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Browsing Institutt for geologi by Issue Date
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Vanneste, Maarten; Mienert, Jurgen; Bünz, Stefan; Haflidason, H (Journal article; Tidsskriftartikkel; Peer reviewed, 2010)[+][-]
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Rydningen, Tom Arne (Master thesis; Mastergradsoppgave, 19-Apr-2010)[+][-]
Abstract: Batymetriske og seismiske data er analysert for å utrede den senkenozoiske utviklingen av kontinentalmarginen utenfor Troms. Prograderende kiler av glasigene avsetninger er identifisert nær munningen av de glasiale trauene Andfjorden og Malangsdjupet. En seismisk stratigrafi med to hovedenheter, S1 og S2, er definert. Enhet S2 viser hovedsakelig et prograderende mønster mot nordvest, mens S2 er aggraderende på kontinentalhylla og prograderende på skråninga. En utviklingsmodell for studieområdet er utledet, der en tidlig (glasi-)fluvial fase er etterfulgt av en fase karakterisert av større isdekker som nådde ut til eggakanten gjentatte ganger. Landformer på havbunnen er beskrevet og genesen til disse er tolket. Tre grupper av landformer er identifisert: subglasiale formelementer, formelementer dannet ved breranden, og post-glasiale formelementer. Under siste glasiale maksimum beveget isstrømmer seg i trauene, mens bankene var okkupert av en mer passiv is. Deglasiasjonen av studieområdet var trolig hurtig i trauene, da megaskala glasiale lineasjoner er godt bevart på havbunnen. Lineasjonene er overlagret av avsetninger som viser noen stopp eller mindre fremrykk under tilbaketrekningen. Forekomsten av en serie frontavsetninger på banken tyder på at tilbaketrekningen var langsommere her. Etter at området var deglasiert har havstrømmer og vertikal migrasjon av fluider modifisert havbunnen. URI: http://hdl.handle.net/10037/3789 File(s) in this item: 2
Errata-tar.pdf (13.54Kb)thesis.pdf (24.87Mb) -
Kovacova, Tanya (Master thesis; Mastergradsoppgave, May-2010)[+][-]
Abstract: During previous studies of the Upper-Palaeozoic carbonate build-ups at the Loppa High in SW Barents Sea, a connection between locations of the build-ups and syn-depositional faults was observed. This thesis is studying this relationship in detail, applying the Ant-tracking semi-automated method for detection of faults. To my knowledge, this relatively new method has not been used in the Barents Sea area before. The Ant-tracking is a patent protected technology developed by Schlumberger Stavanger Research for PetrelTM software for automatic detection of faults and fractures from three dimensional seismic data. In this thesis, two 3D seismic surveys were used, the SG9810 survey and the high resolution NH0372 site survey. In both of these surveys faults and fractures were revealed. These were further analyzed and also visualized in three dimensions. The connection between the positions of the Upper-Palaeozoic carbonate build-ups and the positions of faults and fractures was confirmed. Furthermore, all the detected build-ups were associated with one or two faults or fractures. URI: http://hdl.handle.net/10037/2494 File(s) in this item: 1
thesis.pdf (31.30Mb) -
Eilertsen, Håkon Andre (Master thesis; Mastergradsoppgave, 15-May-2010)[+][-]
Abstract: The Nyegga study area of the thesis is located at the north-eastern escarpment of the Holocene giant Storegga Slide. It lies on the southern part of the Vøring plateau on the mid-Norwegian continental margin at approximately 700-1000m water depth. The area has been known to be prone for submarine sliding and is therefore an excellent location for studying morphological features to infer slide mechanisms and development. A major effect of submarine slides is seen on the seafloor of the Nyegga area, as the Storegga Slide sidewall marks a clear transition from undisturbed marine sediments to the disrupted, chaotic morphology in the slide scar. Two other slides termed the T and U slides have been discovered in the study area. All three slides lie within the Plio-Pleistocene Naust Formation; both the T and U slides are likely of middle Pleistocene age, at 200 and 400 Ka respectively. The three slides have been investigated using 3D seismic data provided by Statoil (ST0408 cube). It allowed mapping the top and bottoming horizons of the slides and utilizing a volumetric approach for visualization and interpretation of the sliding processes and directions. The identified kinematic indicators, which include slide blocks, ridges and head-/sidewalls, suggest a similar north-south direction of material transport for all three slides. For the Storegga Slide it refers to the post-sliding after the major east-west directed slide event at 8180 cal years BP. 27 depression, fault-like features interpreted to be crown cracks distributed amongst the slides were identified and their extension quantified. The presence of crown cracks and other morphological features suggest retrogressive slide developments though alternatives are possible. Failure within the study area was initiated because of a retrogression of slide material that occurred down-slope where excess pore pressure may have decreased along layers that provided zones of weakness. A number of glide planes have been observed for each slide, all of them occurring in marine deposits representing zones of weakness. Today’s areas of spreading and crown cracks at Nyegga may be a geohazard and a risk for nearby pipelines and installations on the seabed. URI: http://hdl.handle.net/10037/2493 File(s) in this item: 1
thesis.pdf (7.832Mb) -
Johansen, Runar (Master thesis; Mastergradsoppgave, 18-May-2010)[+][-]
Abstract: To 3D-seismiske datasett fra den sørvestlige delen av Vøringmarginen på midtnorsk kontinentalsokkel er blitt brukt til å analysere den øvre del av Naustformasjonen (~0,5-0,2 ma). En seismisk stratigrafi med fire hovedenheter er etablert (enhet 1-4). De to eldste enhetene (enhet 1 og 2) er dominert av glasiale debrisstrømmavsetninger dannet under glasiale maksima da det Fennoskandiske isdekket nådde ut til eggakanten. Deler av enhet 2 er senere deformert ved yngre rashendelser. De to yngste enhetene (enhet 3 og 4) er karakteriseres som rasavsetninger og er relatert til Vigridraset og Sklinnadjupraset. I enhet 3 er det identifisert kompresjonsstrukturer dannet ved at godt konsoliderte avsetninger er blitt brutt opp og skjøvet inn over mer uforstyrrete deler. Mindre konsoliderte avsetninger er deformert ved kompresjon som resulterte i dannelse av foldestrukturer. Avsetningene i enhet 4 viser at utrasningene var karakterisert ved en komplisert strømningsprosess med utvikling av gjennomgående skjærsoner som skiller soner av sedimenter med ulik grad av deformasjon. De ulike sonene kan være avsatt til noe ulik tid eller ha bevegd seg med ulik hastighet i en hendelse. Sklinnadjupraset ble trolig utløst like etter Vigridraset. Sklinnadjupraset har trolig utviket seg retrogressivt og fylt igjen øvre del av rasgropa dannet av Vigridraset. URI: http://hdl.handle.net/10037/2498 File(s) in this item: 1
thesis.pdf (10.88Mb) -
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) -
Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 14-Aug-2010)[+][-]
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Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 28-Aug-2010)[+][-]
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Andreassen, Karin (Conference object; Konferansebidrag, 02-Sep-2010)[+][-]
Description: Innlegg på seminaret "Science - who cares?" ved NT-fak, Universitetet i Tromsø. URI: http://hdl.handle.net/10037/2695 File(s) in this item: 1
article.pdf (7.811Mb) -
Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 25-Sep-2010)[+][-]
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Romundset, Anders; Bennike, Ole; Bondevik, Stein (Preprint; Manuskript, Oct-2010)[+][-]
Abstract: The outer coast of Finnmark in northern Norway is where the former Fennoscandian and Barents Sea ice sheets coalesced. This key area for isostatic modelling and deglaciation history of the ice sheets has abundant raised shorelines, but only a few existing radiocarbon dates relate to them. Here we present three Holocene sea-level curves based on radiocarbon ages from deposits in isolation basins at the outermost coast of Finnmark; located at the islands Sørøya and Rolvsøya and at the Nordkinn peninsula. We analysed animal and plant remains in the basin deposits to identify the transitions between marine and lacustrine sediments. Terrestrial plant fragments from these transitions were then radiocarbon dated. Radiocarbon-dated mollusk shells and marine macro-algae from the lowermost deposits in several basins suggest that the first land at the outer coast became ice free around 14.6 cal kyr BP. We find that the gradients of the shorelines are much lower than elsewhere along the Norwegian coast because of substantial uplift of the Barents Sea. After the Younger Dryas the coast emerged 1.6-1.0 cm per year until about 9500-9000 cal yr BP. Between 9000 and 7000 yr BP relative sea-level rose 2-4 m and several of the studied lakes became submerged. At the outermost locality Rolvsøya, relative sea level was stable at the transgression highstand for more than 3000 years, between ca. 8000 and 5000 cal yr BP. Deposits in five of the studied lakes were disturbed by the Storegga tsunami ca. 8100-8200 cal yr BP. Description: This paper is part of Anders Romundset's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/2703 URI: http://hdl.handle.net/10037/2972 File(s) in this item: 1
article.pdf (6.899Mb) -
Propagation of the Storegga tsunami into ice-free lakes along the southern shores of the Barents SeaRomundset, Anders; Bondevik, Stein (Preprint; Manuskript, Oct-2010)[+][-]
Abstract: 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 layers and re-deposited organic remains. Some of the organic remains are rip-up clasts of lake mud, peat and soil and suggest strong erosion of the lake floor and neighbouring land. In this part of the Arctic coastal lakes are usually covered by > 1 m of solid lake ice in the winter season. The significant erosion and deposition of rip-up clasts indicate that the lakes were ice free and that the ground was probably not frozen. We suggest that the Storegga slide and tsunami event happened sometime in the summer season; between April and October. Minimum run-up has been reconstructed to 3-4 m. Description: This paper is part of Anders Romundset's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/2703 URI: http://hdl.handle.net/10037/2973 File(s) in this item: 1
article.pdf (3.365Mb) -
Vorren, Tore Ola; Laberg, Jan Sverre (Chronicle; Kronikk, 02-Oct-2010)[+][-]
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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) -
Rydningen, Tom Arne; Vorren, Tore Ola (Conference object; Konferansebidrag, 2011)[+][-]
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Blomeier, Dierk; Dustira, Anna Marie; Forke, Holger; Scheibner, Christian (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: A detailed facies study of Early Permian strata within NE Svalbard reveals a fundamental change of the depositional setting, from a restricted-marine, warm-water carbonate platform to an open-marine, temperate-water, mixed siliciclastic-carbonate ramp. The uppermost strata of the Gipshuken Formation (Templet and Sørfonna members; Sakmarian–early Artinskian?) consist of microbialites (algal mats), mudstones, bioclastic/peloidal limestones, carbonate breccias and Microcodium facies reflecting peritidal platform areas and supratidal sabkhas. A mixed heterozoan/reduced photozoan assemblage indicates temperate-water conditions within neighboring deeper, open-marine mid-platform areas, while warm-water conditions still prevailed within inner platform zones. In contrast, the lowermost strata of the overlying Kapp Starostin Formation (Vøringen Member; late Artinskian?–Kungurian) show a fully heterozoan biotic assemblage reflecting temperate water conditions within open-marine, storm-dominated, nearshore to transitional offshore areas of a mixed carbonate-siliciclastic ramp. The Vøringen Member comprises three facies associations, which form a shallowing-upward sequence subsequent to an initial transgression. The sediments reflect bryozoan bioherms in most distal areas, followed by stacked tempestites of sandy brachiopodal shell banks and Skolithos piperocks, grading into broad sand flats in most proximal areas of the inner ramp. The above environmental change is regarded as a regional event taken place across the entire shelf along the northern margin of Pangea and is attributed to paleoclimatic, paleoceanographic, as well as paleogeographic changes, possibly related to the overall northwards drift of the supercontinent. An abrupt increase in terrigenous input coinciding with this change is ascribed to the uplift of a new local source area, probably to the north or east of the investigation area. URI: http://hdl.handle.net/10037/4053 File(s) in this item: 1
article.pdf (3.852Mb) -
Menegon, Luca; Nasipuri, Pritam; Stunitz, Holger; Behrens, Harald; Ravna, Erling J Krogh (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: Granulite facies migmatitic gneisses from the Seiland Igneous Province (northern Norway) were deformed during deep crustal shearing in the presence of melt, which formed by dehydration melting of biotite. Partial melting and deformation occurred during the intrusion of large gabbroic plutons at the base of the lower crust at 570 to 520 Ma in an intracontinental rift setting. The migmatitic gneisses consist of high-aspect-ratio leucosome-rich domains and a leucosome-poor, restitic domain of quartzitic composition. According to thermodynamic modeling using synkinematic mineral assemblages, deformation occurred at T = 760°C–820°C, P = 0.75–0.95 GPa and in the presence of ≤5 vol % of residual melt. There is direct evidence from microstructural observations, Fourier transform infrared measurements, thermodynamic modeling, and titanium-in-quartz thermometry that dry quartz in the leucosome-poor domain deformed at high differential stress (50–100 MPa) by dislocation creep. High stresses are demonstrated by the small grain size (11–17 μm) of quartz in localized layers of recrystallized grains, where titanium-in-quartz thermometry yields 770°C–815°C. Dry and strong quartz forms a load-bearing framework in the migmatitic gneisses, where ∼5% melt is present, but does not control the mechanical behavior because it is located in isolated pockets. The high stress deformation of quartz overprints an earlier, lower stress deformation, which is preserved particularly in the vicinity of segregated melt pockets. The grain-scale melt distribution, water content and distribution, and the overprinting relationships of quartz microstructures indicate that biotite dehydration melting occurred during deformation by dislocation creep in quartz. The water partitioned into the segregated melt crystallizing in isolated pockets, in the vicinity of which quartz shows a higher intracrystalline water content and a large grain size. On the contrary, the leucosome-poor domain of the rock, from which melt was removed, became dry and thereby mechanically stronger. Melt removal at larger scale will result in a lower crust which is dry enough to be mechanically strong. The application of flow laws derived for wet quartz is not appropriate to estimate the behavior of such granulite facies parts of the lower crust. URI: http://hdl.handle.net/10037/3944 File(s) in this item: 1
article.pdf (7.533Mb) -
Menegon, Luca; Piazolo, Sandra; Pennacchioni, Giorgio (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: We present an electron backscatter diffraction analysis of five quartz porphyroclasts in a greenschist facies (T = 300–400°C) granitoid protomylonite from the Arolla unit of the NW Alps. Mechanical Dauphiné twinning developed pervasively during the incipient stage of deformation within two porphyroclasts oriented with a negative rhomb plane {z} almost orthogonal to the compression direction (z-twin orientation). Twinning was driven by the anisotropy in the elastic compliance of quartz and resulted in the alignment of the poles of the planes of the more compliant positive rhomb {r} nearly parallel to the compression direction (r-twin orientation). In contrast, we report the lack of twinning in two porphyroclasts already oriented with one of the {r} planes orthogonal to the compression direction. One twinned porphyroclast has been investigated with more detail. It shows the localization of much of the plastic strain into discrete r-twins as a consequence of the higher amount of elastic strain energy stored by r-twins in comparison to z-twins. The presence of Dauphiné twins induced a switch in the dominant active slip systems during plastic deformation, from basal (regions without twinning) to {π} and {π′} (pervasively twinned regions). Dynamic recrystallization is localized along an r-twin and occurred dominantly by progressive subgrain rotation, with a local component of bulging recrystallization. Part of the recrystallized grains underwent rigid-body rotation, approximately about the bulk vorticity axis, which accounts for the development of large misorientation angles. The recrystallized grain size piezometer for quartz yields differential stress of 100 MPa. The comparison of this palaeostress estimate with literature data suggests that mechanical Dauphiné twinning could have a potential use as palaeopiezometer in quartz-bearing rocks. URI: http://hdl.handle.net/10037/3939 File(s) in this item: 1
article.pdf (1.748Mb) -
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) -
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)
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