USGS Home
Contact USGS
Search USGS

Potentially Toxic Substance Availability to the Regional Aquifer System from Mineralized Ground and Mining Activity in the Northern Patagonia Mountains, Arizona

Project Home Geology Geophysics Remote Sensing Geochemistry Publications Gallery

Byron R. Berger, W. Ian Ridley, and Frederick E. Lichte, U.S. Geological Survey

Hydrothermally altered and mineralized ground may be important sources of toxic metals and compounds to aquifer systems. In this regard, the areal extent, intensity, and volume of hydrothermally altered ground, geometric interconnectivity of fracture systems, hydraulic conductivity, and geoavailability of metals to a flow system are important variables that require study and evaluation. Such studies are also important in developing general geoenvironmental models of hydrothermal mineral deposits. An investigation of this nature is being made in the Sonoita Creek drainage system, northern Patagonia Mountains, Arizona₁ and this report describes the progress made during 1994.
Rugged canyons and peaks to approximately 6600 feet altitude typify the Patagonia Mountains as do hilly areas between about 4500 and 5800 feet altitude. Evergreen woodlands intermixed with semidesert grasslands blanket the area. Various oak species, juniper, mesquite, and manzanita are widespread throughout the range (Houser and others, 1994), being particularly lush in the upper Alum Gulch and upper southern Harshaw Creek drainages.
Sonoita Creek is a major collection basin for surface and ground water in the regional Santa Cruz River aquifer system, the primary source for recharge of the Tucson hydrologic basin. Extensive and intensive hydrothermal activity has altered rocks within the Sonoita Creek drainage system, and led to the precipitation of metals and compounds that are potentially toxic when mobilized into the ground water environment. The many square kilometers of altered rock includes extensive advanced argillic alteration mineral assemblages, and Cu-Pb-Zn-Ag-Au mineralization. Mining activity has left behind extensive underground workings, open adits, dumps, and tailings piles (cf. Schrader, 1915; Simon, 1972, 1974) that further facilitate the availability of metals and compounds to the local and regional drainage basins.

Back to Publications