The western margin of the U.S. was the site of complex tectonic interactions during the Neogene. Basin and Range extension was encroaching westward into Sierran Crust while distributed dextral slip (thought to be plate margin related) was occurring in the Walker Lane region. Cessation of arc-related volcanism with associated thermal effects also occurred, having migrated northward roughly in parallel with the Mendocino triple junction. The interrelationships between these regional phenomena has been controversial. This project will utilize the paleogeography and deformation evidence recorded in Neogene basins of northwestern Nevada to address these issues, and will involve structural, stratigraphic and geochronologic studies of exhumed Neogen basins in a broad zone along the Sierra Nevada-Basin and Range boundary. Results will help answer several long-standing questions including temporal and kinematic between Walker Lane faulting and extensional faults to the east and west and uplift of the present Sierra Nevada. This information will help illuminate other areas of active transtension in marginal continental crust. ***
