Institutt for geovitenskap: Recent submissions
Now showing items 401-420 of 1107
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Seasonal shifts of microbial methane oxidation in Arctic shelf waters above gas seeps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-07)The Arctic Ocean subseabed holds vast reservoirs of the potent greenhouse gas methane (CH<sub>4</sub>), often seeping into the ocean water column. In a continuously warming ocean as a result of climate change an increase of CH<sub>4</sub> seepage from the seabed is hypothesized. Today, CH<sub>4</sub> is largely retained in the water column due to the activity of methane-oxidizing bacteria (MOB) that ... -
Reconstruction of the paleocenaography west of Lofoten during the Last Glacial Maximum
(Master thesis; Mastergradsoppgave, 2021-05-15)<p>A 513 cm long sediment core from the Lofoten Contourite Drift at the continental slope west of the Lofoten Islands has been investigated. The aim was to reconstruct the paleoceanography during the Last Glacial Maximum (LGM). The Lofoten Contourite drift was relatively protected by the Lofoten Islands from the ice streams of the Scandinavian Ice Sheet during LGM. <p>An age model was constructed ... -
Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-24)The Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream ... -
Testing miniaturized extraction chromatography protocols for combined 87Sr/86Sr and δ88/86Sr analyses of pore water by MC‐ICP‐MS
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-04)We tested two miniaturized extraction chromatography protocols for strontium isolation based on 300 μL (Protocol 1) and 30 μL (Protocol 2) column volumes of Sr‐Spec resin, for the simultaneous determination of 87Sr/86Sr and δ88/86Sr by MC‐ICP‐MS. The accuracy and precision of the Sr isotope ratios have been evaluated by analyzing JCt‐1 and SRM 1640a reference materials, resulting in a reproducibility ... -
The Role of Mineral Assemblages in the Environmental Impact of Cu-Sulfide Deposits: A Case Study from Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-12)Metallic mineral deposits represent natural geochemical anomalies of economically valuable commodities but, at the same time, their weathering may have negative environmental implications. Cu-sulfide mineral deposits have been recognized as deposits with a particularly large environmental footprint. However, different Cu deposits may result in significantly different environmental impacts, mostly ... -
Planktic foraminiferal and pteropod contributions to carbon dynamics in the Arctic Ocean (north Svalbard margin)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-09)Planktic foraminifera and shelled pteropods are some of the major producers of calcium carbonate (CaCO<sub>3</sub>) in the ocean. Their calcitic (foraminifera) and aragonitic (pteropods) shells are particularly sensitive to changes in the carbonate chemistry and play an important role for the inorganic and organic carbon pump of the ocean. Here, we have studied the abundance distribution of planktic ... -
Characterizing slope processes along the Piggtind mountain ridge, using 2D InSAR
(Mastergradsoppgave; Master thesis, 2021-05-15)Large rock slope deformations potentially evolving into catastrophic rock avalanches pose an eminent threat to the Norwegian society. A comprehensive characterization of their kinematic behavior, progressive slope development, and current deformation rates are thus required for hazard management. Njunnás and Piggtind/Skulvatindane are two adjacent rock slopes located in Troms County, Norway. Both ... -
Rockfall and snow avalanche impact dynamics for road protection design at Svarthola, Senja. A hazard evaluation aided by numerical models and physical formulas
(Master thesis; Mastergradsoppgave, 2021-05-14)Rockfalls and snow avalanches are a major natural hazard and common phenomenon in mountainous areas in Norway, endangering people and infrastructure. Svarthola, on Fv 862, Senja, is a 100 m long unprotected stretch of road that experiences a high frequency of mass movements. The road is situated at a tunnel portal, between a 100 m high cliff and the fjord. As such, it is the only short access route ... -
Environmental impact of sediment-hosted stratiform iron deposits: an on-land vs. submarine tailing simulation. A study of the stratiform iron mineralization in Dunderland Valley.
(Mastergradsoppgave; Master thesis, 2019-05-14)This thesis studies possible environmental impacts of tailings from the stratiform iron deposits. The study was conducted on selected mineralized samples from the Dunderland Valley, Nordland, simulating on-land and submarine tailing disposal conditions. The Dunderland Valley mineralization is hosted by Neoproterozoic (Tonian, 800-730 Ma) meta-sedimentary sequence of the Caledonian Uppermost ... -
Rapid temperature rise may have triggered glacier surges all over Svalbard
(Mastergradsoppgave; Master thesis, 2020-05-04)Observational and geomorphological records suggest that most glaciers on Svalbard reached their maximum Little Ice Age extents by means of surging. Furthermore, it seems to have happened within just a few decades, suggesting that the rapid concurrent changes in climate might have triggered this widespread surging. The specific precipitation and temperature range of Svalbard seems optimal for glacier ... -
The fate of plastic in the ocean environment – a minireview
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-14)The presence of plastics in the marine environment poses a threat to ocean life and has received much scientific and public attention in recent years. Plastics were introduced to the market in the 1950s and since then, global production figures and ocean plastic littering have increased exponentially. Of the 359 million tonnes (Mt) produced in 2018, an estimated 14.5 Mt has entered the ocean. In ... -
Deformation Behavior and Inferred Seismic Properties of Tonalitic Migmatites at the Time of Pre‐melting, Partial Melting, and Post‐Solidification
(Journal article; Tidsskriftartikkel, 2021-01-21)As seismic data from the lower crust becomes more readily available, it is important to link seismic properties to the ongoing processes within lower crustal evolution. This includes high temperature, pre‐ and post‐migmatization solid state deformation as well as melt‐present deformation. We selected two tonalitic migmatites with variable former melt content (one metatexite and one diatexite) from ... -
Evidence for influx of Atlantic water masses to the Labrador Sea during the Last Glacial Maximum
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-21)The Last Glacial Maximum (LGM, 23–19,000 year BP) designates a period of extensive glacial extent and very cold conditions on the Northern Hemisphere. The strength of ocean circulation during this period has been highly debated. Based on investigations of two marine sediment cores from the Davis Strait (1033 m water depth) and the northern Labrador Sea (2381 m), we demonstrate a significant influx ... -
Insights into the REY inventory of seep carbonates from the Northern Norwegian margin using geochemical screening
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-27)Rare earth element and yttrium (REY) systematics of authigenic seep carbonates can provide insights into the physico-chemical characteristics of seep systems and allow discrimination of carbonate precipitation under seawater- or porewater-dominated fluid regimes. However, care must be taken when interpreting their REY systematics, since seep carbonates comprise a mixture of detrital silicates and ... -
Multiscale characterisation of chimneys/pipes: Fluid escape structures within sedimentary basins
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-19)Evaluation of seismic reflection data has identified the presence of fluid escape structures cross-cutting overburden stratigraphy within sedimentary basins globally. Seismically-imaged chimneys/pipes are considered to be possible pathways for fluid flow, which may hydraulically connect deeper strata to the seabed. The properties of fluid migration pathways through the overburden must be constrained ... -
Effectiveness of Fluorescent Viability Assays in Studies of Arctic Cold Seep Foraminifera
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-09)Highly negative δ<sup>13</sup>C values in fossil foraminifera from methane cold seeps have been proposed to reflect episodes of methane release from gas hydrate dissociation or free gas reservoirs triggered by climatic changes in the past. Because most studies on live foraminifera are based on the presence of Rose Bengal staining, that colors the cytoplasm of both live and recently dead individuals ... -
Cenozoic uplift and erosion of the Norwegian Barents Shelf – A review
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-23)Uplift and erosion are complex phenomena in terms of their governing processes, precise timing and exact magnitude. The intricate relationship between different geodynamic processes leading to uplift may increase uncertainties in estimating spatial and temporal patterns. Sediment distribution from uplifted (and eroded) topography and the corresponding paleoenvironmental reconstructions require ... -
Interactions between deep formation fluid and gas hydrate dynamics inferred from pore fluid geochemistry at active pockmarks of the Vestnesa Ridge, west Svalbard margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-11)Seafloor seepage sites along the Vestnesa Ridge off west-Svalbard have been, for decades, a natural laboratory for the studies of fluid flow and gas hydrate dynamics at passive continental margins. The lack of ground truth evidence for fluid composition and gas hydrate abundance deep in the sediment sequence however prohibits us from further assessing the current model of pockmark evolution from the ... -
Younger Dryas ice margin retreat in Greenland: new evidence from southwestern Greenland
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-04)To date the final stage in deglaciation of the Greenland shelf, when a contiguous ice sheet margin on the inner shelf transitioned to outlet glaciers in troughs with intervening ice-free areas, we generated cosmogenic <sup>10</sup>Be dates from bedrock knobs on six outlying islands along a stretch of 300 km of the southwestern Greenland coast. Despite <sup>10</sup>Be inheritance influencing some ... -
Millennial‐scale changes in bottom water temperature and water mass exchange through the Fram Strait 79ºN, 63–13 ka
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-31)The Svalbard margin, in the eastern Fram Strait with its high sediment accumulation, form a key area for the reconstruction of water mass and heat exchange between the North Atlantic and Arctic Ocean in relation to abrupt climate changes as seen in glacial Greenland Interstadial and Greenland Stadial (GI‐GS) events. Here, we present a bottom water temperature (BWT) record from the northern Nordic ...