REGIONAL ISOSTATIC GRAVITY ANOMALIES AND MANTLE PLUMES IN SOUTHERN EAST SIBERIA (RUSSIA) AND CENTRAL MONGOLIA

Abstract

Isostatic gravity anomalies were inverted under the assumption that compensation of topographic loads is only partly provided by Moho depth variations but is to a large extent due to the geometry of the lithosphere/asthenosphere boundary. This approach allowed us to reveal regional (long-wavelength) gravity lows possibly associated with Late Cenozoic mantle plumes beneath the Baikal rift and mountains in Central Mongolia. The plume tails were simulated in several 3D gravity versions. The position of plumes predicted from gravity inversion is consistent with zones of low seismic velocities in the mantle and with azimuthal anisotropy as the plumes control mantle flow above their tails. The position of most plumes does not contradict the pattern of Late Cenozoic flood volcanism known from geological evidence.