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norskInstitutt for geovitenskap: Recent submissions
Now showing items 221-240 of 1011
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Struktur- og Intrusjonshistorie for pegmatittiske gangsvermer knyttet til den paleoproterozoiske Ersfjordgranitten, Vest-Troms Grunnfjellskompleks
(Mastergradsoppgave; Master thesis, 2022-03-31)Vest-Troms Grunnfjellkompleks er marginen og kontinuasjonen av det Fennoskandiske Skjold under de Kaledonske skyvedekkene. WTBC har utviklet seg gjennom flere fjellkjededannelser, dannelse av riftbassenger, høy- til lav-metamorf omvandling og flere episoder med bimodal magmatisme. Dette gjør at WTBC er et viktig studieområdet for å forstå jordas utvikling i Arkeikum og Palaeoproterozoikum. Formålet ... -
Methane hydrate formation in Ulleung basin under conditions of variable salinity: reduced model and experiments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-06-13)In this paper, we present a reduced model of methane hydrate formation in variable salinity conditions, with details on the equilibrium phase behavior adapted to a case study from Ulleung Basin. The model simplifies the comprehensive model considered by Liu and Flemings using common assumptions on hydrostatic pressure, geothermal gradient, and phase incompressibility, as well as a simplified ... -
A new methodology for quantifying bubble flow rates in deep water using splitbeam echosounders: Examples from the Arctic offshore NW-Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-05-08)Quantifying marine methane fluxes of free gas (bubbles) from the seafloor into the water column is of importance for climate related studies, for example, in the Arctic, reliable methodologies are also of interest for studying man-made gas and oil leakage systems at hydrocarbon production sites. Hydroacoustic surveys with singlebeam and nowadays also multibeam systems have been proven to be a ... -
High-temperature fracturing and subsequent grain-size-sensitive creep in lower crustal gabbros: Evidence for coseismic loading followed by creep during decaying stress in the lower crust
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015)The mechanism of shear zone formation in lower crustal, relatively “dry” rocks is still poorly understood. We have studied the high-temperature deformation of the Hasvik gabbro (northern Norway) which commences by fracturing. The 10–20 μm wide fractures show little displacement. The fine-grained plagioclase and orthopyroxene in the fractures lack a crystallographic preferred orientation (CPO) or ... -
Impact of Gas Saturation and Gas Column Height at the Base of the Gas Hydrate Stability Zone on Fracturing and Seepage at Vestnesa Ridge, West-Svalbard Margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-26)The Vestnesa Ridge, located off the west Svalbard margin, is a >60 km long ridge consisting of fine-grained sediments that host a deep-marine gas hydrate and associated seepage system. Geological and geophysical observations indicate the predominance of vertical fluid expulsion through fractures with pockmarks expressed on the seafloor along the entire ridge. However, despite the apparent evidence ... -
Recent acceleration of a rock glacier complex, Ádjet, Norway, documented by 62 years of remote sensing observations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-23)Recent acceleration of rock glaciers is well recognized in the European Alps, but similar behavior is hardly documented elsewhere. Also, the controlling factors are not fully understood. Here we provide evidence for acceleration of a rock glacier complex in northern Norway, from 62 years of remote sensing data. Average annual horizontal velocity measured by aerial feature tracking increased from ... -
Effects of climate change on methane emissions from seafloor sediments in the Arctic Ocean: A review
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-17)Large quantities of methane are stored in hydrates and permafrost within shallow marine sediments in the Arctic Ocean. These reservoirs are highly sensitive to climate warming, but the fate of methane released from sediments is uncertain. Here, we review the principal physical and biogeochemical processes that regulate methane fluxes across the seabed, the fate of this methane in the water column, ... -
Compositions of dissolved organic matter in the ice-covered waters above the Aurora hydrothermal vent system, Gakkel Ridge, Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-20)Hydrothermal vents modify and displace subsurface dissolved organic matter (DOM) into the ocean. Once in the ocean, this DOM is transported together with elements, particles, dissolved gases and biomass along with the neutrally buoyant plume layer. Considering the number and extent of actively venting hydrothermal sites in the oceans, their contribution to the oceanic DOM pool may be substantial. ... -
Automated mapping of glacial overdeepenings beneath contemporary ice sheets: Approaches and potential applications
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-17)Awareness is growing on the significance of overdeepenings in ice sheet systems. However, a complete understanding of overdeepening formation is lacking, meaning observations of overdeepening location and morphometry are urgently required to motivate process understanding. Subject to the development of appropriate mapping approaches, high resolution subglacial topography data sets covering the whole ... -
Chromium evidence for protracted oxygenation during the Paleoproterozoic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-24)It has commonly been proposed that the development of complex life is tied to increases in atmospheric oxygenation. However, there is a conspicuous gap in time between the oxygenation of the atmosphere 2.4 billion years ago (Ga) and the first widely-accepted fossil evidence for complex eukaryotic cells . At present the gap could either represent poor sampling, poor preservation, and/or difficulties ... -
1.80–1.75 Ga granite suites in the west Troms Basement Complex, northern Norway: Palaeoproterozoic magma emplacement during advancing accretionary orogeny, from field observations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-25)The Ersfjord Granite is part of a suite of c.1.80–1.75 Ga syeno-granites in the West Troms Basement Complex, northern Norway, presumed to belong to the Transscandinavian Igneous Belt (TIB-1) in the Fennoscandian Shield. Previous data suggest the granite formed post-collisional and ascended as a batholith pluton from a source generated by delamination of mafic-intermediate lower crust. We argue that ... -
Seal characterization and integrity in uplifted basins: Insights from the northern Barents Shelf
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-16)Seal integrity is a key property for petroleum exploration. This is even more the case in uplifted basins, as exemplified by the northern Barents Shelf. Uplift may lead to fracturing, decompaction, gas expansion and fluid flow. Therefore, it is critical to understand the mechanical behaviour of the Jurassic shale caprocks in the Greater Hoop area, where hydrocarbon accumulations are situated as ... -
Luminescence characteristics of Scandinavian quartz, their connection to bedrock provenance and influence on dating results
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-23)The success of optically stimulated luminescence (OSL) dating relies to a large extent on suitable characteristics of the analysed mineral, in this case quartz. Previous OSL dating of Quaternary sediments in Scandinavia has shown that quartz characteristics vary widely across the region, resulting in dating studies with varied success. The aim of this study is to provide an overview of quartz ... -
Hydrocarbon leakage driven by quaternary glaciations in the Barents Sea based on 2D basin and petroleum system modeling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-25)The Barents Sea has experienced intense erosion throughout the Cenozoic due to uplift and repeated episodes of glaciation. This, in turn, has driven large pressure and temperature fluctuations in the sediment substrate along with rearrangement of thermogenic oil and gas accumulations. As a result, some hydrocarbon fields have relatively shallow depths, and natural gas release is widespread. This ... -
Tracing Lower Cretaceous organic-rich units across the SW Barents Shelf
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-28)On the Barents Shelf, the northernmost and least explored hydrocarbon province of the Norwegian Continental Shelf, Upper Jurassic organic-rich shales have traditionally been given most attention as these represent the most prolific source rock unit of the region. However, in the western frontier areas of the Barents Shelf, the Upper Jurassic is too deeply buried. By combining high-resolution 2D ... -
Tectono-Metamorphic Evolution of the Northern Dom Feliciano Belt Foreland, Santa Catarina, Brazil: Implications for Models of Subduction-Driven Orogenesis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-27)The Dom Feliciano Belt in southern Brazil and Uruguay represents the western half of a Neoproterozoic orogenic belt located in the southern portion of the South Atlantic Neoproterozoic Orogenic System. Current interpretations are divided as to the nature of orogenesis in this belt, in part owing to lacking geochronological constraints. Metamorphosed and deformed supracrustal sequences of the Brusque ... -
Arctic and sub-Arctic lake water δ2H and δ18O along a coastal-inland transect: Implications for interpreting water isotope proxy records
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-04)High-latitude lakes are sensitive to climate change and store information about large-scale circulation changes and catchment-integrated processes. Lakes are mainly recharged by meteoric water, meaning that some lake sediment proxies may indirectly archive the stable isotopic composition of hydrogen (δ<sup>2</sup> H) and oxygen (δ<sup>18</sup>O) of past precipitation. Yet, despite similar ... -
Early and middle Miocene ice sheet dynamics in the Ross Sea: Results from integrated core-log-seismic interpretation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-11)Oscillations in ice sheet extent during early and middle Miocene are intermittently preserved in the sedimentary record from the Antarctic continental shelf, with widespread erosion occurring during major ice sheet advances, and open marine deposition during times of ice sheet retreat. Data from seismic reflection surveys and drill sites from Deep Sea Drilling Project Leg 28 and International Ocean ... -
An updated Weichselian chronostratigraphic framework of the Kongsfjorden Trough Mouth Fan and its implications for the glacial history of Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-02)The Arctic is a climate-sensitive area, responding rapidly to present changes, but for the past changes, the recordis still incomplete. Forinstance, theWeichselian glacial historyof the Svalbard–Barents Sea Ice Sheet (SBIS) haslargely been reconstructed based on studies of the fragmentary Spitsbergen terrestrial and shelf records. However, the sediments removed from the land and shelf areas during ... -
Introduction to the volume, and definition and use of the term ‘tectono-sedimentary element’
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-20)The present volume is rooted in a map of sedimentary successions of the Arctic Region by Grantz et al. (2011), and contains a brief, but comprehensive compilation of geological and geophysical data characterizing all significant sedimentary successions in the Arctic, which cover 57% of the polar area north of 64°N. Two main goals have been designated: (i) to provide, based on the present-day ...
