T142 Linking Critical Minerals and the Geologic Framework of North America I: The USGS Earth Mapping Resources Initiative (Earth MRI) and Related Activities

Tuesday, 17 October 2023
8:00 AM - 12:00 PM
324

THE ALABAMA GRAPHITE-V BELT EARTH MRI PROJECT: PRELIMINARY MAPPING, GEOCHEMISTRY, AND PETROLOGY RESULTS

Paper number: T142-5
Program: Technical Sessions
Time: 8:50 AM – 9:05 AM

Authors

Abstract

Graphite and vanadium (V), two critical commodities recognized by multiple federal and state government agencies, including the U.S. Geological Survey (USGS) and Geological Survey of Alabama (GSA), are found in the Alabama graphite-V belt. The Alabama graphite-V belt covers an area of c. 1,130 km2 in the eastern Blue Ridge terrane of the northern Piedmont province and includes the graphite- and V-bearing lithologies of the Poe Bridge Mountain and Higgins Ferry Groups. Due to the history of graphite mining in the area between the late 1800s to 1950s and renewed interest by the mineral exploration industry, the GSA, in partnership with the USGS Earth Mapping Resources Initiative (EMRI), conducted a 2-year mapping and geochemical sampling project on two 7.5-minute quadrangles in the southwestern most extent of the graphite-V belt (Flag Mountain and Mitchell Dam). Previous investigations of this area are restricted to broad reconnaissance studies and large-scale mineral exploration surveys that provide only a limited amount structural, metamorphic, and geochemical information. This study, as well as future studies in the region, will be complemented by ongoing and planned airborne USGS geophysical surveys (e.g., magnetic, radiometric, and resistivity) of the area.

Herein, we present preliminary mapping, geochemistry, petrography, and metamorphic pressure-temperature models for the flake graphite and V-bearing Higgins Ferry Group on the Flag Mountain and Mitchell Dam quadrangles. Most of the graphite in this unit occurs as <1 to 3 mm flakes in schist, gneiss, and quartzite, with modal abundances between c. 1 to 15%, although they may locally be higher. Graphite also occurs as centimeter-scale veins in quartz and is associated with large 1-10 cm long kyanite blades. Green V-bearing roscoelitic mica commonly occurs in combination with the flake graphite. The Higgins Ferry Group was metamorphosed to amphibolite-facies conditions and contains igneous veins and pegmatites interpreted to be partial melt. The V-mica coarsens in proximity to the partial melts and quartz veins, suggesting a relationship between metamorphism, partial melting, and V-mobility. Major and trace element analysis will be used in tandem with petrography and metamorphic pressure-temperature modeling to investigate the potential link.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-390278

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