Linear Inversion of geoid anomalies of Borborema Province: Compositional Variation or Thermal Perturbation in the Mantle?

Abstract

This MSc project aims to model and to interpret a 10 meters positive geoid anomaly over Borborema Province, NE Brazil. Geoid anomaly due to topography and crust thickness variation will be removed from observed geoid. Preliminary results suggest the existence of a negative geoid anomaly of deeper origin, caused by negative density contrast in the lower crust and upper mantle, possibly extending down into deep mantle (mantle plume?). Density variation may be either caused by compositional variation or thermal perturbation. Linear inversion of geoid anomalies techniques will be used to determine the extension, density contrast and origen of these anomalies. The hypothesis of thermal origin or compositional will be tested using independent constraints provided by geological and new geophysical observations scheduled to be collect withing two projects, the Instituto do Milenio-CMPq and FAPESP regular research grant # 2006/01211-1.