Institutt for geovitenskap: Recent submissions
Now showing items 61-80 of 1046
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Sedimentological and geochemical investigations of hydrothermally impacted sediments at the Aurora vent field, Fram Strait
(Mastergradsoppgave; Master thesis, 2023-05-15)Hydrothermal vents are the result of the interaction between seawater and magma and occur at regular intervals along mid ocean ridges. The first visual confirmation of plumes was done in 1977. The detection of hydrothermal plumes has both provided indirect evidence for their existence and a resolution of the occurrences . In deep ocean with low sedimentation rates, hydrothermal plumites have the ... -
Formation of non-evaporitic gypsum in gas hydrate-bearing sediments at Håkon Mosby mud volcano, SW Barents sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-29)Authigenic minerals such as carbonate and iron sulfide are known features at cold seeps worldwide and form as a result of the anaerobic oxidation of methane in the sulfate-methane transition zone (SMTZ). Recent findings of seep-related non-evaporitic gypsum raise questions regarding its distribution, formation mechanisms, and relationships with the other proxies for confident paleo-seep reconstructions. ... -
Petrochronology of the Dom Feliciano Belt foreland in southernmost Brazil reveals two distinct tectonometamorphic events in the western central Kaoko–Dom Feliciano–Gariep orogen
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-26)The Dom Feliciano Belt is the South American part of an extensive Neoproterozoic orogenic system that developed during the late Cryogenian–early Cambrian close to the margin of southwest Gondwana. The link of its evolution with the tectonic processes in its African counterpart is still not well understood. P–T estimates, Lu–Hf garnet–whole-rock ages, U–Pb monazite SIMS ages and REE garnet and monazite ... -
The Roles of Light Absorbing Particles in the Norwegian Arctic Snow
(Mastergradsoppgave; Master thesis, 2023-05-08)Light absorbing particles (LAPs) such as black carbon (BC) and dust can reduce snow albedo and have a positive radiative forcing. Previous studies investigating LAP in snow in Tromsø focused on black carbon (BC) also called elemental carbon because it has human sources, but dust should also be considered because, while largely from natural sources, it is present in higher concentrations. To quantify ... -
Biodegradable plastics in Mediterranean coastal environments feature contrasting microbial succession
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-08)Plastic pollution of the ocean is a top environmental concern. Biodegradable plastics present a potential “solution” in combating the accumulation of plastic pollution, and their production is currently increasing. While these polymers will contribute to the future plastic marine debris budget, very little is known still about the behavior of biodegradable plastics in different natural environments. ... -
The Eurasian Ice Sheet: Status and Challenges
(Conference object; Konferansebidrag, 2024-03-15) -
Modelling the Eurasian Ice Sheet
(Conference object; Konferansebidrag, 2024-03-15) -
Contamination of 8.2 ka cold climate records by the Storegga tsunami in the Nordic Seas
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-04)The 8200-year BP cooling event is reconstructed in part from sediments in the Norwegian and North Seas. Here we show that these sediments have been reworked by the Storegga tsunami – dated to the coldest decades of the 8.2 ka event. We simulate the maximum tsunami flow velocity to be 2–5 m/s on the shelf offshore western Norway and in the shallower North Sea, and up to about 1 m/s down to a water ... -
NordVulk 1974-2024
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024)Nordisk Vulkanologisk Institut, senare känt som Nordisk Vulkanologisk Center (NordVulk) på Island fyller 50 år 2024. Tyvärr sammanfaller jubileet med att NordVulk upphör i sin nuvarande form och en lång och framgångsrik era med nordisk vulkanologisk forskning på Island tar slut. Här berättar vi lite om NordVulks historia och bifogar några korta anekdoter från livet där. -
Glacial-interglacial sedimentation control on gas seepage exemplified by Vestnesa Ridge off NW Svalbard margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-08)Vestnesa Ridge is built-up of thick contourites mainly deposited during the last ∼5 million years. Methane leaks from deep gas reservoirs creating pockmarks on its crest, and which have been the focus of numerous studies. Sedimentation patterns in relation to the pronounced changes in oceanography and climate of the last glacial-interglacial cycles and its possible impact of seepage of gas have ... -
New cold seep sites on the continental slope southwest to Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-09)We discovered seafloor features such as bacterial mats and carbonate crusts typical for active methane seeps on the continental slope southwest of Svalbard. These features are associated with two main northwest-southeast trending morphological structures that are oriented parallel to the regional continental slope. Both structures occur at c. 800 m water depth, at the boundary between the Storfjorden ... -
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 ...