ON THE STRUCTURAL FEATURE IN THE CENTRAL PART OF XIZANG (TIBET) AND OBDUCTION OF THE INDIAN PLATE

The feature of the aeromagnetic field in the central part of Xizang, with negative values as its background, reveals the flexible nature of the basement, which is composed of low-grade parametamorphic rocks.The North Xizang fault is not clear in the aeromagnetic map.Yarlung Zangbo rift is a suture line between the colliding plates. The aeromagnetie anomalous zone over the rift, is characterised by high intensity, excellent continuity and great extention. Geological and various geophysical data indicate that the fault plane is inclined to the south.Since the beginning of the upper Triassic epoch, the Indian plate upthrusted to the north over the Tethys oceanic crust and led to the closure of the Tethys in Eocene epoch. After the collision of the two plates, the obduction movement was replaced by the pushment of the Indian plate towards the southern edge of the Eurasian plate.