The Sonoran Desert Heritage Proposal: An evaluation of the mineral resource potential of lands proposed for withdrawal from mineral entry v. 2.0
KeywordsArizona Geological Survey Open File Reports
Little Harquahala Mountains
Painted Rock Mountains
Sentinel volcanic field
Gila Bend Mountains
Big Horn Mountains
Basin and Range Province
MetadataShow full item record
CitationSpencer, J.E., 2013, The Sonoran Desert Heritage Proposal: An evaluation of the mineral resource potential of lands proposed for withdrawal from mineral entry. Arizona Geological Survey Open File Report, OFR-13-03, 30 p.
DescriptionIn 2011, the Arizona Wilderness Coalition, Sonoran Institute, and The Wilderness Society proposed that the Federal Government designate approximately 1170 square miles (~750,000 acres) of Arizona public lands as Wilderness Area, National Conservation Area, and Special Management Area (Marlow and Richins, 2012). These lands are located primarily west of Phoenix in the low deserts of western Arizona. Enactment of this “Sonoran Desert Heritage” proposal would prevent mining and quarrying on these lands, and would prohibit or impede exploration activity such as drilling and geophysical surveying. This report is an evaluation of the mineral resource potential of these lands, but is limited to the following types of deposits: (1) sand and gravel (aggregates), which are used for concrete and asphalt, (2) porphyry copper deposits, which are a specific type of large copper deposit that is common in Arizona (these deposits may yield large amounts of byproduct molybdenum, silver, and gold), (3) gold deposits in veins, some of which contain substantial silver, and (4) manganese deposits, which are present over a large area in western Arizona but, historically, have been too low grade for mining. The geology of the lands included within the Sonoran Desert Heritage proposal is complex, and varies greatly from range to range. Geologic mapping of almost the entire area, done by Arizona Geological Survey geologists under the joint State-Federal STATEMAP and COGEOMAP programs over the past 30 years, allows informed evaluation of mineral resource potential. This report identifies areas that have high potential for future aggregate production, and areas considered favorable for future discovery of porphyry copper deposits, precious-metal vein deposits, and manganese deposits. One area encompassed by the Sonoran Desert Heritage proposal, which includes the Harquahala and Big Horn Mountains, is identified as having high potential for all of these deposit types. Other metallic mineral commodities such as uranium, iron, and rare-earth elements, and industrial minerals such as clay and zeolite, were not evaluated. This report also includes a brief review of USGS designations of proposed SDH lands as “permissive” and “not permissive” for future discovery of several mineral commodities. Finally, it should be noted that evaluations of potential for undiscovered mineral deposits are inherently speculative, and are complicated by the fact that new technologies for mining and quarrying, changing economic conditions, and changes in commodity demand may result in some uneconomic deposits becoming economic, or in previously uninteresting deposits becoming targets for exploration and mining. As a result, removal of even unattractive lands from mining and quarrying can eventually have adverse economic consequences.
Series/Report no.OFR-13-03 v2.0
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North Bounding Coordinate33.9283
South Bounding Coordinate32.7951
West Bounding Coordinate-113.752
East Bounding Coordinate-112.324
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