CHALLENGES OLD AND NEW: MAPPING A POTENTIAL RESOURCE IN THE SOUTHERN APPALACHIAN BASIN

Assessment of critical mineral and rare-earth element resources in coal, coal related sediments, and coal mining and processing wastes in the Southern Appalachian Basin (SAB) of northern Alabama, northwestern Georgia, and southern Tennessee is a goal of the Manufacturing Coal Derived Products in Southern Appalachia project. In addition to geochemical data, outcrop maps, structure contour maps, and isopach/isocore maps are needed, presenting various challenges for the project.

The SAB includes the Black Warrior Basin, Cahaba Coal Field, Coosa Coal Field, the southern Tennessee coal field, and several coal fields/areas within the Appalachian fold and thrust belt in Alabama and Georgia. Each of the coal fields has unique stratigraphy; and stratigraphy for some coal fields can be correlated to neighboring areas. However, this is not always possible. Various maps and data sources for coal and coal related sediments exist in the literature and in the records of the Tennessee Geological Survey (TGS) and the Geological Survey of Alabama (GSA). Coal seam data (depth and thickness) are more common than data for coal-related sediments (e.g., underclays, shale interbeds, roof rock), as coals have long been a resource of interest. Location and depth of related sediments can be estimated from the coal seam data. Thicknesses of coal-related sediments are harder to estimate. Additionally, all data become sparser away from major production areas, particularly subsurface data. In the past, maps of coal seams were often more localized, and broader correlations were not necessary, particularly in areas with little coal production; however, for this effort, the broader correlations are needed. Owing to time-constraints, new field mapping for thicknesses of underclays is not possible.

Existing public geochemical data for the coal is limited, but there is even less for related sediments or mining and processing waste. Sampling for this project is focusing on the underclays and coal mine/processing plant waste. Underclay sampling has begun from cores in the GSA core repository. However, gaining access to coal mine and processing waste is proving a challenge, making it difficult to obtain needed samples for analysis.