Cenozoic rocks of the Santa Rita Mountains, southeast of Tucson, Arizona

The Santa Rita Mountains of southeastern Arizona are underlain, in part, by volcanic and sedimentary rocks and by many small intrusives, of Cenozoic age. These rocks provide a more complete geologic record than that of other ranges in the region, and consequently the Santa Rita Mountains are a useful reference area from which to develop the Cenozoic geologic history of the region. Many isotopic ages provide the basis for dating key units and add to the confidence in the interpretations of the geologic record of the rocks themselves. The rocks of the greatest potential economic interest are the Greaterville intrusives of the Helvetia and Greaterville mining districts and the quartz vein swarm of the Tyndall and Wrightson mining districts.