CONSTRAINTS ON LATE PALEOZOIC SLIP HISTORY AND POSSIBLE QUATERNARY REACTIVATION, EASTERN PIEDMONT FAULT SYSTEM, NORTH CAROLINA AND VIRGINIA

The Contentnea Creek pluton is a previously unstudied granitic pluton located in southern Wilson County, North Carolina, United States. This granitic body is located immediately adjacent to the Hollister mylonite zone, which is the eastern limit of the Eastern Piedmont Fault System, a major late Paleozoic dextral transpressional tectonic boundary. Previous work suggests the Hollister mylonite zone deformed granites during the Alleghanian orogeny from at least 290 to 250-240 Ma. U-Pb zircon geochronology is in progress and will help test the hypothesis that the Contentnea Creek pluton is also Alleghanian in age. These new age data will also help constrain slip history of the Hollister mylonite zone because our recent field and laboratory work demonstrates the pluton is syntectonic. Our results from field observations, petrography, and laboratory fabric quantification help constrain spatial variation in fabric development during pluton emplacement and cooling. Within the mylonite zone, we observe high-temperature solid-state fabrics consistent with dextral transpression. Adjacent to mylonite zone, fabrics are dominantly magmatic and mimic the orientation of the nearby mylonite zone. Away from the mylonite zone, solely magmatic fabrics exist and orientations are more closely related to pluton margins. All of these high-temperature fabrics are overprinted by a later low-temperature brittle fabric recognized by micro-breccias and fractured minerals in shear fractures. This fabric may be related to late Cenozoic reactivation of the ancient Eastern Piedmont Fault System, as has been recognized in southern Virginia. Measuring the orientation of these shear fractures and slickenlines we can attempt to reconstruct how 3-D kinematics may change over time.