KINEMATIC AND GEOCHRONOLOGIC CONSTRAINTS FOR DEFORMATION ON THE HOLLAND MOUNTAIN FAULT, ASHEVILLE, NORTH CAROLINA

The Holland Mountain thrust fault (HMT) in western North Carolina is part of a major fault system that separates basement gneisses that record Grenville deformation (~1-1.2 Ga) from the overlying Neoproterozoic Ashe Metamorphic Suite (AMS). The HMT was previously thought to be a syn- to post-metamorphic Taconic thrust fault that has since been folded. The HMT has been correlated to the Chattahoochee fault to the south where the contact is interpreted as a Neoacadian or Alleghanian thrust fault. To the north, the HMT correlates to the Burnsville fault where this contact has been interpreted to represent Acadian dextral strike-slip reactivation of the HMT. Microstructural and geochronological analyses were conducted on samples from the HMT just north of Asheville, NC to constrain the kinematic and temporal evolution of the fault at this location. Microstructural investigations show a stretching lineation parallel to the strike of the foliation that combined with observations of shear sense indicators record dextral strike-slip motion, consistent with other studies. We collected U-Pb zircon ages from two dikes, one deformed and one undeformed, that cut through the HMT at this location. Evaluation of preliminary ²⁰⁶Pb/²³⁸U zircon rim ages suggests that the most recent ductile movement on this fault at this location may have ceased during the Acadian. These preliminary data combined with other studies of this fault system suggest that although the temporal and kinematic history along the entire fault system may be variable, the Acadian dextral history along the Burnsville fault extends at least south to Asheville.