A geological carbon cycle sink hosted by ocean crust talus breccias
Calcium carbonate precipitation in ageing ocean crust sequesters carbon dioxide dissolved in seawater through seafloor weathering reactions, influencing atmospheric CO<sub>2</sub> concentrations on million-year timescales. However, this crustal carbon sink, and the extent it balances CO<sub>2</sub> degassing during crustal formation at mid-ocean ridges, remain poorly quantified due to limited sampling of the vast ridge flanks where CO<sub>2</sub> 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<sub>2</sub>, 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<sub>2</sub> sink equivalent to a large proportion of the CO<sub>2</sub> 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<sub>2</sub> release and uptake in Earth's carbon cycle.
Authors
- Rosalind M. Coggon (ORCID: https://orcid.org/0000-0002-9228-9707)
- Jason B. Sylvan (ORCID: https://orcid.org/0000-0001-7361-7472)
- Pamela D. Kempton (ORCID: https://orcid.org/0000-0003-0798-1836)
- Elliot J. Carter (ORCID: https://orcid.org/0000-0002-0180-0419)
- L.J.C. Grant (ORCID: https://orcid.org/0000-0002-0668-9633)
- Trevor Williams (ORCID: https://orcid.org/0000-0001-9204-2731)
- J. Reece (ORCID: https://orcid.org/0000-0003-3521-8520)
- C.M. Routledge (ORCID: https://orcid.org/0000-0002-6037-6638)
- Gail Christeson (ORCID: https://orcid.org/0000-0002-4749-4429)
- Thomas M. Belgrano (ORCID: https://orcid.org/0000-0003-2160-1895)
- Michelle Harris (ORCID: https://orcid.org/0000-0001-9618-2862)
- Christopher M. Lowery (ORCID: https://orcid.org/0000-0002-0101-4397)
- Matthew J. Cooper (ORCID: https://orcid.org/0000-0002-2130-2759)
- Justin Estep (ORCID: https://orcid.org/0000-0002-2004-4786)
- E. Albers (ORCID: https://orcid.org/0000-0002-0874-5926)
- D.A.H. Teagle (ORCID: https://orcid.org/0000-0002-4416-8409)
- Emily R. Estes
- A. Evans (ORCID: https://orcid.org/0000-0003-3252-5998)
Institutions
- University College Dublin (IE)
- Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (DE)
- U.S. National Science Foundation (US)
- Texas A&M International University (US)
- Kansas State University (US)
- National Oceanography Centre (GB)
- Northern Arizona University (US)
- Christian-Albrechts-Universität zu Kiel (DE)
- Discovery Place (US)
- University of Southampton (GB)
- Keele University (GB)
- The University of Texas at Austin (US)
- University of Plymouth (GB)
- Texas A&M University (US)
Publication Details
- Journal
- Nature Geoscience
- Published
- 2025-11-24
- DOI
- https://doi.org/10.1038/s41561-025-01839-5
- Citations
- 1
- Primary Topic
- Paleontology and Stratigraphy of Fossils
- Type
- article
- Field-Weighted Citation Impact
- 4.33
Funders
- National Science Foundation
- University of Southampton
- University of Bristol
- Deutsche Forschungsgemeinschaft