Abstract

Long-term weathering rates (RLT) were determined from base cation depletion in soil profiles developed on six granitic glacial moraines varying in age from 0.4 to ≥297 ka in the Wind River Mountains, Wyoming. Weathering rates were found to decrease with soil age (t) according to the power-law equation RLT = 15 ċ t(−0.71) where RLT is in meq ċ m −2 ċ yr −1, and t is in ka. Comparable data from the literature are consistent with this function, and it is similar to power-law equations describing changes in laboratory weathering rates with time. On the basis of our study, we predict that for a catchment unaffected by anthropogenic inputs and in a steady state with respect to the organic and cation exchange pools, RLT should be higher than present-day weathering rates derived from stream fluxes (RPD) by a factor of about 3.4.

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