董蕾^1,,
沈旭章^2,,,
钱银苹³
1. 重庆市地震局, 重庆 401147
2. 中山大学地球科学与工程学院, 广州 510275
3. 广东省地震局, 广州 510070

基金项目: 国家自然科学基金项目（41730212，41574077和41704057）和国家重点研发计划（2017YFC1500100），广东省引进人才创新创业团队（2017ZT07Z066）-深部地球探测与资源环境团队联合资助


详细信息

作者简介: 董蕾, 女, 1986年生, 工程师, 从事地震监测工作.E-mail:dongleiyue@163.com

通讯作者: 沈旭章, 男, 博士, 教授, 主要从事地球深部结构、地震学和定点形变观测方面的研究.E-mail:shenxzh5@mail.sysu.edu.cn

中图分类号: P315

收稿日期:2019-04-28
修回日期:2020-01-13
上线日期:2020-03-05

Study on velocity and density contrasts across the Moho in the southeastern margin of the Tibetan Plateau

DONG Lei^1,,
SHEN XuZhang^2,,,
QIAN YinPing³
1. Chongqing Earthquake Agency, Chongqing 401147, China
2. School of Earth Sciences and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
3. Guangdong Earthquake Agency, Guangzhou 510070, China


More Information

Corresponding author: SHEN XuZhang,E-mail:shenxzh5@mail.sysu.edu.cn

MSC: P315

--> Received Date: 28 April 2019
Revised Date: 13 January 2020
Available Online: 05 March 2020


摘要
摘要:青藏高原东南缘地下深部结构的研究对了解青藏高原的变形机制和动力学过程具有重要意义.本文利用四川、云南固定台站记录到的远震波形资料，首先采用接收函数H-k叠加方法获得青藏高原东南缘台站下方的地壳厚度和波速比.进而利用接收函数一次转换波和多次波幅度信息确定了青藏高原东南缘Moho面上的S波速度和密度跃变.研究结果表明：研究区由南到北地壳厚度逐渐增加，从永德、沧源、孟连地区的33 km左右增至巴塘地区的69.7 km左右，厚度变化了近乎37 km.四川盆地和松潘甘孜块体南部的姑咱地区具有高泊松比、速度密度跃变较小特征，表明这两个地区含有较多铁镁物质.腾冲地区、龙门山西侧的汶川地区、四川盆地西南缘的沐川地区以及则木河断裂的石门坎至东川地区同属于高泊松比、速度密度跃变较大，显示这些地区壳内存在部分熔融.
关键词: Moho面/
速度跃变/
密度跃变/
青藏高原东南缘/
接收函数

Abstract:The deep structure of the southeastern margin of the Tibetan Plateau is of great significance for understanding the deformation mechanism and dynamic process of the Tibetan Plateau. On the basis of teleseismic waveform data recorded at permanent stations in Sichuan and Yunnan, we estimated the crustal thickness and Poisson's ratio beneath the stations in the southeastern Tibetan Plateau by the H-K stacking method. And we use the velocity-density contrast (δβ-δρ) scanning stacking algorithm, which constrains the velocity and the density contrasts across the Moho with receiver function amplitudes, to study S-wave velocity and density contrasts across the Moho in the study area. The results show that the crustal thickness in the study area increases gradually from south to north. From Yongde, Cangyuan and Menglian where the thickness is 33 km to Batang where the thickness is 69.7 km, the thickness has changed by 37.5 km. Sichuan Basin and the Guzan area south of the Songpan-Garzê block are characterized by high Poisson's ratio and low velocity and density contrasts. These two areas contain more mafic composition. The Tengchong area, west side of the Longmenshan fault, Muchuan area in the southwestern margin of the Sichuan Basin and Shimenkan to the Dongchuan area of Zemuhe fault exhibit high Poisson's ratio and high velocity density contrasts, implying possible partial melting in the crust of these areas.
Key words:Moho discontinuity/
Velocity contrast/
Density contrast/
Southeastern margin of Tibetan Plateau/
Receiver function



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