Institutt for geovitenskap: Nye registreringer
Viser treff 281-300 av 1092
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Rapid post-glacial bedrock weathering in coastal Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-26)Quantifying bedrock weathering rates under diverse climate conditions is essential to understanding timescales of landscape evolution. Yet, weathering rates are often difficult to constrain, and associating a weathered landform to a specific formative environment can be complicated by overprinting of successive processes and temporally varying climate. In this study, we investigate three sites ... -
MIS 3 age of the Veiki moraine in N Sweden – Dating the landform record of an intermediate-sized ice sheet in Scandinavia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-14)The Veiki moraine in northern Sweden, a geomorphologically distinct landscape of ice-walled lake plains, has been interpreted to represent the former margin of an intermediate-sized pre–Last Glacial Maximum (LGM) Fennoscandian ice sheet, but its age is debated as either marine isotope stage (MIS) 5c or MIS 3. We have applied optically stimulated luminescence (OSL) and radiocarbon dating to four sites ... -
Combined X-Ray Computed Tomography and X-Ray Fluorescence Drill Core Scanning for 3-D Rock and Ore Characterization: Implications for the Lovisa Stratiform Zn-Pb Deposit and Its Structural Setting, Bergslagen, Sweden
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-29)We present the results of a pilot study that integrates automated drill core scanning technology based on simultaneous X-ray computed tomography (XCT) and X-ray fluorescence (XRF) analyses to provide high-spatialresolution (<0.2 mm) information on 3-D rock textures and structures, chemical composition, and density. Testing of its applicability for mineral exploration and research was performed by ... -
Tectonic evolution of the Indio Hills segment of the San Andreas fault in southern California, southwestern USA
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-01)Transpressional uplift domains of inverted Pliocene–Pleistocene basin fill along the San Andreas fault zone in Coachella Valley, southern California (USA), are characterized by fault linkage and segmentation and deformation partitioning. The Indio Hills wedge-shaped uplift block is located in between two boundary fault strands, the Indio Hills fault to the northeast and the main San Andreas fault ... -
Ammonium and Sulfate Assimilation Is Widespread in Benthic Foraminifera
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-20)Nitrogen and sulfur are key elements in the biogeochemical cycles of marine ecosystems to which benthic foraminifera contribute significantly. Yet, cell-specific assimilation of ammonium, nitrate and sulfate by these protists is poorly characterized and understood across their wide range of species-specific trophic strategies. For example, detailed knowledge about ammonium and sulfate assimilation ... -
Evolution of the Gállojávri ultramafic intrusion from U-Pb zircon ages and Rb-Sr, Sm-Nd and Lu-Hf isotope systematics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-05)The Karasjok–Central Lapland Greenstone Belt is one of the largest Palaeoproterozoic greenstone belts in the Fennoscandian Shield and includes multiple (ultra)mafic intrusions, some with notable ore reserves, formed during three episodes at 2.44, 2.22 and 2.05 Ga. This study presents new mineralogical, geochronological and isotopic data for the Gállojávri ultramafic intrusion, in the Karasjok ... -
Late Quaternary tephra stratigraphy and paleoenvironmental reconstruction based on lake sediments from North and Northeast Iceland
(Mastergradsoppgave; Master thesis, 2020-07-12)Due to Iceland’s position in the middle of the North Atlantic, the island is highly sensitive to oceanic and atmospheric fluctuations, which lead to changes in the environment. These fluctuating environmental conditions in addition to Iceland’s high volcanic activity make it a strategic study area for paleoenvironmental and tephra studies. Lake sediments contain information about such past climate ... -
Grounding-line fan formation during an Early Holocene readvance of Aldegondabreen, Svalbard.
(Mastergradsoppgave; Master thesis, 2021-12-10)In this study, two ridge-shaped cross-valley sedimentary landforms, in the lower forefield of Aldegondabreen, a small valley glacier on the west coast of Spitsbergen, Svalbard, were studied to reconstruct the Holocene glacial history of Aldegondabreen prior to the Little Ice Age. Sedimentological and geomorphological methods were used in conjunction with radiocarbon dating to examine the sediments ... -
Evolution of ore-forming fluids in a post-collisional porphyry Cu-Au system: A case study from the Bučim deposit, Republic of North Macedonia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-27)The Bučim porphyry Cu-Au deposit is situated in the westernmost part of the Serbo-Macedonian Massif, Republic of North Macedonia. The deposit is hosted by Precambrian gneisses with tectonically imbedded rare lenses of Palaeozoic amphibolites. The mineralization is spatially associated with intrusions of andesitic to trachyandesitic magmatic bodies. The geochemical signature of the intrusions and ... -
Characteristics and failure mechanisms of the unstable rock slope Dusnjárga
(Mastergradsoppgave; Master thesis, 2022-05-15)Large slowly creeping rock slope deformations, with an annual displacement in the range of millimeters to centimeters, have been prone to rapid catastrophic failures in the past. This master thesis focuses on the unstable rock slope of Dusnjárga in Northern Norway. A sudden rapid failure of Dusnjárga would pose a threat to the local society in Lille Altafjord and Burfjord, due to potential secondary ... -
The effect of lithology and microstructure on the deformation of unstable rock slopes in northern Norway
(Mastergradsoppgave; Master thesis, 2022-05-14)Rock avalanches are a type of natural catastrophe in Norway with very high consequences, and the alpine landscape makes Troms and Finnmark County the region with the highest frequency of unstable rock slopes. The bedrock geology is highly relevant to assess and understand the failure mechanisms, and mechanical properties that influence deformation in rock slopes. Pre-existing structures and lithological ... -
Sedimentology and architecture of a deep-water turbidite system; Kongsfjord Formation, Finnmark, northern Norway
(Mastergradsoppgave; Master thesis, 2022-05-15)The Kongsfjord Formation is a Late Precambrian deep-marine sedimentary succession exposed along the northern coastline of the Varanger Peninsula, northern Norway. Several studies in the 1970s and 1980s led to the recognition of the Formation as an ancient submarine fan system and to the identification of several architectural elements, including lobes and channels. However, there are no published ... -
Upper cretaceous-paleogene stratigraphy and development of the Mímir High, Vøring transform margin, Norwegian Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-19)Transform margins represent strike-slip type of plate boundaries that form during continental breakup and initial ocean opening. They are often characterized by margin-parallel highs with exposed pre- and syn-rift sequences. The Vøring Transform Margin, offshore mid-Norway, initiated in the earliest Eocene during the opening of the NE Atlantic. Here, 2D seismic reflection data reveal a transform ... -
A Phenomenographic Analysis Of Students’ Experience Of Geological Time
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-01)Geological time is by many geoscience instructors considered a threshold concept for geoscience students, being a central concept for how we experience geosceince phenomena that takes place on a spatio-temporal scale ranging from micro (e.g. cloud formation) to macro (e.g. plate tectonics). If one wishes to understand geoscience phenomena that goes beyond human perception, one must move from the ... -
The Use of Foraminiferal Geochemistry to Investigate Methane Seepage at the Svyatogor Ridge, Arctic Ocean
(Master thesis; Mastergradsoppgave, 2022-05-12)Methane is a greenhouse gas contributing to contemporaneous global warming, and seepage is one of the ways through which it migrates from the deep sedimentary basins, all the way up to the hydro- and atmosphere. The study of methane seepage is still young as scientists are yet to discover most seep sites as well as seep associated biological species. A record of past methane seepage can be derived ... -
A Quantitative Analysis of Seasonal and Regional Forcing on the Terminus of Store Glacier, Greenland, from High Resolution Photogrammetry
(Master thesis; Mastergradsoppgave, 2022-01-15)A quantitative analysis of seasonal and regional forcing on the terminus of Store Glacier, Greenland, from high resolution photogrammetry for the period between 10 May 2014 and 13 June 2014. Imagery is analyzed through ImGRAFT processing to create a detailed velocity and strain rate for the proglacial mélange and glacial terminus in order to investigate changes to glacial calving dynamics during ... -
The role of ocean and atmospheric dynamics in the marine-based collapse of the last Eurasian Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-19)Information from former ice sheets may provide important context for understanding the response of today’s ice sheets to forcing mechanisms. Here we present a reconstruction of the last deglaciation of marine sectors of the Eurasian Ice Sheet, emphasising how the retreat of the Norwegian Channel and the Barents Sea ice streams led to separation of the British-Irish and Fennoscandian ice sheets at ... -
Permafrost in monitored unstable rock slopes in Norway-New insights from temperature and surface velocity measurements, geophysical surveying, and ground temperature modelling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-01)The warming and subsequent degradation of mountain permafrost within alpine areas represent an important process influencing the stability of steep slopes and rock faces. The unstable and monitored slopes of Mannen (Møre and Romsdal county, southern Norway) and Gámanjunni-3 (Troms and Finnmark county, northern Norway) were classified as high-risk sites by the Norwegian Geological Survey (NGU). ... -
Reconstruction of the Kråknes landslide event, Alta
(Master thesis; Mastergradsoppgave, 2021-05-15)On June 3rd, 2020 a major quick clay landslide occurred at Kråknes in Alta municipality, Northern Norway. The landslide event destroyed eight buildings and was estimated to be 650 meters wide and 40 meters high. Two days later, another landslide occurred, this time causing the old E6 road above the previous landslide area to slip out towards the sea. People lost cabins and other valuable possessions, ... -
Multi-elemental chemostratigraphy of Triassic mudstones in eastern Svalbard: implications for source rock formation in front of the World’s largest delta plain
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-03)The Triassic Boreal Ocean was a shallow epicontinental basin and the sink of the World's largest delta plain known to date. Nutrient and freshwater supply from this delta have been regarded as important causes for high productivity and water mass stratification, forming Middle Triassic oil-prone source rocks. Recent studies attribute upwelling and a productivity-induced oxygen minimum zone as ...