Antarctica 3-D crustal structure investigation by means of the Bayesian gravity inversion: the Wilkes Land case study

Abstract

SUMMARY In this study, a Bayesian gravity inversion algorithm is applied to infer a complete 3-D density model of the crust in the region of the Wilkes Land. One of the main objective of this work is to provide information on the thickening/thinning of the crust beneath the basin or the amount and characteristics of sediment deposits in the area. After collecting all the latest available geophysical data and models of the study region, neglecting gravity derived information, a first 3-D model was defined in terms of principal geological horizons and density distribution together with an estimate of its accuracy. Then, two gravity observations, namely gravity disturbances and second radial derivative of the anomalous potential, were jointly inverted in order to adjust the a-priori 3-D model and obtain the so-called a posterior improved model, now coherent with gravity. The present work summarizes the principal results obtained within the inversion performed in the Wilkes Land region together with a sensitivity analysis to assess the reliability of the inverted 3-D model. The results show a crustal thickness below the Wilkes Land higher than 25 km, characterized by higher densities, sedimentary basins that reach in some zones thicknesses of about 7 km and geometries below the Trans-Antarctic Mountains that suggest a large root of the mountains and lighter mantle densities.