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Transient mobilization of subcrustal carbon coincident with Palaeocene-Eocene thermal maximum

Transient mobilization of subcrustal carbon coincident with Palaeocene-Eocene thermal maximum
Transient mobilization of subcrustal carbon coincident with Palaeocene-Eocene thermal maximum
Plume magmatism and continental breakup led to the opening of the northeast Atlantic Ocean during the globally warm early Cenozoic. This warmth culminated in a transient (170 thousand year, kyr) hyperthermal event associated with a large, if poorly constrained, emission of carbon called the Palaeocene–Eocene Thermal Maximum (PETM) 56 million years ago (Ma). Methane from hydrothermal vents in the coeval North Atlantic Igneous Province (NAIP) has been proposed as the trigger, though isotopic constraints from deep sea sediments have instead implicated direct volcanic carbon dioxide (CO2) emissions. Here we calculate that background levels of volcanic outgassing from mid-ocean ridges and large igneous provinces yield only one-fifth of the carbon required to trigger the hyperthermal. However, geochemical analyses of volcanic sequences spanning the rift-to-drift phase of the NAIP indicate a sudden ~220 kyr-long intensification of magmatic activity coincident with the PETM. This was likely driven by thinning and enhanced decompression melting of the sub-continental lithospheric mantle, which critically contained a high proportion of carbon-rich metasomatic carbonates. Melting models and coupled tectonic–geochemical simulations indicate that >104 gigatons of subcrustal carbon was mobilized into the ocean and atmosphere sufficiently rapidly to explain the scale and pace of the PETM.
1752-0894
Gernon, Thomas
658041a0-fdd1-4516-85f4-98895a39235e
Barr, Ryan
71c873c7-c9d9-4029-9068-0d7dc9fd1972
Fitton, Godfrey
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Hincks, Thea
9654038a-2f5c-40bc-8f0e-33afc0b1fb71
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Longman, Jack
84e3d567-8575-477e-8d2f-5b21a1c709e4
Merdith, Andrew
6e6e4af3-ae97-42eb-9b81-36e3c1d6783b
Mitchell, Ross
2033970b-0254-4967-b6ec-e69f1e52a0ea
Palmer, Martin
d2e60e81-5d6e-4ddb-a243-602537286080
Gernon, Thomas
658041a0-fdd1-4516-85f4-98895a39235e
Barr, Ryan
71c873c7-c9d9-4029-9068-0d7dc9fd1972
Fitton, Godfrey
7a50a2fd-5e52-48d3-990c-bbcdb2564db5
Hincks, Thea
9654038a-2f5c-40bc-8f0e-33afc0b1fb71
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Longman, Jack
84e3d567-8575-477e-8d2f-5b21a1c709e4
Merdith, Andrew
6e6e4af3-ae97-42eb-9b81-36e3c1d6783b
Mitchell, Ross
2033970b-0254-4967-b6ec-e69f1e52a0ea
Palmer, Martin
d2e60e81-5d6e-4ddb-a243-602537286080

Gernon, Thomas, Barr, Ryan, Fitton, Godfrey, Hincks, Thea, Keir, Derek, Longman, Jack, Merdith, Andrew, Mitchell, Ross and Palmer, Martin (2022) Transient mobilization of subcrustal carbon coincident with Palaeocene-Eocene thermal maximum. Nature Geoscience. (doi:10.1038/s41561-022-00967-6).

Record type: Article

Abstract

Plume magmatism and continental breakup led to the opening of the northeast Atlantic Ocean during the globally warm early Cenozoic. This warmth culminated in a transient (170 thousand year, kyr) hyperthermal event associated with a large, if poorly constrained, emission of carbon called the Palaeocene–Eocene Thermal Maximum (PETM) 56 million years ago (Ma). Methane from hydrothermal vents in the coeval North Atlantic Igneous Province (NAIP) has been proposed as the trigger, though isotopic constraints from deep sea sediments have instead implicated direct volcanic carbon dioxide (CO2) emissions. Here we calculate that background levels of volcanic outgassing from mid-ocean ridges and large igneous provinces yield only one-fifth of the carbon required to trigger the hyperthermal. However, geochemical analyses of volcanic sequences spanning the rift-to-drift phase of the NAIP indicate a sudden ~220 kyr-long intensification of magmatic activity coincident with the PETM. This was likely driven by thinning and enhanced decompression melting of the sub-continental lithospheric mantle, which critically contained a high proportion of carbon-rich metasomatic carbonates. Melting models and coupled tectonic–geochemical simulations indicate that >104 gigatons of subcrustal carbon was mobilized into the ocean and atmosphere sufficiently rapidly to explain the scale and pace of the PETM.

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Accepted/In Press date: 13 May 2022
e-pub ahead of print date: 23 June 2022
Published date: 23 June 2022

Identifiers

Local EPrints ID: 458020
URI: http://eprints.soton.ac.uk/id/eprint/458020
ISSN: 1752-0894
PURE UUID: 08177604-f469-4efc-adad-69b0e755e4c4
ORCID for Thomas Gernon: ORCID iD orcid.org/0000-0002-7717-2092
ORCID for Thea Hincks: ORCID iD orcid.org/0000-0003-4537-6194
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 24 Jun 2022 21:27
Last modified: 13 Nov 2022 05:01

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Contributors

Author: Thomas Gernon ORCID iD
Author: Ryan Barr
Author: Godfrey Fitton
Author: Thea Hincks ORCID iD
Author: Derek Keir ORCID iD
Author: Jack Longman
Author: Andrew Merdith
Author: Ross Mitchell
Author: Martin Palmer

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