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

The North Carolina Geological Survey presents a new bedrock geologic map compilation of the northern half of the Hendersonville 1:100,000 scale Quadrangle (100K). This map is a combination of new work and previous 1:24,000-scale detailed geologic maps created by 14 authors over a span of 51 years. Funds for compilation and previous comprehensive geologic mapping for four of the sixteen 24K geologic maps 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. It provides the first cohesive view of the project area that straddles the Blue Ridge and Piedmont physiographic provinces. First order geologic elements include the Tugaloo terrane in the eastern Blue Ridge and western Inner Piedmont, Brevard zone, Cartoogechaye terrane, and Dahlonega Gold Belt terrane. Map information is contained in a level 3 GeMS geodatabase with 31,395 structural measurements spread over 23,116.stations. Structural measurements include 18,029 foliations and 9,247 joints. New fracture/joint data were collected over the entire 100K as very little previously published fracture/joint data were available for many constituent 24K quadrangles. 24K 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, six were sent for zircon analysis to determine crystallization age (three) or detrital age (three) distributions (awaiting results as of abstract deadline).

Previously unrecognized silicic breccia zones were identified in the 100K that are likely correlative with Mesozoic faulting mapped by Garihan and Ranson (1993) to the southeast, marking the northernmost extent of these features. Rose diagrams of structural data indicate a strong correlation between outcrop-scale joint sets and LiDAR-identified lineaments. Joint sets trend predominantly NW-SE in the western portion of the 100K. In the southeastern portion of the 100K, outcrop-scale joints predominantly parallel E-W trending features including brittle faults.