HR: 11:20h
AN: U32A-05 INVITED     [Abstracts]
TI: Basin-scale Denudation Rates for the Siberian Craton From in situ-Produced Beryllium-10 in River-Borne Sands
AU: * Brown, E T
EM: etbrown@d.umn.edu
AF: University of Minnesota Duluth, Large Lakes Observatory Dept. of Geological Sciences, Duluth, MN 55812 United States
AU: Bourles, D L
EM: bourles@cerege.fr
AF: CEREGE, Europole de l'Arbois, Aix-en-Provence, F-13545 France
AB: in situ-produced cosmogenic nuclides are becoming more widely applied for examining weathering and erosional processes. In particular, the cosmogenic nuclide content of river-borne sand has been utilized to determine basin-scale denudation rates averaged over ~10⁴ year timescales. However, in some cases, the accuracy of rates deduced by this approach may be limited by imperfect knowledge of the systematics of cosmogenic nuclide production. Nevertheless, such studies have proven to be an important counterpart to work utilizing modern riverine chemistry to evaluate weathering and erosion. For example, studies of the chemistry of rivers draining the cratons and shield terrains of Siberia (Zakharova et al, 2005; Huh et al 1998, Huh and Edmond, 1999) suggest that chemical weathering in these cold regions occurs at rates comparable to those observed in temperate regions. This result is at odds with the view that low runoff and low temperatures should be associated with decreased rates of chemical weathering. It has thus been suggested that relatively high weathering rates found in Siberia result from enhancement of physical erosion by ice and freeze-thaw processes. We present ¹⁰Be results on riverine sands from group of Siberian streams that indicate high rates of total denudation, confirming that the high chemical yields inferred from modern riverine chemistry have persisted over long timescales.
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 1815 Erosion
DE: 1886 Weathering (0790, 1625)
SC: Union [U]
MN: Fall Meeting 2005