Institutt for geovitenskap: Recent submissions
Now showing items 341-360 of 1102
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Impact of Timanian thrust systems on the late Neoproterozoic–Phanerozoic tectonic evolution of the Barents Sea and Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-12)The Svalbard Archipelago consists of three basement terranes that record a complex Neoproterozoic– Phanerozoic tectonic history, including four contractional events (Grenvillian, Caledonian, Ellesmerian, and Eurekan) and two episodes of collapse- to rift-related extension (Devonian–Carboniferous and late Cenozoic). Previous studies suggest that these three terranes likely accreted during the early ... -
How Academics and the Public Experienced Immersive Virtual Reality for Geo-Education
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-24)Immersive virtual reality can potentially open up interesting geological sites to students, academics and others who may not have had the opportunity to visit such sites previously. We study how users perceive the usefulness of an immersive virtual reality approach applied to Earth Sciences teaching and communication. During nine immersive virtual reality-based events held in 2018 and 2019 in ... -
Mineral paragenesis and sulphide trace element distribution in the metamorphosed Lovisa Zn-Pb deposit, Bergslagen (Sweden), as revealed by 3D X-ray tomography, ore petrography and LA-ICP-MS analysis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-29)This study encompasses the ore mineralogy, textures and sulphide trace element chemistry of the Palaeoproterozoic Lovisa stratiform Zn-Pb deposit and the stratigraphically underlying Lovisa Fe Formation in the Bergslagen ore province (Sweden). We investigate the relative timing of formation and subsequent modifications of its ores in relation to the c. 1.87–1.80 Ga Svecokarelian orogeny. The Lovisa ... -
Physical weathering by glaciers enhances silicon mobilisation and isotopic fractionation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-06)Glacial meltwaters export substantial quantities of dissolved and dissolvable amorphous silicon (DSi and ASi), providing an essential nutrient for downstream diatoms. Evidence suggests that glacially exported DSi is isotopically light compared to DSi in non-glaciated rivers. However, the isotopic fractionation mechanisms are not well constrained, indicating an important gap in our understanding ... -
Origin and Periodic Behavior of Short Duration Signals Recorded by Seismometers at Vestnesa Ridge, an Active Seepage Site on the West-Svalbard Continental Margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-02)Short duration events (SDEs) are reported worldwide from ocean-bottom seismometers (OBSs). Due to their high frequency (4–30 Hz) and short duration, they are commonly attributed to aseismic sources, such as fluid migration related processes from cold seeps, biological signals, or noise. We present the results of a passive seismic experiment that deployed an OBS network for 10-month (October 2015–July ... -
Glacier response to the Little Ice Age during the Neoglacial cooling in Greenland
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-04)In the Northern Hemisphere, an insolation driven Early to Middle Holocene Thermal Maximum was followed by a Neoglacial cooling that culminated during the Little Ice Age (LIA). Here, we review the glacier response to this Neoglacial cooling in Greenland. Changes in the ice margins of outlet glaciers from the Greenland Ice Sheet as well as local glaciers and ice caps are synthesized Greenland-wide. ... -
Development of the NORSAR Network over the Last 50 Yr
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-27)This contribution describes the development of Norwegian Seismic Array (NORSAR), from its origin 50 yr ago as a project for installing a single seismic array in southern Norway to a seismological research institute operating a network of six arrays and 14 three‐component stations located in Norway and Antarctica. In addition, we document the different instrumentations from narrowband, mostly ... -
Seismic and electrical geophysical characterization of an incipient coastal open-system pingo: Lagoon Pingo, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-24)Whilst there has been a recent appreciation for the role of open-system pingos in providing a fluid-flow conduit through continuous permafrost that enables methane release, the formation and internal structure of these ubiquitous permafrost-diagnostic landforms remains unclear. Here, we combine active-source seismic measurements with electrical resistivity tomography (ERT) to investigate the structural ... -
Autonomous methane seep site monitoring offshore western Svalbard: hourly to seasonal variability and associated oceanographic parameters
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-18)Improved quantification techniques of natural sources are needed to explain variations in atmospheric methane. In polar regions, high uncertainties in current estimates of methane release from the seabed remain. We present unique 10- and 3-month time series of bottom water measurements of physical and chemical parameters from two autonomous ocean observatories deployed at separate intense seabed ... -
Decadal trend of plankton community change and habitat shoaling in the Arctic gateway recorded by planktonic foraminifera
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-16)The Fram Strait plays a crucial role in regulating the heat and sea-ice dynamics in the Arctic. In response to the ongoing global warming, the marine biota of this Arctic gateway is experiencing significant changes with increasing advection of Atlantic species. The footprint of this ‘Atlantification’ has been identified in isolated observations across the plankton community, but a systematic, ... -
A practical method to determine the five-parameter orientation of intragranular boundaries in polycrystals
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-04)Intragranular boundaries are important features of polycrystalline materials and impact on many physical and chemical properties. Knowledge of their physical orientation is often crucial to explain such properties. However, it has proved difficult to determine the complete orientation of intragranular boundaries, which involves the misorientation angle and axis about which the adjacent crystal ... -
Benthic foraminiferal assemblages and environmental drivers along the Kveithola Trough (NW Barents Sea)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-14)We describe the population density, biodiversity and vertical distribution in the sediment of benthic foraminifera, and their relationship to environmental parameters, in the Kveithola Trough (NW Barents Sea). Two staining methods, Cell Tracker Green (CTG) and Rose Bengal (RB), were used to distinguish between living and dead tests. CTG proved to be more effective than RB, and we therefore used this ... -
Sheared Peridotite and Megacryst Formation Beneath the Kaapvaal Craton: A Snapshot of Tectonomagmatic Processes across the Lithosphere-Asthenosphere Transition
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-27)The cratonic lithosphere–asthenosphere boundary is commonly invoked as the site of sheared peridotite and megacryst formation, a well-recognized petrological assemblage whose genetic relationships—if any—remain poorly understood. We have undertaken a comprehensive petrology and Sr–Nd–Hf–Ca isotope study of sheared peridotite xenoliths and clinopyroxene megacrysts from the c. 1150 Ma Premier kimberlite ... -
Evolution and temporal constraints of a multiphase postglacial rock slope failure
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-05)Large rock slope failures are temporal processes which act to modify the landscape after glacial retreat. The slope failure process often shows a lag time of thousands of years after deglaciation, with multiple failure events possible. While global datasets constrain this lag time from extensive mapping and dating of paraglacial rock avalanches, the timeline is poorly refined in northern Norway. We ... -
Heterogeneous REE + Y distribution in Early Paleozoic shelly phosphorites: Implications for enrichment mechanisms
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-27)Sedimentary phosphorites are important carriers of Rare Earth Elements and Yttrium (REE + Y). Primary biogenic and sedimentary apatite contain very low amounts of REE + Y and enrichment of these elements occurs during diagenesis. Although the influence of post-depositional processes on REE + Y concentrations in sedimentary phosphorites is well established, the processes controlling the degree of ... -
Regional Morpho-Kinematic Inventory of Slope Movements in Northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-25)Mountain slopes in periglacial environments are affected by frost- and gravity-driven processes that shape the landscape. Both rock glaciers and rockslides have been intensively inventoried worldwide. Although most inventories are traditionally based on morphologic criteria, kinematic approaches based on satellite remote sensing have more recently been used to identify moving landforms at the regional ... -
Evolution of ultrapotassic volcanism on the Kaapvaal craton: deepening the orangeite versus lamproite debate
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-02)Orangeites are a significant source of diamonds, yet ambiguity surrounds their status among groups of mantle-derived potassic rocks. This study reports mineralogical and geochemical data for a c. 140 Ma orangeite dyke swarm that intersects the Bushveld Complex on the Kaapvaal craton in South Africa. The dykes comprise distinctive petrographic varieties that are linked principally by olivine ... -
Proximal to distal grain-size distribution of basin-floor lobes: A study from the Battfjellet Formation, Central Tertiary Basin, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-09)The grain-size distribution of sediment particles is an important aspect of the architecture of submarine fans and lobes. It governs depositional sand quality and reflects distribution of particulate organic carbon and pollutants. Documenting the grain-size distribution of these deep-marine sedimentary bodies can also offer us an insight into the flows that deposited them. Submarine lobes ... -
Rapid Atlantification along the Fram Strait at the beginning of the 20th century
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-24)The recent expansion of Atlantic waters into the Arctic Ocean represents undisputable evidence of the rapid changes occurring in this region. Understanding the past variability of this “Atlantification” is thus crucial in providing a longer perspective on the modern Arctic changes. Here, we reconstruct the history of Atlantification along the eastern Fram Strait during the past 800 years using ... -
Putative fossils of chemotrophic microbes preserved in seep carbonates from Vestnesa Ridge, off northwest Svalbard, Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-20)The microbial key players at methane seeps are methanotrophic archaea and sulfate-reducing bacteria. They form spherical aggregates and jointly mediate the sulfate-dependent anaerobic oxidation of methane (SD–AOM: CH4 + SO42– → HCO3– + HS– + H2O), thereby inducing the precipitation of authigenic seep carbonates. While seep carbonates constitute valuable archives for molecular fossils of SD–AOM-mediating ...