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Efficient transport of fossil organic carbon to the ocean by steep mountain rivers: An orogenic carbon sequestration mechanism

Hilton, R.G.; Galy, A.; Hovius, N.; Horng, M.J.

Efficient transport of fossil organic carbon to the ocean by steep mountain rivers: An orogenic carbon sequestration mechanism Thumbnail


Authors

R.G. Hilton

A. Galy

N. Hovius

M.J. Horng



Abstract

Mountain building exposes fossil organic carbon (OCfossil) in exhumed sedimentary rocks. Oxidation of this material releases carbon dioxide from long-term geological storage to the atmosphere. OCfossil is mobilized on hillslopes by mass wasting and transferred to the particulate load of rivers. In large fluvial systems, it is thought to be oxidised in transit, but in short, steep rivers that drain mountain islands, OCfossil may escape oxidation and re-enter geological storage due to rapid fluvial transfer to the ocean. In these settings, the rates of OCfossil transfer and their controls remain poorly constrained. Here we quantify the erosion of OCfossil from the Taiwan mountain belt, combining discharge statistics with measurements of particulate organic carbon load and source in 11 rivers. Annual OCfossil yields in Taiwan vary from 12 ± 1 to 246 ± 22 tC km−2 yr−1, controlled by the high physical erosion rates that accompany rapid crustal shortening and frequent typhoon impacts. Efficient transfer of this material ensures that 1.3 ± 0.1 × 106 tC yr−1 of OCfossil exhumed in Taiwan is delivered to the ocean, with <15% loss due to weathering in transit. Our findings suggest that erosion of coastal mountain ranges can force efficient transfer and long-term re-accumulation of OCfossil in marine sediments, further enhancing the role of mountain building in the long-term storage of carbon in the lithosphere.

Citation

Hilton, R., Galy, A., Hovius, N., & Horng, M. (2011). Efficient transport of fossil organic carbon to the ocean by steep mountain rivers: An orogenic carbon sequestration mechanism. Geology, 39(1), 71-74. https://doi.org/10.1130/g31352.1

Journal Article Type Article
Publication Date Jan 1, 2011
Deposit Date Oct 21, 2010
Publicly Available Date Mar 29, 2024
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 39
Issue 1
Pages 71-74
DOI https://doi.org/10.1130/g31352.1

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