Sierra Madre

Region West, Rocky Mountains
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Pegmatites with similar lithology and in proximity to the Platt Mine/Big Creek district pegmatites are enriched in REE-bearing minerals (Osterwald and others, 1966). Granitoids and gneisses analyzed by Souders and Frost (2006) showed enrichment in light REE.
Identified resources None.
Production None.
Status From Hausel (1986): "Uranium-bearing pegmatites associated with vermiculite and rare earths were prospected for vermiculite on the west side of the districts and south of the Mullen Creek-Nash Fork shear zone...
Estimated resources Unknown.
Geologic maps Houston and Graff (1995), scale 1:50,000; Sutherland and Hausel (2004), scale 1:100,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage, poor ground gravity coverage.
Favorable rocks and structures Columbite- and samarskite-bearing felsic pegmatite and numerous other regional felsic pegmatite; mineralized quartz veins; stratabound cupriferous quartzite.
Deposits King Claims (MRDS dep_id: 10018834), Union Asbestos (Platt Ranch) (MRDS dep_id: 10400295).
Evidence from mineral occurrences MRDS.
Geochemical evidence No direct geochemical evidence from pegmatites in Sierra Madre, but inferred from similar pegmatite lithologies in Medicine Bow Mountains focus area; reported occurrences of samarskite from "pre-Cambrian granite" (Osterwald and others, 1966). From Souders and Frost (2006), "All Sierra Madre granitoids and gneisses have modest LREE enrichment (Lan/Smn > 4).
Geophysical evidence No data.
Evidence from other sources No data.
Cover thickness and description Variable, mix of good exposure to abundant surficial cover and heavily forested areas.
Authors Rachel N. Toner, Patricia M. Webber, Benjamin J. Drenth, Michael L. Zientek, Robert W. Gregory, Kevin Mosser, Joshua M. Rosera.
New data needs 1:24,000 scale geologic mapping supported by high-quality geophysics and lidar, especially along trace of Cheyenne Belt; new reconnaissance geochemistry.
Geologic mapping and modeling needs 1:24,000 scale geologic mapping of the igneous and metamorphic stratigraphy, structural and deformation features (especially along Cheyenne Belt), and mineralization trends with precise ground control is essential. Requires outcrop-level mapping.
Geophysical survey and modeling needs Rank 1 aeromagnetics and aeroradiometrics, also a major ground gravity campaign.
Digital elevation data needs Lidar in progress with small areas complete.