Abstract

The Colombian Andes are characterized by a dominant NE structural trend, which is offset by ENE-trending right-lateral and NW-trending left-lateral structures. NE-trending faults are either dip-slip or oblique thrusts, generated as a result of a trans-pressive regime active since at least Palaeogene times. NW-trending faults are considered to be reactivated pre-Cretaceous extensional structures. Right-lateral shear on ENE-trending faults has resulted from oblique convergence between the Nazca Plate and the Northern Andes. Major changes in the geometry of the oblique-plate convergence between the Nazca and South American plates have generated the northward ‘escape’ of the Northern Andes and stress-strain partitioning within the mountain belt. These strike-slip structures have exerted important controls on sedimentation, source-rock distribution, fluid flow and ore mineralization during Cenozoic times. The interpretation of the Northern Andes as a mountain belt affected by strike-slip deformation provides a structural context in which to reassess the exploration plays.