GEOLOGY, MINERAL RESOURCES, AND GEOARCHAEOLOGY OF THE MONTOYA BUTTE QUADRANGLE, INCLUDING THE OJO CALIENTE NO. 2 MINING DISTRICT, SOCORRO COUNTY, NEW MEXICO

The Montoya Butte 7½ quadrangle is part of the Mogollon-Datil volcanic field in the Sierra Cuchillo and San Mateo Mountains. Cañada Alamosa is the main drainage. The purposes of mapping the quadrangle were to 1) map and describe the structures controlling the mineral resources (including the boundaries of the Nogal Canyon caldera), 2) describe geologic processes that formed the landscape, 3) determine the mineral resource potential, 4) describe the geoarchaeology, 5) provide regional correlations of the rocks, and 6) provide the data required for studies of the surface and groundwater. Geologic mapping of the quadrangle was at a scale of approximately 1:12,000, using the USGS topographic map as a base as part of the NMBGMR state geologic map and mineral resources programs. Outcrop mapping techniques were employed where the approximate extent of the outcrop of the lithology was mapped in a darker color; the lighter color was used to identify areas of the same lithology that were covered and inferred to be present. Mapping showed that at least 3 separate geothermal systems were/are present: 1) the oldest forming the volcanic-epithermal veins (~28-36 Ma), 2) the system forming the Apache Warm Springs Be deposit (~24.4-28 Ma), and 3) the current, modern system related to Ojo Caliente and other warm springs feeding Cañada Alamosa. The mineral resource potential of the Apache Warm Springs Be deposit is low to moderate. But, additional exploration drilling could locate additional Be at depth. Any potential exploration or subsequent mining would have to plan for environmental issues, especially the affects of mining on the warm and cold springs feeding the Cañada Alamosa. Most Pueblo sites are found along the Montoya (Qtm) and Victorio (Qtv) stream terraces, downstream of the intersection of Kelly Canyon with Cañada Alamosa. The Pueblo people utilized local rhyolite and tuff, andesite, basalt, and siltstone in the majority of their lithic artifacts (including stone tools, hammer stones, and projectile points) found at the Pueblo sites. Some of the lithic artifacts, including obsidian, chert, quartzite, and silicified wood, are not found in the immediate area and were imported into the canyon. Local clays were likely used in the production of common pottery, but some of the glazed pottery was made elsewhere and imported into the canyon.