Southwest Laramide Porphyry Belt

Region West, Southwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Extent of known Laramide (late Cretaceous to early Paleogene) magmatism and mineralization; in New Mexico, includes the area from Lordsburg to Hillsboro (Leveille and Stegen, 2012; Greig and Barton, 2019).
Identified resources Identified resources and historical production in Arizona and New Mexico of copper, gold, molybdenum, and silver.
Production Arizona: 75 million tonnes, ca. 2011 (Leveille and Stegen, 2012); New Mexico: Cu, Ag, Au, Mo production in many districts (see McLemore, 2017); total Cu production from 1804-2006 of 8,360,929 short tons (McLemore, 2008).
Status Arizona: Past and active mining and exploration; New Mexico: Chino and Tyrone currently active, Copper Flat being permitted, exploration in Lordsburg and Little Hatchet Mountains.
Estimated resources Arizona: 220 million tonnes, in about 2011 (Leveille and Stegen, 2012); New Mexico: Chino, 53.9 million tons 0.687% Cu and 0.03% Mo and 360Mt of ore at 0.1 g/t In (Werner and others, 2017); Tyrone, 230.2 million tons 0.35% Cu (leachable); Copper Flat, 60 million tons 0.42% Cu and 0.012% Mo (mineable) (McLemore, 2008).
Geologic maps Ferguson and others (2019), scale 1:24,000; Johnson, Ferguson and others (2019), scale 1:24,000; Richard and others (2019), scale 1:24,000; Spencer and others (2019), scale 1:24,000; Cornwall and others (1971), scale 1:24,000; Cornwall and Krieger (1975a, b), scale 1:24,000; Creasey and others (1983), scale 1:24,000; New Mexico Bureau of Geology and Mineral Resources (2003), scale 1:500,000.
Geophysical data Variable, with inadequate and adequate areas.
Favorable rocks and structures Laramide (Late Cretaceous-Early Paleogene) intrusive rocks, and Paleozoic carbonates in southeastern Arizona and southwestern New Mexico. Regional structures do not convincingly play a role with location of emplaced plutons, but the regional extensional deformation plays a significant role in the exposure and exploration of dismembered porphyry deposits.
Deposits Ajo, Bagdad, Bisbee (Jurassic), Carlotta, Casa Grade West/Santa Cruz, Cerrillos, Chilito, Christmas, Copper Basin, Copper Creek, Copper Flat, Dos Pobres-San Juan, Gibson, Hanover/Cobre, Johnson Camp/I-10, Lone Star, Lonesome Pine, Miami-Inspiration, Mineral Butte, Mineral Park, Mission-Pima, Morenci, Pine Flat, Pinto Valley/Castle Dome, Poston Butte/Florence, Ray, Red Mountain, Resolution, Rosemont/Helvetia, Sacaton, San Manuel-Kalamazoo, San Xavier North, Sanchez, Santa Rita/Chino, Sheep Mountain, Sierrita/Esperanza, Silver Bell, Squaw Peak, Sunnyside, Superior East, Tohono/Lakeshore, Twin Buttes, Two Peaks, Tyrone, Vekol Hills.
Evidence from mineral occurrences MRDS; USMIN; New Mexico Mines Database (McLemore and others, 2005).
Geochemical evidence Surface, soil, and rock anomalies, especially in reanalyzed NURE stream sediment data. Cobalt, REE, Al, Re, PGE in process and leachate waters, waste rock, and tailings; some critical minerals produced from smelter wastes.
Geophysical evidence Aeromagnetic, aeroradiometric, and EM surveys can all be useful if properly interpreted.
Evidence from other sources Skarns and epithermal-vein deposits can be spatially associated with porphyry copper deposits.
Comments Large regional geochemical sampling of porphyry copper deposits between Arizona and New Mexico is proposed, drill core at NMBGMR on selected deposits.
Cover thickness and description Variable and largely dependent on the degree of structural dismemberment. Largely upright unfaulted deposits are typically 1-2 km beneath the surfaces (for example, Sunnyside, Red Mountain, Resolution), whereas more extensively faulted deposits often have surface or near surface expressions, with faulted fragments at different levels. The cover can include faulted host-rocks, as well as synextensional sedimentary-volcanic rocks, and Quaternary deposits. See Richardson and others (2019, and references therein) for descriptions of variations in cover for porphyry deposits along the Pinal-Gila County border. Potential for buried or eroded deposits in fault-bounded basins in New Mexico.
Authors Carson A. Richardson, Virginia T. McLemore.
New data needs Regional geochemistry to identify areas with elevated critical mineral levels, and therefore areas for future detailed mapping; regional geophysics.
Geologic mapping and modeling needs Detailed mapping and detailed structural and subsurface analysis for subsequent mapping focus areas.
Geophysical survey and modeling needs High resolution, Rank 1 aeromagnetic and aeroradiometric coverage for subsequent mapping focus areas.
Digital elevation data needs Lidar variable across large focus area; some complete, some in progress, some inadequate.