Year: 2025
Type: article
Abstract: Calcium carbonate precipitation in ageing ocean crust sequesters carbon dioxide dissolved in seawater through seafloor weathering reactions, influencing atmospheric CO 2 concentrations on million-year timescales. However, this crustal carbon sink, and the extent it balances CO 2 degassing during crustal formation at mid-ocean ridges, remain poorly quantified due to limited sampling of the vast ridge flanks where CO 2 uptake continues for millions of years. Here we quantify the carbon sink hosted within talus breccias that accumulated through mass wasting 61 million years ago during rift faulting at the slow spreading Mid-Atlantic Ridge, cored during International Ocean Discovery Program South Atlantic Transect Expedition 390. After 40 million years of carbonate cementation, these breccias contain ~7.5 wt% seawater-derived CO 2 , 2 to 40 times more than previously cored upper crust. Our estimates of talus breccia abundance based on fault geometries indicate that talus formed at slow-spreading ridges can accommodate a CO 2 sink equivalent to a large proportion of the CO 2 released during accretion of the underlying crust. The proportion of plate divergence accommodated by faulting, and hence talus abundance, increases nonlinearly with decreasing spreading rate. Consequently, past variations in spreading rate may have impacted the balance between ocean crust CO 2 release and uptake in Earth’s carbon cycle.
Source: Nature Geoscience
Authors: Rosalind M. Coggon, Elliot J. Carter, Lewis J. C. Grant, Aled D. Evans, Christopher M. Lowery, Damon A. H. Teagle, Pamela D. Kempton, Matthew J. Cooper, Claire M. Routledge, Elmar Albers, Justin Estep, Gail L. Christeson, Michelle Harris, Thomas M. Belgrano, Jason B. Sylvan, Julia S. Reece, Emily R. Estes, Trevor Williams, on behalf of The South Atlantic Transect IODP Expedition 390 & 393 Scientists
Institutions: National Oceanography Centre, University of Southampton, Keele University, University of Texas Institute for Geophysics, The University of Texas at Austin, Kansas State University, Christian-Albrechts-Universität zu Kiel, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Northern Arizona University, U.S. National Science Foundation, University of Plymouth, University College Dublin, Texas A&M University
Language: English
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $12,690
Awards: Developing continuous volcano-stratigraphies across the South Atlantic Transect: NERC UK-IODP Moratorium support for Aled Evans - IODP Expedition 393, G1566475027, G2444640347, Hydrothermal alteration during the aging of the ocean crust: IODP Expedition 393 South Atlantic Transect, Sixty million years of seafloor alteration: spatial-temporal controls on volatile incorporation along a 1000 km transect of oceanic crust, A Proposal to Manage the U.S. Science Support Program Office associated with the International Ocean Discovery Program (USSSP-IODP), G5564971023, Timescales of South Atlantic ridge flank hydrothermal exchange; UK-IODP Moratorium Award for Thomas Belgrano - Shipboard Scientist, Expedition 393., UK-IODP Moratorium Co-Chief Support for Expedition 393: Quantifying the geochemical impacts of ocean crustal ageing., G8012196077, Management and Operations of the JOIDES Resolution as a Facility for the International Ocean Discovery Program (IODP), UK-IODP Moratorium Award for Lewis Grant - Shipboard Scientist Expedition 390: The role of ridge flank dolomitization in the ocean Mg budget
OpenAlex ID: W4416599782