Laramide bulldozing of lithosphere beneath the Arizona transition zone, southwestern United States
Affiliation
Department of Geosciences, University of ArizonaIssue Date
2023-08-01Keywords
geology
Metadata
Show full item recordPublisher
Geological Society of AmericaCitation
Kapp, P., Jepson, G., Carrapa, B., Schaen, A. J., He, J. J., & Wang, J. W. (2023). Laramide bulldozing of lithosphere beneath the Arizona transition zone, southwestern United States. Geology, 51(10), 952-956.Journal
GeologyRights
© 2023 Geological Society of America.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
The northwest-trending transition zone (TZ) in Arizona (southwestern United States) is an ~100-km-wide physiographic province that separates the relatively undeformed southwestern margin of the Colorado Plateau from the hyperextended Basin and Range province to the southwest. The TZ is widely depicted to have been a Late Cretaceous–Paleogene northeastdipping erosional slope along which Proterozoic rocks were denuded but not significantly deformed. Our multi-method thermochronological study (biotite 40Ar/39Ar, zircon and apatite [U-Th-Sm]/He, and apatite fission track) of Proterozoic rocks in the Bradshaw Mountains of the west-central Arizona TZ reveals relatively rapid cooling (~10 °C/m.y.) from temperatures of?>180 °C to <60 °C between ca. 70 and ca. 50 Ma. Given minimal ca. 70–50 Ma upper-crustal shortening in the TZ, we attribute cooling to exhumation driven by northeastward bulldozing of continental lower crust and mantle lithosphere beneath it by the Farallon flat slab. Bulldozing is consistent with contemporaneous (ca. 70–50 Ma) underplating and initial exhumation of Orocopia Schist to the southwest in western Arizona and Mesozoic garnet-clinopyroxenite xenoliths of possible Mojave batholith keel affinity in ca. 25 Ma TZ volcanic rocks.Note
12 month embargo; 1 August 2023ISSN
0091-7613EISSN
1943-2682DOI
10.1130/g51194.1Version
Final accepted manuscriptae974a485f413a2113503eed53cd6c53
10.1130/g51194.1