"Timing and tectonic history of low grade deformation along the Rockfish Valley Deformation Zone in the Central Blue Ridge, VA"

Jenna Biegel, Thesis 2017

Abstract: The Rockfish Valley Deformation Zone in Central Virginia is a 1-10 km wide zone of mylonitic rocks separating two differently hydrated massifs. Significant disagreement exists around the timing, extent, and significance of low-grade deformation along this zone, and the proposed timing of deformation in this zone ranges from pre-750 Ma to approximately 350 Ma. Based on petrologic evidence, I propose that the variation between the similar but distinct basement units to the east and west of the deformation zone may be explained by fluid-assisted retrogression of the seaward unit during shortening along the deformation zone. Further, syn-deformational titanite grains identified in mylonites and protomylonites of the shear zone which have incorporated Uranium into their chemical structures suggest an age of 396±230 Ma, the timing of low grade deformation.

Full thesis available. Contact the Geology Department at 540-458-8800.