The structure and the surface manifestation of mantle plumes in depth-dependent three-dimensional models

Abstract

Thermal convection has been modeled using a 3D Cartesian model, in order to study the structure of mantle plumes and their surface manifestation. Hotspots can be regarded as the surface manifestation of mantle plumes. The main characteristic features of the hotspots are their volcanism, topographic, geoid and heat flow anomalies. The following characteristics of the hotspot-generator plumes are studied: their geometrical size, temperature distribution, the horizontal extent and maximum amplitude of the surface features: geoid, topographic and heat flow anomalies. The aim of the model calculations is to investigate the effect of depth-dependent viscosity and internal heating in case of scaling the non-dimensional result for upper and whole mantle convection. When upper mantle convection is supposed, the calculated amplitudes of the anomalies fit well to the observed values, but their lateral extent is too small. The extent of the anomalies suggests whole mantle plume. Taking into account the high viscosity of the lithosphere, the low viscosity of the asthenosphere and the D″ layer at the CMB and using internal heating helps to gain better fit to the observations. The most complex whole mantle model predicts quite realistic features, except the topographic height.