New Mexico Geological Society Annual Spring Meeting — Abstracts

Copper Hill, in the Picurus Mountains of northern New Mexico, is the expression of a west-plunging anticline of Ortega Quartzite. The Ortega Quartzite at Copper fill has been divided into three stratigraphic units: massive quartzite (0_q1), kyanite quartzite (0_q2), and andalusite quartzite (0_q3). During structural deformation, the lower two quartzite units behaved brittely, while 0_q3 and the overlying Rinconada schists behaved ductilely. These ductile units formed an impermeable cap to a series of N10°E-trending quartz veins that cut the lower quartzite units. Oxidized copper minerals with silver, arsenic, and antimony occur in 0_q1 and 0_q2 quartzite and in the quartz veins on Copper Hill. The deposit, of probable Precambrian age, has been subjected to considerable metamorphism, deformation, and oxidation. Although a genetic model involving original strata-hound copper mineralization must be considered for the deposit, most evidence supports an origin involving epigenetic, although pre- or synmetamorphic, emplacement of copper minerals from a source at depth.