Lithospheric breakup: observations from magma-poor settings

As we multiply observations from magma-poor lithospheric breakups (i.e. the very last stage where mantle is exhumed and is finally replaced by oceanic crust), we are able to identify more and more similarities and differences, which could be characteristic from the initial rheology or from the inheritance of the broken lithosphere. Here we explore several study areas allowing to cover very different settings where mantle is exhumed: (1) The Australo-Antarctic Basin where breakup occurred in continental lithosphere in the East and in old oceanic lithosphere in the West, (2) the South-West Indian Ridge where very young oceanic lithospheric mantle is exhumed, (3) the young Gulf of Aden margins where the magma-poor or -rich nature varies laterally. We used seismic reflection data and potential field data in order to identify the key boundaries allowing to identify the lithospheric breakup. Different styles of deformation are observed, not all are understood. The on-going projects include the better understanding of the non-oceanic magnetic anomalies (not linked to magma-rich oceanic crust), the 3D modelling of the thermal state of the most distal margins, and acquisition of new data in the Bay of Biscay.