Bulletin 118—Isotopic ages of post-Paleocene igneous rocks within and bordering the Clifton 1º x 2º Quadrangle, Arizona–New Mexico

By R. F. Marvin, C. W. Naeser, M. Bikerman, H. H. Mehnert, and J. C. Ratté, 1987, 63 pp., 10 tables, 5 figs., 1 plate.

This report is a compilation of isotopic ages and analytical data from more than 200 samples of volcanic and subvolcanic igneous rocks of the western and central parts of the Mogollon-Datil volcanic field. More than one-half of the tabulated ages have never been published. In addition to the compilation of ages, the report includes brief discussions of some of the problems involved in conventional K-Ar and fission-track dating of rapidly erupted volcanic sequences in a large, complex volcanic field and includes some of the specific volcano-stratigraphic problems in this part of the Mogollon-Datil field.

In recent years, numerous K-Ar and fission-track ages have been determined for volcanic rocks of the Mogollon–Datil volcanic field. Most of these dated rocks were collected within or peripheral to the Clifton 1º x 2º quadrangle of Arizona and NM. However, the Clifton quadrangle encompasses only part of the Mogollon-Datil volcanic field. This compilation of isotopic ages lists more than 200 samples of post-Paleocene igneous rocks. Slightly more than ½ of the tabulated ages have never been published. Also included in this compilation are unpublished analytical data pertaining to tabulated ages that have already appeared in print. The purposes of this compilation are 1) to present the currently available age data that are pertinent to establishment of viable volcanic stratigraphic sequences in the western and central parts of the Mogollon-Datil volcanic field, 2) to describe some of the problems associated with dating the rocks of a complex volcanic field and the efficacy of different radiometric dating methods, and 3) to discuss the application of the ages in the compilation to certain specific geologic problems in the western and central parts of the Mogollon-Datil field.

In the main body of the compilation, the source of the age is indicated, and an accurate sample location is given. The entry number is followed by the author and date of publication, if the age has been published previously. If the age is new, the entry number is followed by a field number. For a few samples, the published age was not accompanied by a sample number. The entry line is followed by the rock name or stratigraphic unit; the correlations are generally those of the authors unless a reference is given. Where the correlation differs from that of other workers, an explanation commonly follows. Samples are located according to latitude and longitude, section and township and range, name of 7½- or 15-min topographic quadrangle, county, state, and additional descriptive location if available and useful.