Institutt for geovitenskap: Recent submissions
Now showing items 81-100 of 1046
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Biogeochemical investigations of methane seepage at the ultraslow-spreading Arctic mid-ocean ridge: Svyatogor ridge, Fram Strait
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-13)The Arctic continental shelves are important reservoirs of methane stored in gas hydrates and deeper geological formations. However, little is known about methane dynamics in deeper oceanic settings such as mid-ocean ridges, mainly due to operational challenges related to their remoteness. This study investigates a recently discovered methane seepage environment at Svyatogor Ridge, a sediment-covered ... -
Shallow and deep groundwater moderate methane dynamics in a high Arctic glacial catchment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-07)Glacial groundwater can mobilize deep-seated methane from beneath glaciers and permafrost in the Arctic, leading to atmospheric emissions of this greenhouse gas. We present a temporal, hydro-chemical dataset of methane-rich groundwater collected during two melt seasons from a high Arctic glacial forefield to explore the seasonal dynamics of methane emissions. We use methane and ion concentrations ... -
Assessment of the ecological quality status of the Sepetiba Bay (SE Brazil): When metabarcoding meets morphology on foraminifera
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-09)In recent years, the region surrounding Sepetiba Bay (SB; SE Brazil) has become a hub of intense urban expansion and economic exploitation in response to ore transport and industrial and port activities. As a result, contaminants have been introduced into the bay, leading to an overall worsening of the environmental quality. The present work applies for the first time a foraminiferal morphology-based ... -
Sea ice-ocean coupling during Heinrich Stadials in the Atlantic–Arctic gateway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-11)The variability of Arctic sea-ice during abrupt stadial-interstadial shifts in the last glacial period remain poorly understood. Here, we investigated the millennial-scale relationship, with a focus on Heinrich Stadials (HS), between sea-ice cover and bottom water temperature (BWT) during Marine Isotope Stages (MIS) 3 and 2 (64–13 ka) in the Fram Strait using new molecular sea ice biomarker data and ... -
The current status of environmental forensic science in the member institutes of the European Network of Forensic Science Institutes (ENFSI)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-04)The paper presents the results of a questionnaire survey carried out by The Forensic laboratory of the National Bureau of Investigation (NBI-FL), aiming to get an overview of the current status of environmental forensic science (EFS) and environmental crimes investigation in the European Network of Forensic Science Institutes (ENFSI). A questionnaire was sent out to 71 ENFSI member institutes and ... -
The submarine fault scarp of the 2011 Tohoku-oki Earthquake in the Japan Trench
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-26)Rupture of the plate boundary fault during the 2011 Tohoku-oki earthquake with moment magnitude 9.0 is thought to have propagated to the trench. Surface exposure of the fault has not yet been confirmed because of great depths that are challenging to access and study. Using a manned submersible in the Japan Trench, we explored and visually assessed the seafloor near the epicenter. On the eastern slope ... -
Retreat patterns and dynamics of the former Norske Trough ice stream (NE Greenland): An integrated geomorphological and sedimentological approach
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-09)A better understanding of past extent and dynamics of the Greenland Ice Sheet (GrIS) is required to provide context for present-day observations, to constrain numerical climate models and to predict future scenarios of ice-sheet response to recent climatic change. The presence of a grounded GrIS on the NE Greenland shelf during the Last Glacial Maximum (LGM) is supported by high-resolution seismic ... -
Quantifying short-term changes in snow strength due to increasing liquid water content above hydraulic barriers
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-31)The rapid weakening of snow layers that accumulate infiltrating liquid water is a well-known, but poorly quantified, mechanism for wet-snow slab avalanche formation. Therefore, quantifying this mechanical process is a crucial part of forecasting these snow avalanches accurately. Currently, studies do not agree on how snow strength should change as a function of volumetric liquid water content ( ) ... -
Calcium isotopes track volatile components in the mantle sources of alkaline rocks and associated carbonatites
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-16)The volatile components CO2 and H2O induce mantle melting and thus exert major controls on mantle heterogeneity. Primitive intraplate alkaline magmatic rocks are the closest analogues for incipient mantle melts and provide the most direct method to assess such mantle heterogeneity. Given the considerable Ca isotope differences among carbonate, clinopyroxene, garnet, and orthopyroxene in the mantle ... -
Local Seismicity and Sediment Deformation in the West Svalbard Margin: Implications of Neotectonics for Seafloor Seepage
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-12)In the Fram Strait, mid-ocean ridge spreading is represented by the ultra-slow system of the Molloy Ridge, the Molloy Transform Fault and the Knipovich Ridge. Sediments on oceanic and continental crust are gas charged and there are several locations with documented seafloor seepage. Sedimentary faulting shows recent stress release in the sub-surface, but the drivers of stress change and its influence ... -
Elevated methane alters dissolved organic matter composition in the Arctic Ocean cold seeps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-15)Cold seeps release methane (CH<sub>4</sub>) from the seafloor to the water column, which fuels microbially mediated aerobic methane oxidation (MOx). Methane-oxidising bacteria (MOB) utilise excess methane, and the MOB biomass serves as a carbon source in the food web. Yet, it remains unclear if and how MOx modifies the composition of dissolved organic matter (DOM) in cold seeps. We investigated MOx ... -
The transition from normal marine to evaporitic conditions recorded in a cold seep environment: The Messinian succession of Northern Italy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-26)Messinian pre-evaporitic seep carbonates outcropping in the Tuscan-Romagna area share a common upward stratigraphic trend: massive seep carbonates rich in large lucinids, modiolids and planktonic foraminifera pass upward to horizontally laminated carbonates free of macrofauna and foraminifera. A transitional macrofauna-free facies marks the passage in some sections, sometimes with faint lamination. ... -
Diel and seasonal methane dynamics in the shallow and turbulent Wadden Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-25)The Wadden Sea is a coastal system along the fringe of the land–sea borders of Denmark, Germany and the Netherlands. The Wadden Sea is extremely productive and influenced by strong variations in physical and biological forcing factors that act on timescales of hours to seasons. Productive coastal seas are known to dominate the ocean's methane emission to the atmosphere, but knowledge of controls and ... -
The Subglacial Lake That Wasn't There: Improved Interpretation From Seismic Data Reveals a Sediment Bedform at Isunnguata Sermia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-26)Radio Echo Sounding (RES) surveys conducted in May 2010 and April 2011 revealed a 2 km2 flat area with increased bed reflectivity at the base of Isunnguata Sermia at the western margin of the Greenland Ice Sheet. This flat reflector was located within a localized subglacial hydraulic potential (hydropotential) minimum, as part of a complex and elongated trough system. By analogy with comparable ... -
Deep-time Arctic climate archives: high-resolution coring of Svalbard's sedimentary record – SVALCLIME, a workshop report
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-26)We held the MagellanPlus workshop SVALCLIME “Deep-time Arctic climate archives: high-resolution coring of Svalbard's sedimentary record”, from 18 to 21 October 2022 in Longyearbyen, to discuss scientific drilling of the unique high-resolution climate archives of Neoproterozoic to Paleogene age present in the sedimentary record of Svalbard. Svalbard is globally unique in that it facilitates ... -
Characterizing Håkon Mosby Mud Volcano (Barents Sea) cold seep systems by combining ROV-based acoustic data and underwater photogrammetry
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-31)Cold-seep systems have a unique geo-ecological significance in the deep-sea environment. They impact the variability of present-day submarine sedimentary environments, affecting the evolution of the landscape over time and creating a variety of submarine landforms, one of which is Mud Volcanoes (MVs). MVs are submarine landforms form due extrusion of mud, fluids, and gas, mainly methane, from deeper ... -
An Arctic natural oil seep investigated from space to the seafloor
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-19)Due to climate change, decreasing ice cover and increasing industrial activities, Arctic marine ecosystems are expected to face higher levels of anthropogenic stress. To sustain healthy and productive ocean ecosystems, it is imperative to build baseline data to assess future changes. Herein, a natural oil seep site offshore western Svalbard (Prins Karls Forland, PKF, 80–100 m water depth), discovered ... -
An Integrative Taxonomic Survey of Benthic Foraminiferal Species (Protista, Rhizaria) from the Eastern Clarion-Clipperton Zone
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-24)The abyssal Pacific Clarion Clipperton Zone (CCZ) hosts vast, commercially valuable seafloor deposits of polymetallic nodules. Foraminifera (testate protists) dominate benthic communities in this region. Here, we present a taxonomic survey, combining morphological and genetic data and focussing on mainly meiofauna-sized Foraminifera from the eastern CCZ. Sequences obtained from >100 specimens, the ... -
Origin and Economic Potential of Lithium-mineralized Granitic Pegmatites in Helgeland, North Norway
(Mastergradsoppgave; Master thesis, 2023-08-04)A comprehensive set of analytical techniques, encompassing geological, petrographic, mineralogical, and zircon U-Pb-Hf isotopic compositions, was employed to investigate a relatively poorly known pegmatite field located in Helgeland, North Norway. The Paleoproterozoic basement gneisses in the area have U-Pb zircon crystallization ages between 1870 ± 12 and 1811 ± 6 Ma, meaning that they belong to ... -
Exploring late Pleistocene bioturbation on Yermak Plateau to assess sea-ice conditions and primary productivity through the Ethological Ichno Quotient
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-13)Central Arctic, interglacial intervals have traditionally been associated with diverse and intense bioturbation, and abundant foraminifera, interpreted as indicating relatively low sea-ice concentrations and productive surface waters, while glacial intervals, typically barren, support the inverse. In this respect, the Yermak Plateau is anomalous. Biomarker studies suggest that glacial intervals were ...