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| Titel |
Carbon isotope (δ13C) excursions suggest times of major methane release during the last 14 kyr in Fram Strait, the deep-water gateway to the Arctic |
| VerfasserIn |
C. Consolaro, T. L. Rasmussen, G. Panieri, J. Mienert, S. Bünz, K. Sztybor |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 4 ; Nr. 11, no. 4 (2015-04-17), S.669-685 |
| Datensatznummer |
250117259
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| Publikation (Nr.) |
 copernicus.org/cp-11-669-2015.pdf |
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| Zusammenfassung |
| We present results from a sediment core collected from a pockmark field on
the Vestnesa Ridge (~ 80° N) in the eastern Fram Strait.
This is the only deep-water gateway to the Arctic, and one of the
northernmost marine gas hydrate provinces in the world. Eight 14C AMS
dates reveal a detailed chronology for the last 14 ka BP. The δ
13C record measured on the benthonic foraminiferal species
Cassidulina neoteretis shows two distinct intervals with negative values termed carbon isotope
excursion (CIE I and CIE II, respectively). The values were as low as
−4.37‰ in CIE I, correlating with the
Bølling–Allerød interstadials, and as low as −3.41‰
in CIE II, correlating with the early Holocene. In the Bølling–Allerød
interstadials, the planktonic foraminifera also show negative values,
probably indicating secondary methane-derived authigenic precipitation
affecting the foraminiferal shells. After a cleaning procedure designed to
remove authigenic carbonate coatings on benthonic foraminiferal tests from
this event, the 13C values are still negative (as low as
−2.75‰). The CIE I and CIE II occurred during periods
of ocean warming, sea-level rise and increased concentrations of methane
(CH4) in the atmosphere. CIEs with similar timing have been reported
from other areas in the North Atlantic, suggesting a regional event. The
trigger mechanisms for such regional events remain to be determined. We
speculate that sea-level rise and seabed loading due to high sediment supply
in combination with increased seismic activity as a result of rapid
deglaciation may have triggered the escape of significant amounts of methane
to the seafloor and the water column above. |
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