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norskArtikler, rapporter og annet (geovitenskap)
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Climate-controlled submarine landslides on the Antarctic continental margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-18)Antarctica’s continental margins pose an unknown submarine landslide-generated tsunami risk to Southern Hemisphere populations and infrastructure. Understanding the factors driving slope failure is essential to assessing future geohazards. Here, we present a multidisciplinary study of a major submarine landslide complex along the eastern Ross Sea continental slope (Antarctica) that identifies ... -
The Heliconoides Modified Dissolution Index-HMDI: Do methane seepage environments affect the preservation state of Heliconoides inflatus?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-24)Pteropods are holoplanktonic molluscs presently endangered because their fragile aragonitic shell is very sensitive to ocean acidification. The preservation of pteropods, and in particular of the mesopelagic Heliconoides (Limacina) inflatus, has been used to assess aragonite saturation state in Quaternary sediments (Limacina Dissolution Index, LDX) as an inferred proxy for climatic changes. Three ... -
Deep-water sand transfer by hyperpycnal flows, the Eocene of Spitsbergen, Arctic Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-11)Flood-generated hyperpycnal flows are dense, sediment-laden, turbulent flows that can form long-lived, bottom-hugging turbidity currents, which undoubtedly transport large volumes of fine-grained sediments into the ocean. However, their ability in transferring sand into deep-water basins is debated. This study presents sedimentological evidence of sandy hyperpycnal flow deposits (hyperpycnites) in ... -
Advances in understanding subglacial meltwater drainage from past ice sheets
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-17)Meltwater drainage beneath ice sheets is a fundamental consideration for understanding ice–bed conditions and bed-modulated ice flow, with potential impacts on terminus behavior and iceshelf mass balance. While contemporary observations reveal the presence of basal water movement in the subglacial environment and inferred styles of drainage, the geological record of former ice sheets, including ... -
The Hambergfjellet Formation on Bjørnøya – sedimentary response to early Permian tectonics on the Stappen High
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-14)On Bjørnøya, the exhumed crest of the Stappen High, the lower Permian (Cisuralian) Hambergfjellet Formation represents the only exposed part of the Bjarmeland Group carbonate platform, which occurs widely elsewhere in the subsurface of the Barents Shelf. A complex stratigraphic architecture has earlier been noted for the Hambergfjellet Formation and thickness estimates range from c. 50 to more than ... -
Can big data and random forests improve avalanche runout estimation compared to simple linear regression?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-05)Accurate prediction of snow avalanche runout-distances in a deterministic sense remains a challenge due to the complexity of all the physical properties involved. Therefore, in many locations including Norway, it has been common practice to define the runout distance using the angle from the starting point to the end of the runout zone (α-angle). We use a large dataset of avalanche events from ... -
Spatial Changes in Gas Transport and Sediment Stiffness Influenced by Regional Stress: Observations From Piezometer Data Along Vestnesa Ridge, Eastern Fram Strait
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-25)Gas transport through sediments to the seabed and seepage occurs via advection through pores, faults, and fractures, and as solubility driven gas diffusion. The pore pressure gradient is a key factor in these processes. Yet, in situ measurements for quantitative studies of fluid dynamics and sediment deformation in deep ocean environments remain scarce. In this study, we integrate piezometer data, ... -
Widespread subseafloor gas hydrate in the Barents Sea and Norwegian Margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-01)The distribution and concentration of subseafloor natural gas hydrate across margins is not well understood, because these systems are challenging to image and quantify remotely. Furthermore, it is unknown if shallow hydrate systems are linked to deeper oil and gas reservoirs. Herein, we analyze petroleum industry well logs with data in the gas hydrate stability zone and find that low concentrations ... -
Distinct modes of meltwater drainage and landform development beneath the last Barents Sea ice sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-18)The flow of glacial ice is impacted by basal meltwater drainage systems that fluctuate on a continuum from distributed, high-pressure environments to channelized, lower pressure networks. Understanding the long-term development of dominant drainage modes and impacts on ice flow and landform development is a crucial step in predicting palaeo and contemporary ice-mass response to changes in ... -
Arc-like magmatism in syn- to post-collisional setting: The Ediacaran Angra Fria Magmatic Complex (NW Namibia) and its cross-Atlantic correlatives in the south Brazilian Florianópolis Batholith
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-27)Ediacaran syn-tectonic plutonic rocks (amphibole gabbros, quartz diorites/tonalites to biotite- and muscovite-bearing granites) of the Angra Fria Magmatic Complex (Kaoko Belt, north-western Namibia) belong to two compositionally similar, magnesian, transitional tholeiitic–calc-alkaline suites, the Older (∼625–620 Ma) and the Younger (∼585–575 Ma). Both have counterparts in the broadly contemporaneous ... -
Evidence of Arctic methane emissions across the mid-Pleistocene
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-08)During the Pleistocene, Earth’s climate changed dramatically. The mid-Pleistocene transition (MPT; ~1.3–0.7 million years (Ma)) featured an important ice volume increase at both poles. The evolution of large Arctic ice sheets caused the sequestration of methane as free gas and hydrates in subseabed sediments. Ice volume changes, associated with variable pressures and temperatures, perturbed those ... -
HgCl2 addition to pore water samples from cold seeps can affect the geochemistry of dissolved inorganic carbon ([DIC], δ13CDIC)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-03)The conventional use of mercuric chloride (HgCl<sub>2</sub>) as an antimicrobial agent in water samples for dissolved inorganic carbon (DIC) analysis poses health and environmental risks related to its handling and disposal. Even though there is an increasing interest in quantifying pore water DIC contribution to the ocean carbon cycle and deep-sea acidification, the paucity of comparative studies ... -
Widespread natural methane and oil leakage from sub-marine Arctic reservoirs
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-30)Parceling the anthropogenic and natural (geological) sources of fossil methane in the atmosphere remains problematic due to a lack of distinctive chemical markers for their discrimination. In this light, understanding the distribution and contribution of potential geological methane sources is important. Here we present empirical observations of hitherto undocumented, widespread and extensive methane ... -
The effect of muscovite on the microstructural evolution and rheology of quartzite in general shear
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-13)We conducted general shear experiments on synthetic mixtures of quartz and muscovite aggregates at 800 °C and 1.5 GPa with 0.1 wt% H<sub>2</sub>O added in the Griggs apparatus to investigate the role of muscovite content on the microstructural evolution and rheological properties of quartz aggregates. Muscovite content varied between 0, 5, 10 and 25% muscovite. Mechanically, the sample strengths ... -
The phylogeography and ecology of Oligobrachia frenulate species suggest a generalist chemosynthesis-based fauna in the arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-02)We used ancient DNA (aDNA) extraction methods to sequence museum voucher samples of Oligobrachia webbi, a frenulate siboglinid polychaete described from a northern Norwegian fjord over fifty years ago. Our sequencing results indicate a genetic match with the cryptic seep species, Oligobrachia haakonmosbiensis (99% pairwise identity for 574 bp mtCOI fragments). Due to its similarity with O. webbi, ... -
Late Holocene pteropod distribution across the base of the south-eastern Mediterranean margin: the importance of the > 63 µm fraction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-17)Euthecosomata pteropods were analysed in core sediments collected in the framework of the 2016 EUROFLEETS2 SEMSEEP cruise, offshore of Israel, in the eastern Mediterranean Sea. The investigated cores were retrieved in a deep-sea coral area at 690 m depth, an actively methane-seeping pockmark area at 1038 m depth, and a deep-sea channel area at 1310 m water depth. We identified and documented the ... -
Dating submarine landslides using the transient response of gas hydrate stability
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-02)Submarine landslides are prevalent on the modern-day seafloor, yet an elusive problem is constraining the timing of past slope failure. We present a novel age-dating technique based on perturbations to underlying gas hydrate stability caused by slide-impacted seafloor changes. Using three-dimensional (3-D) seismic data, we mapped an irregular bottom simulating reflection (BSR) underneath a submarine ... -
Pleistocene depositional environments and links to cryosphere-ocean interactions on the eastern Ross Sea continental slope, Antarctica (IODP Hole U1525A)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-22)The repeated proximity of West Antarctic Ice Sheet (WAIS) ice to the eastern Ross Sea continental shelf break during past ice age cycles has been inferred to directly influence sedimentary processes occurring on the continental slope, such as turbidity current and debris flow activity; thus, the records of these processes can be used to study the past history of the WAIS. Ross Sea slope sediments ... -
GEO-3144/8144 Teaching Cruise: Geologically controlled hydrocarbon seepage in Hopendjupet and the wider Barents Sea
(Research report; Forskningsrapport, 2022-11-18)The CAGE22-6 cruise on-board R/V Helmer Hanssen hosted UiT´s Arctic Marine Geology and Geophysics (GEO-8144 and GEO-3144) field course for PhD and Master students, and was carried out in collaboration with NPD – the Norwegian Petroleum Directorate and the INTPART project HOTMUD based at Centre for Earth Evolution and Dynamics (CEED) the University of Oslo. The cruise was also a part of the UNESCO ... -
Handwritten letters and photo albums linking geoscientists with school classes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-14)Was something lost as society moved away from “traditional” media such as handwritten letters and photography and into the digital age? Some of the authors remember this age fondly, and we wanted to see if this fondness could be translated into a science dialogue project with school classes. We designed and carried out a communication process with four classes at different schools across Europe. ...
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