Masteroppgave i Geovitenskap Studieretning: Geobiologi og geokjemi

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1 Masterprosjekt til materopptaket høst 2013 Prosjekttittel: Provenance of metamorphosed clastic sediments in the developing continental rift Veileder: Jiří Konopásek Medveileder: Jan Košler The project is dealing with the study of the Neoproterozoic clastic sediments in the Coastal - Punta del Este Terrane of the Kaoko-Dom Feliciano belts in NW Namibia and E Uruguay, which represents fossil Neoproterozoic rift domain developed during the break-up of Rodinia supercontinent. Detrital zircons from metasedimentary rocks in the tectonically lowermost part of this unit will be dated by using the laser ablation ICP-MS technique. The data will be interpreted in terms of maximum sedimentary age of studied samples and possible source regions of detrital material. The resulting age spectra will be compared with known detrital zircon record from rift-related (meta)sediments covering the neighboring cratonic basement. The student will gain an up-todate knowledge of the technique of detrital zircon dating that is widely used in basin analysis and also in oil prospecting. Eksterne data: No Feltarbeid: No Laboratoriearbeid zircon separation, laser ablation ICP-MS dating of zircons, Nd isotopes Finansiering: prosjekt Størrelse på oppgaven: 60 sp GEOV 103; GEOV 109; GEOV241, GEOV 342, GEOV343, GEOV347

2 Masterprosjekt til materopptaket høst 2013 Prosjekttittel: Metamorphic evolution and tectonic position of metasediments of the Austevoll islands Veileder: Jiří Konopásek Medveileder: Rolf-Birger Pedersen, Jan Košler Metasedimentary rocks of the westernmost Austevoll islands are represented by quartzites, marbles and garnet-bearing micaschists. The primary goal of this project will be the petrological study of mineral assemblages in marbles and micaschists and the study of detrital zircon populations in metasedimentary rocks. Computer modelling of metamorphic evolution and interpretation of detrital zircon ages will provide insight into the thermal and tectonic evolution of this part of the Norwegian Caledonides and the results will be compared with tectonic position of rocks in the Bergen Arcs during Caledonian orogeny. The student will gain an up-to-date knowledge of petrological analysis of rocks, and will also master the technique of detrital zircon dating that is widely used in basin analysis and oil prospecting. Eksterne data: No Feltarbeid: Yes Laboratoriearbeid: microscopy of rock-forming minerals, electron microprobe, computer modelling, zircon separation, laser ablation ICP-MS dating of zircons Finansiering: Centre for Geobiology Størrelse på oppgaven: 60 sp GEOV 103; GEOV 109; GEOV241, GEOV 342, GEOV343, GEOV347

3 Masterprosjekt til materopptaket høst 2013 Prosjekttittel: Development of elemental mapping by laser ablation ICP-MS Veileder: Jan Košler Medveileder: Jiří Konopásek Spatial distribution of elements in minerals and other geological and environmental samples is often crucial for understanding the behavior of elements and their isotopes in nature. Two-dimensional mapping of element concentrations by laser ablation ICP-MS is a unique tool for studying the element distribution since it can capture variations at sub-ppm level. This is a laboratory-based project that will focus on integration of data from scanning electron microscopy and laser ablation ICP-MS mapping with a goal to develop a mapping procedure for major and trace elements. Part of the project will be dedicated to application of this technique to real samples of candidate s choice, such as accessory minerals, rock-forming minerals in petrographical thin section, fish otoliths or archaeological samples. It is expected that the candidate will have interest in mineralogy, analytical geochemistry and be able to handle analytical instruments and computer software. Eksterne data: No Feltarbeid: No Laboratoriearbeid electron microbeam analysis, laser ablation ICP-MS dating of zircons, computer modelling. Finansiering: CGB Størrelse på oppgaven: 60 sp GEOV 109; GEOV241, GEOV 342, GEOV347

4 Masterprosjekt til materopptaket høst 2013 Prosjekttittel: Testing the accuracy of U-Pb laser ablation ICP-MS dating Veileder: Jan Košler Medveileder: Jiří Konopásek, Rolf-Birger Pedersen Laser ablation ICP-MS has become a method of choice for U-Pb dating of zircons in sedimentary provenance. Several recent studies have shown that the accuracy of this dating is not better than 2-4% while short-term reproducibility and precision of individual data is often better than 1%. The aim of this project is to identify the factors that contribute to inaccuracy of the U-Pb age data, specifically the elemental decoupling of Pb and U during laser ablation of zircon and the way this fractionation is linked to structural and chemical variation in the zircon matrix. This is exclusively a laboratory-based project that will utilize a variety of electron beam microbeam techniques, ion probe, Raman spectroscopy and laser ablation ICP-MS. It is expected that the results of this study will have a significant impact on the application of the technique to zircon dating as well as on interpretation of detrital zircon age data in sedimentary provenance studies. Eksterne data: No Feltarbeid: No Laboratoriearbeid electron microbeam analysis, Raman spectroscopy, laser ablation ICP-MS dating of zircons. Finansiering: CGB Størrelse på oppgaven: 60 sp GEOV 109; GEOV241, GEOV 342, GEOV347

5 (H2013) Studieretning: Geobiologi og Geokjemi Prosjekttittel: Forvitring av olivin og anortositt i aktive jordsmonn: karakterisering av mineralmikrobe interaksjoner. Veileder: Pål Tore Mørkved Medveileder: Ingunn Thorseth Masteroppgaven vil være en del av et større prosjekt som utforsker muligheten for å redusere klimagassutslippene fra landbruksjord betydelig ved å erstatte kalk med andre mineraler som har basisk reaksjon ved forvitring. Dette vil kunne redusere lystgass (N 2 O) og CO 2 -utslipp fra jord og samtidig bidra til en netto fangst av CO 2 i jordsmonnet. Masterprosjektet vil undersøke hvordan olivin (Forsteritt) og anortositt (anortitt) løses opp under forhold som er spesifikke for jord og hvilke parametere som påvirker oppløsningsratene i laboratorie eksperimenter. Dette omfatter effekter av relevante organiske syrer og biofilmdannelse på mineraloverflatene. Det kan være aktuelt å sammenlikne mineralprøver fra forskjellige lokaliteter. Det er også ønskerlig å sammenlikne prøver fra naturlige jordsmonn som inneholder disse mineralene med de eksperimentelle resultatene. Det er aktuelt å måle mikrobiell nitrogen- og karbonomsetning i eksperimentene, og eventuell økt tilgjengelighet av tungmetaller- Eksterne data (ved bruk av data fra eksterne bedrift, er disse tilgjengelige ved oppstart av masteroppgaven?): Ingen data, men det vil være samarbeid med Institutt for Energiteknikk og Universitetet for miljø- og biovitenskap. Feltarbeid (noter forventet tid på året): Noe feltarbeid for å samle inn prøvemateriale. Laboratoriearbeid (noter forventet mengde): Oppgaven vil for en stor del bestå av eksperimenter og analyser. Finansiering: Senter for Geobiologi (CGB). Evt kr fra instituttet for deltagelse i nordisk kurs utenfor UiB (Island). Størrelse på oppgaven: (normalt 60 stp = 1 år fulltidsstudium) 60 stp GEOV243, GEOV342, GEOV343, GEOV344, GEOV347

6 Masterprosjekt til masteropptaket høst 2013 Prosjekttittel: Layered Mafic Intrusion Formation: Sill Intrusions and/or Magma Reservoir Replenishments by Ultramafic Melts (Isle of Rum, Scotland) Hovedveileder: Romain Meyer Medveileder: Rolf Birger Pedersen, Micheal Cheadle (University of Wyoming) Igneous layering is a texture of plutonic rocks described from layered intrusions, ophiiolites and in-situ fast-spread oceanic crust (IODP 345). As a result, knowledge on igneous layering formation will be beneficial for a large part of the igneous petrology community. A solidified layered igneous cumulate results from complex interactions between physical and chemical processes both during and after the fractional crystallization of a melt, and thus provides a means of decrypting physical-chemical conditions within larger magma reservoir lenses within the crust. The well-known Palaeocene Rum Layered Intrusion, N.W. Scotland is a classical example for igneous layering. The plutonic rocks related to this intrusion are peridotites, felspathic peridotites, dunites, anorthosites, troctolites, olivine gabbros and gabbros. This Layered Intrusion has been subdivided into Units with a lower mostly felspathic peridotite layer and an upper troctolite to gabbro alternating layer. Following Brown (1956) the assumed petrogenetic interpretation is that every Unit represents a separate melt replenishment event into a large magma chamber. A hot and dense picritic melt injects into the chamber, and starts crystallisation and sedimentation - first the olivine rich peridotite layer followed by the more evolved troctololitic gabbroic series. Alternatively Bedard et al. (1998) proposed that peridotite sub-units might actually represent intruded sills into a partly solidified layered troctolitic crystal mush zone. To cast some light into this debate, it is

7 proposed to perform micro-drilling of olivine, pyroxene and plagioclase crystals for trace element and Sr isotope from different lithologies from the same unit. Trace element data will provide insights into magma evolution and causal links between troctolitic, and peridotitic melts. Plagioclase (and pyroxene) Sr isotopic intracrystalline heterogeneity from troctolitic and peridotitic layers would also mirror different magmatic processes, as isotopic zoning reflects the evolution of the melt during consolidation and during later alteration processes. Potential involved isotopic end-members are the primary mantle signature, continental crust, hydrothermal fluids and seawater. Annen informasjon: Eksterne data: Samples (Mike Cheadle) Dept. Of Geology and Geophysics; University of Wyoming (ved bruk av data fra eksterne bedrift, er disse tilgjengelige ved oppstart av masteroppgaven?) Feltarbeid: NO (noter forventet tid på året) Laboratoriearbeid : SEM, micro-drilling, ICP-MS, TIMS (noter forventet mengde) Finansiering: * Ekstern prosjekt støtte: (i første omgang skal finansiering tas fra eksterne prosjekt) JA Nei * Påkrevd med støtte fra Instituttet: Fyll ut skjema "Følgeskjema - støtte til CGB masterprosjekt" 60 (det er spesielt viktig å foreslå emner studenten skal velge første semester) GEOV109, GEOV241, GEOV342, GEOV 347 C GB

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