La Isla Santa Clara, testigo morfoestructural de la evolución geodinámica plio-cuaternaria y actual del Golfo de Guayaquil.

Abstract

Este contexto estratigráfico y estructural, hace que la Isla Santa Clara sea un testigo directo de los eventos neotectónicos del Golfo de Guayaquil. El estudio realizado en la Isla Santa Clara se ha desarrollado bajo dos objetivos: 1. Obtener datos detallados de la evolución temprana y actual de la Isla, en base a nuevos datos de estratigrafía y morfología, 2. Encuadrar la evolución de la Isla dentro del contexto sismotectónico y estructural del Golfo de Guayaquil, a fin de precisar la localización de las fallas potencialmente activas.

We made a detailed revision of the stratigraphic, morphologic and structural data of the Santa Clara Island and its area, with the prospect of define the recent geodynamic evolution of the island during quaternary up to present. A descordance has been evidenced in the Santa Clara island Mayor between the deposits of the Verdosa (below) and Amarilla series (over). It allows to point out the change from a relatively stable sedimentation and paleogeography to a system of transgresive and prograding sequences. This change is accompanied by the occurrence of sismites just over the discordance. The island appear mostly during the quaternary, and seem to fit with the rising of a clay diapiro, as suggested by the batimetric data showing the rounded shape of the subtidal platform around the island. A comparison between the regional sismicity and the structures known from seismic profiles near the island allows to precise the position of the Dolores-Guayaquil fault inside the gulf. From the Puná Island the Dolores-Guayaquil fault continues to the WSW, passing near the south border of the Santa Clara Island, and continuing along the south margin of the Esperanza structure, joining known structures on the border and the continental shelf. This result allow to precise the position of the presently active fault segments of the Dolores-Guayaquil fault system in the central and western part of the Gulf of Guayaquil, that remain uncertain on previous published schemes.