Cenozoic volcanic geology of the Basin and Range province in Hidalgo County, southwestern New Mexico
— Edmond G. Deal, W. E. Elston, E. E. Erb, S. L. Peterson, D. E. Reiter, P. E. Damon, and M. Shafiqullah

This is a preliminary report on the Cenozoic volcanic geology of an area of about 5,000 km² (fig. 1). Hidalgo County occupies the southwestern corner of New Mexico, a part of the Mexican Highlands section of the Basin and Range province. The region of which it is a part was involved in the mid- Tertiary "ignimbrite flareup" and its volcanic stratigraphy is characterized by numerous sheets of felsic ash-flow tuff. A number of source calderas have been identified and seem to be associated with small mineral deposits. This paper summarizes the stratigraphy and structure of the mid-Tertiary volcanic rocks.

 

This project began in 1973 and is still in progress. The first stages of the present study, in 1973 and 1974, were supported by NASA grant NGR-32-004-062 from the Planetology Office. For the main part of the present study, the New Mexico authors gratefully acknowledge support from New Mexico Energy Resources Board grants 75-109, 75-117, 76-264, 76-350, and 77-3104 and U.S. Geological Survey grants 14-08-001-G-255 and 14-08-001-G-348. Peterson's work was partly supported by Leonard Resources of Albuquerque, N.M. and the New Mexico Bureau of Mines and Mineral Resources. Damon and Shafiqullah are responsible for K-Ar dating and acknowledge support from NSF grant EAR 76-02590 and the State of Arizona. D. J. Lynch assisted in the analytical work at the University of Arizona.

 

Previous work by others includes mapping in the Animas Mountains by Zeller (1967) and Zeller and Alper (1965), in the Alamo Hueco Mountains by Zeller (1958), in the Peloncillo Mountains by Gillerman (1958) and Wrucke and Bromfield (1961), in the Pyramid Mountains by Flege (1959) and in the Apache Hills by Strongin (1958). These authors did their work at a time when the relationship of ash-flow tuff sheets to large central caldera complexes was not understood. Our work has involved not only new geologic mapping but also extensive revision of older interpretations. All work, including ours, is limited by lack of knowledge from the border area of Mexico. Also, virtually all information comes from the ranges and very little comes from the intervening basins. Only fragments of the proposed caldera complexes are exposed to view. Considerably more petrographic and chemical work needs to be done before the stratigraphic correlations between ranges suggested in the paper are firmly established.