English
norskBlar i forfatter "Sauer, Simone"
Viser treff 1-12 av 12
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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 ... -
Fracture-controlled fluid transport supports microbial methane-oxidizing communities at Vestnesa Ridge
(Journal article; Peer reviewed, 2019-05-29)We report a rare observation of a mini-fracture in near-surface sediments (30 cm below the seafloor) visualized using a rotational scanning X-ray of a core recovered from the Lomvi pockmark, Vestnesa Ridge, west of Svalbard (1200 m water depth). Porewater geochemistry and lipid biomarker signatures revealed clear differences in the geochemical and biogeochemical regimes of this core compared with ... -
Implications of transient methane flux on associated biological communities in high-arctic seep habitats, Storbanken, Norwegian Barents sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-21)The continental margins of the Arctic Ocean basin contain methane seeps, where transient fluxes of seafloor methane are released due to the thermal dissociation of gas hydrates. An increase in shallow methane seeps identified over the past decade, potentially due to enhanced warming of the Arctic Ocean bottom water and associated destabilization of hydrate structure. Biological communities associated ... -
An integrated view of the methane system in the pockmarks at Vestnesa Ridge, 79°N
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-08)The Vestnesa Ridge is a NW-SE trending, ~ 100 km-long, 1–2 km-thick contourite sediment section located in the Arctic Ocean, west of Svalbard, at 79°N. Pockmarks align along the ridge summit at water depths of ~ 1200 m; they are ~ 700 m in diameter and ~ 10 m deep relative to the surrounding seafloor. Observations of methane seepage in this area have been reported since 2008. Here we summarize and ... -
Iron cycling in Arctic methane seeps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-26)Anoxic marine sediments contribute a significant amount of dissolved iron (Fe<sup>2+</sup>) to the ocean which is crucial for the global carbon cycle. Here, we investigate iron cycling in four Arctic cold seeps where sediments are anoxic and sulfidic due to the high rates of methane-fueled sulfate reduction. We estimated Fe<sup>2+</sup> diffusive fluxes towards the oxic sediment layer to be in the ... -
Methane seepage at Vestnesa Ridge (NW Svalbard) since the Last Glacial Maximum
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-21)<p>Multiple proxies in the geological record offshore NW Svalbard track shallow subseafloor diagenesis and seafloor methane seepage during the Last Glacial Maximum (LGM) extent and the disintegration of the Svalbard Barents Sea Ice Sheet (SBIS). Vestnesa Ridge, located at 79°N and in 1200 m water depth, is one of the northernmost known active methane seep sites and is characterised by a subseafloor ... -
Methane transport and sources in an Arctic deep-water cold seep offshore NW Svalbard (Vestnesa Ridge, 79°N)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-29)We investigate the uppermost 60 cm of sediment in active pockmarks of a deep-water methane seep site from Vestnesa Ridge offshore NW Svalbard. Using video guided core sampling with a remotely operated vehicle we collected push cores directly from bacterial mats within two active pockmarks, Lunde and Lomvi. Pore water analyses show very shallow sulphate methane transition zones and transport-reaction ... -
Past and present natural methane seepage on the northern Norwegian continental shelf
(Doctoral thesis; Doktorgradsavhandling, 2016-06-30)This thesis represents an integrated research effort to understand past and present methane cycling on the northern Norwegian margin. Active hydrocarbon seeps in the Hola trough on the Vesterålen continental shelf are found to be fed predominantly by thermogenic methane (and ethane, propane and butane). Most likely derived from Late Jurassic to Early Cretaceous source rocks, these gaseous hydrocarbons ... -
Removal of methane through hydrological, microbial, and geochemical processes in the shallow sediments of pockmarks along eastern Vestnesa Ridge (Svalbard)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)The recent discovery of methane seeps in the Arctic region requires a better understanding of the fate of methane in marine sediments if we are to understand the contributions of methane to Arctic ecosystems and climate change. To further this goal, we analyze pore water data from five pockmarks along eastern Vestnesa Ridge, a sediment drift northwest of Svalbard, to quantify the consumption ... -
Sources and turnover of organic carbon and methane in fjord and shelf sediments off Northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-10-22)To better understand the present and past carbon cycling and transformation processes in methane-influenced fjord and shelf areas of northern Norway, we compared two sediment cores from the Hola trough and from Ullsfjorden. We investigated (1) the organic matter composition and sedimentological characteristics to study the sources of organic carbon (C<sub>org</sub>) and the factors influencing ... -
Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)Gas hydrates stored on continental shelves are susceptible to dissociation triggered by environmental changes. Knowledge of the timescales of gas hydrate dissociation and subsequent methane release are critical in understanding the impact of marine gas hydrates on the ocean–atmosphere system. Here we report a methane efflux chronology from five sites, at depths of 220–400 m, in the southwest Barents ... -
U-Th chronology and formation controls of methane-derived authigenic carbonates from the Hola trough seep area, northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-20)We investigated methane-derived authigenic carbonate (MDAC) crusts and nodules from a cold seep site on the northern Norwegian continental shelf in ca. 220 m water depth to determine the timing and mode of their formation. Gas bubbling observed during remotely operated vehicle (ROV)-assisted sampling of MDAC crusts revealed ongoing seep activity. Authigenic carbonates were present as crusts on the ...
