Abstract by Jake Voorhees
Precambrian collisional metamorphism, submarine sliding, and low-angle normal faulting in the Beaver Dam Mountains, SW UT.
Pre-Cambrian metamorphic rocks display asymmetric, isoclinal folds with consistent fold axes plunging to the NW. This folding has a recursive nature and occurs on wavelengths from centimeters to perhaps kilometers as part of a shear zone dipping 36 degrees to the south with top-to-the-south shear sense, which may be associated with the collision of Yavapai Province island arcs with Laurentia. Structurally overlying the metamorphic rocks are allochthonous and attenuated blocks of Paleozoic strata debated to be the result of mega-landsliding or low-angle normal faulting. We document previously unreported cataclastic damage zones tens of meters thick, a zone of greenschist facies alteration hundreds of meters thick, and polished low-angle fault surfaces beneath these blocks. Additionally, previously unrecognized submarine landsliding on the continental shelf is noted, which formed soft-sediment recumbent folds hundreds of meters across within Mississippian to Permian formations.