川滇地区不同构造块体壳幔过渡带研究

发布时间：2018-08-17 17:20

【摘要】：本文主要研究川滇地区不同构造块体的壳幔过渡带,川滇地区地处青藏高原东南缘,是研究高原物质侧向逃逸的关键地区,开展壳幔过渡带结构特征研究,可为揭示研究区的构造演化提供地震学证据。本文详细研究了远震接收函数Pms转换波所携带的台站下方壳幔过渡带精细结构的分频特征,波形特征所对应的壳幔过渡带结构类型,利用显示出不同壳幔过渡带结构类型的特征频率计算其厚度范围的方法。利用震源位置相近的地震记录,提取川滇地区各台站的不同高斯系数的接收函数,利用接收函数中的,来得到壳幔过渡带厚度以及壳幔过渡带速度结构,壳幔边界的精细结构,利用固定地震台站记录的远震波形数据,采用接收函数Ps转换波的分频特征和H-k方法,对研究区不同块体的壳幔过渡带结构进行了研究,取得了如下主要成果:1.稳定的扬子块体下方壳幔过渡带比较简单,主要由一阶间断面组成,其厚度介0.86km--1.44km之间,扬子块体的壳幔过渡带表现为一阶间断面,反映其构造稳定;2.南北松潘甘孜地区的壳幔过渡带为高低速相间结构,其过渡带厚度为1.8km--3.4km,松潘甘孜地区的壳幔过渡带为高、低速相间结构,暗示构造活动强烈;3.保山和兰坪块体地幔过渡带则表现为速度渐变结构,其过渡带厚度为1.1-3.6km,保山和兰坪块体的壳幔过渡带以速度渐变结构为主要特征,其活动性弱于松潘甘孜地区。由于川滇地区地处青藏高原东南缘,是高原物质逃逸的主要地区,青藏高原的不断隆升,使得川滇地区各块体构造强烈,结构复杂。根据本文的研究结果,可以发现靠近青藏高原的南北松潘甘孜地块活动性较为强烈,远离青藏高原的保山兰坪地块活动性则明显弱于松潘甘孜地区,而稳定的扬子板块岩石圈相当坚硬,构造稳定。
[Abstract]:This paper mainly studies the crust-mantle transition zone of different tectonic blocks in Sichuan-Yunnan area, which is located in the southeast margin of the Qinghai-Tibet Plateau and is the key area to study the lateral escape of the plateau material. The structural characteristics of the crust-mantle transitional zone have been studied. It can provide seismological evidence for revealing the tectonic evolution of the study area. In this paper, the frequency division characteristics of the fine structure of the crust-mantle transition zone under the station carried by the Pms transform wave of the remote seismic reception function and the structural types of the crust-mantle transition zone corresponding to the waveform characteristics are studied in detail. The method of calculating the thickness range of the transition zone by using the characteristic frequency which shows the structural types of different crust-mantle transition zones. The reception function of different Gao Si coefficients of stations in Sichuan-Yunnan region is extracted by using the seismic records with similar focal positions. The thickness of the crust-mantle transition zone, the velocity structure of the crust-mantle transition zone and the fine structure of the crust-mantle boundary are obtained by using the reception function. Using the data of remote seismic waveforms recorded by fixed seismic stations, the structure of crust-mantle transition zones of different blocks in the study area is studied by using the frequency-division characteristics of the received function Ps converted waves and H-k method. The main results are as follows: 1. The stable crust-mantle transition zone under the Yangtze block is relatively simple and is mainly composed of a first-order intersecting section. The crust and mantle transition zone of the Yangtze block is characterized by a first-order discontinuity surface between its thickness and 0.86km--1.44km, reflecting the structural stability of the Yangtze block. The crust-mantle transitional zone in Songpan Ganzi area is of a high and low velocity interphase structure with a thickness of 1.8 km-3.4 km. The crust mantle transitional zone in Songpan-Ganzi area is characterized by a high and low velocity interphase structure, implying a strong tectonic activity. The mantle transition zone of Baoshan and Lanping blocks shows a velocity gradient structure with a thickness of 1.1-3.6km. the crust-mantle transition zone of Baoshan and Lanping blocks is mainly characterized by velocity gradient structure, and its activity is weaker than that of Songpan Ganzi area. The Sichuan-Yunnan region is located in the southeast margin of the Qinghai-Xizang Plateau and is the main region where the material escapes from the plateau. The continuous uplift of the Qinghai-Tibet Plateau makes the blocks in the Sichuan-Yunnan region strong in structure and complex in structure. Based on the results of this study, it can be found that the activity of the Songpan-Ganzi block near the Qinghai-Tibet Plateau is relatively strong, while the activity of the Baoshan Lanping block far from the Qinghai-Tibet Plateau is obviously weaker than that of the Songpan-Ganzi area. The stable Yangtze plate lithosphere is rather hard and structurally stable.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.2

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