Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Clim. Past, 11, 669-685, 2015
https://doi.org/10.5194/cp-11-669-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
17 Apr 2015
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
C. Consolaro1,2, T. L. Rasmussen1, G. Panieri1, J. Mienert1, S. Bünz1, and K. Sztybor1 1CAGE – Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geology, UiT the Arctic University of Norway, Dramsveien 201, 9037 Tromsø, Norway
2School of Geography, Earth & Environmental Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK
Abstract. 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.

Citation: Consolaro, C., Rasmussen, T. L., Panieri, G., Mienert, J., Bünz, S., and Sztybor, K.: 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, Clim. Past, 11, 669-685, https://doi.org/10.5194/cp-11-669-2015, 2015.
Publications Copernicus
Download
Short summary
A sediment core collected from a pockmark field on the Vestnesa Ridge (~80N) in the Fram Strait is presented. Our results show an undisturbed sedimentary record for the last 14 ka BP and negative carbon isotope excursions (CIEs) during the Bølling-Allerød interstadials and during the early Holocene. Both CIEs relate to periods of ocean warming, sea-level rise and increased concentrations of methane (CH4) in the atmosphere, suggesting an apparent correlation with warm climatic events.
A sediment core collected from a pockmark field on the Vestnesa Ridge (~80N) in the Fram Strait...
Share