HR: 13:55h
AN: H52D-02    [PDF]
TI: Geochemistry of the Red River and Chang Jiang - Constraints on the Weathering Flux Associated with the Indo-Tibetan collision
AU: * Ellis, A
EM: andre@earth.northwestern.edu
AF: Northwestern University - Department of Geological Sciences, 1850 Campus Dr, Evanston, IL 60208 United States
AU: Huh, Y
EM: huh@earth.northwestern.edu
AF: Northwestern University - Department of Geological Sciences, 1850 Campus Dr, Evanston, IL 60208 United States
AB: Red River and the headwaters of the Chang Jiang in western China and Vietnam are in the tectonically active part of the Himalayan-Tibetan orogeny. Riverine fluxes associated with weathering along these rivers contribute to the total weathering yield associated with the main collision. The riverine flux carried by Himalayan rivers is considered to be a significant fraction of continental weathering budgets globally. Interpreting the geochemistry of rivers in terms of lithology, weathering rates, tectonics and global climate implications pose a challenge and we therefore use a suite of geochemical tools, including but not limited to, major ion and trace element concentrations and analyses of various isotope systems namely Sr, Os, Li, U among others. Over 150 samples were obtained from pristine locations along these rivers during the summer and winter seasons spanning a period of 3 years. Major element chemistry along with some trace element analyses (Sr, Rb, Ba, Cs, U and Th) is comparable to that of the large rivers draining the Himalayan mountain belt. For example, Sr concentrations range from 0.2 to 7.0 uM for Red River and 0.07 to 13 uM for the Chang Jiang. Sr isotope analyses provide additional constraints on the source of the weathering flux (silicate v/s carbonate), which in turn provides constraints on interpretations of the global marine Sr isotope record, atmospheric CO$_{2}$ drawdown and changing global climate.
DE: 1030 Geochemical cycles (0330)
DE: 1040 Isotopic composition/chemistry
DE: 1065 Trace elements (3670)
DE: 1625 Geomorphology and weathering (1824, 1886)
SC: Hydrology [H]
MN: 2003 Fall Meeting