| 华北克拉通地壳结构及动力学机制分析 |
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| 引用本文： | 武岩,丁志峰,王兴臣,朱露培.华北克拉通地壳结构及动力学机制分析[J].地球物理学报,2018,61(7):2705-2718. |
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| 作者姓名： | 武岩 丁志峰 王兴臣 朱露培 |
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| 作者单位： | 1. 中国地震局地球物理研究所, 北京 100081;2. 中国地震局地球物理研究所 地震观测与地球物理成像重点实验室, 北京 100081;3. Department of Earth and Atmospheric Sciences, Saint Louis University, Missouri 63103, USA |
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| 基金项目： | 国家自然科学基金（41404074，41404069）资助. |
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| 摘 要： | 本文对布设在华北克拉通三个陆块的199个宽频带台站记录的远震数据进行了接收函数计算.利用H-κ迭代方法获得了该区域基岩地区的地壳结构，平滑处理后作为背景结构模型中的基岩地区地壳结构；利用相邻算法对沉积层地区的接收函数进行了波形拟合计算，获得了沉积层结构，平滑后作为背景结构模型中的沉积层结构；结合前人的研究成果，完善了研究区域的背景结构模型.以此模型为基础，对接收函数进行了CCP（Common Conversion Point，共转换点）叠加成像，获得了Moho面成像结果，对比沉积层的成像结果发现：西部陆块中鄂尔多斯块体东部地区地壳厚度较大，约为42 km，泊松比较低，小于0.24，为长英质含量较多的地壳层；位于中部陆块的山西地堑地壳厚度小于鄂尔多斯块体，且变化较大，西侧地壳厚度约为40 km，东侧重力梯度带附近地壳厚度迅速减薄至36 km左右，张家口-怀来-大同一带出现了地壳的局部抬升，地壳厚度等值线基本以北北东方向为主，与构造带方向基本一致，地堑内泊松比约为0.26~0.28，前人对此区域的层析成像研究结果表明太行山隆起和阴山隆起存在壳内低速层，推测为地壳部分熔融以及上地幔物质上涌造成的；东部陆块中渤海湾盆地的地壳厚度较薄，约为32 km，部分地区小于30 km，其中冀中坳陷带地壳厚度最薄，约为28 km，沉积层基底分布与Moho面分布呈镜像对称趋势，沉积层较厚地区的地壳较薄，推测东部陆块在太平洋板块俯冲作用下，存在北西-南东向的拉张作用，使其内发育了大量断陷盆地.
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| 关 键 词： | 接收函数 共转换点叠加 华北克拉通 拉张减薄 |
| 收稿时间： | 2017-07-07 |
Crustal structure and geodynamics of the North China Craton derived from a receiver function analysis of seismic wave data |
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| WU Yan,DING ZhiFeng,WANG XingChen,ZHU LuPei.Crustal structure and geodynamics of the North China Craton derived from a receiver function analysis of seismic wave data[J].Chinese Journal of Geophysics,2018,61(7):2705-2718. |
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| Authors: | WU Yan DING ZhiFeng WANG XingChen ZHU LuPei |
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| Institution: | 1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;2. Key Laboratory of Seismic Observation and Geophysical Imaging, China Earthquake Administration, Beijing 100081, China;3. Department of Earth and Atmospheric Sciences, Saint Louis University, Missouri 63103, USA |
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| Abstract: | Receiver functions are obtained from the teleseismic data recorded by the 199 broad-band stations which are located on three blocks of the North China Craton (NCC). The crustal structure of the consolidated area is then imaged using the method of H-κ stacking. Sedimentary structure of the unconsolidated area is mapped by fitting the theoretical receiver functions and observed ones using the neighborhood algorithm. The smoothed crustal structure of the consolidated area and the smoothed sedimentary structure, as well as the crustal structure of the unconsolidated area and the upper mantle structure proposed by previous research are then taken as the background model. Based on this model, the crustal structure is imaged using the common conversion point (CCP) stacking. Investigating the sedimentary and crustal structures suggests that in the eastern Ordos Block, the crust is about 42 km thick, and the Poisson's ratio is about 0.24. Such a low Possion's ratio means a crustal layer with a high content of felsic. The Moho depth of the Shanxi graben basin changes from 40 km in the west to 36 km in the east which is thinner than that in the eastern Ordos block. Local uplift of the Moho occurs surrounding the area of Zhangjiakou-Huailai-Datong. Contour lines of the crustal thickness exhibit a dominating NNE trend consistent with the tectonic zone. The Poisson's ratio in the graben is about 0.26~0.28. Previous tomography on the Taihang uplift and Yanshan uplift show that there is a crustal low-velocity layer which means partial melting of the crust and the upwelling of the upper mantle material. The Moho depth of the Bohai Bay Basin (BBB) is about 32 km, and smaller than 30 km in some areas. The Jizhong depression has a thinnest crust, which is about 28 km. The shape of the sedimentary basement is mirror symmetrical with the Moho depth. This characteristic may be formed by the north-west extension that resulted from the subduction of the Pacific plate, serving as a force to generate a large number of graben basins in the eastern block of the NCC. |
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| Keywords: | Receiver function Common conversion point stacking North China Craton Extension and thinning |
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