利用接收函数、背景噪声频散和Rayleigh波ZH振幅比联合反演青藏高原东北缘及周边地区地壳结构  被引量:2

Joint inversion of receiver function,ambient noise dispersion,and Rayleigh wave ZH ratio for the crustal structure beneath the northeastern margin of the Tibetan plateau and its surrounding regions

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作  者:高天扬 丁志峰[1,2] 徐小明[1,2] 王兴臣[1,2] GAO TianYang;DING ZhiFeng;XU XiaoMing;WANG XingChen(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Key Laboratory of Earthquake Source Physics,China Earthquake Administration,Beijing 100081,China)

机构地区:[1]中国地震局地球物理研究所,北京100081 [2]中国地震局震源物理重点实验室,北京100081

出  处:《地球物理学报》2023年第10期4074-4094,共21页Chinese Journal of Geophysics

基  金:国家自然科学基金项目(41941016-01,4194100040,41974100);科技部重大研究项目专题(2019QZKK0701);中国地震局地球物理研究所基本科研业务专项(DQJB21B32)联合资助。

摘  要:本文对在青藏高原东北缘及邻近地区架设的571套宽频带流动地震台站记录到的连续波形数据进行处理,通过联合反演P波接收函数、背景噪声频散和Rayleigh波ZH振幅比,获得了研究区高分辨率三维地壳S波速度(VS)结构.研究结果显示,松潘—甘孜块体和西秦岭造山带以及北祁连造山带下方15~40 km的深度范围内存在很显著的S波低速异常体.其中,松潘—甘孜块体和西秦岭造山带下方的低速异常体很可能与部分熔融有关,且造成部分熔融的原因除了剪切加热外,还有可能是软流圈物质上涌和地壳内部的放射生热.而北祁连造山带的低速异常体则可能由地表隆升和地壳增厚所造成.阿拉善块体内部分布有很多不太显著的低速异常体,这可能与阿拉善块体经历了复杂的构造变形有关.在银川—河套地堑下方20~35 km的深度范围内同样观测到了相对不太显著的低速异常体,这更可能与基性岩浆的底侵作用有关.We process the continuous waveform data recorded by 571 broadband temporary seismic stations in the northeastern(NE)margin of the Tibetan plateau and its surrounding regions,and jointly invert the ambient noise dispersion,Rayleigh wave ZH ratio,and P-wave receiver function to obtain high-resolution 3D S-wave velocity structure(VS)of the crust.The results demonstrate that significant low-velocity anomalies of S-wave appear in the depth interval of 15~40 km beneath the Songpan-Garzêblock and the western Qinling orogen as well as the northern Qilian orogen.The low-velocity zone below the Songpan-Garzêblock and the western Qinling orogen may be related to the crustal partial melting,and the causes of partial melting are not only shear heating but also asthenosphere material upwelling and crustal radioactivity.While that of the northern Qilian orogen may be related to surface uplift and crustal thickening.Many insignificant low-velocity anomalies are observed beneath the Alxa block,which may be related to the complex tectonic deformation of the Alxa block.Relatively insignificant low-velocity anomalies are also observed at the depth interval of 20~35 km beneath the Yinchuan-Hetao graben,which is more likely to be related to the underplating of mafic magmas.

关 键 词:青藏高原东北缘 联合反演 接收函数 背景噪声频散 ZH振幅比 低速体 

分 类 号:P315[天文地球—地震学]

 

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