Modelo sedimentológico del miembro medio de la formación Gonzanamá.

Abstract

The intramountainous basins in Ecuador represent continental, marine and transitional sequences, developed during periods of tectonic activity. In particular, the Gonzanamá-Catamayo Basin, located in the Loja province, developed in continental and shallow marine environments during the Miocene. In this context, the stratigraphic and sedimentological study of the Middle Member of the Gonzanamá Formation, which is part of the Miocene succession of the Gonzanamá-Catamayo Basin, provides information on the transition from marine-continental environments and proposes a model of geological evolution of this basin during the Middle Miocene. Sedimentological and provenance analyses were performed on samples collected from outcrops of the Lower and Middle Member of the Gonzanamá Formation. The results of the heavy mineral and petrographic analyses reveal that the rocks that constitute the Lower and Middle Member of the Gonzanamá Formation came from volcanic arcs. In addition, the results of the sedimentological analysis indicate that the depositional environment for the Lower Member of the Gonzanamá Formation is a continental environment, while for the Middle Member the accumulation of the sediments is in a marine-marginal environment. The discussion of the present work concentrates on interpreting the depositional environments and the origin of the sediments for the Lower and Middle Members of the Gonzanamá Formation. In addition, geological model consistent with the results obtained is discussed and proposed. This study provides stratigraphic and sedimentological notions necessary to understand the evolution of the Gonzanamá-Catamayo Basin during the Middle Miocene.