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Paleo-methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard

Paleo-methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard
Paleo-methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard
We present stable isotope and geochemical data from four sediment cores from west of Prins Karls Forland (ca. 340 m water depth), offshore western Svalbard, recovered from close to sites of active methane seepage, as well as from shallower water depths where methane seepage is not presently observed. Our analyses provide insight into the record of methane seepage in an area where ongoing ocean warming may be fueling the destabilization of shallow methane hydrate. The ?13C values of benthic and planktonic foraminifera at the methane seep sites show distinct intervals with negative values (as low as ?27.8‰) that do not coincide with the present-day depth of the sulfate methane transition zone (SMTZ). These intervals are interpreted to record long-term fluctuations in methane release at the present-day landward limit of the gas hydrate stability zone (GHSZ). Shifts in the radiocarbon ages obtained from planktonic foraminifera toward older values are related to methane-derived authigenic carbonate overgrowths of the foraminiferal tests, and prevent us from establishing the chronology of seepage events. At shallower water depths, where seepage is not presently observed, no record of past methane seepage is recorded in foraminifera from sediments spanning the last 14 ka cal BP (14C-AMS dating). ?13C values of foraminiferal carbonate tests appear to be much more sensitive to methane seepage than other sediment parameters. By providing nucleation sites for authigenic carbonate precipitation, foraminifera thus record the position of even a transiently stable SMTZ, which is likely to be a characteristic of temporally variable methane fluxes.
methane emissions, gas hydrate, western svalbard, foraminifer ?13C, authigenic carbonate, arctic ocean
1525-2027
521-537
Panieri, Giuliana
c0559a7d-cf2c-4d0a-b61a-60889e963164
Graves, Carolyn A.
9f1c821a-dc07-413b-b577-6e6b55839853
James, Rachael
79aa1d5c-675d-4ba3-85be-fb20798c02f4
Panieri, Giuliana
c0559a7d-cf2c-4d0a-b61a-60889e963164
Graves, Carolyn A.
9f1c821a-dc07-413b-b577-6e6b55839853
James, Rachael
79aa1d5c-675d-4ba3-85be-fb20798c02f4

Panieri, Giuliana, Graves, Carolyn A. and James, Rachael (2016) Paleo-methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western Svalbard. Geochemistry, Geophysics, Geosystems, 17 (2), 521-537. (doi:10.1002/2015GC006153).

Record type: Article

Abstract

We present stable isotope and geochemical data from four sediment cores from west of Prins Karls Forland (ca. 340 m water depth), offshore western Svalbard, recovered from close to sites of active methane seepage, as well as from shallower water depths where methane seepage is not presently observed. Our analyses provide insight into the record of methane seepage in an area where ongoing ocean warming may be fueling the destabilization of shallow methane hydrate. The ?13C values of benthic and planktonic foraminifera at the methane seep sites show distinct intervals with negative values (as low as ?27.8‰) that do not coincide with the present-day depth of the sulfate methane transition zone (SMTZ). These intervals are interpreted to record long-term fluctuations in methane release at the present-day landward limit of the gas hydrate stability zone (GHSZ). Shifts in the radiocarbon ages obtained from planktonic foraminifera toward older values are related to methane-derived authigenic carbonate overgrowths of the foraminiferal tests, and prevent us from establishing the chronology of seepage events. At shallower water depths, where seepage is not presently observed, no record of past methane seepage is recorded in foraminifera from sediments spanning the last 14 ka cal BP (14C-AMS dating). ?13C values of foraminiferal carbonate tests appear to be much more sensitive to methane seepage than other sediment parameters. By providing nucleation sites for authigenic carbonate precipitation, foraminifera thus record the position of even a transiently stable SMTZ, which is likely to be a characteristic of temporally variable methane fluxes.

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Accepted/In Press date: 19 January 2016
Published date: 26 February 2016
Keywords: methane emissions, gas hydrate, western svalbard, foraminifer ?13C, authigenic carbonate, arctic ocean
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 388820
URI: http://eprints.soton.ac.uk/id/eprint/388820
ISSN: 1525-2027
PURE UUID: c42215df-a2bf-4288-95e4-e84c5a9960f7
ORCID for Rachael James: ORCID iD orcid.org/0000-0001-7402-2315

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Date deposited: 03 Mar 2016 11:06
Last modified: 15 Mar 2024 03:30

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Contributors

Author: Giuliana Panieri
Author: Carolyn A. Graves
Author: Rachael James ORCID iD

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