COUPLING RELATIONSHIPS BETWEEN OROGENS AND BASINS,LOWER CRUST AND UPPER CRUST IN THE QINGHAI—TIBET PLATEAU

摘要

Uplift|related geological and geophysical data available from regional geological mapping , detailed structural, tectonic, granitic, volcanic, metamorphic , geochronological studies, deep seismic reflection, wide|angle seismic experiment, seismic tomography, broadband seismic network, and magnetotelluric sounding of key areas of the Qinghai—Tibet plateau are radically different from models of plate subduction or collision. Key geological features include: (1) obvio us time difference between plate collision and uplift of the plateau; (2) developments of intracrustal low|velocity layers , low resistivity layers and discontinuous subhorizontal reflectors; (3) similar results between the rate and time of uplift of the Qinghai|Tibet plateau and the time and rate of subsidence of its surrounding basins; (4) subhorizontal detachments and metamorphic core complexes occurred in Himalayan and Longmenshan; (5) weak deformation of late Cenozoic sediments and development of major steeply to gently dipping normal faults in the central part of the plateau; (6) discovery of high pressure and ultrahigh pressure metamorphic rocks in Nanbajiawa; (7) young volcanic rocks distributed from the northern plateau to the southern plateau; (8) nearly concordant processes among thrusting , mountain building, horizontal extension and intrusion of leucogranite in Himalayans.