印度板块俯冲到藏南之下的深反射证据  

Deep Seismic Reflection Evidence for Continental Underthrusting beneath Southern Tibet

作　　者：赵文津[1] K.D.纳尔逊 

机构地区：[1]中国地质科学院,美国纽约锡拉丘兹大学

出　　处：《地球学报（中国地质科学院院报）》1996年第2期131-137,共7页Acta Geoscientia Sinica

基　　金：国家自然科学基金

摘　　要：喜马拉雅和相邻的西藏高原，构成了地球上最大的高原和异常厚地壳的地区，是作为印度板块和亚洲板块新生代碰撞的结果，并被认作是典型的陆－陆碰撞［１．２．３．］地带。在此，我们报道了用深地震反射剖面方法进行本区地壳成像的第一个结果，试验的１００ｋｍ长剖面，布置在特提斯喜马拉雅（ＴｅｔｈｙａｎＨｉｍａｌａｙａ）最南端，且跨过了喜马拉雅山脊，接近高喜马拉雅（ＨｉｇｈＨｉｍａｌａｙａ）地带，剖面显示了在地壳中部有一强反射带。它可能代表了一个活动的道冲断裂，印度板块是沿此断裂俯冲到藏南之下；上地壳反射使人们联想到上地壳存在着大规模的叠瓦状结构；莫霍反射来自本区双倍正常地壳厚度的巨厚地壳的底部。这些结果对西藏南端地壳增厚，是由于印度大陆地壳整体俯冲到包括特提斯喜马拉雅地区地壳之下的观点，给予了实质性的支持。he Himalaya and adjacent Tibetan plateau, constituting Earth's largest region of elevated topography and anomalously thick crust, formed as a consequence of Cenozoic collision between india and Asia-itself considered the archetypal continent-continent collision. Here we rePOrt the first results from an attempt to image the structure of the crust beneath this region using deep seismic reflection profiling. Our￣100km-long profile, acquired in the Tethyan Himalaya, shows a midcrustal reflection that probably marks the active thrust fault along which the indian plate is underthrusting southern Tibet; upper-crustal reflections with geometries suggestive of large-scale structural imbrication of the upper crust; and Moho reflections from the base of the double-normal-thickness crust underlying the region. These results lend substantial support to the view that crustal thickening beneath southernmost Tibet was accomplished by wholesale underthrusting of indian continental crust beneath the structurally imbricated upper crust comprising the Tethyan Himalaya.

关 键 词：深地震反射 印度板块 亚洲板块 陆-陆碰撞 

分 类 号：P542.4[天文地球—构造地质学]