Institutt for geovitenskap: Recent submissions
Now showing items 41-60 of 1015
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Characterizing vegetation and return periods in avalanche paths using lidar and aerial imagery
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-14)Snow avalanches are a hazard and ecological disturbance across mountain landscapes worldwide. Understanding how avalanche frequency affects forests and vegetation improves infrastructure planning, risk management, and avalanche forecasting. We implemented a novel approach using lidar, aerial imagery, and a random forest model to classify imagery-observed vegetation within avalanche paths in southern ... -
Influence of a rigid backstop on the flow pattern during thrusting of the supracrustal Balsfjord Series of the North Norwegian Caledonides
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-17)The Caledonian evolution of the low–medium grade Balsfjord Series (Troms, Northern Norway) is characterized by four sets of deformation structures that developed progressively during burial and exhumation from underneath the high-grade Nakkedal and Tromsø nappe complexes. The Balsfjord Series commonly displays top-to-the SSE–SE directed movement during the development of the main metamorphic fabric ... -
Persistence of Holocene ice cap in northeast Svalbard aided by glacio-isostatic rebound
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-29)The deglaciation of the Svalbard-Barents Sea Ice Sheet was driven by relative sea-level rise, the incursion of North Atlantic waters around Spitsbergen, and increasing summer insolation. However, ice retreat was inter rupted by asynchronous re-advances that occurred into high relative seas, during a period associated with warm regional waters and elevated summer temperatures. Better understanding ... -
Tracing Subducted Carbonates in Earth's Mantle Using Zinc and Molybdenum Isotopes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-23)Although carbonates are the primary form of carbon subducted into the mantle, their fate during recycling is debated. Here we report the first coupled high-precision Zn and Mo isotope data for Cenozoic intraplate basalts from western China. The exceptionally high δ<sup>66</sup>Zn values (+0.39 to +0.50‰) of these lavas require involvement of recycled carbonates in the mantle source. Variable ... -
Biogeochemical impact of historical submarine mine tailings on benthic ecosystems in the Repparfjord (Northern Norway)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-08)Historical copper mine tailings deposited in the Repparfjord, Northern Norway, provided new insight into the biogeochemical impact of submarine tailings disposals on high-latitude coastal ecosystems. The submarine tailings disposal in the Repparfjord represents a product of mining activities between 1972 and 1979. Their environmental impact has been extensively studied during the last decade, but ... -
Redox state of the Dharwar craton root as inferred from eclogite and peridotite sourced mantle cargo, with implications for kimberlite and lamproite magma formation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-16)Despite over 400 occurrences of kimberlites and related rocks in India, mantle-derived xenoliths are known only from a few occurrences. This paucity of mantle-derived xenoliths in Indian kimberlites has hampered investigations of the subcontinental lithospheric mantle (SCLM). Using a valuable selection of the rare xenolith inventory, we here report Fe<sup>3+</sup>/ΣFe measurements for garnets using ... -
Assigning the unassigned: A signature-based classification of rDNA metabarcodes reveals new deep-sea diversity
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-29)Environmental DNA metabarcoding reveals a vast genetic diversity of marine eukaryotes. Yet, most of the metabarcoding data remain unassigned due to the paucity of reference databases. This is particularly true for the deep-sea meiofauna and eukaryotic microbiota, whose hidden diversity is largely unexplored. Here, we tackle this issue by using unique DNA signatures to classify unknown metabarcodes ... -
Depositional environments and source rock potential of some Upper Palaeozoic (Devonian) coals on Bjørnøya, Western Barents shelf
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-27)Upper Palaeozoic strata are potential sources for hydrocarbon plays on the Norwegian Barents Shelf. The island of Bjørnøya (Bear Island) is located on the western margin of the Barents Shelf and represents an exposed part of the Stappen High, which makes it an excellent location to investigate the source rock potential of this succession. Here, we investigate the organic geochemical composition and ... -
Protracted post-glacial hydrocarbon seepage in the Barents Sea revealed by U–Th dating of seep carbonates
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-01)The hydrocarbon seepage chronology during deglaciation across the formerly glaciated Barents Sea was established using uranium-thorium (U–Th) dating of seep carbonates. Seep carbonates were sampled with remotely operated vehicles (ROV) from the seafloor at three active hydrocarbon seeps (water depth 156–383 m), located in the north-west (Storfjordrenna), north-central (Storbanken High), and south-west ... -
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 ...