Geotectonic evolution of the Great Basin

Abstract

The crust of the Great Basin has occupied a range of tectonic settings through geologic time. Archean and Paleoproterozoic crustal genesis preceded residence of Laurentia within the Mesoproterozoic supercontinent Rodinia, which rifted in the late Neoproterozoic to delineate the Cordilleran flank of Laurentia. Successive stages of Phanerozoic evolution included (1) early to middle Paleozoic miogeoclinal sedimentation along a passive continental margin, (2) late Paleozoic to earliest Mesozoic thrusting of oceanic Antler and Sonoma allochthons over the continental margin in response to episodic slab rollback beneath an offshore Klamath-Sierran island-arc complex, (3) Mesozoic to mid-Cenozoic arc-rear and backarc thrusting, together with pulses of interior magmatism, associated with development of the Cordilleran magmatic arc to the west where subduction and arc accretion expanded the continental margin, and (4) middle to late Cenozoic crustal extension, which involved initial intra-arc to backarc deformation and later transtensional torsion of the continental block inland from the evolving San Andreas transform system. Potential metallogenic influences on Great Basin tectonic evolution included transfer of substance from mantle to crust by magmatism and associated metasomatism, and reworking of crustal materials by both magmatism and intracrustal fluid flow, the latter of which was induced both by thermal effects of magmatism and by reconfiguration of fluid-bearing rock masses during multiple episodes of Great Basin deformation.