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Long-distance migration and venting of methane from the base of the hydrate stability zone

Lookup NU author(s): Professor Richard DaviesORCiD, Dr Mark IrelandORCiD, Dr Miguel Morales MaquedaORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© 2023, The Author(s).Marine methane hydrate is an ice-like substance that is stable in sediment around marine continental margins where water depths are greater than ~450–700 m. The release of methane due to melting of hydrates is considered to be a mechanism for past global carbon-cycle perturbations and could exacerbate ongoing anthropogenic climate change. Increases in bottom-water temperature at the landward limit of marine hydrate around continental margins, where vulnerable hydrate exists at or below the seabed, cause methane to vent into the ocean. However, this setting represents only ~3.5% of the global hydrate reservoir. The potential for methane from hydrate in deeper water to reach the atmosphere was considered negligible. Here we use three-dimensional (3D) seismic imagery to show that, on the Mauritanian margin, methane migrated at least 40 km below the base of the hydrate stability zone and vented through 23 pockmarks at the shelf break, probably during warmer Quaternary interglacials. We demonstrate that, under suitable circumstances, some of the 96.5% of methane bound in deeper water distal hydrates can reach the seafloor and vent into the ocean beyond the landward limit of marine hydrate. This reservoir should therefore be considered for estimating climate change-induced methane release during a warming world.


Publication metadata

Author(s): Davies RJ, Yang J, Ireland MT, Berndt C, Maqueda MAM, Huuse M

Publication type: Article

Publication status: Published

Journal: Nature Geoscience

Year: 2023

Pages: epub ahead of print

Online publication date: 06/12/2023

Acceptance date: 23/10/2023

Date deposited: 18/12/2023

ISSN (print): 1752-0894

ISSN (electronic): 1752-0908

Publisher: Nature Research

URL: https://doi.org/10.1038/s41561-023-01333-w

DOI: 10.1038/s41561-023-01333-w


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Funding

Funder referenceFunder name
NERC
NE/W00996X/1

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