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norskArtikler, rapporter og annet (geovitenskap): Recent submissions
Now showing items 481-500 of 729
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High-resolution landform assemblage along a buried glacio-erosive surface in the SW Barents Sea revealed by P-Cable 3D seismic data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-01)The Quaternary sedimentary record in the Arctic captures a diverse and evolving range of landscapes reflecting cli-mate changes. Here we study the geological landform assemblage of the Upper Regional Unconformity (URU) in theSW Barents Sea. The aims are (i) to characterize buried geological landforms on a meter-scale resolution, (ii) to un-derstand their link with underlying structures, and (iii) ... -
Deglacial dynamics of the Vestfjorden - Trænadjupet palaeo-ice stream, northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-18)Few well‐dated records of the deglacial dynamics of the large palaeo‐ice streams of the major Northern Hemisphere ice sheets are presently available, a prerequisite for an improved understanding of the ice‐sheet response to the climate warming of this period. Here we present a transect of gravity‐core samples through Trænadjupet and Vestfjorden, northern Norway, the location of the Trænadjupet – ... -
Reply to 'Challenges with dating weathering products to unravel ancient landscapes'
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-15)<i>Introduction</i>: As the title of the correspondence by Fossen et al.1 suggests, determining the age of landscape elements of the Earth surface is difficult. We thus welcome the opportunity to clarify our arguments on the contentious themes touched upon by Fredin et al.2 The age of landscapes has been a recurring research topic for the last century. Often, landscape ages can be deduced indirectly ... -
Submarine geomorphology at the front of the retreating hansbreen tidewater glacier, hornsund fjord, southwest spitsbergen
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-01)A 1:10,000 scale bathymetric map as well as 1:20,000 scale backscattering and geomorphological maps of two bays Isbjørnhamna and Hansbukta in the Hornsund fjord (Spitsbergen) present the submarine relief that was primarily formed during and after the retreat of the Hansbreen tidewater glacier. Geomorphological mapping was performed using multibeam bathymetric data and seismoacoustic profiling. The ... -
Depositional processes on the distal Scoresby Trough Mouth Fan (ODP Site 987): Implications for the Pleistocene evolution of the Scoresby Sund Sector of the Greenland Ice Sheet
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-28)The investigation of trough mouth fans (TMFs), important paleoclimatic archives on mid- and high-latitude continental margins, has so far mainly been based on the integration of various types of acoustic data supplemented with short sediments cores. In consequence, sedimentological and chronological data about parts of TMFs deposited prior to the Last Glacial Maximum remains sparse. Here, we re-evaluate ... -
Repeatability of high-resolution 3D seismic data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)High-resolution 4D (HR4D) seismic data have the potential for improving the current state-of-the-art in detecting shallow (≤500−1000 m below seafloor) subsurface changes on a very fine scale (approximately 3–6 m). Time-lapse seismic investigations commonly use conventional broadband seismic data, considered low to moderate resolution in our context. We have developed the first comprehensive time ... -
Evolution in H2O contents during deformation of polycrystalline quartz: An experimental study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-15)Shear experiments were performed in a Griggs-type apparatus at 800 °C and 1.5 GPa, at a strain rate of 2.1 × 10<sup>−5</sup>s<sup>−1</sup> using different starting materials: (i) Powder (grain size 6–10 μm) of dry Brazil quartz with 0.15 wt% added H<sub>2</sub>O, (ii) “dry” Brazil quartz porphyroclasts (grain size ∼100–200 μm), devoid of fluid inclusions embedded in the same fine grained powder, and ... -
Cryptic frenulates are the dominant chemosymbiotrophic fauna at Arctic and high latitude Atlantic cold seeps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-28)We provide the first detailed identification of Barents Sea cold seep frenulate hosts and their symbionts. Mitochondrial COI sequence analysis, in combination with detailed morphological investigations through both light and electron microscopy was used for identifying frenulate hosts, and comparing them to Oligobrachia haakonmosbiensis and Oligobrachia webbi, two morphologically similar species ... -
Fault-controlled asymmetric landscapes and low-relief surfaces on Vestvågøya, Lofoten, North Norway: inherited Mesozoic rift-margin structures?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-20)The Lofoten Ridge is an integral basement horst of the hyperextended continental rift-margin off northern Norway. It is a key area for studying onshore–offshore rift-related faults, and for evaluating tectonic control on landscape development along the North Atlantic margin. This paper combines onshore geomorphological relief/aspect data and fault/fracture analysis with offshore bathymetric and ... -
Geological controls on fluid flow and gas hydrate pingo development on the Barents Sea margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-16)In 2014, the discovery of seafloor mounds leaking methane gas into the water column in the northwestern Barents Sea became the first to document the existence of non‐permafrost related gas hydrate pingos (GHP) on the Eurasian Arctic shelf. The discovered site is given attention because the gas hydrates occur close to the upper limit of the gas hydrate stability, thus may be vulnerable to climatic ... -
Evidences of accelerating the increase in the concentration of methane in the atmosphere after 2014: satellite data for the Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017)Проанализированы результаты спутникового зондирования с помощью европейского орбитального интерферометра IASI/MetOP-A и алгоритма обработки данных, разработанного в NOAA. Спутниковые измерения для умеренных и высоких широт Северного полушария дают рост скорости концентрации метана от 4–9 ppbv/год (частей на миллиард по объему) в 2010–2013 гг. до 12–17 ppbv/год в 2015–2016 гг. Глобальные оценки на ... -
Spreading of drill cuttings and sediment recovery of three exploration wells of different ages, SW Barents Sea, Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-14)Five stations (≤250 m from the well heads) from three exploration wells of different ages from the SW Barents Sea were studied to investigate the spreading of drill cuttings and sediment quality. Two of the wells were drilled before the restriction of use of oil-based drilling fluids (1993). Elevated concentrations of Ba were found in sediments near all the wells with the highest concentrations ... -
Ionospheric Response Observed by EISCAT During the 6–8 September 2017 Space Weather Event: Overview
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-03)We present ionospheric plasma conditions observed by the EISCAT radars in Tromsø and on Svalbard, covering 68°–81° geomagnetic latitude, during 6–8 September 2017. This is a period when X2.2 and X9.3 X‐ray flares occurred, two interplanetary coronal mass ejections (ICMEs) arrived at the Earth accompanied by enhancements of MeV‐range energetic particle flux in both the solar wind (SEP event) and inner ... -
Cordilleran ice-sheet growth fueled primary productivity in the Gulf of Alaska, northeast Pacific Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-15)Fertilization of the ocean by eolian dust and icebergs is an effective mechanism to enhance primary productivity. In particular, high-nutrient, low-chlorophyll (HNLC) areas where phytoplankton growth is critically iron-limited, such as the subarctic Pacific Ocean and the Southern Ocean, are proposed to respond to increases in bioavailable Fe supply with enhanced phytoplankton productivity and carbon ... -
Area and volume of mid-latitude glacier-like forms on Mars
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-04)Although a substantial ice cover has been identified within the mid-latitudes of Mars, there is uncertainty regarding the formation, current and former volume, and dynamic evolution of these ice masses. Here, we present the first comprehensive ice volume estimate of martian glacier-like forms (GLFs) from systematic population scale mapping and volumetric analysis. The outlines of 1243 GLFs were ... -
Holocene development of subarctic permafrost peatlands in Finnmark, northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-01)Subarctic permafrost peatlands are important soil organic carbon pools, and improved knowledge about peat properties and peatland sensitivity to past climate change is essential when predicting future response to a warmer climate and associated feedback mechanisms. In this study, Holocene peatland development and permafrost dynamics of four subarctic peat plateaus in Finnmark, northern Norway have ... -
EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity of Polar Mesospheric Summer Echoes Associated With a Geomagnetic Disturbance
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-04)By analyzing a data set from the European Incoherent SCATter (EISCAT) Very High Frequency (VHF) radar at Tromsø, we find that both radar reflectivity and upward ion velocity in a polar mesospheric summer echo (PMSE) layer simultaneously increased at the commencement of a local geomagnetic disturbance, which occurred at midnight on 9 July 2013. The onset of the upward velocity was followed by periodic ... -
Early to middle Cenozoic paleoenvironment and erosion estimates of the southwestern Barents Sea: Insights from a regional mass-balance approach
(Journal article; Tidsskriftartikkel, 2018-06-02)The Cenozoic pre-glacial development of the southwestern Barents Sea is discussed, with focus on the early to middle Cenozoic net erosion that was poorly constrained. From 2D and 3D seismic mapping, the western Barents Sea continental margin development shows a complex history of structural configuration of highs and basins related to the Greenland and Eurasian plate movement and subsequent seafloor ... -
Biogeochemical evidence of anaerobic methane oxidation on active submarine mud volcanoes on the continental slope of the Canadian Beaufort Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-20)In this study, we report lipid biomarker patterns and phylogenetic identities of key microbial communities mediating anaerobic oxidation of methane (AOM) in active mud volcanoes (MVs) on the continental slope of the Canadian Beaufort Sea. The carbon isotopic compositions (δ13C) of sn-2- and sn-3-hydroxyarchaeol showed the highly 13C-depleted values (−114 ‰ to −82 ‰) associated with a steep depletion ... -
From widespread Mississippian to localized Pennsylvanian extension in central Spitsbergen, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-21)In the Devonian–Carboniferous, a rapid succession of clustered extensional and contractional tectonic events is thought to have affected sedimentary rocks in central Spitsbergen, Svalbard. These events include Caledonian post-orogenic extensional collapse associated with the formation of thick Early–Middle Devonian basins, Late Devonian–Mississippian Ellesmerian contraction, and Early–Middle ...
