HR: 0800h
AN: T31A-1257 INVITED     [Abstracts]
TI: Timescales and topographic expression of lithospheric extension in the western Great Basin, NV, USA
AU: * Friedrich, A M
EM: anke@alum.mit.edu
AF: Institute of Geosciences, University of Potsdam, Karl-Liebknechtstr. 24, Golm, 14476 Germany
AU: * Friedrich, A M
EM: anke@alum.mit.edu
AF: Laboratoire de Tectonique, Mecanique de la Lithosphere, Laboratoire de Tectonique, Institut de Physique du Globe de Paris Institut de Physique du Globe de Paris, 4, place Jussieu, Cedex 05, Paris, 75252 France
AU: Gaudemer, Y
EM: gaudemer@ipgp.jussieu.fr
AF: Laboratoire de Tectonique, Mecanique de la Lithosphere, Laboratoire de Tectonique, Institut de Physique du Globe de Paris Institut de Physique du Globe de Paris, 4, place Jussieu, Cedex 05, Paris, 75252 France
AU: King, G
EM: king@ipgp.jussieu.fr
AF: Laboratoire de Tectonique, Mecanique de la Lithosphere, Laboratoire de Tectonique, Institut de Physique du Globe de Paris Institut de Physique du Globe de Paris, 4, place Jussieu, Cedex 05, Paris, 75252 France
AU: Armijo, R
EM: armijo@ipgp.jussieu.fr
AF: Laboratoire de Tectonique, Mecanique de la Lithosphere, Laboratoire de Tectonique, Institut de Physique du Globe de Paris Institut de Physique du Globe de Paris, 4, place Jussieu, Cedex 05, Paris, 75252 France
AU: Strecker, M
EM: strecker@rz.uni-potsdam.de
AF: Institute of Geosciences, University of Potsdam, Karl-Liebknechtstr. 24, Golm, 14476 Germany
AB: One of the goals of the Plate Boundary Observatory is to determine how continental lithosphere responds to changes in driving forces. Because many geodynamic processes occur on timescales much longer than geodetic recording time intervals, longer term deformation measurements are required. On what timescale, however, should these longer term (geological) measurements be made to allow a meaningful integration with geodetic time series? Traditional geological and tectonic studies appear to indicate that continental fault systems are active continuously for millions of years, whereas more precise paleoseismological measurements often document irregular fault displacement. In order to study the evolution of individual fault systems, measurements are needed on an intermediate timescale: long enough to average over many seismic cycles, but short enough to provide the incremental strain history. For continental fault systems such as those of the Basin and Range Province (c. 10 nstrain at present, e.g., Bennett et al., TECTONICS 2003, Friedrich et al., JGR 2003), the expected time interval is on the order of a few hundred thousand years and the expected signal size should range from several to a few hundred meters. In climatically sensitive regions, such as the Great Basin, such surface deformation features (fault trace in alluvial sediments, triangular facets, etc.) may, on one hand, be preserved extremelly well over several hundred thousand years; On the other hand, however, such regions are also sensitive to weather extremes and medium-term climatic variations (tens of ka) as exhibited during wet periods. In the Great Basin, both cases are represented. For example, (1) on the 10 ka timescale, many internally drained basins filled to large lakes (Bonneville and Lahontan) which left thick sedimentary sections covering most pre-existing fault traces; and (2) on the 500 ka timescale, growth or reactivation of faults affected drainage, erosion and deposition patterns. We document such tectonogeomorphic features along the W-flank of the Shoshone Range and Cortez Mountains and surrounding region. We speculate that these features are the expression of active crustal or lithospheric thinning.
DE: 8107 Continental neotectonics
DE: 8109 Continental tectonics--extensional (0905)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting