The GRACE-satellite gravity and geoid fields in analysing large-scale,

Abstract

The recently released gravity potential field development derived from the Gravity Recovery and Climate Experiment satellite allows an unprecedented opportunity to use the gravity field to make global comparisons of structures of geological interest. The spatial resolution of the gravity field is sufficiently good to map large-scale or intracratonic and cratonic basins, as the areal extent of these basins is 0.5 × 106 km2 and greater. We present the gravity anomaly, Bouguer, geoid and terrain corrected geoid fields for a selection of nine large-scale basins and show that the satellite-derived field can be used to successfully identify distinctive structures of these basins, e.g., extinct rifts underlying the basins and generally the isostatic state. The studied basins are the Eastern Barents Sea, West Siberian, Tarim, Congo, Michigan, Amazon, Solim ˜ oes, Parnaiba and Paran`a basins. We complete the mapping of the gravity field with a description of the basins in terms of areal extension and depth, sedimentary age and presence and age of volcanism. Interpretation of the satellite gravity anomalies and considerations regarding the crustal thickness as known from seismic investigations, allows us to conclude that for the greater part of the basins there is evidence for high-density material in the lower crust and/or upper mantle. This density anomaly is, at least partly, compensating for the low-density sedimentary infill instead of the crustal thinning mechanism. For our selection of basins, crustal thickness variations and Moho topography cannot be considered as mechanisms of compensation of the sedimentary loading, which is a clear difference to well-defined rift basins.