MESOPROTEROZOIC TO CENOZOIC FAULTS AND FAULT ZONES ASSOCIATED WITH THE COMPLEX TECTONIC HISTORY OF THE APPALACHIAN BLUE RIDGE
Evidence of brittle normal faults that accompanied extension are associated with: 1) ca. 780-750 Ma rift basins that contain bi-modal volcanic deposits; 2) linear batholiths of ca. 750-700 Ma granitoids; 3) half-grabens that contain seismites that are older than ca. 575 Ma bi-modal volcanism associated with rifting; 4) a submarine slide in ca. 540 Ma marine clastic deposits; 5) a post-ca. 510 Ma half-graben of shelf carbonate rocks juxtaposed on ca. 575 Ma basalt; 6) growth faults associated with 220-200 Ma basin deposits that also cut ca. 200 Ma diabase, and 7) Cenozoic uplift along older FFZs.
FFZs associated with orogenies are more complex. Some contraction predates metamorphism and others exhibit syn- and post-metamorphic ductile deformation. Examples include: 1) northwest-striking foliated units associated with the Grenville orogeny; 2) FFZs interpreted to be “sutures” bounding different “terranes” may juxtapose the remains of a slope-rise sequence and oceanic rocks that are younger than the older continental margin rocks; bodies of mafic rocks could constitute sedimentary blocks and tectonic mélange that post-dates crystallization and emplacement; and 3) Devonian-Mississippian FFZs that are broad zones of mylonitic foliation that were folded above Pennsylvanian-Permian duplex.