English
norskBlar i forfatter "Dessandier, Pierre-Antoine"
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Benthic Foraminifera in Arctic Methane Hydrate Bearing Sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-10)Benthic foraminifera have been widely used as proxy for paleo-methane emissions, mainly based on their stable isotopic signature. In cold seeps, the ecology of these organisms remains uncertain, in particular their ability to thrive during active phases of seepage. In this study, we evaluate the benthic foraminiferal response to methane seepage in Arctic sediments. We do so by examining living and ... -
A Continuous Seismostratigraphic Framework for the Western Svalbard-Barents Sea Margin Over the Last 2.7 Ma: Implications for the Late Cenozoic Glacial History of the Svalbard-Barents Sea Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-14)Here we present a high-resolution, continuous seismostratigraphic framework that for the first time, connects the over 1,000 km long western Svalbard-Barents Sea margin and covers the last ∼2.7 million years (Ma). By exploiting recent improvements in chronology, we establish a set of reliable age fix-points from available boreholes along the margin. We then use a large 2-D seismic database to extend ... -
Distribution of living benthic foraminifera in the northern Chukchi Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-27)Living (Rose Bengal stained) benthic foraminifera were studied in the topmost sediments of five multi- and box cores collected on the continental shelf, upper and lower slopes, of the Chukchi Sea to provide background information on modern benthic foraminiferal distribution, useful for future studies. Sediment cores were collected during August–September 2015, when the area is seasonally ice-free. ... -
Foraminiferal δ18O reveals gas hydrate dissociation in Arctic and North Atlantic ocean sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-07)Paleoceanographic investigations in the Arctic and north Atlantic are crucial to understanding past and current climate change, in particular considering amounts of pressure-temperature sensitive gas stored in marine sediments of the region. Many paleoceanographic studies are based on foraminiferal oxygen and carbon stable isotope compositions (δ<sup>18</sup>O, δ<sup>13</sup>C) from either planktonic ... -
Hot Vents Beneath an Icy Ocean: The Aurora Vent Field, Gakkel Ridge, Revealed
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-28)Evidence of hydrothermal venting on the ultra-slow spreading Gakkel Ridge in the Central Arctic Ocean has been available since 2001, with first visual evidence of black smokers on the Aurora Vent Field obtained in 2014. But it was not until 2021 that the first ever remotely operated vehicle (ROV) dives to hydrothermal vents under permanent ice cover in the Arctic were conducted, enabling the ... -
Ice-sheet melt drove methane emissions in the Arctic during the last two interglacials
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-22)Circum-Arctic glacial ice is melting in an unprecedented mode, and release of currently trapped geological methane may act as a positive feedback on ice-sheet retreat during global warming. Evidence for methane release during the penultimate (Eemian, ca. 125 ka) interglacial, a period with less glacial sea ice and higher temperatures than today, is currently absent. Here, we argue that based on ... -
The Impact of Methane on Microbial Communities at Marine Arctic Gas Hydrate Bearing Sediment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-24)Cold seeps are characterized by high biomass, which is supported by the microbial oxidation of the available methane by capable microorganisms. The carbon is subsequently transferred to higher trophic levels. South of Svalbard, five geological mounds shaped by the formation of methane gas hydrates, have been recently located. Methane gas seeping activity has been observed on four of them, ... -
Variations in benthic foraminiferal assemblages in the Tagus mud belt during the last 5700 years: Implications for Tagus River discharge
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-31)We analyzed a 10-m sediment core retrieved at 82 m water depth off the coast of the Tagus River (Western Iberian Margin, Portugal) to investigate a linkage between variations in benthic foraminiferal assemblages and Tagus River discharge over the last 5700 years. Benthic foraminiferal assemblages were studied at high resolution in combination with the stable carbon and oxygen isotopic composition ...
