Stratigraphy, Sedimentology, and Paleoenvironment of Esquias Formation of Honduras

Abstract

The Formation of central Honduras is a thick sequence of carbonate rocks conformable within the upper part of the Valle de Angeles Group. The usage of the term Esquias in stratigraphic literature on Central America has been ambiguous and confusing. Some workers even have doubted that the exists. Recent studies in and near the type area of Esquias, Honduras, have clarified the nature, age, and stratigraphic relation of the Formation and constitute a basis of formal redefinition. The Upper Cretaceous Valle de Angeles Group is dominantly a succession of red, mixed terrigenous and marine strata that conformably overlie carbonate rocks of the Lower Cretaceous Yojoa Group. These red strata are about 3,000 m thick and are distributed widely throughout Honduras. The only named formation within the Valle de Angeles Group is the Formation, which essentially divides the Group into upper and lower redbed sequences. At its type locality the Formation is a 470-m thick sequence of calcilutite, marlstone, and calcarenite. Lithically it is similar to, although somewhat more argillaceous than, limestones of the Yojoa Group exposed in the same area. Collections of molluscan and echinoid faunas indicate that the Formation is probably Cenomanian in age. > Interpretations of stratigraphic relation, petrology, biofabric, and faunal assemblage suggest that the was deposited under shallow, nearshore marine conditions, probably within lagoons and marine embayments that encroached across a complex paleogeographic surface. The region simultaneously was being subjected to early phases of Laramide orogenesis. The Formation seems to be an enigmatic synorogenic transgressive-marine sequence, and thus reflects the Mesozoic tectonic evolution of northern Central America.