120-11 Preliminary Geologic map of the Bessemer City 7.5-minute quadrangle, North Carolina: Insight into the geologic framework of critical mineral deposits in the southern Appalachian Piedmont

Abstract:

New geologic mapping supported by the FEDMAP component of the USGS National Cooperative Geologic Mapping Program (NCGMP) and in cooperation with the USGS Earth Mapping Resources Initiative (Earth MRI) provides insights into the geology and critical mineral deposits in the Bessemer City 7.5-minute quadrangle, NC.  The map extends from the eastern flank of the Inner Piedmont Cat Square terrane across the central Piedmont suture into the Kings Mountain sequence of the peri-Gondwanan Carolina superterrane.  The dextral greenschist facies Kings Mountain shear zone marks the central Piedmont suture within the map area.    The Inner Piedmont Cat Square terrane is composed of polydeformed, variably migmatitic muscovite schist, metagraywacke and amphibolite intruded by the Devonian Cherryville Granite (380–355 Ma) and Mississippian(?) pegmatite.    The Cambrian to late Neoproterozoic Kings Mountain Sequence consists of schist, phyllite, quartzite, and marble of the Blacksburg Formation, and schist, phyllite, quartzite, metaconglomerate, manganiferous schist, and amphibolite of the Battleground Formation.  Map units generally strike north to northeast and dip gently to moderately southeast in the Inner Piedmont, whereas map units dip steeply in the Kings Mountain Sequence.  The Blacksburg and Battleground Formations are folded and cut by several dextral shear zones, which expose two elongate bodies of metatrondhjemite and metadacite of the Bessemer City gneiss (~514 Ma). The High Shoals Granite (~319 Ma) intruded the Battleground Formation; the Sunnyside granite stitches the Central Piedmont suture between the Inner Piedmont Cat Square terrane and the Carolina superterrane.  Early Jurassic diabase dikes strike north-northwest across the older rocks. 

 The map area contains industrial, precious, and critical mineral deposits.  The central portion of the Carolina tin-spodumene belt lies within the quadrangle, as well as numerous historic prospects and mines for tin and lithium (spodumene) including the Hallman-Beam Mine.  Mapped spodumene-bearing and muscovite-bearing pegmatites are discontinuous bodies that are generally parallel to strike; however, the main spodumene ore pegmatite in the Hallman-Beam Mine strikes about N80°W.  Other potential critical mineral deposits include cassiterite (tin), rare earth element-enriched regolith, and manganese.  Aeromagnetic and radiometric surveys conducted by Earth MRI over the Piedmont will provide additional insight into the framework geology and critical mineral deposits.

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-21671

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