strata and Moho depth variations it was determined that the eastern Kunlun fault continues to extend eastward through the Ruoergai Basin;in addition,an inheritance relationship between the Tazang and eastern Kunlun faults was identified based on crustal structure similarities.The results of this study provide high-resolution evidence for the outward expansion of the Tibetan Plateau.

关 键 词：东昆仑断裂 接收函数 青藏高原东北缘 塔藏断裂 

分 类 号：P315.2[天文地球—地震学]