The Paraná-Etendeka Large Igneous Province (LIP) at the conjugate plate margins of South America and Africa is investigated with GOCE gradients. The LIP is associated to Gondwana breakup, and is asymmetric between the two margins. The study intends to investigate how the lithosphere is affected by continental breakup and what caused the asymmetry, considering that successive spreading is symmetric. The gradients at satellite and surface height are modelled with other geophysical data as seismic profiling, seismic tomography and bore-hole logs. Densities and velocities are modelled with a petrologic model. The residual gravity gradients, reduced of crustal thickness variations and sediments, are continuously high along the Angola and Namibia margin. Inversion shows the high is due to a density increase about 6 km thick with the top at about 23 km depth, placing it above the Moho. It is probable that the densification be due to magmatic intrusions, increasing the volume of the LIP at the African side, which remained trapped in the crust and produced only small volumes of surface basalts. This is true also for the margin of Angola, which in literature is claimed to be void of magmatism along its margin.

GOCE gradient tensor characterization of the coupled Parana' (South America) and Etendeka (Africa) magmatic provinces

BRAITENBERG, CARLA
2015

Abstract

The Paraná-Etendeka Large Igneous Province (LIP) at the conjugate plate margins of South America and Africa is investigated with GOCE gradients. The LIP is associated to Gondwana breakup, and is asymmetric between the two margins. The study intends to investigate how the lithosphere is affected by continental breakup and what caused the asymmetry, considering that successive spreading is symmetric. The gradients at satellite and surface height are modelled with other geophysical data as seismic profiling, seismic tomography and bore-hole logs. Densities and velocities are modelled with a petrologic model. The residual gravity gradients, reduced of crustal thickness variations and sediments, are continuously high along the Angola and Namibia margin. Inversion shows the high is due to a density increase about 6 km thick with the top at about 23 km depth, placing it above the Moho. It is probable that the densification be due to magmatic intrusions, increasing the volume of the LIP at the African side, which remained trapped in the crust and produced only small volumes of surface basalts. This is true also for the margin of Angola, which in literature is claimed to be void of magmatism along its margin.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11368/2840659
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