Phanerozoic palinspastic reconstructions of Great Basin geotectonics (Nevada-Utah, USA)

摘要

Palinspastic reconstructions of Phanerozoic geotectonic elements in the Great Basin (Nevada-Utah, USA) to restore the effects of Basin and Range extension, Sevier thrust telescoping, and evolution of the Cordilleran magmatic arc and forearc region to the west provide the following insights: (1) the position of the Neogene Walker Lane incipient transform system was controlled by thermal weakening of the lithosphere beneath the extinct southern segment of the ancestral Cascades arc; (2) Eocene to Miocene magmatism swept across the Great Basin from northeast to southwest, in a direction normal to the continental margin, rather than from north to south parallel to the continental margin; (3) the elevated Paleogene Nevadaplano and Sevier thrust belt between the Sierra Nevada and the Sevier foreland basin was comparable in width to the modern Altiplano and Subandean thrust belt between the Andean volcanic chain and the Brazilian foreland; (4) the late Mesozoic Sierra Nevada and Idaho batholiths formed in the roots of the Cordilleran magmatic arc as segments of a linear batholith belt that lacked curvature; (5) early to middle Mesozoic backarc basins, thrusts, and plutons were coordinated geodynamically with arc accretion and closure of a suture belt in the Sierran foothills, Klamath Mountains, and Blue Mountains of the Cordilleran arc terrane to the west; and (6) Devoniana€“Mississippian Roberts Mountains and Permiana€“Triassic Golconda thrusts and allochthons, emplaced successively from the west upon the flank of the Cambriana€“Devonian miogeoclinal belt, were formed as linear features subparallel to the Wasatch hinge line marking the western edge of undeformed craton.