Chemical weathering and lithologic controls of water chemistry in a high‐elevation river system: Clark's Fork of the Yellowstone River, Wyoming and Montana

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Abstract
Seasonal analyses of surface water geochemistry were conducted in the Clark's Fork of the Yellowstone watershed to determine whole‐rock weathering rates. The Clark's Fork of the Yellowstone is a high‐elevation catchment with distinct bedrock lithologies. Using dissolved solute concentrations and stream flow data, we calculated cation denudation rates of 119 g m−2 yr−1 (65,900 eq ha−1 yr−1) for carbonate‐rich sedimentary rocks, 16.6 g m−2 yr−1 (8200 eq ha−1 yr−1) for andesitic volcanics, and 9.8 g m−2 yr−1(5300 eq ha−1 yr−1) for granitic gneisses. Ca/Na ratios indicate that chemical weathering of disseminated calcite in granitic rocks contributes to the total solute load in these subcatchments. Removal of this c(2100 eq ha−1 yr−1).