Abstract

This work characterizes Late Cretaceous calc-alkaline volcanic rocks in Gastre, Northern Patagonia, Argentina. These newly found porphyritic rocks bear an 40Ar–39Ar amphibole age of ~ 74–76 Ma, a subduction-type geochemical signature and a deep, garnet-bearing source. Extruded in a stage of low magmatic activity in the Northern Patagonian Andes (~ 41–44° S), they could represent an eastward migration of the Late Cretaceous magmatic arc that was associated with a regional compressive deformational stage in the South American margin.

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