HR: 08:15h
AN: T21E-02 INVITED    [Abstracts]
TI: Detrital dating of Asian orogenesis: insights and caveats
AU: * Burbank, D W
EM: burbank@crustal.ucsb.edu
AF: Dept. of Earth Science, Univ. of California, Santa Barbara, CA 93106, United States
AB: Technological advances over the past two decades have facilitated increasingly routine application of single- crystal dating and cosmogenic nuclide dating to studies of orogenic erosion. Both approaches commonly utilize grab samples of detrital sediment, either modern or ancient. Whereas detrital cosmogenic data are typically used to define mean erosion rates for upstream catchments, single-crystal ages are used both to discern provenance and to define lag times: interval between isotopic closure and deposition. Recent results from dating modern fluvial sediments illuminate key concepts that underpin interpretations of results from older strata: the fidelity of the detrital signal, its evolution through an orogen, its relationship to discrete source areas, and its temporal evolution. Despite the increasing availability of dates and rates for detrial grains, relatively few studies have addressed the sources of uncertainty that modulate the precision and accuracy with which detrital results should be interpreted. Such uncertainties derive not only from sampling statistics and measurement uncertainties, but also from both geomorphic sources (seasonal variation in sediment supply and source, changes in glacial cover, the impact of stochastic geomorphic events, such as landslides), as well as tectonic ones (time-dependent deformation and thermal models, particle paths through the orogen). A better understanding of the impact of these uncertainties will underpin more reliable and less speculative interpretations of future dating results from both ancient and modern detrital fluvial sediments.
DE: 1815 Erosion
DE: 8108 Continental tectonics: compressional
DE: 8175 Tectonics and landscape evolution
DE: 8177 Tectonics and climatic interactions
DE: 9320 Asia
SC: Tectonophysics [T]
MN: 2007 Fall Meeting