Provenance and paleogeography of the Black Rock Terrane, northwestern Nevada: Implications of U-Pb detrital zircon geochronology

Abstract

U-Pb ages have been determined for 50 detrital zircon grains from Mississippian and Triassic strata of the Black Rock terrane, northwestern Nevada. The Devonian(?) to Mississippian Pass Creek unit has three broad age groups: 976-1132 Ma (n = 8), 1595-1927 Ma (n = 10), and 2504-266 0 Ma (n = 3). The Triassic Bishop Canyon formation contains a dominant group of grains between 268 and 441 Ma (n = 11), a cluster of ages between 1868 and 1925 Ma (n = 5), and scattered ages between 1184 and 1813 Ma (n = 10) and between 2183 and 3183 Ma (n = 3).Most of the ages in these samples match well with the ages of grains present in basement provinces and off-shelf assemblages in the western United States. Grains in the Pass Creek unit were most likely recycled from lower Paleozoic strata of the Roberts Mountains allochthon and from strata exposed in the Salmon River arch region of Idaho, western Montana, and eastern Washington. These provenance links suggest that the Black Rock terrane was located along the northern Nevada-I daho segment of the Cordilleran margin, near its current location, during late Paleozoic time. Because the upper Paleozoic stratigraphy of the Black Rock terrane is similar to that found in more outboard arc assemblages, including those of the Klamath Mountains and Sierra Nevada, this relation provides an indirect but important link between the U.S. continental margin and the more outboard arc assemblages. Zircon grains in the Upper Triassic Bishop Canyon formation were derived from a source containing both upper Paleozoic igneous rocks and clastic strata bearing 1.1-3 .2 Ga detrital zircons. The most likely source for this combination of grains is Paleozoic basement rocks of Mesozoic arc assemblages in the eastern Klamath Mountains and Black Rock terrane. These provenance links provide evidence of uplift and erosion of arc basement in the western Cordillera during early Mesozoic time, and support interpretations that lower Mesozoic arc assemblages in this region of the Cordillera were isolated from the continental margin by a Triassic backarc basin.

Understanding a critical basinal link in Cretaceous Cordilleran paleogeography: Detailed provenance of the Hornbrook Formation, Oregon and California

“…These Precambrian age distributions are not unique (LaMaskin, 2012), and match well with detrital ages found in the Antelope Mountain Quartzite of the eastern Klamath terranes (Wallin et al, 2000), quartzose sedimentary rocks in the Eastern Hayfork terrane of the Klamath Mountains (Scherer et al, 2010), and the Shoo Fly complex and overlap assemblage in the Sierran Foothills belt (Harding et al, 2000;Spurlin et al, 2000). Detrital zircon ages in the Blue Mountains Province and the Black Rock terrane also overlap with the Klamath River Conglomerate cobble ages (Darby et al, 2000), but these regions are not characterized by quartzite units and therefore are not considered likely sources here.…”

“…The upper Hornbrook Precambrian age distribution is typical of southwestern Laurentian sources (cf. Grove et al, 2008), and the best match for these Precambrian ages may be in the Nevada portion of the Cordilleran miogeocline (Gehrels and Dickinson, 1995) or in the Black Rock terrane (Darby et al, 2000). The Rocky Gulch Sandstone sample contains only two Precambrian grains; both grains fall within the 1300-1500 Ma peak in the Rancheria Gulch Sandstone Beds sample (Fig.…”

New evidence for Cretaceous strike-slip faulting in the United States Cordillera and implications for terrane-displacement, deformation patterns, and plutonism

“…Schweickert andLahren, 1990, 1993) and from the WNS. (3) It assumes that the Black Rock terrane, basinal terrane, and arc assemblages of west-central Nevada (Pine Nut Range [PNR] and vicinity) have not moved significantly relative to the adjacent continent, based on stratigraphic and detrital zircon data presented in Dilles and Wright (1998), Wyld and Wright (1993), Darby, Wyld, and Gehrels (2000), Manuszak, Satterfield, and Gehrels (2000), and . Several relations argue that this reconstruction is more compatable with the early Mesozoic evolution of rock assemblages within this part of the Cordillera than is the current arrangement of terranes.…”

“…First, the Black Rock and basinal terranes can be tied to the adjacent continental margin during their evolution (Speed, 1978;Lupe and Silberling, 1985;Darby, Wyld, and Gehrels, 2000;. Second, there is no evidence that the WNS marks a suture zone reflecting collision of allochthonous terranes with this part of the margin; there are no blueschists, ophiolites, or melanges along the boundary, nor is there any evident shared structural history across the boundary that is consistent with collisional tectonism.…”

New data on the lithostratigraphy, detrital zircon and Nd isotope provenance, and paleogeographic setting of the El Antimonio Group, Sonora, Mexico

“…The closest probable source for the volcanoplutonic components are Permian and Triassic plutons in the southwestern United States (Mojave Desert region and El Paso Mountains as discussed above) as are for the zircon grains with ages between 240 and 270 Ma found in samples 2000-0 and 2000-1. A single zircon grain from the Río Asunción Formation that yielded an age of 340 Ma is a rare contribution, although scarce grains of that age are present in Triassic rocks of Nevada, like in the Lovelock assemblage and the Bishop Canyon Formation of the Black Rock terrane (Manuszak et al, 2000;Darby et al, 2000). Sources for grains of that age have been attributed by these authors to igneous rocks of the Sierra-Klamath terranes, which is also a probable source for the grain in the El Antimonio Group.…”