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norskBlar i tittel Institutt for geovitenskap
Viser treff 603-622 av 982
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OBS Data Analysis to Quantify Gas Hydrate and Free Gas in the South Shetland Margin (Antarctica)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-25)The presence of a gas hydrate reservoir and free gas layer along the South Shetland margin (offshore Antarctic Peninsula) has been well documented in recent years. In order to better characterize gas hydrate reservoirs, with a particular focus on the quantification of gas hydrate and free gas and the petrophysical properties of the subsurface, we performed travel time inversion of ocean-bottom ... -
Occurence of free gas and focused fluid systems in the Veslemøy High area, SW Barents Sea
(Master thesis; Mastergradsoppgave, 2009-05-15)The high-resolution 3D seismic survey EL0001 allowed to document the subsurface fluid migration system and fluid accumulations within Veslemøy High, SW Barents Sea. Fluids migrate both through Cretaceous and Tertiary sediments, but also through younger glacial sediments. Veslemøy High is a structurally isolated high at the Cretaceous and Tertiary levels bounded by N-S trending west-dipping normal ... -
The occurrence of flow transformations within sandy submarine fans: A case study from the Eocene on Spitsbergen
(Master thesis; Mastergradsoppgave, 2017-05-15)The Van Keulenfjorden transect on Spitsbergen offers valuable insight into submarine processes, with well exposed seismic scale clinoforms of Paleocene and Eocene age, which show the distribution of sediments from deltaic to basin floor environments. Several progradational submarine fans are preserved as cliffs on Hyrnestabben. They serve as an analogues to coarse grained submarine fans in provinces ... -
Ocean temperature variability for the past 60 years on the Norwegian-Svalbard margin influences gas hydrate stability on human time scales
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012-10-23)The potential impact of future climate change on methane release from oceanic gas hydrates is the subject of much debate. We analyzed World Ocean Database quality controlled data on the Norwegian‐Svalbard continental margin from the past 60 years to evaluate the potential effect of ocean temperature variations on continental margin gas hydrate reservoirs. Bottom water temperatures in the Norwegian‐Svalbard ... -
Offshore permafrost decay and massive seabed methane escape in water depths >20 m at the South Kara Sea shelf
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013-07-14)Since the Last Glacial Maximum (~19 ka), coastal inundation from sea-level rise has been thawing thick subsea permafrost across the Arctic. Although subsea permafrost has been mapped on several Arctic continental shelves, permafrost distribution in the South Kara Sea and the extent to which it is acting as an impermeable seal to seabed methane escape remains poorly understood. Here we use >1300 km ... -
On Palaeozoic-Mesozoic brittle normal faults along the SW Barents Sea margin: fault processes and implications for basement permeability and margin evolution
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014) -
On the causes of Arctic sea ice in the warm Early Pliocene
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-30)Scattered and indirect evidence suggests that sea ice occurred as far south as the Iceland Sea during the Early Pliocene, when the global climate was warmer than present. However, conclusive evidence as well as potential mechanisms governing sea ice occurrence outside the Arctic Ocean during a time with elevated greenhouse gas concentrations are still elusive. Here we present a suite of organic ... -
The onset of flysch sedimentation in the Kaoko Belt (NW Namibia) – Implications for the pre-collisional evolution of the Kaoko–Dom Feliciano–Gariep orogen
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-17)<p>Detrital zircon provenance study of a metamorphosed sedimentary succession in the eastern part of the Kaoko Belt in Namibia has revealed two distinct sources for the Neoproterozoic sedimentation along the southwestern Congo Craton margin. The lower part of the succession shows detrital zircon ages consistent with erosion of Paleoproterozoic basement of the Congo Craton with an inferred Mesoproterozoic ... -
Onshore-offshore correlation in the Andfjorden area and the structural controls on the opening and evolution of the Mesozoic sedimentary basins on Andøya and Andfjorden, northern Norway
(Master thesis; Mastergradsoppgave, 2014-05-14)Onshore-offshore correlation of brittle faults has been undertaken in the Andfjorden area defining the boundary between the passive Lofoten-Vesterålen margin and the transform SW Barents Sea margin. This study has focused its efforts on onshore mapping of faults and fractures, the mapping of offshore faults and associated basin-ridge systems from seismic interpretation and the link between fault ... -
Optimising the use of marine tephrochronology in the North Atlantic: a detailed investigation of the Faroe Marine Ash Zones II, III and IV
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014) -
Ore petrography and fluid evolution in the Cu-(Zn) VMS deposits at Sulitjelma, Northern Norway
(Master thesis; Mastergradsoppgave, 2018-05-29)The Sulitjelma deposits, Nordland, Northern Norway, with more than 20 Zn-Cu ore bodies (total tonnage excesses 35 Mt of ore at 1.84 % Cu, 0.86 % Zn, 10 g/t Ag and 0.25 g/t Au) have been described as a classic example of the Zn-Cu volcanogenic massive sulfide (VMS) mineralization. The mineralization is spatially associated with metamorphosed mafic rocks of Ordovician age. Both, ore bodies and their ... -
Organic Matter Sources in North Atlantic Fjord Sediments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-31)To better constrain the global carbon cycle fundamental knowledge of the role of carbon cycling on continental margins is crucial. Fjords are particularly important shelf areas for carbon burial due to relatively high sedimentation rates and high organic matter fluxes. As terrigenous organic matter is more resistant to remineralization than marine organic matter, a comprehensive knowledge of the ... -
Origin and Economic Potential of Lithium-mineralized Granitic Pegmatites in Helgeland, North Norway
(Mastergradsoppgave; Master thesis, 2023-08-04)A comprehensive set of analytical techniques, encompassing geological, petrographic, mineralogical, and zircon U-Pb-Hf isotopic compositions, was employed to investigate a relatively poorly known pegmatite field located in Helgeland, North Norway. The Paleoproterozoic basement gneisses in the area have U-Pb zircon crystallization ages between 1870 ± 12 and 1811 ± 6 Ma, meaning that they belong to ... -
Origin and K-Ar age of the phreatomagmatic breccia at the Trepča Pb-Zn-Ag skarn deposit, Kosovo: Implications for ore-forming processes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-29)The Trepča Pb-Zn-Ag skarn deposit in Kosovo is spatially and temporarily related to the phreatomagmatic breccia of Oligocene age (~23Ma). The deposit shows features typical for skarn deposits worldwide, including a stage of isochemical metamorphism, a prograde stage of an anhydrous, low oxygen and low sulfur fugacity character, and a retrograde stage characterized by an increase in the water ... -
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 ... -
Origin and transformation of light hydrocarbons ascending at an active pockmark on Vestnesa Ridge, Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-25)We report on the geochemistry of hydrocarbons and pore waters down to 62.5 mbsf, collected by drilling with the MARUM‐MeBo70 and by gravity coring at the Lunde pockmark in the Vestnesa Ridge. Our data document the origin and transformations of volatiles feeding gas emissions previously documented in this region. Gas hydrates are present where a fracture network beneath the pockmark focusses migration ... -
The origin of driftwood on eastern and south-western Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-02)The Arctic is one of the regions where the effect of global change is most evident. Associated with warming are changes in snow, sea ice and hydroclimate, all which have significant impacts on environments and society. However, due to short observational records, it is difficult to set the current climate in a long-term context. Arctic driftwood (DW), available throughout the Holocene, is a paleoclimate ... -
The Origin of Gas Seeps in the Northern Adriatic Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06)A multidisciplinary approach has been used for the first time to study the widespread occurrence of hydrocarbon seeps in the northern Adriatic Sea. Geological, geophysical and geochemical analyses were performed to identify and characterize the gas-charged fluids occurring throughout the Plio-Quaternary succession, and to date the shallow gas seeping at three leakage sites. The analysis of CHIRP, ... -
The origin of quartz-carbonate veins hosted by ductile shear zones of the Astridal Supracrustal Belt, West-Troms Basement Complex.
(Master thesis; Mastergradsoppgave, 2018-05-29)An approximately 1 meter wide NE-SW-oriented mylonitic shear zone hosts hydrothermally precipitated quartz and carbonate veins. The shear zone mainly consists of a secondary mylonitic fabric enriched in chlorite. A similar mylonitic shear zone striking NE-SW, oriented parallel to the axial plane of a F3-fold, consists of the same secondary mylonitic chloritized fabric and are therefore assumingly ... -
Overgangen fra eklogitt til amfibolitt. Et detaljstudium
(Master thesis; Mastergradsoppgave, 2007-05)Formålet med oppgaven er å gjøre en systematisk petrografisk og petrologisk undersøkelse av en mafisk linse med omgivende granat-glimmerskifer/marmor innen Tromsødekket. Den mafiske linsa har opprinnelig sannsynlig vært en basaltisk gang/sill som har blitt metamorfosert under eklogittfacies. Lokaliteten er blottlagt i ei veiskjæring ved universitetet i Tromsø (UiT). Den valgte mafiske linsa har en ...
