苏鲁大别及其周围地区深部P波速度结构特征的初步分析  

Characteristic outline of P wave velocity structure in the depth beneath the Sulu-Dabie region.

作　　者：赵志新[1] 徐纪人[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037

出　　处：《岩石学报》2005年第2期525-532,共8页Acta Petrologica Sinica

基　　金：国家重点基础研究发展(973)计划2003CB716505课题国家自然科学基金(40399141)国土资源部重点项目(20001010203)共同资助

摘　　要：本文分析了苏鲁大别及其周围地区200km深的地震波速度结构。对上地幔50至200km不同深度的水平切面的速度结构特征进行了详细研究。结果表明,位于大别山地区下的西南侧存在着一个呈西北-东南延展的带状高速区;在苏鲁东海地区的下方,及东北方面也有高速度区域存在。这两个高速度区不相连。在大别山区东北端区与苏鲁超高压变质带的南端地区深部的两个高速区之间,即郯庐断裂的中部存在一个西北-东南延展的低速度区。大别山区下方深部呈现明显的速度梯度变化带。大别山区东端边界也是速度梯度变化带。郯庐断裂的北段,即与苏鲁超高压变质带为邻的部分下方,似乎是一个速度分界带或者速度不连续带。郯庐断裂的北段下方的速度结构与其两侧地区的速度结构明显不同。该段的两侧速度结构常常存在着明显差异。The velocity structures to 200 km deep beneath the Sulu-Dabie and the surrounding were discussed in the present analysis. The characteristics of velocity structure in the horizontal sections for several different layers between the 50 and 200 km were investigated in detail. The results suggest that the high velocity belt extending along the NW-SE direction exists beneath the region southwest of the Dabie mountain region. Another high velocity area exists evidently beneath the Sulu ultrahigh-pressure metamorphosed (UHPM) belt and the region east of the UHPM belt. It looks that the two high velocity areas exist separately in each deep place. The low velocity area extending along NW-SE direction exists beneath the link region between the southern end of Sulu UHPM belt and the northeastern end of the Dabie mountain region, crossing the middle segment of the Tan-Lu fault. The velocity gradient variations along the NE-SW direction reveal beneath the Dabie UHPM belt. The velocity gradient belt strikes along about the NW-SE direction. Such velocity gradient variation belt striking nearly N-S direction also reveals beneath the eastern boundary of the Dabie mountain region. A velocity boundary zone exists beneath the northern segment of the Tanlu fault. The velocity variation is discontinuity as crossing the western boundary of the Sulu UHPM belt. The velocity structures beneath the both sides of the northern segment of the Tanlu fault are usually different from each other. The velocity structure beneath the northern segment of the Tanlu fault is usually different from that beneath each side.

关 键 词：地震波速度成像 苏鲁大别造山带 超高压变质带 P波速度 郯庐断裂 

分 类 号：P315.31[天文地球—地震学]