Polyphase structures in the southeasternmost Blue Ridge and western Piedmont, central Virginia: Constraints on evolution of the Mountain Run fault zone
Conference
·
· Geological Society of America, Abstracts with Programs; (United States)
OSTI ID:6786517
- Virginia Div. of Mineral Resources, Charlottesville, VA (United States)
Recent geologic mapping in chlorite-grade metamorphic rocks of Albemarle and Fluvanna Counties in central Virginia has refined the stratigraphic framework of Early Paleozoic passive-margin cover rocks on the southeastern limb of the blue Ridge anticlinorium, and poses new constraints on the regional tectonic boundary between the rocks, and Early paleozoic metagraywacke and melange of uncertain stratigraphic affinity which occur to the southeast. This boundary equivalent to the Mountain Run fault zone of Pavlides (1989), is a zone of complex structure, derivative of multiple episodes and styles of deformation. Metagraywacke and melange were first juxtaposed against Blue Ridge cover rocks during syn-metamorphic (D1--Taconic) contractional deformation that transposed primary layering in hanging-wall metagraywackes and footwall slates and limestones, and produced pinstriped mylonitic schists (D1 tectonites) adjacent to a regionally-extensive, subhorizontal to gently-southeast-dipping, low-angle reverse fault. Subsequent post-metamorphic contractional deformation D(2--Alleghanian) imbricated a pseudostratigraphy consisting of Blue Ridge cover rocks in the footwall, D1 tectonites, and hanging-wall metagraywackes, along northwest-directed thrust faults. D2 faults are associated with cataclastic tectonites, and are geometrically related to northwest-verging, asymmetric map-scale F2 folds. Mesozoic extensional faulting was localized along several D2 faults, further contributing to map-scale structural complexity.
- OSTI ID:
- 6786517
- Report Number(s):
- CONF-9404221--
- Conference Information:
- Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 26:4
- Country of Publication:
- United States
- Language:
- English
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