Fundamental framework geology in the southern Appalachian crystalline core: The U.S. Geological Survey National Cooperative Geologic Mapping Program (FEDMAP Component) Piedmont-Blue Ridge pPoject

Abstract

The USGS NCGMP Piedmont-Blue Ridge (PBR) Project aims to develop 4D geologic framework models across the southern Appalachian orogen. The primary objective of the Project is to construct geologic maps and accompanying GeMS geodatabases at scales of 1:24K and 1:100K across the VA-NC-TN state lines where existing geologic map coverage is not adequate (>1:250K) to solve societal and scientific challenges. Two tasks and regional field areas comprise the PBR Project: (1) Piedmont Geology Along the Southeastern Fall Zone, Virginia and North Carolina focuses on eastern Piedmont geology from Richmond, Virginia to Rocky Mount, North Carolina; and (2) Blue Ridge-Inner Piedmont geology covers from the junction of Virginia, North Carolina, and Tennessee eastward into the Piedmont. Both areas host potential critical mineral deposits, including rare earth elements (REE), lithium, tin, and others (e.g., Ti, U, Ta, Nb, Be, Mn, Ba, Zr). Radon in groundwater is a concern in northwestern North Carolina and southwestern Virginia where preliminary investigation suggests a correlation between REE concentration and radon/uranium in certain rock units and major shear zones. The Fall Zone in southeastern Virginia and northeastern North Carolina is the recharge area for the largest aquifer (Cretaceous Potomac Group) on the southeastern seaboard; this region also hosts marketable deposits of REE-bearing heavy minerals. Slope-stability and earthquake hazards are issues in both areas. Developing the 4-D geologic framework of these relatively unexplored regions and producing seamless geologic maps and geodatabases is necessary to address societal needs and resolve “state-line border faults”. Both Tasks work closely with USGS NCGMP STATEMAP and EDMAP components to further the overall goals of the Program.