Neodymium isotopic evidence for decreasing crustal contributions to Cenozoic ignimbrites of the western United States: Implications for the thermal evolution of the Cordilleran crust

Research Article| July 01, 1993 Neodymium isotopic evidence for decreasing crustal contributions to Cenozoic ignimbrites of the western United States: Implications for the thermal evolution of the Cordilleran crust FRANK V. PERRY; FRANK V. PERRY 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 Search for other works by this author on: GSW Google Scholar DONALD J. DePAOLO; DONALD J. DePAOLO 2Center for Isotope Geochemistry, Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar W. SCOTT BALDRIDGE W. SCOTT BALDRIDGE 3Earth and Environmental Sciences Division, M.S. D462, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Search for other works by this author on: GSW Google Scholar Author and Article Information FRANK V. PERRY 1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 DONALD J. DePAOLO 2Center for Isotope Geochemistry, Department of Geology and Geophysics, University of California, Berkeley, California 94720 W. SCOTT BALDRIDGE 3Earth and Environmental Sciences Division, M.S. D462, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1993) 105 (7): 872–882. https://doi.org/10.1130/0016-7606(1993)105<0872:NIEFDC>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation FRANK V. PERRY, DONALD J. DePAOLO, W. SCOTT BALDRIDGE; Neodymium isotopic evidence for decreasing crustal contributions to Cenozoic ignimbrites of the western United States: Implications for the thermal evolution of the Cordilleran crust. GSA Bulletin 1993;; 105 (7): 872–882. doi: https://doi.org/10.1130/0016-7606(1993)105<0872:NIEFDC>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Numerous studies of large-volume rhyolite systems from the western United States conclude that rhyolite is primarily generated by extensive fractional crystallization of basalt accompanied by assimilation of crustal wallrock. Relative crustal contributions to large-volume rhyolite can be estimated by comparing the Nd isotopic composition of the rhyolite with the Nd isotopic characteristics of crust and mantle reservoirs associated with different continental basement age provinces. We have estimated the crustal contributions to 12 early Oligocene to Pleistocene rhyolite systems located throughout the Cordillera. We have determined that (1) crustal contributions to large-volume rhyolite systems decrease from the Oligocene to the Miocene, and (2) rhyolite systems younger than 20 Ma are dominated by mantle components. The crustal contributions to rhyolite systems may be controlled by system size and duration, crustal thickness, tectonic setting, crustal composition, crustal density, and crustal temperature. We conclude that regional cooling of the lower crust, which progressively limited the amount of crustal wallrock assimilated by rhyolite systems, is the only parameter that is consistent with geologic and geochemical data for rhyolite systems and the geologic evolution of the Cordillera. A quantitative model that relates the amount of crustal contribution to assimilation/recharge rates and the temperature of the crust indicates that lower-crustal temperatures would have to decrease about 300 °C between early Oligocene and early Miocene time to account for the decrease in crustal contributions. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.