The Kerguelen plateau: Records from a long-living/composite microcontinent

The Kerguelen Plateau lies in the Southern Indian Ocean and is classically considered as a Large Igneous Magmatic Province (LIP) emplaced above an oceanic crust. The interpretation of the gravimetric/bathymetric anomalies shows that the Plateau is structured by NNW- and NW-trending en échelon fractures along its north-eastern border and by WNW-trending faults along its western side which separate very differentiated zones (i.e. Elan Bank and Enderby Basin). A geochemical contamination by continental material has been evidenced for all the studied magmatic rocks of the southern and central part of the Plateau, only the basalts of the northern zone recording the signature of ridge emitted magmas. The facies evolution of the overlying sediments also shows that the deposition began in a subaerial environment for the southern part of the Plateau and that the subsidence notably increased after 60 Ma. All these evidences suggest that the Southern part of the Kerguelen Plateau is underlain by stretched continental crust as it is the case for Elan Bank, and that the Central Kerguelen Plateau is most probably also underlain by attenuated continental crust. In reconstructions, the South and Central Kerguelen Plateaus resulted from the interaction between these remnants of continental crust with the Kerguelen Plume while the latter interacted with the South East Indian Ridge to form the North Kerguelen Plateau. We thus propose a cinematic scenario characterised by the formation of a composite microcontinent composed of fragments of stretched continental crust, separated by ridge propagators which were emplaced successively or contemporaneously between India and Antarctica, during the rifting process, being triggered by the Kerguelen plume emplacement.