Refined weathering CO2 budget of the Tibetan Plateau strongly modulated by sulphide oxidation

Abstract

Abstract Estimation of net CO2 consumption by weathering in orogen is complicated as high erosion rate promotes competing processes of CO2 consumption (silicate weathering) and releasing (sulfuric acid (H2SO4) dissolution of carbonate). Quantification of H2SO4 disturbing on weathering is missing in the Tibetan Plateau, hindering the understanding of Himalayan orogenesis impact on global carbon cycle. Here we calculate the riverine solute contributions from both carbonic and sulfuric acid mediated weathering, and their weathering fluxes with major river geochemistry dataset from the Tibetan Plateau. We find that silicate weathering is not anomalous, while carbonate weathering flux is 2.09% of the global value with 1.01% drainage area. Over 80% H2SO4 originated from pyrite oxidation is consumed by carbonate weathering, which counteracts ~58% of the CO2 consumption flux by silicate weathering. The refined weathering CO2 budget in this work provides quantitative modern evidence for pyrite weathering in orogen serving as negative feedback on atmospheric pCO2.