HR: 08:15h
AN: T11G-02    [Abstracts]
TI: Stable Isotope Paleoaltimetry of Evolving Orogenic Plateaus
AU: * Mulch, A
EM: mulch@geowi.uni-hannover.de
AF: Universität Hannover, Institut für Geologie Callinstr. 30, Hannover, 30167, Germany
AU: * Mulch, A
EM: mulch@geowi.uni-hannover.de
AF: Stanford University, Geological and Environmental Sciences 450 Serra Mall, Stanford, CA 94305, United States
AU: Chamberlain, C P
EM: chamb@pangea.stanford.edu
AF: Stanford University, Geological and Environmental Sciences 450 Serra Mall, Stanford, CA 94305, United States
AU: Teyssier, C
EM: Christian.Teyssier@unil.ch
AF: Universite de Lausanne, Institut de Geologie Anthropole, Lausanne, 1015, Switzerland
AU: Graham, S A
EM: graham@pangea.stanford.edu
AF: Stanford University, Geological and Environmental Sciences 450 Serra Mall, Stanford, CA 94305, United States
AU: Wells, M
EM: michael.wells@unlv.edu
AF: University of Nevada, Geoscience 4505 Maryland Pkwy, Las Vegas, 89154,
AB: High-elevation orogenic plateaus and mountain ranges exert a strong control on global climate and precipitation patterns and respond to tectonic processes in the lithosphere and upper mantle. Reconstructing the history of surface elevation thus provides a critical link between erosive, climatic, and tectonic processes. Stable isotope studies of lacustrine, fluvial and pedogenic environments, intermontane and intra foreland basins, as well as core complex-bounding detachment faults record the Cenozoic isotopic and sedimentologic fingerprint of the evolving landscape of the North American Cordillera. Stable isotope paleoaltimetry allows the determination of long-term elevation changes, yet complex terrestrial precipitation and hydraulic patterns necessitate integrative approaches, comprising various isotope systems and mineral proxies. Combined stable isotope, geochronological, sedimentological, and structural data suggest that during the early Eocene the western edge of Cordilleran orogen consisted of a proto-Sierra Nevada that continued into a broad plateau of the Sevier hinterland bordered on its eastern flanks by intra foreland basins with local basement uplifts. Following Mesozoic shortening, topography and regional mean elevation were spatially and temporally transient. Stable isotopic and sedimentological data suggest that a landscape characterized by increased peak elevations and elevated relief migrated from northeast to southwest as the landscape became high and more rugged. This occurred between 50 and 47 Ma in SW Montana, between 40 to 35 Ma in northern Nevada, and by ~22 Ma in southern Nevada. Embedded in the context of stable isotopic studies in terrestrial basins across and along strike of the Cordillera, we see an emerging picture of major readjustments in surface elevation and relief combined with reorganization of continental drainage systems and envisage a landscape that first responds to mid-crustal flow followed by normal faulting in crustal-scale detachment systems.
DE: 8175 Tectonics and landscape evolution
DE: 8177 Tectonics and climatic interactions
SC: Tectonophysics [T]
MN: 2007 Fall Meeting