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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

Glacial Dispersal of Indicator Minerals from the Izok Lake Zn-Cu-Pb-Ag VMS Deposit, Nunavut, Canada

HICKEN, ANNA 01 February 2012 (has links)
Volcanogenic massive sulphide (VMS) deposits have a characteristic geochemical suite of enriched metals, mineralization and related hydrothermal alteration minerals; however, very little research has been carried out to determine which of these minerals may be useful for exploration in glaciated terrains and there are very few case studies in the public realm that document down-ice dispersal of these from known volcanogenic massive sulphide (VMS) deposits. In response to these needs and to refine and optimize surficial exploration methods in northern Canada, this study was conducted to examine the mineralogical signature of the Izok Lake Zn-Cu-Pb-Ag VMS deposit, Nunavut and its glacial till dispersal. Glacial sediments were deposited in the Izok Lake region by the Laurentide Ice Sheet. Detailed ice flow mapping indicates four stages of ice flow (oldest to youngest): 1) southwest (255 ̊); 2) weak flow to the northwest (315 ̊); a dominant ice flow and landform trend to the west-northwest (292 ̊), and 4) northwest (318 ̊) that was only observed east of the Iznogoudh Lake area (Hicken et al., 2011). The till geochemical signature (aqua regia digestion ICP-MS analysis) for the <0.063 mm fraction of the till matrix is defined by elevated (above the 95th percentile) contents of Zn, Cu, Pb, Fe, Ag, Cd, Bi, Hg, Se, In and Tl. These element signatures in till can be detected up to 8 km down-ice from the deposit. Till geochemical data is used to evaluate which till samples are metal-rich and may contain indicator minerals. Indicator minerals for the amphibolite metamorphic grade Izok Lake VMS deposit includes: gahnite, staurolite, axinite, chalcopyrite, sphalerite and pyrite. Sulphide minerals are present at lower abundances than gahnite and staurolite as they are not physically and chemically as robust/resistant during postglacial weathering. Gahnite is the most useful VMS indicator mineral in the postglaciated Izok Lake area, as it was readily identified in till heavy mineral concentrates, it is abundant (100 of grains), its chemically stable in the surficial weathering environment, and can be detected up to 40 km down-ice. This study is one of the first to document indicator minerals down-ice from a VMS deposit in a postglaciated terrain. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-01-31 18:24:19.909
2

Development of mineralogical and geochemical exploration techniques for carbonatite-related Nb (±Ta) and REE deposits in the Canadian Cordillera

Mackay, Duncan Alisdair Robert 23 April 2015 (has links)
Niobium and rare earth elements (REE) are considered as strategic metals in industrialised countries, and are mainly derived from carbonatite-related deposits. Indicator mineral methods for carbonatites using of portable XRF and Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN®), shows promise in exploration for Nb and REE. Portable XRF analysis of stream sediments from the Aley, Lonnie, and Wicheeda carbonatites identified 125-250 μm as the ideal size fraction for indicator mineral studies. QEMSCAN® provides (with no additional processing) detection and characterisation of indicator minerals (when found in high concentrations) from carbonatite deposits. Preconcentration by Mozley C800 separator is recommended for sediment samples with low concentrations of indicator minerals. Discrimination diagrams for pyrochlore supergroup and columbite-tantalite series minerals show that minerals from carbonatites occupy the pyrochlore field and extend slightly into the betafite field. Columbite-tantalite series minerals from carbonatites have Mn/(Mn+Fe) atomic ratios ≤0.25 and Ta/(Ta+Nb) ≤0.20. The compositional fields for pyrochlore supergroup and colubmite-tanatlite series minerals from different deposit types partially overlap. / Graduate / 0996 / 0411 / 0372

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