HR: 16:00h
AN: V52G-01    [PDF]
TI: Rise and Fall of the Great Basin Region
AU: * Horton, T W
EM: twh@pangea.stanford.edu
AF: Stanford University, Building 320 - Braun Hall, Stanford, CA 94305-2115 United States
AU: Chamberlain, C P
EM: chamb@pangea.stanford.edu
AF: Stanford University, Building 320 - Braun Hall, Stanford, CA 94305-2115 United States
AB: Cenozoic stable isotope records for terrestrial carbonate and authigenic smectite from the Great Basin region are presented. In the northern Great Basin, a ~10% decrease in $\delta$$^{18}$O values is observed in lacustrine carbonates during the Eocene, followed by a ~5% increase in $\delta$$^{18}$O values in authigenic carbonate and smectite between the late Miocene and Pliocene. Thin-section analysis indicates all samples were not exposed to significant burial diagenesis, and evaporative and temperature effects alone are not sufficient to explain the observed isotopic shifts. We suggest the observed isotopic shifts are caused by regional surface uplift and subsidence events during the Eocene and Miocene, respectively. A similar Neogene oxygen isotope record is observed in Mojave Desert and southern Basin and Range province stratigraphic sections.
DE: 1045 Low-temperature geochemistry
DE: 1620 Climate dynamics (3309)
DE: 8110 Continental tectonics--general (0905)
DE: 8404 Ash deposits
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting