Cordilleran Section - 103rd Annual Meeting (4–6 May 2007)

Paper No. 10
Presentation Time: 11:20 AM


CRAFFORD, A. Elizabeth Jones, GeoLogic Services, 9501 Nettleton Drive, Anchorage, AK 99507,

Important tectonic events relating to rifting, extension, transpression and accretion are recorded in the Paleozoic and Mesozoic rocks of Nevada. A new digital synthesis of the geology is used to better constrain these events. To understand the geology of the Paleozoic rocks in Nevada in terms of contemporary plate tectonic and terrane accretion models, the rocks are grouped into domains that reflect paleogeographic, age, and structural characteristics.

Ten domains are described: Three lower Paleozoic domains based on paleogeographic facies – the Shelf, Slope and Basin domains; the Precambrian and lower Paleozoic Nolan belt; the Upper Devonian feldspathic Dutch Flat terrane; an Upper Devonian to Lower Pennsylvanian siliciclastic Foreland Basin domain; the Pennsylvanian and Permian siliciclastic and carbonate Antler Overlap domain; the upper Paleozoic oceanic Golconda terrane; the upper Paleozoic and Mesozoic volcaniclastic and carbonate Black Rock-Jackson terrane; and numerous carbonate and volcaniclastic Mesozoic terranes and assemblages.

The domains reveal multiple lower Paleozoic tectonic environments, and indicate that the “Antler Orogeny” can be reinterpreted as a sequence of tectonic events involving deformation of the margin and the accretion of terranes to the margin over an extended period from the Late Devonian to the Early Pennsylvanian. Some of the accreted terranes contain rocks derived from sources far removed from their present location. A fundamental change in the plate boundary configuration in the Middle Pennsylvanian led to development of a new margin that reflected effects of a new plate boundary farther to the west. Accretion to the margin of upper Paleozoic oceanic terranes at the close of the Paleozoic redefined the margin once again as it changed from a transpressive accretion regime to a true back-arc plate tectonic setting. East-vergent and west-vergent thick-skinned thrusting and exhumation coupled with significant translation of components of Mesozoic and older terranes rearranged the Paleozoic rocks of the shelf and earlier accreted terranes during the Jurassic and later. Digital geologic mapping and GIS analysis provide important tools for the predictive models of regional tectonics needed for successful resource exploration.