New constraints on transient lower mantle rheology and internal mantle buoyancy from glacial rebound data

Abstract

A model of mantle rheology which has an explicit transient component of its relaxation spectrum is shown to reconcile two apparently conflicting inferences of lower mantle viscosity. If recent analyses of isostatic geoid anomalies are correct in requiring a large increase of viscosity with depth, then the weak viscosity stratification demanded by postglacial rebound data implies the importance of such rheological behaviour, at least in the Earth's lower mantle.