利用P波接收函数和瑞利面波联合反演青藏高原东北缘S波速度结构

发布时间：2018-03-03 13:24

本文选题：青藏高原东北缘S波速度结构　切入点：接收函数　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：青藏高原东北缘作为整个高原向内陆延伸的最前缘部分,是研究高原隆升和变形机制的关键区域。本文研究区域包括西秦岭、祁连、东昆仑造山带,柴达木盆地和阿拉善、松潘-甘孜以及羌塘块体。通过收集研究区域内223个台站记录的2007-2010年的远震波形数据,首先利用远震P波接收函数对研究区域壳幔界面进行成像研究。接收函数结果显示:柴达木盆地地壳厚度约为50-55 km;松潘-甘孜块体的地壳厚度自西向东从65-75 km降低到~50 km;西北祁连造山带地壳厚度约为60-65 km;东南祁连造山带和西秦岭造山带的地壳厚度约为50-55km。Vp/Vs值在松潘甘孜块体西部、羌塘块体约为1.8,而其余地区Vp/Vs均值约为1.75。然后利用远震双平面波成像法提取研究区域25-111 s的瑞利波相速度分布,利用背景噪声成像方法获取10-40 s的瑞利波相速度分布。联合接收函数、背景噪声和双平面波法的面波频散结果,反演获得了研究区域地表至地下150km的S波速度结构。S波速度结果表明:(1)松潘-甘孜块体、羌塘块体西部和东昆仑断层的中地壳到140 km范围存在连续的低速带。(2)祁连造山带下方的速度分布特征存在着明显的横向各向异性。西北祁连造山带的中下地壳表现为明显的低速特征,而在东南祁连造山带下方并未观测到低速的中下地壳。西北祁连造山带的地壳厚度约为60-65 km,其中下地壳范围内的低速带很可能与该区域的地壳增厚相关。而在具有较薄地壳(50~55 km)的西秦岭造山带和东南祁连造山带的地壳内没有观测到低速带,这说明地壳流模型可能并不是青藏高原东北缘生长变形的主要机制。
[Abstract]:The front part of the northeastern margin of the Tibetan Plateau as the whole plateau extends inland, is the key area of plateau uplift and deformation mechanism. The research areas include Qilian, West Qinling Mountains, East Kunlun orogenic belt, Qaidam Basin and Alashan, Songpan - Ganzi and Qiangtang block. By Teleseismic waveform data collected for 2007-2010 years in the study area were recorded at 223 stations, first using teleseismic P wave receiver function of regional crust mantle interface imaging. The receiver function results show that the crustal thickness in this basin is about 50-55 km; the Songpan - Ganzi block of the crustal thickness from west to East, reduced from 65-75 km to ~50 km; the thickness of the crust in northwestern Qilian orogenic belt is about 60-65 km; the thickness of the crust in Southeast Qilian orogenic belt and the West Qinling Mountains orogenic belt is about 50-55km.Vp/Vs in Songpan Ganzi west block, the Qiangtang block is about 1.8, while the rest were Vp/Vs About 1.75. and then using teleseismic double plane wave imaging method of Rayleigh wave extraction in the research area of 25-111 S phase velocity distribution, using the method of background noise imaging to obtain 10-40 s Rayleigh wave phase velocity distribution. Combined receiver function, background noise scattered results and double plane wave method of surface wave frequency, S wave velocity inversion the structure of.S wave velocity results of regional surface to underground 150km showed that: (1) Songpan - Ganzi block, crust in the Qiangtang block in the West and the East Kunlun fault to the range of 140 km with low speed continuous. (2) under the Qilian orogenic belt, the velocity distribution characteristics are transverse anisotropy northwest of the Qilian orogenic belt. The lower crust showed low speed characteristics, and in the southeast of Qilian orogenic belt is not observed at low speed. The lower crust in northwestern Qilian orogenic belt of crustal thickness is about 60-65 km, of which the lower crust in the range of The low velocity zone may be related to crustal thickening in the region. But in having a relatively thin crust (50~55 km) were observed in the low velocity zone of the crust in Western Qinling Mountains orogenic belt and the East Qilian orogenic belt, which shows that the main mechanism of the crustal flow model may not be the growth of the northeastern margin of the Tibetan Plateau deformation.

【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2

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