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norskBlar i tittel Artikler, rapporter og annet (geovitenskap)
Viser treff 507-526 av 711
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Postglacial relative sea level change and glacier activity in the early and late Holocene: Wahlenbergfjorden, Nordaustlandet, Svalbard
(Journal article; Peer reviewed, 2019-05-01)Sediment cores from Kløverbladvatna, a threshold lake in Wahlenbergfjorden, Nordaustlandet, Svalbard were used to reconstruct Holocene glacier fluctuations. Meltwater from Etonbreen spills over a threshold to the lake, only when the glacier is significantly larger than at present. Lithological logging, loss-on-ignition, ITRAX scanning and radiocarbon dating of the cores show that Kløverbladvatna ... -
Postglacial response of Arctic Ocean gas hydrates to climatic amelioration
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-05)Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been argued that a gas hydrate gun could trigger abrupt climate ... -
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 ... -
Pre-orogenic connection of the foreland domains of the Kaoko–Dom Feliciano–Gariep orogenic system
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-30)Neoproterozoic metasedimentary rocks in the foreland domains of the Kaoko–Dom Feliciano–Gariep orogenic system record sedimentation from the breakup of Rodinia to the amalgamation of Gondwana, and thus provide ideal subjects for investigation of the mutual pre-orogenic positions of rifted margins of the African and South American cratonic blocks. U–Pb isotopic dating of zircon in the Brusque Complex ... -
Production of fluorescent dissolved organic matter in Arctic Ocean sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the ... -
Production, consumption, and migration of methane in accretionary prism of southwestern Taiwan
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-15)To systematically quantify the production, consumption, and migration of methane, 210 sediment cores were collected from offshore southwestern Taiwan and analyzed for their gas and aqueous geochemistry. These data, combined with published results, were used to calculate the diffusive methane fluxes across different geochemical transitions and to develop scenarios of mass balance and constrain deep ... -
Progradation rates measured at modern river outlets: A first-order constraint on the pace of deltaic deposition
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-29)We present a compilation of modern shoreline progradation rates measured close to river outlets entering deltaic coastlines, and we discuss how these observations relate to the overall evolution of both modern and ancient deltaic coastlines. We analyzed Landsat‐derived satellite images to identify plan view changes in the subaerial morphology of 331 modern deltaic coastlines. Our rate compilation ... -
Propagation of the Storegga tsunami into ice-free lakes along the southern shores of the Barents Sea
(Journal article; Tidsskriftartikkel, 2011-06-08)There is clear evidence that the Storegga tsunami, triggered by the giant Storegga slide offshore western Norway 8100-8200 years ago, propagated into the Barents Sea. Cores from five coastal lakes along the coast of Finnmark in northern Norway reveal major erosion and deposition from the inundation of the tsunami. The deposits rest on a distinct erosional unconformity and consist of graded sand ... -
Prospecting biotechnologically-relevant monooxygenases from cold sediment metagenomes: An in silico approach
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-09)The goal of this work was to identify sequences encoding monooxygenase biocatalysts with novel features by in silico mining an assembled metagenomic dataset of polar and subpolar marine sediments. The targeted enzyme sequences were Baeyer–Villiger and bacterial cytochrome P450 monooxygenases (CYP153). These enzymes have wide-ranging applications, from the synthesis of steroids, antibiotics, mycotoxins ... -
Protracted post-glacial hydrocarbon seepage in the Barents Sea revealed by U–Th dating of seep carbonates
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-01)The hydrocarbon seepage chronology during deglaciation across the formerly glaciated Barents Sea was established using uranium-thorium (U–Th) dating of seep carbonates. Seep carbonates were sampled with remotely operated vehicles (ROV) from the seafloor at three active hydrocarbon seeps (water depth 156–383 m), located in the north-west (Storfjordrenna), north-central (Storbanken High), and south-west ... -
Provenance, depositional setting and diagenesis as keys to reservoir quality of the Lower Cretaceous in the SW Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-06)This study examines the role of the depositional environment for the final reservoir quality in four Lower Cretaceous sandstone reservoirs in the southwestern Barents Sea by linking facies to the distribution of primary textures, composition, and diagenetic alteration. Facies analysis reveals slope-to-basin-floor, distal shallow-marine, and deltaic depositional environments. The slope-to-basin-floor ... -
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 ... -
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 ... -
The pyrite multiple sulfur isotope record of the 1.98 Ga Zaonega Formation: Evidence for biogeochemical sulfur cycling in a semi-restricted basin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-21)The pyrite sulfur isotope record of the 1.98 Ga Zaonega Formation in the Onega Basin, NW Russia, has played a central role in understanding ocean-atmosphere composition and inferring worldwide fluctuations of the seawater sulfate reservoir during the pivotal times of the Paleoproterozoic Era. That, in turn, has led to a concept that Earth's atmospheric oxygen levels underwent global-scale changes. ... -
Quantification of the magnitude of net erosion in the southwest Barents Sea using sonic velocities and compaction trends in shales and sandstones
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-19)During specific intervals within Mesozoic and Cenozoic times, several areas of the southwestern Barents Sea were subjected to uplift and erosion. Areas with missing shallow stratigraphic interval sections and major erosion can be seen at several places along interpreted regional profiles in the southwestern Barents Sea. A new Normal Compaction Trend (NCT) for two selected shale– and ... -
Quantifying short-term changes in snow strength due to increasing liquid water content above hydraulic barriers
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-31)The rapid weakening of snow layers that accumulate infiltrating liquid water is a well-known, but poorly quantified, mechanism for wet-snow slab avalanche formation. Therefore, quantifying this mechanical process is a crucial part of forecasting these snow avalanches accurately. Currently, studies do not agree on how snow strength should change as a function of volumetric liquid water content ( ) ... -
Quantitative interpretation using inverse rock-physics modeling on AVO data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08-16)Quantitative seismic interpretation has become an important and critical technology for improved hydrocarbon exploration and production. However, this is typically a resource-demanding process that requires information from several well logs, building a representative velocity model, and, of course, high-quality seismic data. Therefore, it is very challenging to perform in an exploration or appraisal ... -
Quartz rheology constrained from constant-load experiments: Consequences for the strength of the continental crust
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-21)The mechanical properties of quartz are fundamental to control the plastic behaviour of the continental crust. Our understanding of quartz rheology is still limited in the following respects: i) the large variability of flow law parameters in the earlier literature (stress exponent n = 4 to ≤ 2 and activation energy Q = 120 to 242 kJ/mol), and ii) the difficulty to identify the rate-limiting deformation ... -
Quartz textural analysis from an anastomosing shear zone system: Implications for the tectonic evolution of the Ribeira belt, Brazil
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-18)Strain localization and influence of grain-size reduction processes were investigated from field and microstructural observations, and from quartz textural analysis using EBSD, in rocks deformed along an anastomosing network of shear zones in the Ribeira belt in Brazil. Rocks deformed along the Lancinha shear zone (LSZ) display high percentage of recrystallized grains, in which quartz recrystallized ... -
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 ...
