Estudio lito estratigráfico y sedimentológico de la división Guamote al occidente de la cordillera real, en Ecuador.

Abstract

The Guamote Division in the east of Riobamba city is formed by meta-sedimentary rocks affected by low-grade regional metamorphism and dynamo-metamorphism zones. It includes three stratigraphic units: Guasuntos Unit, Punín Unit and Cebadas Unit. This project characterizes these units based on lithostratigraphic, chemostratigraphy and petrographic studies. The Guamote Division is part of a tide dominated estuary system, including, subtidal-intertidal facies, with retrogradation to shelf faciesto the top. The Guamote Division has a reworking and transitional stratigraphic contact with the Maguazo Unit belonging to the Alao Division at the end of the sequence. These interpretations correlate with diagrams of tectonic discrimination, provenance, and rare earths (REE). Geochronology and biostratigraphic data indicate that the Guamote Division was deposited during the Late Jurassic to Early Cretaceous (Kimmeridgian-Valanginian) as a forearc basin. Finally, a possible analog present in the Abejorral Meta-sedimentary Complex of Colombia, which has lithological and geochronological characteristics like those recorded in the Guamote Division.