| 喜马拉雅地区深反射地震──揭示印度大陆北缘岩石圈的复杂结构 |
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| 关键词:deep reflection underthrust MHT secondary Moho |
| 基金项目:国家自然科学基金 |
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| Deep Seismic Reflection in Himalaya Region Reveals the Complexity of the Crust and Upper Mantle |
| The abrupt rise of Himalaya and the uplift of Qinghai-Tibet plateau have been considered as the consequence of convergence, collision and compression between Indian and Asian plates, since Mesozoic and Cenozoic. Here we report the results of our first deep seismic reflection survey in Himalayan mountain country. The test profile is located within North Himalaya region,from Pagri, south of the Himalayan crest, to Samada, south of Kangmar. On the CMP stacke section following features are observed: 1) a mid-crustal strong reflection zone, that extends as far as 100 km and more, dipping gently to the north. It probably represents an active thrust or a huge decollement zone, along which the intact indian crust or its lower crust undsrthrusts southern Tibet; 2) an abundance of reflections in the upper crust, suggestive of large-scale structural imbrications; 3) the reflections of the lower crust suggesting some plastic rheological features; 4)a distinct Moho reflection in the southern part of the profile at a depth of about 72-75 km; and an additional secondary Moho in the south; 5) informative reflections acquired from beneath Moho at 32s 36s, 48s. TWas, implying stratifications (dipping north) of the upper mantle. All these results give substantial support to such views, that the intact indian continental crust or its lower crust underthrusts South Tibetan Tethyan Himalaya crust, resulting in thickening of southernmost Tibetan crust. |
| ZHAO Wen-jin,K. D. Nelson,CHE Jing-kai,L. D. Brown,XU Zhong-xin,GUO Zong-fen.1996.Deep Seismic Reflection in Himalaya Region Reveals the Complexity of the Crust and Upper Mantle[J].Acta Geoscientica Sinica,17(2):138-152. |
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