Tectono - estratigrafía del borde centro – occidental de la cuenca de Manabí entre Bahía de Caráquez y Pedernales

Abstract

The central - western sector of the Manabí basin between Bahía de Caráquez and Pedernales, east of Jama, is constituted by an igneous Cretaceous basement that is overlay by a sedimentary sequence of different ages that go from the Cretaceous to the Plio - Pleistocene. The petrographic analysis carried out from field work has allowed the definition of seven lithological units located in the area. While the structural analysis indicates that the zone is dominated by a transpressive tectonic environment evidenced by the presence of a positive flower structure attributed to the Jama fault system. The evolution of the zone is marked by different deformation events, establishing itself as the most important: the accretion of the oceanic plateau to the paleo-continental margin in the Campanian. The development of an extension phase in the Miocene evidenced by a normal fault of direction NNE - SSW (Jama proto fault) in the southwestern edge of the basin. The tectonic inversion produced by a change to compressive stresses in the Middle Miocene that generates a drag anticline and the migration of the depocenter of the basin. Finally, for the Pleistocene the coastal block is segmented with the transpressive dynamics of the current Jama Faults System.