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Paleozoic and Mesozoic rocks exposed near Quinn River Crossing, Humboldt County, Nevada, constitute two terranes that have played important roles in the tectonic history of this region. Data collected from these terranes provide insight into the tectonic events that shaped the margin of western North America during the late Paleozoic and the early Mesozoic. The Jackson terrane at Quinn River is composed of a chert-quartzite arenite containing Late Devonian and pre–Late Devonian chert pebbles. This unit sits below a Jurassic(?) ash-flow tuff that has embedded limestone blocks, mafic and felsic volcanic clasts, and hornblende porphyry blocks K-Ar dated at 191 ± 9 Ma. Thrust over the Jurassic(?) ash-flow tuff is the Black Rock terrane, which includes the Lower Permian Bilk Creek limestone, Permian clastic and arc-derived volcaniclastic rocks, and the Upper Permian to Middle Triassic Quinn River Formation, composed of chert, siltstone, shale, sandstone, and tuffaceous and volcaniclastic rocks.

The Jackson terrane has an enigmatic paleogeographic relation with the Black Rock terrane. Lithologic, age, structural, and biogeographic data indicate that the Black Rock terrane at Quinn River is correlative with the eastern Klamath terrane in northern California. In contrast, the Black Rock terrane at Quinn River is lithologically, biogeographically, and structurally distinct from coeval rocks of the Golconda allochthon in the nearby Osgood Mountains and Hot Springs Range. The lack of Sonoman deformation in the Black Rock terrane, the lack of Permian arc-derived volcaniclastic rocks in the Golconda allochthon in the Osgood Mountains and Hot Springs Range, the absence of any linking facies between these two areas, and the presence of post–Early Jurassic deformation in rocks between these areas all do not support models that imply relative proximity of the Black Rock arc terrane to the northwesternmost part of the Golconda allochthon during Permian-Triassic time. The evidence implies instead that the present relative positions of the Black Rock terrane and the northwesternmost exposures of the Golconda allochthon are the result of younger Mesozoic tectonic events unrelated to the original paleogeographic settings of these rocks.

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