Nevada Test Site and Yucca Mountain
The Nevada Test Site (NTS), in southern Nye County, Nevada, straddles significant pre-Tertiary structural and stratigraphic boundaries. Detailed stratigraphy and biostratigraphy of the Upper Paleozoic section delineates the regional thrust sheets and constrains their burial histories. The Paleozoic rocks record three phases of contractional deformation, overprinted by strike-slip faulting. These occurred in the following order: (1) foreland-vergent folding and imbricate thrusting in the footwall of the Belted Range thrust; (2) hinterland-vergent folding and thrusting; and (3) north-vergent folding that we interpret as footwall deformation below a third major thrust system. Sinistral slip, typically accompanied by minor east-west shortening, has occurred along a series of north-northeast-north-northwest-striking faults around Yucca Flat. This strike-slip faulting postdates both foreland-vergent and hinterland-vergent deformation, and predates the Cretaceous Climax stock; its age relative to the north-vergent folding and thrusting is unknown. Our new understanding of the geometry of these structures provides new insights into the correlation and interpretation of regional structural features. Field trip stops will examine: (1) the stratigraphic dif-ferences that allow us to distinguish the regional thrust sheets and constrain their burial histories; and (2) the field relationships that document the kinematics and relative ages of the penetrative deformational events.