Specific gravity field of the ''''Himalayas east structural knot''''
喜玛拉雅“东构造结”地区特异重力场的探讨

More than half of the 'Himalayas east structural knot' area (92°E~97°E, 26°N~30°N) that stretch cross boundaries of China, India and Burma has no ground gravity measuring point yet. Here it is hard to research directly the gravity field characteristic and the deep crustal structure. In this paper, the satellite gravity anomaly data are employed as pseudo free air gravity anomaly to calculate Bouguer gravity anomaly. The calculated Bouguer gravity anomaly exhibits well mirror correlation with the topography altitude of this district. It can be used to research the deep crustal structure. Three profiles of deep crust structure according to three Bouguer gravity anomaly profiles are obtained. In Tibetan plateau the crust thickness is more than 70 km, in orogenic belt of Himalayan mountains it is about 55 km of, in Brahmaputra basin valley it is 33 to 35 km, and in Naga mountain it is 40 to 45 km. Three tectonic units are displayed. The Brahmaputra tectonic unit in 'east structural knot' is composed of high-density matter, moves northward after collision and extrusion by Indian Ocean plate, and then inserts into east margin of Tibetan plateau. This dynamic process results in violent tectonic movement of southeast and northeast edges of Tibetan plateau, induces a series of earthquakes frequently. At last, some conclusions are advanced.