The gravity and isostatic Moho undulations in Qinghai-Tibet plateau

It is our interest to study the Moho depths in the Qinghai-Tibet. An iterative hybrid spectral-classical methodology is applied to invert the gravity data and obtain the 3D variation in Moho depth. The gravity inversion is constrained by results from deep seismic sounding and seismological investigations. The Moho is found between 70 and 75 km depth over most of Tibet. Maximum depths of up to 80 km are found along the margins of the plateau, and shallower depths of 65 km correlate with an important suture running along central Tibet (Bangong Nujiang). At Moho level most of Tibet is isostatically compensated at 90-110%, according to the Airy isostatic model. The Qaidam basin in NorthEastern Tibet and the Tarim basin to the North-West are found to be over-compensated.