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| 华北克拉通东北部的远震S波走时层析成像研究 | |
| 引用本文： | 胡刚,滕吉文,何正勤,丁志峰.华北克拉通东北部的远震S波走时层析成像研究[J].地球物理学报,2017,60(5):1703-1712. |
| 作者姓名： | 胡刚 滕吉文 何正勤 丁志峰 |
| 作者单位： | 1. 中国科学院地质与地球物理研究所, 北京 100029;2. 中国科学院大学, 北京 100049;3. 中国地震局地球物理研究所, 北京 100081 |
| 基金项目： | 基本科研业务费专项“太原盆地浅层速度结构探测（DQJB14C04）”与科技部科技基础性工作专项“华北地下精细结构探查”（2006FY110100）联合资助. |
| 摘 要： | 华北克拉通是近年来我国地学界研究的热点之一.本文利用布设在华北东北部地区的华北地震科学台阵所记录的远震波形资料,用波形互相关方法拾取了9105条S波走时残差数据,进而用体波走时层析成像方法反演获得了研究区从地表至600 km深度的S波速度结构.所获得的S波层析成像结果表明,华北克拉通中部块体的山西断陷带低速异常一直从地面延伸至上地幔约300 km深处,推测该低速异常体可能与中、新生代的大同火山群的形成与活动有关.研究发现华北东部存在一高速异常体由东部渤中凹陷的地壳一直向西延伸至太行山山前断裂下方地幔转换带410 km附近,推测该高速异常体可能为太平洋板片向西俯冲在华北克拉通东部块体下方地幔过渡带内的滞留.研究结果显示华北克拉通东部的华北盆地表现为高低速相间分布,表明该地区下方的岩石圈发生了破坏,而位于华北克拉通北缘的燕山造山带显示为高速异常,表明燕山造山带下方的岩石圈没有明显的破坏迹象. |
| 关 键 词： | 体波层析成像 波形互相关 走时残差 华北克拉通 S波速度结构 |
| 收稿时间： | 2016-05-16 |
A traveltime tomography study by teleseismic S wave data in the northeastern part of North China Craton |
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| HU Gang,TENG Ji-Wen,HE Zheng-Qin,DING Zhi-Feng.A traveltime tomography study by teleseismic S wave data in the northeastern part of North China Craton[J].Chinese Journal of Geophysics,2017,60(5):1703-1712. | |
| Authors: | HU Gang TENG Ji-Wen HE Zheng-Qin DING Zhi-Feng |
| Institution: | 1. Institute of Geology and Geophysics, Chinese Academy of Science, Beijing 100029, China;2. University of Chinese Academy of Science, Beijing 100049, China;3. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China |
| Abstract: | Seismic body wave tomography is one of the effective methods to reveal the crust-mantle velocity structure. A large number of seismic wave imaging studies have been conducted in the North China Craton, in order to study the formation and evolution of the Craton, and provided important deep information. In this paper the waveform data recorded by 190 sets of broadband seismometers of the North China Earthquake Science array in October 2006—March 2009 from the teleseismic events in epicenter range 30°~90° were used, after extracting 9105 S wave travel time residual data with the waveform cross-correlation method, to determine the S-wave velocity structure of the study area from the surface to a depth of 600 km by the FMTT body wave tomographic inversion method. All seismic stations are consistent with each other, the teleseismic events are evenly distributed with a very good back-azimuthal coverage, which allows us to get a higher resolution S wave structure than existing seismic body wave tomography result, and it can well reveal the deep crust and mantle structure and the dynamic mechanism of the study area, and provide new deep information for the major research project of North China craton lithospheric thinning and destruction. The conclusions are as follows: (1) The low velocity anomaly in Shanxi rift in the western part of the study area extends from the surface to the depth of the mantle transition zone at about 300 km, this reflects that hot materials exist beneath Shanxi rift. It is found that the low velocity anomaly does not penetrate the mantle transition zone to reach the lower mantle; it is speculated that the low velocity anomaly may be associated with the formation of the Mesozoic to Cenozoic Datong volcanoes and the upwelling of asthenosphere substance. (2) Regional seismic tomography study found that the leading edge of the Pacific Plate subduction has arrived at approximately 120°E (Huang and Zhao, 2006). We find that a high velocity anomaly extends from the crust of the Bozhong depression west- and down-wards to the mantle transition zone near 410 km beneath the Taihang piedmont fault, it is speculated to be the westward subducting Pacific plate in the mantle transition zone beneath eastern North China Craton. (3) Compared with the old cratonic lithosphere thickness the lithosphere of North China has been thinned, showing the complex phenomenon of alternating high and low velocities within the North China Plain, while the Yanshan region shows high-speed anomalies, indicating that the North China Plain lithosphere beneath the region has undergone significant erosion and destruction, and in the Yanshan region no significant erosion and destruction took place. |
| Keywords: | Body wave tomography Waveform cross-correlation Travel-time residual NCC S-wave velocity structure |
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