Master’s Thesis Defense: Sarah Wells-Hull

The Masters Thesis Defense of Sarah Wells-Hull is presented by the University of North Carolina at Chapel Hill’s Earth, Marine, and Environmental Sciences Department. This event will be held on Friday, December 10th at 12:30 pm. This event will be held in person and will also be streamed online. The physical location of the event is on UNC-CH campus in Mitchell Hall’s Martin Lounge (Room 121). To watch online join via Zoom Meeting ID 963 7970 0752.

Title: Pre-Alleghanian extension and post-Alleghanian brittle deformation in the southern Appalachians

Abstract: The southern Appalachians have a well-documented geologic history, however there are structures in the Blue Ridge that do not fit into the previously known events. Thrust faults related to the orogenic events that formed the Appalachians dominate the Blue Ridge province, but no clear extensional faults have been identified. We discovered the first documented synorogenic normal fault within the southern Appalachian Blue Ridge, which we name the Grassy Creek fault (GCF). The GCF may be associated with extension due to underplating and overthickening of the crust during the Devonian-Mississippian and may also explain the exhumation of an eclogite facies terrane within the Ashe Metamorphic Suite.
Other structures that do not correspond with the well-documented geologic history of the southern Appalachians are topographic lineaments that cut the Paleozoic structures. Recent work has shown that one of these lineaments corresponds to a Neogene, high-angle, dip-slip fault, which has been named the Boone fault. Hill (2018) proposed that vertical motion along the Boone fault accommodates Miocene uplift of the southern Appalachians. North of Boone, NC, a set of lineaments are parallel to the Boone fault. We performed fracture and paleostress analyses along the lineaments, which indicate that they are likely fracture controlled and related to the same deformation event responsible for the Boone fault.