Abstract A multi-event tectonic episode that affected the Caribbean and South American Plate boundaries as well as Cenozoic oil generation is based on new structural and geochemical data from the western Falcón Basin, Venezuela. It involves Late Cretaceous to Middle Eocene emplacement of the Lara Nappes followed by Late Eocene to Early Miocene tectonic collapse and graben formation, Middle Miocene inversion and out of sequence thrusting. Oil-source rock correlation of seeps in the northern part of the basin suggests a Cenozoic siliciclastic source rock deposited under suboxic to anoxic conditions. Potential Cenozoic source rocks and Late Cretaceous La Luna Formation were used to evaluate the generation conditions using one- and two-dimensional thermal modelling. A heat flow of c . 190 mW m −2 was reached during the Oligocene–Early Miocene in the central part of the basin. As a result the Cretaceous source rock is overmature, while the primary Cenozoic source rocks are in the oil window. The thermal modelling also suggests that hydrocarbon accumulations are mainly located on the flanks of the graben, with small amounts possible in the centre, due to erosion during basin inversion. This modelling is highly consistent with the proposed polyphase tectonic model.

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.