Microfossil diversity in the Tarahumara Formation, Sonora

Abstract

A great diversity of permineralized microfossils are found embedded in chert associated to stromatolites that crop out in the Huépac locality, an Upper Cretaceous (Turonian–Maastrichtian) volcano- sedimentary sequence of the Tarahumara Formation, in Sonora, Mexico. The diversity is represented by fossils of microalgae, pollen, spores, conidiospores, fragments of plants and arthropods, achritarchs and undefined structures of biological origin, reflecting the type of organisms that lived asssociated to the water body and part of the surrounding biota. Our observations support the interpretation of a lacustrine depositional environment associated to magmatism in this portion of the Formation. This work documents part of the Upper Cretaceous microflora and microfauna of the northwestern Mexico.