Institutt for geovitenskap: Nye registreringer
Viser treff 161-180 av 1046
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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. ... -
Storm chasing: Tracking Holocene storminess in southern Sweden using mineral proxies from inland and coastal peat bogs
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-25)Severe extratropical winter storms are a recurrent feature of the European climate and cause widespread socioeconomic losses. Due to insufficient long-term data, it remains unclear whether storminess has shown a notable response to changes in external forcing over the past millennia, which impacts our ability to project future storminess in a changing climate. Reconstructing past storm variability ... -
Non-linear response of glacier melting to Holocene warming in Svalbard recorded by sedimentary iron (oxyhydr)oxides
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-01)The recent acceleration of ice-sheet loss with its direct impact on sea-level rise and coastal ecosystems is of major environmental and societal concern. However, the effect of atmospheric temperature increases on long-term glacier retreat remains poorly defined due to limited historical observations and uncertainties in numerical ice-sheet models, which challenges climate change adaptation planning. ... -
Mineralogical distribution and genetic aspects of cobalt at the active Fåvne and Loki’s Castle seafloor massive sulfide deposits, Arctic Mid-Ocean Ridges
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-16)The demand for responsibly sourced cobalt has increased dramatically as a result of the global transition to ‘fossil-free’ electromobility. However, the distribution, mineralogical expressions and mechanisms of concentration of Co in different types of hydrothermal ore deposits remain poorly constrained, inhibiting resource assessments and exploration. Here we report Co and other metal concentrations ... -
Pelagic calcium carbonate production and shallow dissolution in the North Pacific Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-20)Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO<sub>2</sub>. Surprisingly, references to the absolute and relative contribution of these organisms to calcium carbonate production are lacking. Here we report quantification of pelagic calcium carbonate production in the North Pacific, providing new insights on the contribution of the three ... -
Sedimentology of Neoproterozoic storm-influenced braid deltas, Varanger Peninsula, North Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-30)The oldest part of the upper Riphean (Cryogenian) sedimentary succession of the Varanger Peninsula, North Norway, includes a series of sandstone-dominated units of fluvio-deltaic to shallow-marine origin and thinner, intercalated mudstone-rich units. The sedimentology and stratigraphic understanding of the mudstone-rich units are less complete compared to their sandstone-dominated counterparts. In ... -
Quaternary and Neogene Reservoirs of the Norwegian Continental Shelf and the Faroe-Shetland Basin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-01)Glaciogenic reservoirs host important hydrocarbon resources across the globe. Examples such as the Peon and Aviat discoveries in the North Sea show that Quaternary and Neogene reservoirs can be prospective in the region. In this study, we interpret 2D and 3D reflection seismic data combined with borehole information to document unconventional play models from the shallow subsurface of the Norwegian ... -
The Svalbard Carboniferous to Cenozoic Composite Tectono-Stratigraphic Element
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-26)The Svalbard Composite Tectono-Stratigraphic Element is located on the north-western corner of the Barents Shelf and comprises a Carboniferous to Pleistocene sedimentary succession. Due to Cenozoic uplift the succession is subaerially exposed in the Svalbard archipelago. The oldest parts of the succession consist of Carboniferous to Permian mixed siliciclastic, carbonate and evaporite and spiculitic ... -
Climate and sea-ice development between 890 and 1660 CE in SW Greenland revealed by marine diatom studies
(Master thesis; Mastergradsoppgave, 2022-11-24)This thesis presents the results of august Sea Surface Temperature reconstructions from marine diatom assemblages in samples from core Ga3-2 retrieved from Narsaq Sound, inside the Ikersuad fjord, South Greenland. The diatom samples provide a high-resolution (~30-year) reconstruction dating between 890 and 1660 CE (common era). The results show variable conditions with warm periods between 960 and ...