华北东部地区上地幔波速比(Vp/Vs)成像

项目名称： 华北东部地区上地幔波速比(Vp/Vs)成像

项目编号： No.41504045

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 天文学、地球科学

项目作者： 司少坤

作者单位： 国家深海基地管理中心

项目金额： 22万元

中文摘要： 探测华北岩石圈底部减薄、改造和增生的空间分布是理解其破坏机制及过程的关键。深部岩石圈的改变主要表现为橄榄岩矿物成分及其物理状态的变化，相比单纯的地震波速度而言，波速比对于这种变化更为敏感。本项目拟利用接收函数中410公里间断面转换波旅行时对上地幔地震波速度比的强烈依赖，开展利用接收函数研究上地幔速度比的方法；结合华北东部地区内陆长周期、宽频带地震台站以及渤海海域OBS (海底地震仪) 记录的远震数据，对该区上地幔的三维速度比结构进行成像，为华北岩石圈的减薄、改造和增生提供垂向幅度和空间分布的约束；相对于零星或局部的捕虏体研究而言，本项研究可通过地震学方法提高华北岩石圈成分研究的空间分辨能力。

中文关键词： 纵横波速度比；接收函数；层析成像；上地幔；华北克拉通

英文摘要： To detect the destruction、modification and replacement of the basement of the lithosphere is a key step in understanding the destruction mechanism and process of North China lithosphere. The change of the basement of the lithosphere is mainly displayed by the variation of the peridotite compositions and its physical state. Velocity ratio (Vp/Vs) is more sensitive to this change than simply velocity of the seismic wave. By means of the strongly dependent relationship of the travel time of converted wave from the 410 km discontinuity in receiver function to the velocity ratios (Vp/vs) in the upper mantle, a new method for the Vp/Vs ratio in the upper mantle is introduced using receiver function in this project. Combining with broadband seismic data recorded by long-running and broad-band seismic stations in North China and OBS (Ocean bottom seismometer) in Bohai Sea, we obtain 3-D velocity ratio tomography of the upper mantle beneath the study area. It can provide critical constraint on the destruction、modification and replacement of the lithosphere in both vertical direction and spatial variation. Comparing with the scattered xenoliths, this project will improve spatial resolution in the research of the lithospheric material composition by seismology methods.

英文关键词： Vp/Vs ratio;receiver function;tomography;the upper mantle;North China Craton