【摘要】 本文利用华北地震科学台阵190套宽频带地震仪在2006年10月至2009年3月记录的远震事件,采用波形互相关技术提取了52414条P波初动到时数据,进一步使用FMTT(Fast Marching Teleseismic Tomography)方法,获取了华北克拉通中、东部陆块下方上地幔分辨高达0.5°×0.5°的P波速度结构.我们的P波速度结果显示,华北克拉通中、东部块体在40～240 km的深度范围内都表现为相对低速,而燕山造山带则整体表现为相对高速,这暗示华北克拉通中、东部块体下方的壳幔速度结构都遭受了明显的改造,但改造的范围并没有涉及到燕山造山带,或者燕山造山带下方的改造并没有华北克拉通中、东部块体那么显著.华北克拉通中部陆块下方的低速异常向下一直延深至250 km左右,该低速异常很可能与汾渭河地堑及新生代广泛分布的火成岩有关.更多还原

【Abstract】 In this study we used 52414 P wave first motion traveltimes to get the P wave velocity structure of upper mantle beneath the Central Block(CB)and Eastern Block(EB)of North China Craton(NCC)by Fast Marching Teleseismic Tomography(FMTT).There were 190 broadband stations from North China Seismic Array,and all of the teleseismic events occurred during Oct.2006 and Mar.2009.The relative traveltime residuals were got by waveform cross correlation.The checkerboard resolution was～0.5°×0.5°.The results reveal that:an obvious low-velocity anomaly is located at the region beneath the CB and EB of NCC,which extends from 40 km to 240 km;but beneath the Yanshan Uplift region,there is a high-velocity zone.These show that the CB and EB of the NCC have been obviously destructed,but the destruction region does not include the Yanshan Uplift;or the destruction of CB and EB is more apparent than that of Yanshan Uplift.The low-velocity anomaly extends to～250 km depth beneath the CB of NCC,which may have something to do with the formation of Cenozoic pyrogenic rock and Fenwei valley graben.更多还原