Abstract

There are multiple linear fracture systems (lineaments) exposed across western North Carolina that are associated with Cenozoic topographic rejuvenation of the Appalachian Mountains. These fracture systems are composed of joints and faults that strike obliquely to the rock units across the region. This obliquity along with previous constraints on the direction of fault motion, knickpoints along stream channels, and paleostress analysis suggests that these fracture systems are not associated with the Paleozoic assembly of Pangea, but are in fact likely much younger. One of these lineaments, the Laurel Creek Lineament, which extends from Hot Springs, NC east toward Spruce Pine, NC has not been previously mapped. An earthquake on fractures associated with this lineament in 2005 suggests it is still an active fault system. This study included geologic field mapping of rock units and fractures in the Spruce Pine 7.5-minute quadrangle to document fractures, fault offsets, and the direction of fault motion. Vertical joints and faults are exposed throughout the entirety of the quadrangle and dominantly strike toward 080/260°. However, these fractures are denser around the topographic lineament that extends through the town of Spruce Pine. The majority of the fractures found in Spruce Pine exhibited no offsets and offsets that were found were inches to meters in magnitude. Fault slickenlines and offset soil or rock units suggest that the north block moved up relative to the south block. Previous studies on the Boone Lineament, north of Spruce Pine, showed that the fracture system moved with the south side up. These data indicate that the block of crust between the Boone Lineament and the Laurel Creek Lineament has been uplifted by these fracture systems, resulting in the high topography around Grandfather Mountain which is within this uplifted block.

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