3D RESTORATION AND STRAIN ANALYSIS, SUGAR HOLLOW, VIRGINIA BLUE RIDGE: COMPARISON OF NATURAL SAMPLE ANALYSES AND MIDLAND VALLEY MOVE MODEL RESULTS

Sugar Hollow preserves Neoproterozoic Iapetan rift architecture in the central Virginia Blue Ridge. However, Paleozoic contractional deformation has largely overprinted the original graben complex—reactivating normal faults to produce open to overturned folding in the hanging walls. Midland Valley's Move software was used to create 3D models of the current geometry of Sugar Hollow using data gathered from new geological mapping. From this model, surfaces were retrodeformed using the line-length unfolding algorithm provided in the software. In addition, beds were rejoined on faults to determine net NW-directed shortening in Sugar Hollow of 20% since the Mesoproterozoic. The Swift Run Formation at Sugar Hollow is over 15x thicker than its typical section, reaching maximum thicknesses of ~300 m. This anomalous depositional geometry is likely due to accommodation space created by Iapetan rifting and reactivation of normal faults in the Paleozoic. Move was used to forward model this deformation from a restored-state model of Neoproterozoic Sugar Hollow and throughout this process, Move tracked strain during deformation. These data were compared to strain measurements gathered from thin section using the Rs/phi method to determine the plausibility of the interpreted deformational history and the applicability of strain measurements in Move to strain measured in thin section.