Browsing Mastergradsoppgaver i geologi by Title
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Browsing Mastergradsoppgaver i geologi by Title
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Sanchez Borque, Jorge (Master thesis; Mastergradsoppgave, May-2009)[+][-]
Abstract: The aim of this master thesis has been to interpret the Late Cenozoic paleo-environments and the sedimentary processes in the Veslemøy High area, southwestern Barents Sea. Six seismic units and eight seismic unconformities, including the seafloor, are identified in the study area and correlated with previous work in the Sørvestnaget Basin. Submarine channels with a downslope (E-W) orientation suggest a glacimarine environment, i.e. the channels are inferred to have been formed by turbidity currents originating from glacial meltwater on the deepest reflector. On shallower reflectors, megascale glacial lineations, ridges and parts of hill-hole pairs indicate that grounded ice reached the paleo-shelf edge at least six times in the last 1.5 Ma. Moreover, two of the shallower seismic units show indications of sediment blocks that are inferred to have been subglacially eroded, transported and deposited by ice streams. The influence of the ice stream flowing from the Bjørnøyrenna in the last 330 ka is evident in the Veslemøy High; however, the origin of the ice streams is unclear on older paleo-surfaces. URI: http://hdl.handle.net/10037/1911 File(s) in this item: 1
thesis.pdf (11.38Mb) -
Baeten, Nicole Jeanne (Master thesis; Mastergradsoppgave, Nov-2007)[+][-]
Abstract: Three sediment cores, swath multibeam bathymetry data and high-resolution seismic data from Billefjorden, Svalbard have been analysed for a better understanding of the Late Weichselian and Holocene glacier activity as well as sedimentary process and glacigenic deposits in the fjord. The data reveal that glacial linear features were generated in the central part of Billefjorden while it was filled with ice draining the Svalbard-Barents Sea ice sheet during the Last Glacial. A till in the bottom of a sediment core from the central part of the fjord is inferred to have been deposited before the ice front retreated into Billefjorden around 11230 cal. years BP. An overlying glacimarine unit deposited between c. 11230 and 11200 cal. years BP indicates that the glacier retreated from central parts of the fjord to the fjord head in approximately 30 years. Annual recessional moraines deposited during this period suggest that the glacier front retreated approximately 330 m/ year at the end of the last Glacial. High concentration of shells, low amounts of IRD and XRD results indicate a Holocene climatic optimum between c. 11200 – 7930 cal. years BP in which Nordenskiöldbreen was most likely much smaller than it is at present. XRD results and comparatively high amounts of IRD point to a complex pattern of ice rafting between c. 7930 and 3230 cal. BP. IRD deposited before c. 5470 cal. years BP was most likely transported by sea ice, whereas IRD after 5470 cal. years points towards a growth of Nordenskiöldbreen. The time after c. 3230 is mainly characterised by suppressed rafting of sea ice and icebergs because of the possible presence of multi-year shorefast sea ice during the Neoglacial maximum. Glacial lineations on a bedrock terrace in the inner fjord were formed during a Neoglacial advance of Nordenskiöldbreen. Iceberg ploughmarks and recessional moraines were most likely generated during the retreat after the maximum Neoglacial extent of Nordenskiöldbreen. Mass-transport activity in Billefjorden probably occurred throughout the entire Holocene. There might haven been an increased mass-transport activity shortly after the deglaciation of the fjord, because high rates of isostatic uplift might have caused seismic activity. Other triggering mechanisms include the development of oversteepened slopes by high sediment supply and the pushing of sediments at the grounding line of the glacier. Pockmarks in the central part of the fjord were most likely generated by the seepage of thermogenic gas along the Billefjorden fault zone. URI: http://hdl.handle.net/10037/1274 File(s) in this item: 1
Thesis.pdf (42.43Mb) -
Bakkejord, Sandra Johansen (Master thesis; Mastergradsoppgave, May-2011)[+][-]
Abstract: Bergartsprøver fra Skagen på Flakstadøy, Lofoten er mikroskopert, analysert ved mikrosonde og gjort geotermobarometriske estimat på, alt for å kunne fortelle om den metamorfe utviklingen for bergartene. Resultatene forteller om en polymorf utviklingshistorie av de proterozoiske bergartene som Flakstadøy er bygd opp av. Flere eklogittforekomster er funnet på øyen, noe som ikke er så overraskende da øya består av over 20 % mafiske intrusjoner i form av gabbro, mangeritt, troktolitt, anortositt og noritt. Skagen området består mer eksakt av koronagabbro, paragneis, dioritt, retrograderte eklogitter og eklogitt. Det er klare bevis for at de retrograderte bergartene har vært eklogitter, da omfasitt er oppdaget i matriks og som poikiloblastisk korn i granat. De geotermobarometriske estimatene forteller om en maksimal eklogittfaciesparagenese ved metamorfe forhold på 25 ± 3,2 kbar og 660 ± 85 °C og et minimumforhold på ca. 14,5 ± 0,5 kbar 645 °C. Disse forholdene er tolket til å være gitt ved maksimal skorpetykkelse (skorpedybde på ca. 60 km) under subduksjonen for 480-430 Ma år siden, som er starten på dannelsen av kaledonidene. Ved et tidligere stadie og ved en laver skorpedybde ble de første granatene dannet i en koronatekstur. Granatkoronaer opptrer omkring olivin og ortopyroksen, samt plagioklas. Geotermobarometriske estimat gir et trykk på 18 ± 2,2 kbar og temperatur på 680 ± 100 °C for startdannelsen av koronateksturene. Eklogittforekomstene opptrer hovedsaklig i mafiske linser, duktile skjærsoner og i Al-rik protolitt. En retrogresjon etter eklogittfacies til høy amfibolittfacies er datert til 469-461 Ma (Corfu, 2004, 2007). Nedbrytning av omfasitt til symplektitt av diopsidisk klinopyroksen og feltspat er gitt et geotermobarometrisk estimat på 8 ± 0,5 kbar og 550 ± 100 °C. De fleste eklogittforekomstene er retrograderte eklogitter. URI: http://hdl.handle.net/10037/3425 File(s) in this item: 1
thesis.pdf (5.342Mb) -
Rustad, Birgit Katrine (Master thesis; Mastergradsoppgave, 22-Nov-2010)[+][-]
Abstract: The Seiland Igneous Province (SIP) is situated in western Finnmark, Northern Norway. The SIP comprises a suite of mainly gabbroic plutons, with ultramafic, syenitic and felsic intrusions. The origin of the region has been interpreted in different ways and several tectonic models have been proposed. Many different ideas have been suggested about the metamorphic, magmatic and deformation history. New age dates by Roberts (2008) fall within a narrow time range, from 555 Ma to 579 Ma, concluding that the main magmatism took place within ten million years. This is a much shorter period than previously estimated, and the deformation and metamorphic history of the province is therefore reconsidered. In order to better understand the metamorphic and deformation history of the SIP, studies on microstructures, deformation and metamorphism have been carried out in this thesis on a gabbroic pluton and a strongly sheared quartz-feldspathic xenolith of the Seiland Igneous province situated between Langfjord and Øksfjord. Observations from the field and thin sections indicate that the metamorphic and deformational history of these two rocks can be divided into the following stages: contact metamorphism of the country rock caused by the emplacement of the plutonic gabbro (stage I) with subsequent cooling (stage II) and following loading probably as a result of nappe emplacement during the Caledonian orogeny (stage III). Microstructures and metamorphic reactions observed in the rocks support pressure and- temperature estimates given by Elvevold et al. (1994). Both rock types show evidence of a cooling and subsequent solid state deformation. The cooling stage was followed by a higher-pressure metamorphism interpreted to be related to emplacement of a tectonic unit of cold thrust sheet over hot rock during the Caledonian orogeny. The nappe emplacement resulted in the formation of thin mylonitic zones recognized by a strong grain size reduction and a replacement of a pyroxene granulite assemblage to a garnet granulite assemblage. The foliation seen in the Suborg-gabbro and the quartz-feldspathic gneiss is suggested to be a result of extension associated with continental rifting. The emplacement of the Suborg-gabbro is believed to have taken place during regional deformation. The foliation in the Suborg-gabbro shows evidence of magmatic flow overprinted by a solid state flow. Kinematic indictors observed in the quartz-feldspathic xenolith indicate normal faulting supporting extension and a rifting model for the SIP. Keywords: Seiland Igneous Province, metamorphism, deformation, extension. URI: http://hdl.handle.net/10037/2897 File(s) in this item: 1
thesis.pdf (12.40Mb) -
Greig, David (Master thesis; Mastergradsoppgave, 28-Jan-2011)[+][-]
Abstract: The northern Lyngen Peninsula in Troms, northern Norway, displays a suite of glacial and periglacial landforms that describe both a complex interaction of geomorphological processes and its history of deglaciation during the Late Weichselian and Holocene. These features include: cirque and valley glacier moraines, relict ice-cored moraines, rock avalanches, rock glaciers, a protalus rampart, and other talus-derived landforms. Morphological relationships of landforms within the three valleys of Strupskardet, Veidalen and Reindalen were studied in detail; using a combination of geographic information systems (GIS), aerial photograph interpretation, and field research. Seven distinctive glacial stages (comprised of up to 13 minor phases) were identified, and presented as a series of maps that describe the chronology of deglaciation within the study area. Relative-age dating of moraines was performed with a Schmidt hammer, which measured the rebound value (R-value) from boulder surfaces. This technique was found to be an effective tool that offered additional insight into the age of moraines and other landforms. Equilibrium line altitudes (ELA) were also calculated for reconstructed ice limits to elucidate the effects of local topography and regional climatic conditions on glacier formation. URI: http://hdl.handle.net/10037/2960 File(s) in this item: 1
thesis.pdf (9.960Mb) -
Namyatova, Daria Alekseevna (Master thesis; Mastergradsoppgave, 16-May-2011)[+][-]
Abstract: ABSTRACT Three 3D seismic cubes (EL0001, St0309 and ST05M09) from different parts of the SW Barents Sea basin were studied to decipher processes causing depressions in the seabed and subseabed. Since the investigated areas were under the influence of various depositional and erosional conditions during ice ages special attention was given to the potential of ice driven morphologies. Depressions identified at the seafloor and at the upper regional unconformity (URU) sub surface vary in shape, size and depth. Their distribution is governed by large scale glacial morphology and deeper fluid accumulation and migration pathways as inferred from seismic anomalies. The formation of fluid flow related depressions could be a result or a combination of both external (glacial erosion and accumulation) and internal factors (gas expansion). Evidence for fluid flow exists in deeper layers and thus fluids could migrate upward along faults and porous sediment strata and spread laterally in upper sediment layers. A second class of depressions exists that is mainly related to glacier driven surface processes in for example subglacial melt-water channels without any obvious relation to deeper fluid sources. Generally, glacial morphological elements influence sediment facies distributions, the thickness of the deposits and therefore the location and frequency of pockmarks and/or pockmark fields. The pockmarks tend to occur inside iceberg-plough marks, mega scale glacial liniations (MSGL), all regions with reduced sediment thickness through which fluids may penetrate more easily. The timing of pockmark creation varies depending on fluid source areas, the thickness of the glacial sediment blanket and ice sheet retreat. URI: http://hdl.handle.net/10037/3406 File(s) in this item: 1
thesis.pdf (16.15Mb) -
Pless, Gustav (Master thesis; Mastergradsoppgave, 15-May-2009)[+][-]
Abstract: 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 faults. Cretaceous to Miocene sediments that consists of deep marine shales dominate in the older part and Plio-Pleistocene successions deposited by glaciomarine processes dominate in the upper part. Fluid accumulations are identified in L. Paleocene to E. Eocene sediments, and in Pliocene to Pleistocene sediments of glacial origin. An extensive high-seismic amplitude anomaly of 790 km2 appears to occur in a fan system within the eastern section of the 3D survey extending into Tromsø Basin. High and negative seismic amplitudes indicate appreciable gas accumulations within the fan. On the seafloor the existence of pockmarks suggest that pockmark formation most likely occurred after the ice-sheet retreat and thus between 15 ka and 12.5-11.5 ka. Pockmarks may represent fluid flow events from violent eruptions associated with deglaciation processes. Some evidence exists that gas may have been generated in deeper basins. Fluids migrated into Veslemøy High primarily along Plio-Pleistocene strata from Sørvestsnaget Basin in the west and along Creataceous-Paleogene strata from Tromsø Basin in the east. As the fluids reach the apex of Veslemøy High vertical migration through giant chimneys and along normal faults dominate. It is important to note that there is no geophysical evidence for fluid migration from Cretaceous sediments that lie directly below the high. URI: http://hdl.handle.net/10037/1910 File(s) in this item: 1
thesis.pdf (9.943Mb) -
Øiesvold, Marte Beate (Master thesis; Mastergradsoppgave, May-2007)[+][-]
Abstract: 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 tilnærmet udeformert kjerne, og graden av deformasjon og hydrering tiltar mot marginene mot de omgivende sterkt folierte skifere og marmorer. Den mafiske linsa har også en gjennomskjærende felsisk gang som er deformert. Lokaliteten er derfor godt egnet til å se på den gradvise endringen fra massiv og retrogradert eklogitt (høytrykksgranulitt) via ulike retrograderingsstadier til sterkt foliert og rekrystallisert amfibolitt. Datering av den gjennomskjærende felsiske gangen vil kunne gi informasjon om når retrograderingen skjedde. Tromsødekket utgjør den øverste delen av øverste allokton i de Skandinaviske kaledonidene. Under Tromsødekket ligger Skattøra migmatittkompleks, som tilhører Nakkedal dekkekompleks, disse er tektonisk separert av en stor skyveforkastning. Resultatene er basert på dateringer og metamorf utvikling. Proterozoiske aldre på henholdsvis 1105,0 ± 8,6 (Grenvillisk/Svekonorvegisk alder) og 1513,6 ± 3,1 Ma er antatt å representere provenansalder for metasedimentene, og de kan ha blitt termalt påvirket samtidig som intrusjon av den magmatiske gangen/sillen rundt 493 Ma. Avsetningsalderen på sedimentene må da være i tidsrommet 1000-500 Ma. Opptreden av rekrystalliserte symplektitter og stedvis høyt Si-innhold i phengitt tyder på at de mafiske bergartene sannsynligvis har vært eklogitter. De mafiske bergartene viser en overpreging av amfibolittfacies. Det antas at den felsiske gangen er dannet ved oppsmelting av de omliggende metapelittene. Gangen kan ha blitt inturdert under amfibolittfacies metamorfosen ved 447,7 ± 0,5 Ma eller muligens rundt 460 Ma. Granatene i de mafiske bergartene har en prograd vekstsonering og har vokst under økende trykk og temperatur. P-T estimatene viser at både amfibolittfacies metamorfosen og den partielle oppsmeltingen i den mafiske linsa er dannet under samme P-T forhold på 1,15 ± 0,11 GPa og 690 ± 40 °C. Metapelittene viser P-T estimat på 1,15 ± 0,15 GPa ved 710 ± 30 °C og ned til 610 ± 30 °C ved samme trykk (1,1 ± 0,15 GPa). Dette kan tolkes som at den kjemiske ekvilibreringen i noen prøver fortsatte ettersom temperaturen avtok etter at de kjemiske systemene hadde ”frosset” i de andre bergartene. URI: http://hdl.handle.net/10037/1140 File(s) in this item: 1
Thesis.pdf (6.694Mb) -
Priyatkina, Nadezda (Master thesis; Mastergradsoppgave, 31-Jan-2013)[+][-]
Abstract: The studied mafic-ultramafic rock association occurs within Archean tonalitic gneisses and metasupracrustal suites of the Astridal belt belonging to the West Troms Basement Complex in the northwestern part of the Senja Island. The rock association appears in lens-shaped bodies, up to 200 m long, which are oriented conformal to the major metamorphic fabric of the host rock. The rock association is made up by interlayered units of green spinel-bearing olivine orthopyroxene-hornblendite, hornblende peridotite, olivine hornblendite, hornblendite and amphibolite (metagabbroic rock). Microscope studies and whole rock geochemical data indicate that the ultramafic rocks represent a single magmatic series of mafic and ultramafic olivine-amphibole cumulates, which have been significantly affected by metamorphism. Igneous mineral and whole rock trace element data indicate MORB affinity of the cumulates and suggest their emplacement in oceanic rift or rifted continental margin setting. The studied cumulates may represent a crustal remnant of the Paleoproterozic Svecofennian ocean. The rocks were metamorphosed together with the supracrustal suites of the Astridal belt during the major Svecofennian event about 1.74 Ga ago as indicated by a U-Pb age of metamorphic zircons from the metagabbroic rock belonging to the studied suite. URI: http://hdl.handle.net/10037/4843 File(s) in this item: 1
thesis.pdf (13.80Mb) -
Gjerløw, Eirik (Master thesis; Mastergradsoppgave, 15-Nov-2008)[+][-]
Abstract: Formålet med denne oppgaven er å gjøre petrologiske og petrografiske undersøkelser av en mafisk linse på Sandøya i vest-Troms for å rekonstruere metamorfe trykk og temperaturforhold, samt å gjøre dateringer for å utrede alderen på metamorfosen(e). Linsa ligge blottlagt ved havet ved Mjølvika på Sandøya. Kjernen er tilnærmet udeformert og består av en en massiv granatførende bergart med en grønn grunnmasse. Graden av deformasjon og hydrering tiltar mot marginene mot de båndede gneisene som omgir linsa. Den mafiske linsa er også kuttet av en liten felsisk gang, dateringer av denne gangen vil kunne gi minimumsalder på den mafiske linsa. Resultatene er basert på dateringer og metamorf utvikling Aldre på 1776,6 ± 1,1 Ma, 1774,4 ± 1,7, 1777 ± 12 Ma tolkes til å representere granulittfacies metamorfose og intrusjon av den kuttende felsiske gangen og det antaes at denne gangen er dannet ved partiell oppsmelting av omkringliggende bergarter. Ut fra strukturer og mineralkjemiske analyser tolkes det til at det er minst 5 forskjellige faser av metamorfose: Stadium 1 er høytrykks granulittfacies med trykk og temperaturforhold på 715-922 ºC og 1,1-1,43 Gpa. Stadium 2 er granulittfacies med trykk og temperaturverdier på 710-715 ºC og 0,51-0,92 GPa. Stadium 3 er grønnskiferfacies. Stadium 4 er amfibolittfacies med trykk og temperaturverdier på 595-660 ºC og 0,17-0,62 Gpa. Stadium 5 er grønnskiferfacies. URI: http://hdl.handle.net/10037/1657 File(s) in this item: 1
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Janocko, Michal (Master thesis; Mastergradsoppgave, 22-Feb-2008)[+][-]
Abstract: The pinch-out geometry of large sandbodies, such as fluvial or turbiditic palaeochannel margins and deltaic sand wedges, is of a crucial importance to the evaluation of many stratigraphic hydrocarbon traps and can generally be recognized in extensive outcrops or high-resolution seismic sections. Far more difficult to recognize and model are the digitate, feather-edge pinchouts of successions composed of sheet-like sandstone beds, such as turbidite lobes or shore-derived mid-shelf tempestites, where the individual beds may peter out at highly varied basinward distances. Both turbidites and tempestites are expected to pinch out seawards, but their actual thinning rates and pinchout geometries are little-known and unpredictable. Can the lateral variation of sheet-like bed characteristics be empirically defined? In the present pilot study, more than 3750 closely-spaced (2-10 m lateral spacing) measurements of the lateral thickness changes in 146 turbidite and tempestite beds have been collected over lateral outcrop distances of up to 640 m. Turbidites have been measured in the Miocene Marnoso Arenacea Formation of the Northern Apennines, Italy, and the Late Cretaceous Akveren Formation of the Central Pontides, north-central Turkey, with supplementary smaller datasets from the Eocene Kusuri Formation of the Central Pontides and the Miocene Monte Fumaiolo Formation of the Northern Apennines. Tempestites have been measured in the late Miocene Karpuzçay Formation in the Manavgat Basin of Central Taurides, south-western Turkey. The spatial direction of bed thinning relative to the palaeocurrent direction has been taken into account. The datasets show that both turbidites and tempestites have a log-normal thickness frequency distribution, a trend that has been also commonly reported from bed-to-bed thickness measurements of vertical successions. In terms of an exceedence frequency plot with logarithmic scales, the log-normal distribution can be approximated by straight-line segments, which means that the bed thicknesses are self-similar (fractal) within their particular ranges. The statistical method of least-square regression has been used to identify lateral bed-thinning trends, which appear to be consistent for each genetic category of beds, but dependent upon the bed thickness range – as the downflow bed thinning rate apparently changes significantly with the bed thickness. Assuming the bed segments measured in outcrop sections represent downflow-thinning segments of unconfined (non-ponded) basin-plain turbidites and shelf tempestites, their thinning rates can be stacked together according to the local bed-thickness ranges to represent the pinchout geometry of a whole single bed. The stacking of local trends into a laterally continuous bulk trend seems to be justified by the fact that the thinner bed segments are finer-grained and composed of proportionally thinner divisions. The synthetic bulk trend appears to be a concave-upward function that flattens exponentially in the downflow direction. The range-related trend equations allow the pinchout distance of every bed in a turbiditic or tempesitic succession encountered in a well to be predicted and the net spatial pinch-out of a given bed succession to be modelled. However, the trend equations are considered to be tentative, as they require veritication on a wider database. In addition, the statistical analysis revealed occurrence of bed-top undulations in both turbidites and tempestites, which are subtle to gentle and are visually unrecognizable in outcrop sections. Fourier analysis indicates statistically significant, cyclic waveform components in these undulations, with wavelengths of up to 300 m and amplitudes from a few centimetres to 60 cm. The tops of thinner beds have less pronounced and more irregular subtle undulations. The origin of the bed-top undulations is unknown, but there are several wave-like hydrualic phenomena, such as internal waves, to which they may possibly owe their formation. URI: http://hdl.handle.net/10037/1356 File(s) in this item: 2
Janocko_Errata.pdf (126.6Kb)thesis.pdf (26.89Mb) -
Knutsen, Marianne Leinan (Master thesis; Mastergradsoppgave, Jun-2012)[+][-]
Abstract: The Skattøra migmatite complex (SMC) in the north Norwegian Caledonides is a slightly nepheline normative migmatitic meta-cumulate rock sequence, which experienced anatexis under water saturated conditions. In situ- and local crystallization of melt is reflected by leucosomes and the numerous anorthositic dykes net veining the rock complex. Studies of quartz-free rocks gives challenges for implying P-T conditions by traditional geothermobarometric methods. Phase transitions during metamorphism, partial melting metasomatism in the SMC has been studied through optical petrography and bulk chemistry, and pseudosection-modelling has been the main tool for investigating phase topologies and quantifying P-T conditions during evolution of the SMC. Minimum limit for metamorphic peak conditions in the anorthositic part of the complex is suggested to be approximately 1.18 GPa in the temperature interval 800-850 ⁰C. In more complex chemical systems onset of melting occurred at lower temperatures. In the context of the tectonometamorphic evolution of the Upper Most Allochthon results for high grade metamorphism are supportive of earlier work, while for the late retrogressive stage additional suggestions are presented. The discovery of cross-cutting dolerite dykes in the SMC adds a new feature that should be addressed in future studies. URI: http://hdl.handle.net/10037/4234 File(s) in this item: 1
thesis.pdf (16.28Mb) -
Damberg, Ane Johansen (Master thesis; Mastergradsoppgave, May-2012)[+][-]
Abstract: Den øverste alloktone enheten av de kaledonske skyvedekkene i Troms blir kalt Tromsødekket. I Tromsødekket opptrer det tallrike større og mindre kropper som består av bergarten eklogitt, og mafiske og ultramafiske bergarter, sammen med og i skifer, gneis og marmor. Tidligere arbeider har gitt indikasjoner på at de eklogittiske og ultramafiske bergartene har vært på svært store dyp (~100-120 km) med trykk på ~3.0 GPa til ~3.5 GPa og temperaturer på ~750°C. Radiometriske dateringer har vist at dette skjedde for omkring 450-455 millioner år siden. Bergartene befant seg da på bunnen av en fjellkjede som var i ferd med å dannes, og som utviklet seg over tid til det vi kaller den Kaledonske fjellkjeden. I denne oppgaven har hovedfokus vært på å utrede hvilke prosesser disse bergartene har gjennomgått fra denne hendelsen og fram til kontinentene kolliderte for 425-400 millioner år siden. URI: http://hdl.handle.net/10037/4235 File(s) in this item: 1
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Skirbekk, Kari (Master thesis; Mastergradsoppgave, 15-Nov-2007)[+][-]
Abstract: Sedimentkjerne NP05-11-21GC fra Kongsfjordrenna vest for Spitsbergen er analysert for å kartlegge utviklingen av paleomiljø de siste ~11 800 år. Analysene er basert på undersøkelser av bentiske foraminiferer og sedimentologiske egenskaper. Kjernen er 5,15 meter lang og 104 prøver er analysert med hensyn på fauna, droppstein og kornfordeling. Sedimentenes fysiske egenskaper er målt ved hjelp av en Multi-Sensor Core Logger, og røntgenbilder er studert. Kjernens kronologi er basert på 10 radiokarbondateringer, og viser at sedimentasjonsraten varierer mellom 27 og 158 cm/tusen år. Sokkelområdet vest for Spitsbergen har vist seg å være sensitiv for endringer i Vest Spitsbergenstrømmens intensitet. Sedimentene i kjerne NP0511-21GC er avsatt i et distalt glasimarint miljø, med en varierende påvirkning fra atlantiske vannmasser og is. Et kaldt og sjøispåvirket miljø i yngre dryas etterfølges av en tostegs bedring av klima i tidlig holosen. Klimabedringen avbrytes av en nedkjøling under den preboreale svingning 11 300 kalenderår før nåtid, hvor kalde lavsaline vannmasser dominerer, og sjøisdekke hindrer avsetning av droppstein over lokaliteten. En gradvis bedring av klima gjennom tidlig holosen kulminerer i et klimatisk optimum om lag 9000 kalenderår før nåtid. En gradvis nedkjøling observeres gjennom midt-holosen overgangsperiode. Høy påvirkning fra isbreer registreres etter 4000 kalenderår i før nåtid, i sen holosen, hvor mye droppstein avsettes på lokaliteten. De generelle trekkene i klimautviklingen er i overensstemmelse med andre proksidata fra Svalbards margin og de Nordiske hav. Innstrømmingen av atlantisk vann i Kongsfjordrenna følger i stor grad endringer i Vest Spitsbergenstrømmen. URI: http://hdl.handle.net/10037/1272 File(s) in this item: 1
thesis.pdf (8.150Mb) -
Deryabin, Alexey (Master thesis; Mastergradsoppgave, 05-Jun-2012)[+][-]
Abstract: This Master thesis investigates the relationship between glacial erosion, glaciotectonically displaced sediment blocks and indications of fluid flow and shallow gas accumulations in buried glacial sediments of the south-western Barents Sea margin. The thesis is based on two three-dimensional (3D) seismic datasets, NH98003 and EL0001, the two-dimensional (2D) seismic survey NH9702 and exploration well 7216/11-1. 3D seismic techniques have allowed mapping and visualizing of buried geomorphological features in great details within the study area. Large semi-circular depressions and fluid migration pathways are imaged, as well as glacigenic sediment blocks and rafts. A glacigenic origin is inferred for the megablocks and rafts indicating high glaciotectonic activity of the former ice streams. Six large-scale depressions are inferred to be sources for the removal of sediment mega-blocks and rafts at one particular stratigraphic level of the Plio-Pleistocene succession. Mapped fluid migration pathways and shallow gas accumulations show evidence of an active fluid migration system, and its spatial relationship with the erosional depressions is documented. Modeling of the gas hydrate stability zone has been performed for glacial and interglacial conditions and its effect on the sediment properties is discussed. A conceptual model is proposed for the formation of the depressions, where brittle glaciotectonic deformation along a weak layer at the base of gas-hydrate cementing sediments is inferred. Subsequent expulsion of gas-rich fluids is assumed to have followed deglaciation which might further have reworked the depressions. URI: http://hdl.handle.net/10037/4216 File(s) in this item: 1
thesis.pdf (19.35Mb) -
Trulssen, Mads Fremming (Master thesis; Mastergradsoppgave, 04-Dec-2008)[+][-]
Abstract: Lofoten utgjør en opphevet horst i forhold til omkringliggende bassenger og består hovedsakelig av prekambrisk grunnfjell. Tidligere modeller viser at landområdene og sokkelområdene utenfor Lofoten ser ut til å ha hatt en lik ekstensjonshistorie med flere faser av forkastningsbevegelser, innsynkning og oppheving gjennom mesozoikum og kenozoikum. Steile strukturer i berggrunnen danner svakhetssoner der særlig glasial erosjon med botnerosjon har medvirket til dannelsen av det typisk alpine landskapet. Studier av flybilder og bruddplan indikerer både regionale og lokale variasjoner, men har påvist fire dominerende populasjoner av bruddsett; NNØ-SSV, NØ-SV til ØNØ-VSV, VNV-ØSØ og NNV-SSØ. På bakgrunn av ulike kart fremstilt i ArcGIS er det gjort en analyse av orienterte formelemener. Ulike grupper av landformelementer har liknende orientering og kan hovedsakelig korreleres med strukturelementene og deres populasjoner. Forskjeller i landskapet mellom tre provinser ser også til en viss grad ut til å være knyttet til forskjeller i berggrunnens struktur. En modell over roterte forkastningsblokker er fremstilt basert på helning til trendlinjer og kartlagte segmenter av en paleisk overflate. Det antas at de tolkede paleiske overflatene og trendlinjene gjenspeiler eller har vært styrt av en tidligere overflate (av mulig mesozoisk alder), som opprinnelig var tilnærmet horisontal, eller hadde et svakt bølgende landskap. Noen overflater tolkes til å være rotert mot ØSØ, SSØ og SSV, altså vinkelrett på de nevnte populasjonene og gruppene, i episoder fra perm til paleogen. URI: http://hdl.handle.net/10037/1674 File(s) in this item: 1
thesis.pdf (12.42Mb) -
Waage, Malin (Master thesis; Mastergradsoppgave, 15-Nov-2012)[+][-]
Abstract: I study a sand-wave field in ~600 meters water depth on the continental slope offshore Northern Norway. Using multibeam bathymetry data from 2008 and 2011 and P-Cable high-resolution 3D seismic data from 2011, I characterize the field. Sand waves reach up to 6.6 m in height and have wavelengths as large as 140 m. They are mostly asymmetric in shape with the steepest side dipping to the northwest, indicating that current flow over the field is predominantly to the northwest. Larger sand waves (>2 m in height, >100 m wavelength) are observed on topographic highs in the sand-wave field, whereas smaller sand waves (<2 m in height, <100 m wavelength) are present in topographic lows. These topographic lows occur where three ~1-2-km-wide channels cut down the continental slope through the sand-wave field. Seismic data reveal that there are no buried sand waves beneath the seafloor, suggesting that the sand waves are being continually eroded and redeposit at the seabed. Seismic data reveal that the depositional environment over the last ~1 Ma has been largely controlled by debris flows during the glaciations and melt-water plumes and channel formation during the glaciations. High-resolution imaging of the first few meters below the seabed shows that winnowing and associated sand-wave migration is currently the dominant sedimentary process. Data across the study area show that there are no buried sand waves beneath the seafloor. This suggests that the sand waves are being continually eroded and redeposited at the seabed. By measuring the offset of the crest of sand waves in the 2008 and 2011 bathymetry data, I calculate that sand waves migrate from 0 to 3.3 m/yr and have an average migration rate of 1.6 m/yr to the northwest. This migration direction which I directly observe in the bathymetry data is in agreement with the migration direction that I infer from the asymmetry of the sand waves. Integrating these migration rates over the cross section of the sand-wave field, I estimate that sand is transported along the continental slope at a rate of 22.3-118x106 m3/yr. These results provide hard constraints for numerical sand-wave migration models trying to identify the link between ocean currents and sand-wave migration. Furthermore, I show that sand-wave migration has the potential to rapidly move large volumes of sand across the deep water. This movement of sand can complicate drilling and production procedures in the energy industry and may affect slope stability on continental margins around the world. URI: http://hdl.handle.net/10037/4668 File(s) in this item: 2
Errata_MW.pdf (429.4Kb)thesis.pdf (13.12Mb) -
Kempf, Philipp (Master thesis; Mastergradsoppgave, May-2011)[+][-]
Abstract: Swath bathymetry, high resolution seismic and core data are analysed to describe the Late Weichselian and Holocene sedimentary processes and palaeoenvironment in Van Keulenfjorden, Spitsbergen. Bottom currents, the bathymetry of the fjord and the distance from sediment sources are the controlling factors for the sediment distribution as indicated by isopach maps. Sandur deltas at the mouth of tributary valleys cause repeated mass-transport along the slopes. Rapid postglacial isostatic uplift reactivated faults of the West Spitsbergen fold and thrust belt, which acted as pathways for thermogenic gas creating pockmarks. The results from this study confirm previous indications that an ice stream drained the Late Weichselian Barents Sea Ice Sheet through Van Keulenfjorden. The deglaciation of the fjord began ~11.2 cal. ka BP with a retreat rate of ~160 m a-1. A hiatus between 10.7 cal. ka BP and 7.0 cal. ka BP in the outer part of the fjord was most likely caused by bottom currents. Following a warm period between 10.7 cal. ka BP and min. 7.0 cal. ka BP increasing IRD content indicates slow but steady cooling. Glacial activity in the Holocene peaked at 2.8 cal. ka BP, resulting in the deposition of morainal banks. Adjacent to these morainal banks two debris flow lobes were deposited. They are interpreted to be the product of two consecutive surges. This contradicts the conclusions of previous investigations, where the upper lobe is interpreted to be from the Little Ice Age. Since 2.8 cal. ka BP the glacial activity was relatively constant. The terminal position of the Nathorstbreen from 2.8 cal. ka BP was reached in the late 19th century. While the work of this study was conducted Nathorstbreen surged and almost reached the front position from 2.8 cal. ka BP again. URI: http://hdl.handle.net/10037/3422 File(s) in this item: 1
thesis.pdf (12.53Mb) -
Evison, Kenneth André (Master thesis; Mastergradsoppgave, 04-Jun-2012)[+][-]
Abstract: Den nedre delen av Breivikeidet er dominert av postglasiale grunnmarine sedimenter. Den glacio-isostatiske hevning av landmassen har gradvis senket erosjonsbasis og ført til blottleggelse av eldre sedimentene der elvene har skåret seg ned i disse. Den nederste delen av de undersøkte avsettingene er tolket som bottomsets med en rik skeletal fauna dominert av muslinger mens snegler og rester av rur og kråkeboller er mindre vanlig. I øverste del av bottomsetlagene samt i nedre og midtre del av foresetlagene er det påvist konkresjoner. Ved petrografiske undersøkelser er det påvist at konkresjonene inneholder både menisk- og hengende sement som viser at karbonatsementeringen har skjedd i den vadose sonen. I tillegg har katodeluminsensmikroskopi av karbonatsementen også vist at denne er ikke lumineserende, og dette er også evidens for utfelling i et oksyderende porevannsmiljø som er typisk for overflatenært meteroisk porevann. Mange av konkresjonene har en avlang form der den lengste aksen står omtrent vinkelrett på dagens elvebredde, og dette tyder på at retningen på grunnvannsgjennomnstrømningen har vært av betydning for den geometriske utforming av disse konkresjonene. URI: http://hdl.handle.net/10037/4202 File(s) in this item: 1
thesis.pdf (12.39Mb) -
Krogh, Hilde (Master thesis; Mastergradsoppgave, 11-Jun-2010)[+][-]
Abstract: Sedimentologiske og stratigrafiske data er innsamlet fra et lakustrint deltakompleks på Tolokonka i NV-Russland. De innsamlede data fra et 4,2 km langt og 30 m høyt elvesnitt har bidratt til en bedre forståelse av glasiasjonshistorien og bredemte sjøer i NV-Russland gjennom weichsel. Basert på sedimentologiske og stratigrafiske data består faciesfordelingen av sandige facies, vekslinger av kryssjiktet sand, heterolittisks sand og en diamikton. Facies er fordelt innenfor enhetene: A,B,C,D1,D2, E, F og G. Enhetene danner grunnlaget for et utviklingsmiljø fra fluvialt til deltaisk som gradvis endres til et glasilakustrint basseng og til slutt et glasialt miljø. Stratigrafiske grenser har dannet grunnlaget for en miljøtolkning av Tolokonka gjennom weichsel. Ut fra tidligere arbeid er det postulert at en bredemt sjø ble demmet opp i Hvitehavsbassenget av Barents- og Karahavisdekket (ca 70-65 ka BP) i weichsel. Glasilakustrine sedimenter på Tolokonka er i denne oppgaven beskrevet og tolket til å være avsetninger fra denne postulerte bredemte Hvitehavsinnsjøen. URI: http://hdl.handle.net/10037/2495 File(s) in this item: 1
thesis.pdf (5.617Mb)
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