GSA 2020 Connects Online

Paper No. 247-10
Presentation Time: 12:40 PM

A MULTI-OBSERVABLE JOINT INVERSION FOR SOUTHERN AND CENTRAL AFRICA IN FULL 3D


FOMIN, Ilya1, BEN MANSOUR, Walid2, AFONSO, Juan Carlos1, MACDONALD, Andrew3 and JANUSZCZAK, Nicole4, (1)Earth and Environmental Sciences, Macquarie University, Level 1, Office 124, 12 Wally's Walk (E7A), North Ryde, Sydney, NSW 2109, Australia, (2)Department of Earth and Planetary Sciences, Washington University in Saint Louis, Saint Louis, MO 63130; Earth and Environmental Sciences, Macquarie University, Level 1, Office 124, 12 Wally's Walk (E7A), North Ryde, Sydney, NSW 2109, Australia, (3)Exploration Team, De Beers Group, Johannesburg, South Africa, (4)De Beers Group, Toronto, ON 0000, Canada

The thermochemical structure of the Earth’s lithosphere and sublithospheric upper mantle controls the pattern of geophysical observables and is closely linked to the spatial distribution of mineral deposits. Its imaging in 3D is a significant challenge due to the large number of factors that can affect geophysical signatures and the non-linearity of the inverse problem.

We have developed a new software (LITMOD3D_4inv) to perform a multi-observable joint inversion in full 3D, combining several independent sources of data (gravity, seismic and magnetotelluric observations supported with petrological data for mantle composition) to improve the sensitivity and parameter identifiability. The code uses Markov chain Monte-Carlo procedures with highly optimised forward problem solvers to sample the parameter space and determine geological structures and features with full characterisation of their uncertainties.

The program explored the thermochemical structure of the Kalahari craton and the Damara orogenic belt (Southern Africa), an area strongly affected by kimberlitic and carbonatitic volcanism. In this presentation, we will discuss the main results, interpretations in the terms of geological features and discuss the implications for evolutionary models of the region.