Advances on Stratigraphy and Paleontology of the Muhi Quarry from the Mid-Cretaceous (Albian-Cenomanian) of Hidalgo, Central Mexico

The Muhi quarry of Zimapán Hidalgo, Central México, is one of the most important Cretaceous fish localities of the country because of the great diversity of fishes, and the significance of their record in America. Here we present some advances of the stratigraphy, including a litostratigraphic description, a generalized report of the marine fauna recovered, and the depositional environment of the outcrop. The sequence consists of a light gray mudstone/biomicrite, with chert forming nodules and/or thin layers, and additional marls are intercalated; the strata are assigned to La Negra Facies of the Mid-Cretaceous (Albian-Cenomanian) El Doctor Formation from northeastern Querétaro, south-central and northwestern Hidalgo (this report). The lithology and fossils are indicative of open sea shelf to deep shelf margin Standard Facies Zones, comparable to the Standard Microfacies Types SMF 2 (microbioclastic limestone) and SMF 3 (pelagic mudstone).