华北东部地区地壳泊松比异常及其成因  

High Poisson's ratio anomalies in the crust of the eastern part of North China and its origin

作　　者：杨文采[1] 瞿辰[1] 于常青[1] 

机构地区：[1]中国地质科学院地质研究所国土资源部大陆动力学重点实验室,北京100037

出　　处：《地学前缘》2011年第3期13-21,共9页Earth Science Frontiers

基　　金：国家科技专项"汶川地震断裂带科学钻探"(笫15课题);中国地质科学院地质研究所所长基金项目(J0815)

摘　　要：利用地震层析成像方法可以提供地壳上地幔P波和S波速度扰动精细图像,进一步换算还可以得到泊松比的图像。但是,与P波和S波速度扰动图像相比,泊松比成像是否具有独特优点还有待研究。通过对华北东部进行了高分辨率地震层析成像研究,作出了该地区地壳速度结构和泊松比的图像,揭示了该区域存在一个高泊松比异常区,位于恒山—北太行—张家口一带,为深部构造演化提供新的地球物理制约。从上地壳延伸到厚度达26 km左右的中地壳,地壳泊松比增加。根据岩石物理性质和其他地质信息,恒山—北太行—张家口地壳高泊松比异常可以用中新生代华北克拉通地壳减薄过程中上地幔部分熔融及玄武质岩浆底侵作用来解释。The seismic tomography can provide both fine P-wave and S-wave velocity structures of the crust and upper mantle,and also a Poisson＇s ratio image from the seismic velocities via proper computation.However,it is unsure that Poisson＇s ratio images have any advantages comparing with the P-wave and S-wave velocity images.In this study,the high resolution seismic tomography is applied to the determination of detailed 3-D crustal P-and S-wave seismic velocities structure as well as Poisson＇s ratio images under the eastern part of North China region.Results of Poisson＇s ratio imaging show a high Poisson＇s ratio（high-PR）anomalies located in Hengshan-North Taihang-Zhangjiakou（H-NT-Z）region,showing Poisson＇s ratio imaging can provide new geophysical constraints for the regional tectonic evolution.H-NT-Z region shows prominent and continuous high-PR anomalies in upper crust,extending down to the middle crust with thickness up to about 26 km.According to petrophysical property measurements and other geological data,this crustal Poisson＇s ratio anomaly may be explained by the upper mantle partial melting and basaltic magma underplating during the Mesozoic era,related to the lithospheric thinning in North China craton.

关 键 词：地震层析成像 中国华北 克拉通地壳 泊松比异常 岩浆底侵作用 

分 类 号：P584[天文地球—岩石学] P631.4[天文地球—地质学]