Magnetic fabric of diorites and tonalites emplaced in subduction zones (Central Cordillera, Colombia)

Abstract

The Colombian Andes consist of Permo-Triassic to Cretaceous magmatic belts accreted to the South America continental plate. These belts were formed during the subduction of the oceanic Pacific and Caribbean lithospheres combining periods of extension and emplacement of magmatic rocks, and compression (accretion) followed by inversion of sedimentary basins and deformation of the plutonic rocks. The project aims to investigate the magnetic fabric of a Triassic diorite and an Eocene tonalite situated in the Cordillera Central of the Colombia. The diorite was emplaced in an extensional setting associated with subduction of the Pacific plate while the tonalite records the accretion of volcanic arcs to the continental margin during high-oblique convergence of the Caribbean plate. AMS of these plutons provides, therefore, the emplacement structures acquired in well-controlled plate setting. Moreover, Ar/Ar determinations will bring additional information on cooling and exhumation of these rocks. By combining these methodologies we intend to characterize the deformation of plutonic rocks emplaced in a continental magmatic arc and particularly its significance in subduction zones. (AU)