Geology and mineral deposits of the Orogrande mining district, Jarilla Mountains, Otero County, New Mexico
Virginia T. McLemore, Nelia Dunbar, Lynn Heizler, and Matthew Heizler
The Orogrande mining district, in the Jarilla Mountains in Otero County, lies within two important mineralized tectonic provinces of the Southwest USA: (1) the Arizona-Sonora-New Mexico porphyry copper province and (2) the Rocky Mountain alkaline belt. The igneous rocks in the Jarilla Mountains are subalkaline to alkaline, metaluminous to peraluminous, and plot as monzonite to quartz monzonite to granodiorite to syenodiorite on geochemical discrimination diagrams. 40Ar/39Ar hornblende and alkali-feldspar dating show that the intrusions range between 45.6 and 41.4 Ma. The igneous rocks in the Jarilla Mountains and associated mineral deposits represent the transition between arc-magmatism, which formed the porphyry copper deposits, and extension-related alkaline magmatism and related mineral deposits, such as those found in the Rocky Mountain alkaline belt. Types of mineral deposits found in the Orogrande district include (1) placer gold, (2) skarns and replacement deposits, (3) veins, (4) porphyry copper deposits, and (5) turquoise deposits. Gold, silver, copper, lead, tungsten, iron ore, and turquoise have been produced from the Orogrande district and additional mineral resources are likely present. In addition, the district has potential for the production of garnet for the abrasives industry. Additional geochemical analyses of the deposits including tellurium are recommended as future investigations are conducted.
- McLemore, Virginia T.; Dunbar, Nelia; Heizler, Lynn; Heizler, Matthew, 2014, Geology and mineral deposits of the Orogrande mining district, Jarilla Mountains, Otero County, New Mexico, in: Geology of the Sacramento Mountains region, Rawling, Geoffrey; McLemore, Virginia T.; Timmons, Stacy; Dunbar, Nelia, New Mexico Geological Society, Guidebook, 65th Field Conference, pp. 247-259.