Crustal structure of the southern Argentine passive margin and implication for plume influence during breakup.

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Within the proposed study we will investigate the deep structure of the Argentine margin at 50°S to 45°S, i.e. at the transition between the volcanic margin of southern Argentina and the sheared margin which bounds the Falkland Plateau to the North. Existing wide-angle reflection/refraction data will reveal the deep structure of the crust and especially the amount of magmatic underplating. The resulting velocity-depth model will be used to improve processing of the multichannel seismic (MCS) data to confirm the weak indications for seaward dipping reflector sequences (SDRs) at the sheared margin and also the deep structures. The results will be used to quantify the amount of emplaced volcanic/magmatic material as a function of the distance from the plume head. This will enable a re-evaluation of different rift models and of the mechanisms for the emplacement of the volcanics. In a second phase of the project (Post-Doc) we will extent the studies to the north. We propose to study the extent of pre/syn-rift grabens, stretching factors, variations in upper versus lower crustal extension all along the Argentine margin. The study will resolve the variability of crustal and volcanic/magmatic structures along the margin and will shed new light on the evolution of the South Atlantic Rift.