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川滇地区地壳上地幔三维速度结构研究
引用本文:王椿镛,W.D.Mooney,王溪莉,吴建平,楼海,王飞.川滇地区地壳上地幔三维速度结构研究[J].地震学报,2002,24(1):1-16.
作者姓名:王椿镛  W.D.Mooney  王溪莉  吴建平  楼海  王飞
作者单位:1)中国北京100081中国地震局地球物理研究所 2)美国门罗帕克CA94025美国地质调查局
基金项目:国家基础研究发展规划项目“大陆强震机理与预测”(95- 13 - 0 2 - 0 3 ),国家“九五”攀登计划预选项目 (95- S- 0 5- 0 1),国家自然科学基金 (49874 0 2 1)共同资助
摘    要:根据云南和四川地震台网174个台站记录的4625个区域地震初至P波和S波走时资料,并结合其它深部地球物理资料,确定了川滇地区地壳上地幔三维速度结构.在上地壳速度异常分布中,四川盆地为正异常,川西高原为负异常,龙门山断裂带为正、负异常的边界.龙门山断裂、鲜水河断裂以及红河断裂等,在下地壳和上地幔的速度异常中仍显示出构造分界特征,说明它们可能穿透了莫霍界面.腾冲火山区和攀西构造带在50km深度上呈现负速度异常,与上地幔温度和物质组成的差异相联系.川滇地区地壳结构的总体特征是:地壳和上地幔的低平均速度,地壳厚度变化剧烈,地壳和(或)上地幔存在高导层、高热流值.这些同印度板块与欧亚板块碰撞的构造背景有关.川滇菱形块体在地壳内总体上为正常或正异常速度,而其边界的深大走滑断裂存在负速度异常,它有助于地壳块体沿断裂的侧向挤出.在主要的地震带上,中下地壳的负速度异常与地震活动性相关.多数强烈地震发生在具有正速度异常或正常速度分布的上中地壳深度上,而其下方则通常是负速度异常带. 

关 键 词:区域地震  莫霍界面  三维速度结构  网格方法  板块碰撞  地震活动性
文章编号:0253-3782(2002)01-0001-16
修稿时间:2001年3月9日

STUDY ON 3-D VELOCITY STRUCTURE OF CRUST AND UPPER MANTLE IN SICHU-AN-YUNNAN REGION,CHINA
W.D.Mooney.STUDY ON 3-D VELOCITY STRUCTURE OF CRUST AND UPPER MANTLE IN SICHU-AN-YUNNAN REGION,CHINA[J].Acta Seismologica Sinica,2002,24(1):1-16.
Authors:WDMooney
Abstract:Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly velocity zone exists in the western Sichuan plateau. The boundary between the positive and negative anomaly zones is the Longmenshan fault zone. The images of lower crust and upper mantle in the Longmenshan fault, Xianshuihe fault, Honghe fault and others appear the characteristic of tectonic boundary, indicating that the faults likely penetrate the Moho discontinuity. The negative velocity anomalies at the depth of 50 km in the Tengchong volcanic area and the Panxi tectonic zone appear to be associated with the temperature and composition variations in the upper mantle. The overall features of the crustal and the upper mantle structures in the Sichuan-Yunnan region are the lower average velocity in both crust and uppermost mantle, the large crustal thickness variations, and the existence of high conductivity layer in the crust or/and upper mantle, and higher geothermal value. All these features are closely related to the collision between the Indian and the Asian plates. The crustal velocity in the Sichuan-Yunnan rhombic block generally shows normal value or positive anomaly, while the negative anomaly exists in the area along the large strike-slip faults as the block boundary. It is conducive to the crustal block side-pressing out along the faults. In the major seismic zones, the seismicity is relative to the negative anomaly velocity. Most strong earthquakes occurred in the upper-mid crust with positive anomaly or normal velocity, where the negative anomaly zone generally exists below.
Keywords:regional earthquake  Moho discontinuity  3-D velocity structure  network method  plate collision  seismicity
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