Paleozoic tectonic domains of Nevada: An interpretive discussion to accompany the geologic map of Nevada

摘要

The Paleozoic geologic history of Nevada can be viewed in terms of tectonic domains derived from the newly interpreted digital geologic map of Nevada. These domains reveal that Paleozoic tectonic events were shaped by complex interactions between the continental margin in Nevada and accreted terranes outboard of the margin.Ten domains are described. They include lower Paleozoic domains based on paleogeo-graphic facies, the Carbonate Shelf, Slope and Basin domains; the Nolan Belt domain, a structurally complex domain that includes Precambrian and lower Paleozoic slope and basin facies rocks; the Dutch Flat domain, an Upper Devonian feldspathic sandstone of exotic origin; an Upper Devonian to Lower Pennsylvanian siliciclastic Foreland basin domain resting conformably over the Shelf domain; the Pennsylvanian and Permian siliciclastic and carbonate Antler Overlap domain, which sits unconformably over all of the older domains; the Golconda domain of deformed upper Paleozoic oceanic, carbonate and siliciclastic rocks, which is faulted over the Antler Overlap domain; the upper Paleozoic and Mesozoic volcaniclastic Black Rock-Jackson domain; and numerous carbonate, siliciclastic, and volcaniclastic Mesozoic terranes and assemblages that were either accreted to the margin or deposited unconformably over previously accreted Paleozoic terranes.Interpretations of these domains define multiple, distinct, lower Paleozoic tectonic environments. They suggest that the a€?Antler Orogenya€? can be reinterpreted as a sequence of tectonic events involving deformation of the margin and the accretion of multiple terranes to the margin over an extended period from the Late Devonian to the Early Pennsylvanian in a complex transpressive tectonic regime. Some of the accreted terranes contain rocks unlike those from the adjacent margin or other terranes and suggest they are far traveled. A change in the plate boundary configuration in the Middle Pennsylvanian led to the development of a new margin that reflected the 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 backarc plate tectonic setting in the Mesozoic. 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 Jurassic and Cretaceous time. Viewing the geologic history of the region in the context of terrane accretion provides new insight into the complex processes that shaped the continental margin of western North America.