Latest Pennsylvanian and earliest Permian fusulinid biostratigraphy, Robledo Mountains and adjacent ranges, south-central New Mexico

Abstract

The Robledo Mountains of south-central New Mexico, and the Dona Ana and San Andres Mountains to the east, expose rocks of Late Pennsylvanian and Early Permian age (290 million years old). The Robledo Mountains contain one of the most continuous marine carbonate sections through the Pennsylvanian--Permian boundary in the southwestern United States. These strata contain the fossil remains of fusulinids, tiny single-celled animals now extinct. The abundance, diversity, and visibility in these rocks of these microfossils allow a detailed understanding of the age of these strata, and allow the authors to correlate these rocks with rocks of similar age in other parts of the United States. The authors describe this unique stratigraphic section in some detail with an emphasis on fusulinid remains, including descriptions of new species not previously reported from this area. Based on their detailed work in the field and the laboratory, the authors propose the Robledo Mountains section as a new reference for the Pennsylvanian--Permian boundary in southwestern North America