A NEW BEDROCK GEOLOGIC MAP COMPILATION OF THE 1:100,000-SCALE ASHEVILLE QUADRANGLE, WESTERN NORTH CAROLINA

The North Carolina Geological Survey presents a new bedrock geologic map compilation of the Asheville 1:100,000-scale Quadrangle (100K). This map is a combination of new work and previous geologic maps created by 32 authors over a span of 62 years. Funds for compilation and mapping 22 of the 32 24K maps on the 100K were provided by the STATEMAP component of the National Cooperative Geologic Mapping Program.

The map and its digital components were produced as part of an ongoing effort to create a statewide edge-matched geologic compilation at the 100K scale. First order geologic elements comprising the 100K include Mesoproterozoic basement gneisses, Ocoee and Chilhowee metasedimentary and sedimentary rocks, Tugaloo terrane, Cartoogechaye terrane, Brevard zone, and Grandfather Mountain and Hot Springs structural windows.

Map information is contained in a geodatabase with 79,568 stations. Structural measurements include 45,535 foliations and 19,211 joints. New fracture/joint data were collected on constituent quadrangles of the 100K that did not have existing data. Detailed 1:24,000-scale map units were preserved wherever practical. LiDAR-based terrain analysis assisted with identifying various units and topographic lineaments. Whole rock geochemical and thin section analyses were completed for 40 samples. Of those 40 samples, five were sent for zircon analysis to determine crystallization age (three) or detrital age distributions (two) (awaiting results as of abstract deadline).

Rose diagrams of structural data show a strong correlation between outcrop-scale joint sets and NW-directed lineaments identified from LiDAR-hillshade imagery. Correlation of outcrop-scale joint sets and the prominent E-W trending Laurel Creek and Swannanoa lineaments is less clear.