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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Distribuce stopových prvků v karbonatitech pomocí in-situ metod, se zvláštním zřetelem k REE / Distribution of trace elements in carbonatites using in-situ techniques, with focus on REE

Krátký, Ondřej January 2017 (has links)
Carbonatites are unique and enigmatic magmatic rocks of unclear origin, with very specific mineralogy and geochemical properties. They are predominantly composed of magmatic calcite or other carbonate minerals (Le Bas 1987) and have low content of SiO2 (Le Maitre 2002). Origin of these peculiar magmas is still not clear but they appear to represent an important "window" into processes in Earth's mantle. They are considered either as residual melts from a fractionated carbonated nephelinite or melilitite (Gittins 1989; Gittins and Jago 1998), as immiscible fractions of CO2-saturated silicate melts (Freestone and Hamilton 1980; Amundsen 1987; Kjarsgaard and Hamilton 1988, 1989; Brooker and Hamilton 1990; Kjarsgaard and Peterson 1991; Church and Jones 1995; Lee and Wyllie 1997; Dawson 1998; Halama et al. 2005; Brooker and Kjarsgaard 2011), or as primary melts which are were generated from CO2-bearing peridotite through partial melting (Wallace and Green 1988; Sweeney 1994; Harmer and Gittins 1998; Harmer et al. 1998; Ying et al. 2004). Abundances of rare earth elements (REE) are often high in carbonatites because carbonatitic magmas can dissolve these elements much easily than silicate magmas (Nelson et al. 1988). Carbonatitic magma can also dissolve large quantities of Sr, Ba, P and mainly Zr and Nb,...
2

Analys av röda missfärgningar i Gåsgruvans marmor / Analysis of red discolouration found in crystalline limestone in Gåsgruvan quarry

Hesser, Sarina January 2020 (has links)
Detta arbetes mål har varit att hjälpa företaget SMA Mineral att utreda de rödamissfärgningar som allt oftare påträffats i deras marmor. Rapporten är högst visuellpå mikroskopisk nivå, och avhandlar vad missfärgningarna beror på. Provmaterialhar undersökts och karakteriserats mineralogiskt och geokemiskt, och typer avmissfärgningen har identifierats. Även en förklaring över de geologiska processersom ger upphov till missfärgningarna har formats. De metoder som använts underarbetet är egna undersökningar med komplement av en litteraturstudie påavhandlingar som handlar om just missfärgningar i marmor. Provmaterial harinhämtats från tre olika platser i gruvan, dessa har sågats och tvättats och några haräven slipats och polerats. Detta material har sedan använts genom hela arbetet.Optiska observationer med hjälp av binokulär har dokumenterats digitalt, detta gavinformation om att missfärgningen ligger mellan karbonatkristallerna, och sannolikthar varit av en mer löslig karaktär i ett tidigare skede. Utifrån detta kategoriserasmissfärgningen till två olika typer. Typ A förekommer som asymmetriska,koncentrerade fläckar på och mellan kristaller men till synes oregelbundet, medantyp B följer mikrofina sprickor och kan ses i bandade regelbundna formationer imaterialet. Järnrika kristaller upptäcktes i missfärgningarnas omedelbara närhet ochhär skapades hypotesen om att det är järnoxider som orsakat föroreningarna. ÄvenSEM-analyser har gjorts för att kunna identifiera den geokemiska sammansättningenav missfärgningarna. Resultaten från SEM- och XRF-analyserna bekräftade tesen, dåjärn förekom i varierande grad i samtliga analyser utom en. Dessutom hittadeshematit som i sig lämnar röda spår, samt ren rost i form av goetit. Ävenlitteraturstudien bekräftade att förekomster av järnrika mineral i marmor förr ellersenare kommer att orsaka missfärgningar. / The goal of this project has been to assist SMA mineral, a limestone producer, tofind the source of red discolourations found in their crystalline limestone. Thediscolouration has appeared on a more regular basis than before and is starting tobecome a problem for the company.This is a highly visual report focused on a microscopical level, that follows thestudy and finding of the origin of the red discolourations. Specimens from threedifferent locations in the quarry have been collected, then cut to proper sizes to fitthe needs for the scans and examinations suited for the project. Some of the sampleswere polished to fit the requirements of SEM. The material has been opticallyanalysed through a binocular microscope and documented with high resolutionimages. This was the first major breakthrough, since the discolouration showed tobe placed between the carbonate crystals, and appeared to have been more of asolution-like substance at some point. Based on the findings, the discolourationcould be categorised inte two types, type A appears as an irregular spotting oncrystal surfaces with a deeper red colour, whilst type B can be found in fine cracksin the material and follows a more regular pattern. Lots of minerals rich in ironwere also found in close proximity to the discolourations, which led to a hypothesisthat iron oxides might be the source of the problem. The thesis was confirmed bySEM- and XRF analyses of the material. Iron in different weight-percentages wasfound in all of the analyses except for one.The mineralogical and geochemical properties of the discolouration has beendefined, and the geological process that leads to the discolouration is explained.
3

Mineralogická vazba izotopů radia v karlovarských vřídelních sedimentech: Výsledky selektivního rozpouštění / Mineralogical speciation of the radium isotopes in Karlovy Vary hot spring sediments: Results of the selective dissolution

Supiňková, Taťána January 2012 (has links)
Thermal waters in Karlovy Vary are characterized by carbonate sedimentation in places of their emergence. These sediments contain radium. Radium bond in every type of sinter (aragonite, calcite) has been investigated experimentally by acid sinter dissolution. It has been found out, that radium can join dissoluble fraction in both sinter types . The original hypothesis that radium can bond only aragonite-type of sinter has been refuted. Additional experiments have been processed using synthetic radiobarite. Present radium in radiobarite can be partly dissoluted using acids. If radium was incorporated in radiobarite (it is known from locality Vřídlo in Karlovy Vary and elsewhere) then maybe it would be partly dissoluted in experiments.

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