A reappraisal of the cenozoic inner arc magmatism in Southern Peru : consequences for the evolution of the central Andes for the past 50 Ma

The Altiplano, a high plateau 200 km-wide and 1500 km-long is undoubtely the major feature of the Central Andes. One of its most characteristic feature is the presence of varied magmatic events, referred to as the Inner Arc Magmatic Domain by Clark et al. (1990). This magmatism started about 48 Ma ago and shows a greater diversity compared to the Main Arc Domain of the Western Andean Cordillera. Several occurrences of phlogopite lamproites, phlogopite-diopside-sanidine lamproites and ultrapotassic minettes have recently been discovered (Carlier et al., 1996) in addition to the peraluminous magmatism of dominantly crustal origin and high-K calc-alkaline to shoshonitic volcanism previously identified (Pichavant et al.. 1988; Clark et al., 1990). This led to a reappraisal of the Cenozoic Inner Arc magmatism in Southern Peru, which is presented here along with new age determinations and geochemical data on the ultrapotassic lavas, the high-K calc-alkaline to shoshonitic volcanism and the calc-alkaline plutons. These data provide important informations on the evolution of Central Andes for the past 50 Ma.