| 大别─苏鲁碰撞造山带的地震层析成像研究──岩石圈三维速度结构 |
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| 引用本文： | 徐佩芬,刘福田,王清晨,从柏林,陈辉,孙若昧.大别─苏鲁碰撞造山带的地震层析成像研究──岩石圈三维速度结构[J].地球物理学报,2000,43(3):377-385. |
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| 作者姓名： | 徐佩芬 刘福田 王清晨 从柏林 陈辉 孙若昧 |
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| 作者单位： | 中国科学院地质与地球物理研究所,北京100101 |
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| 基金项目： | 国家自然科学基金，中国博士后科学基金，49794044,49794042，，， |
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| 摘 要： | 对包含大别－苏鲁碰撞造山带在内的东经 １１２°－１２４°，北纬２８°－３９°区域进行地 震层析成像研究，重建其地壳及上部地幔的三维速度图像．结果表明：造山带岩石圈速度横 向不均匀性显著；大别造山带以商城－麻城断裂为界，东侧的大别地块与西侧红安地块在地 壳速度上是两个不同的速度块体；中地壳 １５-２５ｋｍ深度范围内存在低速带，与伸展滑脱构造 有关；南、北大别构造单元之下，莫霍面下凹，地壳内发育了速度为６．５－６．６ｋｍ／ｓ、向北倾斜的 相对高速体，与超高压变质岩体相对应；在大别－苏鲁造山带下方的上部地幔中存在向北倾 斜的板片状高速体，结合已有地质、地球化学证据推测，它是三叠纪俯冲的扬子地块的残留 体；俯冲板片在深部发生了断离．本文利用地震层析成像方法揭示的造山带岩石圈速度结构 细节，对研究与地表地质有关的地球动力学无疑是十分重要的．
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| 关 键 词： | 大别-苏鲁造山带地震层析 成像三维速度 结构扬子板片 俯冲板片断离 |
| 文章编号： | 0001-5733(2000)03-0377-09 |
| 收稿时间： | 1999-07-30 |
| 修稿时间： | 1999年7月30日 |
SEISMIC TOMOGRAPHY BENEATH THE DABIE-SULU COLLISION OROGEN--3-D VELOCITY STRUCTURES OF LITHOSPHERE |
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| XU PEI-FEN,LIU FU-TIAN,WANG QING-CHEN,CONG BO-LIN,CHEN HUI,Sun RUO-MEI.SEISMIC TOMOGRAPHY BENEATH THE DABIE-SULU COLLISION OROGEN--3-D VELOCITY STRUCTURES OF LITHOSPHERE[J].Chinese Journal of Geophysics,2000,43(3):377-385. |
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| Authors: | XU PEI-FEN LIU FU-TIAN WANG QING-CHEN CONG BO-LIN CHEN HUI Sun RUO-MEI |
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| Institution: | Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100101, China |
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| Abstract: | The 3-D velocity structures of the crust and upper mantle beneath the region of 112° - 124° E, 28°- 39° N including the Dabie-Sulu orogenic belt are reconstructed by using seismic tomography. The results demonstrate that a significant lateral heterogeneity of velocity structures exists in the crust and upper mantle beneath the Dabie orogenic belt and a low velocity layer in the middle crust corresponds to extensional and nappe structures. Beneath the southern and northern bole tectonic units, the Moho depresses and a north-dipping high-velocity block, which corresponds to the ultralhigh-pressure metamorphic rocks, range from 6.5 to 6.6 km/s, was developed in the crust. In the uppermost mantle beneath the orogenic belt was developed the north-dipping high-velocity slab. Taking into account of geological and geochemistrical data. we inferred that the high--velocity slab is the remnants of ancient subducted Yangtze block. Seismic tomography reveals that the subducted Yangtze ancient block was broken off. In this paper we present tomographic images of the lithospheric velocity structure in details under the Debie-Sulu orogenic belt that such structures may be useful in. associating geodynamic to surface--tectonic processes and is important in study of ancient orogenic belt. |
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| Keywords: | Dabie-Sulu orogenic belt Seismic tomography 3-D velocity structure Subducted Yangtze block Slab breakoff |
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