The effect of lithology on the relationship between denudation rate and chemical weathering pathways – evidence from the eastern Tibetan Plateau
-
Published:2022-06-07
Issue:3
Volume:10
Page:513-530
-
ISSN:2196-632X
-
Container-title:Earth Surface Dynamics
-
language:en
-
Short-container-title:Earth Surf. Dynam.
Author:
Bufe AaronORCID, Cook Kristen L.ORCID, Galy Albert, Wittmann Hella, Hovius Niels
Abstract
Abstract. The denudation of rocks in mountain belts exposes a range of fresh minerals to the surface of the Earth that are chemically weathered by acidic and oxygenated fluids. The impact of the resulting coupling between denudation and weathering rates fundamentally depends on the types of minerals that are weathering. Whereas silicate weathering sequesters CO2, the combination of sulfide oxidation and carbonate dissolution emits CO2 to the atmosphere. Here, we combine the concentrations of dissolved major elements in stream waters with 10Be basin-wide
denudation rates from 35 small catchments in eastern Tibet to elucidate the
importance of lithology in modulating the relationships between denudation
rate, chemical weathering pathways, and CO2 consumption or release. Our catchments span 3 orders of magnitude in denudation rate in low-grade flysch, high-grade metapelites, and granitoid rocks. For each stream, we estimate the concentrations of solutes sourced from silicate weathering, carbonate dissolution, and sulfide oxidation using a mixing model. We find that for all lithologies, cation concentrations from silicate weathering are largely independent of denudation rate, but solute concentrations from carbonates and, where present, sulfides increase with increasing denudation rate. With increasing denudation rates, weathering may therefore shift from consuming to releasing CO2 in both (meta)sedimentary and granitoid lithologies. For a given denudation rate, we report dissolved solid concentrations and inferred weathering fluxes in catchments underlain by (meta)sedimentary rock that are 2–10 times higher compared to catchments containing granitoid lithologies, even though climatic and topographic parameters do not vary systematically between these catchments. Thus, varying proportions of exposed (meta)sedimentary and igneous rocks during orogenesis could lead to changes in the sequestration and release of CO2 that are independent of denudation rate.
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Geophysics
Reference78 articles.
1. Anderson, S. P., Drever, J. I., Frost, C. D., and Holden, P.: Chemical
weathering in the foreland of a retreating glacier, Geochim. Cosmochim. Ac.,
64, 1173–1189, https://doi.org/10.1016/S0016-7037(99)00358-0, 2000. 2. Balco, G., Stone, J. O., Lifton, N. A., and Dunai, T. J.: A complete and
easily accessible means of calculating surface exposure ages or erosion
rates from 10Be and 26Al measurements, Quatern. Geochronol., 3, 174–195, https://doi.org/10.1016/j.quageo.2007.12.001, 2008. 3. Berner, R. A.: Rate control of mineral dissolution under Earth surface
conditions, Am. J. Sci., 278, 1235–1252, https://doi.org/10.2475/ajs.278.9.1235, 1978. 4. Berner, R. A., Lasaga, A. C., and Garrels, R. M.: The carbonate-silicate
geochemical cycle and its effect on atmospheric carbon dioxide over the past
100 million years, Am. J. Sci., 283, 641–683, https://doi.org/10.2475/ajs.283.7.641, 1983. 5. Blattmann, T. M., Wang, S. L., Lupker, M., Märki, L., Haghipour, N.,
Wacker, L., Chung, L. H., Bernasconi, S. M., Plötze, M., and Eglinton, T. I.: Sulphuric acid-mediated weathering on Taiwan buffers geological atmospheric carbon sinks, Sci. Rep., 9, 2945, https://doi.org/10.1038/s41598-019-39272-5, 2019.
Cited by
13 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|