EGU21-15215
https://doi.org/10.5194/egusphere-egu21-15215
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

An integrated thermo-compositional model of the African cratonic lithosphere from gravity and seismic data

Nils-Peter Finger1,2, Mikhail K. Kaban1,3, Magdala Tesauro4,5, Walter D. Mooney6, and Maik Thomas1,2
Nils-Peter Finger et al.
  • 1Helmholtz Centre Potsdam German Research Centre for Geosciences - GFZ, 1.3 Earth System Modelling, Potsdam, Germany
  • 2Free University Berlin, Berlin, Germany
  • 3Schmidt Institute of Physics of the Earth, RAS, Moscow, Russia
  • 4University of Trieste, Trieste, Italy
  • 5University of Utrecht, Utrecht, Netherlands
  • 6US Geological Survey, Menlo Park, USA

The presented model describes the lithospheric state of the cratonic regions of Africa in terms of temperature, density and composition based on joint analysis of gravity and seismic data. In addition, a new model of depth to the Moho was calculated from available seismic data. It was then used in combination with data on topography, sediments, and deep mantle anomalies to obtain residual mantle gravity and residual topography. These residual fields were corrected for thermal effects based on S-wave tomography and mineral physics constraints, assuming a juvenile mantle. Afterwards, the thermally corrected fields are jointly inverted to uncover potential compositional density variations. Following the isopycnic hypothesis, negative variations in cratonic areas are interpreted to be caused by iron depletion. Adapting the initially juvenile mantle composition allows to iteratively improve the thermal and compositional variations, culminating in a self-consistent model of the African lithosphere. Deep depleted lithospheric roots exist under the Westafrican, northern to central Congo, and Zimbabwe Cratons. The temperatures in these areas range from below 800 °C at 100 km depth to 1200 °C at 200 km depth. Higher temperatures and absence of depletion at depths below 100 km in wide areas of the eastern to southern Congo and the Kaapvaal Cratons indicate a thinner and strongly reworked lithosphere.

How to cite: Finger, N.-P., Kaban, M. K., Tesauro, M., Mooney, W. D., and Thomas, M.: An integrated thermo-compositional model of the African cratonic lithosphere from gravity and seismic data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15215, https://doi.org/10.5194/egusphere-egu21-15215, 2021.

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