Dissertations / Theses: 'Ore geochemistry'

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Lundkvist, Anders. "The process water geochemistry of the Kiirunavaara magnetite ore." Licentiate thesis, Luleå tekniska universitet, 1998. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26157.

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Unger, Derick Lee Saunders James A. Hames W. "Geochronology and geochemistry of Mid-Miocene Bonanza low-sulfidation epithermal ores of the northern Great Basin, USA." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Geology_and_Geography/Thesis/Unger_Derick_6.pdf.

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Tanner, Dominique. "In situ mineral geochemistry as a guide to ore-forming processes." Phd thesis, Canberra, ACT : The Australian National University, 2014. http://hdl.handle.net/1885/125140.

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Isotopic and trace element analyses are essential to our understanding ore-forming processes, but traditionally these techniques have required bulk digestion of rocks and minerals. Recent advances in in situ microanalytical techniques permit us to analyse samples on a mineral-by mineral basis and probe the chemistry of individual growth bands in minerals, providing a near-continuous record in any zoned mineral. This thesis is composed of five studies using the in situ geochemistry of 'gangue' (non-ore) minerals to elucidate cryptic ore-forming processes that are obscured using conventional analyses. The first half of this thesis presents coupled isotopic and trace element analyses in quartz and pyrite from magmatic-hydrothermal Cu-Au deposits. These studies revealed complex chemical zonation, providing a detailed record of cryptic fluid chemistry and depositional processes. A distinct isotopic signature and residual metastable silica hydrates in quartz microcrystals from the El Indio deposit, Chile provided the first evidence for silica maturation in a high-temperature environment and the first evidence for non-equilibrium isotope fractionation in quartz. The second half of this thesis focuses on the trace element chemistry of minerals from the Bellevue Core, a ~3 km drillcore intersecting the upper half of the Bushveld Complex, South Africa - the largest known repository of platinum-group elements (PGEs). These studies revealed a prospective PGE horizon and provide the first evidence for extensive equilibration of plagioclase in cumulate rocks.

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Sharman, Elizabeth. "Application of multiple sulfur isotope analysis to Archean ore-forming processes." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104747.

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Identification of sulfur sources in an ore-forming system is important as it provides a greater understanding of how a mineral deposit forms and how best to explore for that particular type of deposit. It can also aid in the understanding of the ocean and atmosphere chemistry at the time of formation. Mass independent sulfur isotope fractionation in the Archean atmosphere provides a fingerprint for identifying non-magmatic sources of sulfur. This makes sulfur multiple isotope measurements a powerful tool for deconvolving ore-forming processes in the Archean. This thesis presents three applications of multiple sulfur isotope analysis for investigation of ore forming processes in the Archean. The first study evaluates proposed models for formation of volcanogenic massive sulfide (VMS) deposits during the Neo- and Mesoarchean, which demand little to no contribution of seawater sulfate to the ore-forming system. This is in contrast to Phanerozoic VMS systems where evidence for a seawater sulfate component is clear. We re-evaluate these models in the context of the ~2.7 Ga Noranda Camp of the Abitibi subprovince, Québec, using a combination of multiple sulfur isotope and trace element data. Sulfide samples analysed for this study have Δ33S values between -0.59 and -0.03 ‰. We interpret these negative values to reflect a sulfur component that originated in the seawater sulfate reservoir. Incorporation of this component appears to have increased during the collapse and subsequent evolution of the Noranda caldera. Higher concentrations of Se in samples with Δ33S values close to 0 ‰, and higher Fe/(Fe + Zn) values in sphalerite, are indicative of higher temperatures of formation.The second study is an investigation of sulfur sources that contributed to the formation of Cu- and Au-rich VMS deposits of the ~2.7 Ga Doyon-Bouquet-LaRonde (DBL) mining camp, also within the Abitibi subprovince. This subgroup of deposits has previously been interpreted as having a significant magmatic-hydrothermal source of ore fluids and metals. Multiple sulfur isotope analysis of deposits within the DBL mining camp, with the exception of one minor lens, indicates a very clear igneous-magmatic affinity (Δ33SV-CDT = 0.14 to +0.04 ‰), with little to no contribution from any surficial source of sulfur. In contrast, sulfide that formed at or very near the paleo-seafloor exhibits a distinct component of sulfur from the seawater sulfate reservoir (Δ33SV-CDT = 1.43 to 0.34 ‰). This study highlights the isotopic difference between the Noranda VMS deposits and those of the DBL. In addition, a lack of variation in Δ33S values between ore lenses which exhibit aluminous alteration and those that do not calls into question the characteristics with which to identify those VMS deposits that required dominant contribution of magmatic fluids.The final study examines sulfur sources within the Platreef, the main PGE bearing horizon of the Northern Limb of the Bushveld Igneous Complex (BIC), South Africa. The Platreef has a high percentage of sulfides relative to the analogous Merensky Reef in the eastern and western limbs of the BIC. It is in direct contact with underlying Neoarchean to Paleoproterozoic sediments, which are potential local sources of sulfur. However, Δ33S analysis of the Platreef sulfides identifies heterogeneous crustal sulfur contribution to the system both prior to and post-emplacement throughout the length of the Platreef.This thesis clearly demonstrates that multiple sulfur isotope analysis is a powerful tool for the identification of sulfur sources in ore forming processes of the Archean, and those involving Archean rocks, and can be applied to a range of problems and deposit types. It also highlights important issues for future consideration, including the role of seawater sulfate in the formation of Archean VMS deposits, and the characteristics of the parent magma of the BIC.
L'identification des sources de soufre dans la minéralisation est importante car elle permet de comprendre les processus et de définir la meilleure méthode d'exploration. Elle peut aussi aider à la compréhension de la chimie des océans et de l'atmosphère lors de sa formation. Le fractionnement indépendant de la masse des isotopes du soufre dans l'atmosphère de l'Archéen fournit une emprunte unique permettant d'identifier les sources de soufre non magmatiques. La nature chimique conservatrice des signatures du Δ33S en fait un outil puissant pour la déconvolution des processus minéralisateurs Archéen.Cette thèse présente trois applications de l'analyse multiple des isotopes du soufre dans l'investigation des processus de minéralisation à l'Archéen. La première étude teste les modèles de formation des sulfures massifs volcanogènes (SMV) Néo- et Mésoarchéen récemment proposés ne requérant peu ou pas d'apport de sulfate marin par rapport aux systèmes SMV du Phanérozoïque et contemporains où le sulfate marin joue un rôle important. Ces modèles sont réévalués en utilisant le camp de Noranda (~2.7 Ga), sous-province de l'Abitibi, et en combinant l'utilisation de données provenant de l'analyse des isotopes du soufre et des éléments traces.Les sulfures analysés pour cette étude ont des valeurs de δ34SV-CDT entre -14.90 et +2.49 ‰, et des valeurs de Δ33SV-CDT entre -0.59 et -0.03 ‰. Selon notre interprétation, les valeurs négatives de Δ33S sont dues à l'incorporation de soufre provenant de l'eau de mer. La proportion de soufre marin aurait augmenté durant l'affaissement et l'évolution subséquente de la caldera de Noranda. Des concentrations plus élevées de Se combinées à des valeurs près de 0 ‰ et d'un haut ratio Fe/(Fe + Zn) dans les sphalérites indiquent une température de formation élevée.La deuxième étude est une investigation des sources de soufre ayant contribuées à la formation des SMV riches en Cu et en Au du camp minier Doyon-Bousquet-LaRonde (DBL; ~2.7 Ga), aussi dans la sous-province de l'Abitibi. Une source magmatique-hydrothermale de fluides minéralisateurs importante était l'interprétation donnée pour ce sous-groupe. À l'exception d'une lentille mineure, l'analyse isotopique multiple des dépôts du camp minier DBL indiquent clairement une affinité ignée-magmatique (Δ33SV-CDT = 0.14 to +0.04 ‰), avec peu ou pas de contribution de soufre provenant de la surface. Par contre, les sulfures formés sur le plancher océanique ou près de celui-ci exhibe une contribution distinctive des sulfates marins (Δ33SV-CDT = 1.43 to 0.34 ‰). D'un autre côté, l'absence de variation des valeurs du Δ33S entre des lentilles minéralisées avec une altération alumineuse et celles ne démontrant pas cette altération remet en question les l'identification des dépôts de type SMV ayant une contribution importante ou dominante de fluides magmatiques. La dernière étude examine les sources de soufre du Platreef – horizon riche en éléments du groupe platine (EGP) du flanc nord du Complexe Igné Bushveld (CIB) en Afrique du Sud. Le Platreef contient un haut pourcentage de sulfures par rapport au dépôt analogue Merensky Reef des flancs est et ouest du CIB. Il est en contact direct avec les sédiments Néoarchéens à Paléoprotérozoïques qui sont une source potentielle de soufre locale. D'un autre côté, les analyses du Δ33S des sulfures du Platreef permettent d'identifier une contribution de soufre hétérogène provenant de la croûte terrestre, avant et après la mise en place du gisement.Cette étude démontre clairement que l'analyse multiple des isotopes du soufre est un outil puissant dans l'identification des sources de soufre des processus minéralisateurs de l'Archéen, ainsi que ceux impliquant des roches archéennes, et cette approche peut être appliquée à un éventail de problèmes et types de dépôt. Aussi, elle soulève des questions importantes sur le rôle du sulfate marin dans la formation des dépôts SMV de l'Archéen et les caractéristiques du magma du CIB.

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Archibald, Sandy M. "The role of vapour in the transport and deposition of metals in ore-forming systems /." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82821.

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The solubility of gold and copper chloride in liquid-undersaturated, HCl-bearing water vapour was investigated experimentally at elevated temperatures and pressures. Experimental results show that the solubility of gold and copper is significant, increasing at higher fHCl and fH2O for gold, and at higher fH2O for copper. These increases are attributed to the formation of hydrated gas species, with a metal:chlorine ratio of 1. Hydration numbers vary from 5 at 300°C to 3 at 360°C for gold, and from 7.6 at 280°C, to 6.0 at 300°C, and 6.1 at 320°C for copper; the results reflect the presence of trimer [Cu3Cl3•(H2O)n] or tetramer [Cu4Cl4•(H2O)n] species. Results indicate that solubility for both vapour species is retrograde, i.e., it decreases with increasing temperature, and formed via the reactions: Ausolid+m·HClgas+n·H2 Ogas=AuClm·H2 Ogasn+m 2·Hgas2 3CuClsolid+n·H2Ogas= Cu3Cl3·H2O gasn
Calculations based on the solubility data indicate an economic high-sulphidation Au deposit (e.g., Nansatsu, Japan; 36 tonnes) could form in ~30,000 years, whereas a porphyry copper deposit (e.g., 50 million tonnes at 0.5% Cu) could form in as little as ~20,500 years, assuming transport only in the vapour phase.
Precious- and base-metal-rich composite scales, containing up to 111 ppm Au and 628 ppm Ag, occur in surface pipes at the Momotombo geothermal field, Nicaragua. Polysulphide scale fragments, comprising chalcopyrite, sphalerite, galena, electrum and hessite grains in a matrix of amorphous silica, formed as a result of cooling and ligand loss induced by boiling, during fluid ascent in well MT-36. Secondary bornite, stromeyerite and chalcocite/digenite replaced chalcopyrite through the addition of Cu and Ag and an increase in fO2 . A drop in pH due to well closure resulted in replacement of primary and secondary sulphides by tetrahedrite.
Reaction-path modelling using the program CHILLER simulates deposition of minerals from the reconstructed deep geothermal fluid, at temperature intervals (depths) along excess enthalpy and isoenthalpic boiling paths. These simulations accurately reproduce the paragenetic sequence of base- and precious-metal mineralization in the scales. The modelling indicates excess enthalpy boiling results in metal precipitation at greater depths than would be expected for isoenthalpic boiling, and that at Momotombo this occurs through the destabilisation of bisulphide complexes in response to loss of CO2 and H2 S during phase separation.

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Jiang, Shao-Yong. "Chemical and boron isotopic compositions of tourmaline from sedex-type and metaevaporite ore deposits." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294950.

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7

Way, Bryan C. "Geology and Geochemistry of Sedimentary Ferromanganese Ore Deposits, Woodstock, New Brunswick, Canada." Thesis, Fredericton: University of New Brunswick, 2012. http://hdl.handle.net/1882/44600.

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The Early-Silurian Woodstock Fe-Mn Deposits are a series of six, northeasttrending, low grade manganiferous-iron deposits in western New Brunswick that collectively represent the largest Mn resource in North America (194,000,000 tonnes; 13% Fe and 9% Mn). Recent expansion of Route 95 has allowed a more detailed local stratigraphy, mineralogy, and geochemistry of the Fe-Mn deposits within the context of the regional stratigraphy to ascertain the genesis of these deposits. Geological mapping during the field seasons of 2008 and 2009 has revealed six Lithofacies Associations (O, I, II, III, IV, V) within the area, that, generally, are lying conformably on top of each other. However complications due to folding and interbedding have resulting in juxtaposition of the lithofacies associations so they are not always in stratigraphic order. These lithofacies associations are composed of a turbidite-rich section of blue grey calcareous sandstone (O) overlain by black pyritic mudstone (I), associated mineralized and nonmineralized green (II) and red siltstone (III), and laminated to massive grey green calcareous sandstone (IV and V). Na/Mg ratios, chondrite-normalized REE patterns, and mineralogical evidence of rapid changes in ocean redox conditions suggest the Fe-Mn mineralized lithofacies were formed in the offshore zone of a continental shelf on a stable cratonic margin. Al-Fe-Mn ternary and SiO2/Al2O3 binary plots developed from archived drill core data indicate the Fe-Mn mineralization was initially derived from hydrogenous-detrital sources without any indication of a hydrothermal input as a source of Fe and Mn.

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Levitan, Denise Madeline. "Statistical Analysis of the Environmental Geochemistry of an Unmined Uranium Ore Deposit." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64782.

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An evaluation of the geochemistry of the environment prior to large-scale changes enables scientists and other stakeholders to assess both baseline conditions and the potential impact of those changes to the environment. One area in which documentation of pre-development geochemistry is particularly important is in the exploitation of ore deposits. Ore deposits consist of concentrations of elements or minerals that are enriched enough to be of potential economic value. Their unusual geochemistry often leaves a signature on the environment that can both aid in location an economic resource and present environmental management challenges during its lifecycle. Coles Hill, Virginia, represents one such site. The Coles Hill property is the location of uranium-enriched rock, commonly referred to as the Coles Hill uranium deposit. This dissertation outlines study design, sampling, and statistical analysis methods that can be used in the geochemical characterization of a potential resource extraction site. It presents three studies on geoenvironmental media at Coles Hill. The first study discusses sampling strategies and statistical analysis to address variability in geology, hydrology and climate for baseline assessment and presents an example of such an assessment at Coles Hill. Results suggest a localized environmental impact of the deposit but that differences in bedrock geology within the area surrounding the deposit could also be responsible for some of the variation. This study also emphasizes the importance of consideration of data below analytical detection limits and describes methods for doing so. The second study compares the geochemistry of soil samples collected at Coles Hill with reference data collected by the U.S. Geological Survey using multivariate statistical techniques. Differences are used to suggest potential pathfinder elements such as light rare earth elements to aid in exploration for similar deposits. The third study uses multivariate statistical analysis to examine differences among rocks, soils, and stream sediments to infer important geochemical processes involved in weathering of the deposit. Overall, the results of these studies can aid in the development of future environmental site studies at Coles Hill and elsewhere.
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Meadows, Holly Rachael. "Mineral Geochemistry, Deformation and Ore Fluid Evolution in the Capricorn Orogen, WA." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/69391.

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The Capricorn Orogen, Western Australia, has a complex history spanning over a billion years. Regional deformation, metamorphism and magmatism has induced migration of ore fluids into local ore deposits. Mineral geochemistry records the chemical environment of ore precipitation and is employed to determine the source of fluids and age of mineral growth. Integration of mineral geochemistry into complex geological systems is used to identify overprinting fluid and deformation events, and evaluate the formation of ore.

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Rempel, Kirsten U. "The solubility and speciation of molybdenum in water vapour at elevated temperatures and pressures : implications for ore genesis." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82411.

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The solubility of molybdenum trioxide in liquid-undersaturated water vapour has been investigated experimentally at 300, 320, and 360°C and 48 to 163 bars. Results of these experiments show that the solubility of MoO3 in the vapour phase is between 1 and 23 ppm, which is 19-20 orders of magnitude higher than that in a water-free system. Molybdenum solubilities increase linearly with fH2O , indicating that the metal forms a gaseous hydrated complex of the type MoO3·nH2O by the reaction: MoO3g+nH 2Og=MoO3· nH2Og A1 The hydration number, n, is interpreted to have a value of 2.6 at 300ºC, 2.5 at 320ºC, and 3.0 at 360ºC. Values of log K for this reaction are 16.9 at 300ºC, 16.5 at 320ºC, and 12.5 at 360ºC.
Calculations based on the extrapolated solubility of MoO 3 in equilibrium with molybdenite at 600ºC and 500 bars, using average H2O and total S fluxes of actively degassing volcanoes, with fO2 and fS2 controlled by the assemblage hematite-magnetite-pyrite, indicate that the vapour phase can transport sufficient Mo in about 900,000 years (within the life of some geothermal systems) to form a deposit of 336 Mt, with an average grade of 0.087% Mo (e.g., the Endako Mo-porphyry deposit, Canada).

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Schuh, Wolfram Dieter, and Wolfram Dieter Schuh. "Geology, geochemistry, and ore deposits of the Bau gold mining district, Sarawak, Malaysia." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/187561.

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District-scale zoning of ore deposits and structural-tectonic setting of Bau was investigated. Regional tectonic studies, structural analysis, and field mapping complemented by aeromagnetic interpretation were integrated to a structural model of Bau. Ores were studied with optical and electron microscopy, followed by major and trace element, fluid inclusion, and lead and sulfur isotope analyses. In the Late Triassic, Bau was in an island arc - back-arc basin environment Following Early Jurassic deformation and uplift, an active margin developed. Subduction of the West Pacific oceanic plate under the NW Kalimantan block began. Erosion of the Triassic Serian Volcanics produced extensive turbidite flows of the Pedawan Formation since the Latest Jurassic. Coeval development of rudist patch reefs on an unstable shelf edge of the overriding plate lasted until Cenomanian. Accretion of the turbidites ended in the Latest Cretaceous. Early Tertiary molasse deposition ended with a Mid-Eocene event. A 200-km-Iong, crustal-scale complex fault system involving dextral strike-slip and wrench faulting, termed the Bau Trend, developed during Mid-Miocene post-subduction regional extension. The principal mineralization event at Bau took place at 12-10 m.a., when I-type, calc-alkaline, reduced granodiorites intruded along the Bau Trend and its intersection with seven parallel, ENE fracture zones, providing channel ways to distribute hydrothermal fluids laterally away from the Bau Trend. Deformation preceding mineralization produced high structural permeability of the host rocks. Central Bau is underlain by an ENE trending, 5x12 km broad plutonic body at depth, inferred from aeromagnetic data. Bau displays district-scale zoning, from proximal porphyry-copper and skarn deposits, via intennediate Cordilleran-Vein base metal mineralization, sediment-hosted precious metal deposits, to distal disseminated Au-As and Ba-Hg-TI deposits. The deposits are hosted in, from proximal to distal, porphyritic granodiorites, limestones, and turbiditic shales. Gradual changes in geochemical, mineralogical, and isotopic compositions across the district indicate consanguinity between them. Epithermal gold mineralization at Bau is most similar to disseminated, sediment-hosted gold deposits of Nevada, except for higher grades, visible occurrence of gold, both base and precious metal signatures, purely structural controls, less radiogenic lead, and magmatic sulfur isotope signatures.

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Robison, Lori Carol 1955. "Geology and geochemistry of Proterozoic volcanic rocks bearing massive sulfide ore deposits, Bagdad, Arizona." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/558078.

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13

Claesson, Lars-Åke. "The geochemistry and palaeotectonic setting of lower proterozoic metavolcanic rocks and related intrusives in the Skellefte massive sulphide ore district, northern Sweden." Licentiate thesis, Luleå tekniska universitet, 1994. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26007.

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Bao, Zhiwei. "Geochemistry of the sediment-hosted disseminated gold deposits in Southwestern Guizhou Province, China." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2001. http://theses.uqac.ca.

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Phillips, I. M. "The geochemistry and mineralogy of Carboniferous shales in relation to ore genesis in Northern England." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378355.

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Carignan, Jean. "Les isotopes du Pb en métallogénie : chronomètres et traceurs du mode de formation de gites de Mo, Au, Ni, Cu et Pb dans les provinces du Supérieur et de Grenville du Bouclier Canadien /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1992. http://theses.uqac.ca.

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Lillo, Ramos Francisco Javier. "Geology and geochemistry of Linares-La Carolina Pb-ore field (southeastern border of the Hesperian Massif)." Thesis, University of Leeds, 1992. http://etheses.whiterose.ac.uk/12721/.

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Base-metal late Hercynian vein and stratabound-type deposits occur in the Linares-La Carolina mining district (Sierra Morena, Spain). No other ore deposits than iron beds and a supergene iron-manganese karst-related deposit were found in the studied area. However, Upper Ordovician-Lower Silurian rocks show Ni, Zn, Pb content above the average values of sandstones. Upper Ordovician-Lower Silurian country rocks are grouped into two stratigraphical sequences that reflect sea-level rise-fall cycles in a basin developed in a passive margin. The duration of these cycles indicates that they were caused by a combination of eustatic processes and intraplate extensional tectonics. The Late Hercynian hydrothermal deposits hosted by metasediments and granitoids, comprise (Ba)-(Pb-Zn-Cu- [Ag]) vein and stratabound type deposits that were emplaced before the Ladinian, during an extensional stage starting in the Upper Permian. Three stages of ore deposition have been recognised, the first stage is characterised by the formation of pyrrhotite, arsenopyrite, Ag sulphosalts and minor arsenopyrite and Bi sulphides. In the second stage, pyrite, Cu sulphides, barite and Ni-Co mineral s precipitated. Main deposition of galena and sphalerite took place at the end of the first stage and the beginning of the second stage. There is no evidence of selective Ag enrichment. Hydrothermal alteration of granitic host rocks is characterised by argillic-phyllic, argillic-propylitic assemblages overprinted by a late alkai metasomatism. There is a strong relation between composition of secondary minerals, mineralogy of the alteration zone and whole-rock composition. Mass transfers of alumina appear to be important. There is a significant introduction of Si, AI, K, Na, Rb and Pb, together with a depletion in Ca and Sr. Chlorite and illite geothermometers indicate temperatures of 276.7-321.5 ·C. Three events of fluid entrapment at hydrostatic pressures have been recognised, with fluids evolved from low to moderate, locally carbonaceous hot fluids to highmoderately polysaline cooler fluids. Ore-lead was derived from Palaeozoic U-'enriched' country rocks, although some participation from the Hercynian granitoids can not be ruled out. The distribution of sulphur isotopes is not homogeneous in the scale of the district. Differences exist between those deposits at the El Centenillo-Santa Elena sector (where the dominant process was the mixing of 'magmatic'-derived sulphur and sulphur derived from the metasediments) and those occurrences at the Linares-La Carolina sector (where the dominant sulphur was 'magmatic'-derived).

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Johnson, Nancy Ann 1958. "Geochemistry of two exhalite horizons at the Copper Chief Mine, Jerome District, Arizona." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/558106.

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Sahlström, Fredrik. "Ore Petrography and Geochemistry of some REE-bearing Fe-oxide Assemblages from the Idkerberget Deposit, Bergslagen, Sweden." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182875.

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The mine dumps of Kiruna-type apatite-iron oxide ore in Bergslagen, South Central Sweden, contain elevated amounts of rare earth elements (REEs). A recently started project at Uppsala University has been initiated to study these ores among others in order to document occurrences of REEs and other critical elements in the mine dumps. In this study a selection of samples from the Idkerberget deposit have been studied with respect to their geochemistry and petrography with a special focus on REE-bearing phases. In addition, their mining potential and their relationship to related ore deposits such as Blötberget, Grängesberg and Kiirunavaara have been considered. The bulk geochemistry of the ores was analyzed using ICP-ES and ICP-MS. Polished sections of the ore samples were studied using ore microscopy, SEM-EDS and WDS microprobe technique. The results indicate that the ores consist mainly of magnetite and hematite, with minor silicates, flourapatite, pyrite, chalcopyrite, monazite-(Ce), allanite-(Ce), thorium silicate, titanite and zircon. Most REEs were originally hosted in flourapatite, but metamorphic and/or hydrothermal overprinting has resulted in complex textures and neomineralisation involving exotic REE-bearing minerals such as monazite-(Ce), allanite-(Ce) and secondary flourapatite. These features have also been observed in the related ore deposits nearby. The ores are enriched in REEs by factors between 1 and 9 compared to crustal values, with LREEs being the most enriched. These enrichments are rather low compared to other REE-ores currently being mined, but the easy access to the ores could mean that mining can be profitable with the current demand of these commodities.
Varphögar av apatitjärnmalm av Kirunatyp ifrån järnmalmsbrytning i Bergslagen, Sydcentrala Sverige, innehåller förhöjda halter av sällsynta jordartsmetaller. Ett projekt vid Uppsala Universitet undersöker förekomster av sällsynta jordartsmetaller och andra kritiska element i varphögar bland annat från apatitjärnmalmer. I denna studie har prover från ett av Bergslagens apatitjärnmalmsfält, Idkerberget, undersökts geokemiskt och petrografiskt med fokus på faser som innehåller sällsynta jordartsmetaller. Deras utvinningspotential och deras relation till liknande förekomster såsom Blötberget, Grängesberg samt Kiirunavaara har också tagits i beaktning. Bulkgeokemin i proverna analyserades med ICP-EM och ICP-MS. Polerprov av malmerna undersöktes medelst optisk mikroskopi, SEM-EDS samt med WDS-mikrosondteknik. Resultaten visar att malmerna framförallt består av magnetit och hematit, med mindre mängder silikater, flourapatit, pyrit, kopparkis, monazit-(Ce), allanit-(Ce), thoriumsilikat, titanit och zirkon. Sällsynta jordartsmetaller är i huvudsak bundna i flourapatit, men metamorfa och/eller hydrotermala processer har resulterat i nybildningen av exotiska mineral såsom monazit-(Ce), allanit-(Ce), och sekundär flourapatit. Dessa egenskaper har även observerats i apatitjärnmalmer från andra platser. Proverna från Idkerberget har 1-9 gånger högre koncentration av sällsynta jordartsmetaller än jordskorpan generellt, och lätta sällsynta jordartsmetaller är de mest anrikade. Dessa halter är relativt låga jämfört med sällsynta jordartsmalmer som bryts i dagsläget, men eftersom materialet förekommer i enorma varphögar gör tillgängligheten att metallerna ändå kan utvinnas med vinst om efterfrågan på denna resurs består.

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20

Rigali, Mark Joseph 1963. "Chemical characterization of solid graphitic carbonaceous matter associated with the Oklo natural fission reactors and uranium ore deposits, Gabon (West Africa)." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/288812.

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Solid graphitic carbonaceous matter (CM) is closely associated with the Oklo uranium ore deposits and several of the natural fission reactors in Gabon, West Africa. This material facilitated the containment of uranium and numerous fissiogenic isotopes in these natural reactors for a period of nearly 2 Ga. Hence it is the subject of detailed studies because it may be useful as an analogue for carbonaceous materials, e.g. technical bitumens, that are currently being considered for the encapsulation and storage of anthropogenic radioactive waste. Chemical and structural analyses of the uraniferous CM associated with the natural fission reactors indicate that it is a polymer-like solid composed mainly of polycyclic aromatic hydrocarbons (PAHs) that are randomly oriented (turbostratic) and vary in size from several to several tens of A. Short-chained aliphatic hydrocarbons and oxygen-bearing moieties are attached to the PAH sheets and frequently bridge adjacent sheets. The Oklo uraniferous CM exhibits very high free radical concentrations, which can exceed 1021 free radicals/g organic carbon. The organic free radicals are stable PAH moieties located at or very near the surfaces of these organic solids, mainly on the internal surfaces of pores. Despite their presence, these pores could not have served as effective conduits for the transport of radionuclides by aqueous solutions through and out of the CM matrix. This is because of the very small average size of the pores, together with the CM's non-wettability by aqueous solutions. The Oklo CM has endured oxidation-reduction reactions during uranium mineralization, exposure to ionizing radiation, and alteration associated with the radiolysis products of water during and after natural reactor operation, perhaps up until the present time. Still, the CM acted as an effective barrier to radionuclide migration out of the CM-rich natural fission reactors. Properties, including its aromatic composition, resistance to alteration by ionizing radiation, and its non-wettability to aqueous solutions, make the Oklo uraniferous CM an effective barrier to radionuclide migration. These properties should be incorporated into man-made carbonaceous materials currently being considered for use in the storage of radioactive waste.

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21

Magnan, Martin. "La zone 87 du gisement d'or et de cuivre du lac Troilus : pétrographie et géochimie /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1993. http://theses.uqac.ca.

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22

Mekkaoui, Alaoui Moulay El Mustapha. "Caractérisation géochimique, pétrologique et métallogénique du gisement de sulfures massifs vocanogènes ANSIL /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1996. http://theses.uqac.ca.

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23

Törmänen, T. (Tuomo). "Ore mineralogy, geochemistry, and formation of the sediment-hosted sea floor massive sulfide deposits at Escanaba Trough, NE Pacific, with emphasis on the transport and deposition of gold." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514276264.

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Abstract Recent sea floor sulfide deposits form when seawater, heated within the oceanic crust, discharges to the sea floor. Upon mixing with cold seawater, sulfide-forming elements such as sulfur, iron, copper, and zinc are precipitated from the fluid. Actively forming sea floor massive sulfide deposits are found from different lithologic and tectonic environments varying from mid-ocean ridges to back-arc spreading centers. At a few localities, sulfide deposits are associated with turbiditic sediments that cover the axial valley of the spreading center. The southern part (Escanaba Trough) of the Gorda Ridge (NE Pacific) is one such example. At Escanaba Trough, massive sulfide deposits are associated with small sediment hills, which were uplifted by the intrusion of sills and laccoliths within the sediments. Hydrothermal deposits are dominated by pyrrhotite-rich massive sulfides, with subordinate amounts of sulfate-rich precipitates and polymetallic sulfides. Compared to deposits hosted by volcanites, Escanaba Trough sulfides contain relatively low amounts of copper and zinc. However, the average gold concentration is relatively high for a sediment-hosted deposit, and is comparable with other, Au-enriched, sea floor sulfide deposits. Despite the relatively high Au concentration in many volcanic-hosted sea floor sulfide deposits, discrete Au grains are rare. They occur mostly with sphalerite, pyrite, chalcopyrite and tetrahedrite-tennantite. Sixteen of the pyrrhotite-rich samples from Escanaba Trough were found to contain visible Au grains. They occur mostly with native Bi and various BiTe phases, and to lesser degree, with Fe-Co sulfarsenides. Transport of Au in sea floor hydrothermal systems is attributed to the presence of Au(HS)2- complex, which is destabilized when the fluid mixes with seawater. Hydrothermal fluids are generally undersaturated with respect to Au complexes and additional mechanisms, such as remobilizing earlier precipitated Au is required to explain the high Au concentrations encountered in many deposits. At Escanaba Trough the mechanism is attributed to early precipitation of Bi as melt droplets, at temperatures greater its melting temperature, as liquid Bi is capable of collecting Au even from an undersaturated fluid. Upon cooling Au is exsolved from the Bi host as native Au or maldonite (Au2Bi).

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24

Harawa, Esau Tonderai. "Mineralogy and geochemistry of structurally-controlled metasomatic alteration of carbonate-rich manganese ore at Mamatwan Mine, Kalahari Manganese Field." Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/4717.

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The Kalahari Manganese Field (KMF) located in the Northern Cape Province about 700km south west of Johannesburg contains 80% of the world manganese ore reserves. Mamatwan Mine is hosted within the low grade Mamatwan type ore and is located in the southernmost tip of the KMF. This mine is an open pit mine which is divided into three benches namely the top cut, middle cut and bottom cut. These three benches are structurally controlled by faults which influence the overall grade of the manganese ore. This study is a follow up work to the previous two studies carried out at Wessels Mine and Mamatwan Mine by (Gutzmer and Beukes) in 1995 and 1996 respectively with regards to alteration processes around fault controlled systems in which they concluded that epithermal fluids caused local reduction and bleaching of ore followed by oxidation and carbonate leaching of manganese ore through ascending oxidized groundwater. Metasomatic activity around fault controlled systems is controlled by three main processes namely redistribution, enrichment and depletion. These processes are determined by mobility/immobility of elements from the fault which are introduced into the pre-existing braunite carbonate rich ore. Elements such as Ca, Mg, Si, Fe, C and Mn interact with pre-existing ore due to temperature, fluid pressure, physico-chemical property of fluid gradient. Structurally, faulting and folding contribute to the movement of elements as one end of the system gets depleted the other end of the system gets enriched and vice versa. To better understand this metasomatic activity, it is crucial to conduct mass balance studies of these elements. Grant (1986) introduced the isocon diagram which is a modification of Gresen’s equation (1967) to ascertain which elements are directly or indirectly related to alteration through enrichment and depletion of Ca, Mg, Si, Fe, C and Mn. As the section approaches from altered to less altered manganese ore the mineral chemistry gradually changes from a manganese rich matrix composed of manganomelane and todorokite to a carbonate rich matrix composed of braunite, dolomite, kutnohorite and Mn-rich calcites.

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Hammond, Napoleon Quaye. "The geochemistry of ore fluids and control of gold mineralization in banded iron-formation at the Kalahari Goldridge deposit, Kraaipan greenstone belt, South Africa." Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1008370.

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The Kalahari Goldridge mine is located within the Archaean Kraaipan Greenstone Belt about 60 km SW of Mafikeng in the Northwestern Province, South Africa. Several gold deposits are located within approximately north - south-striking banded iron-formation (BIF). Current opencast mining operations are focused on the largest of these (D Zone). The orebody is stratabound and hosted primarily in the BIF, which consists of alternating chert and magnetite-chloritestilpnomelane-sulphide-carbonate bands ranging from mm to cm scale. The ore body varies in thickness from 15 to 45 m along a strike length of about 1.5 km. The BlF is sandwiched between a sericite-carbonate-chlorite schist at the immediate footwall and carbonaceous meta-pelites in the hanging-wall. Further west in the footwall, the schists are underlain by mafic meta-volcanic amphibolite. Overlying the hanging-wall carbonaceous metapeiites are schist units and meta-greywackes that become increasingly conglomeratic up the stratigraphy. Stilpnomelane-, chlorite- and minnesotaite-bearing assemblages in the BlFs indicate metamorphic temperatures of 300 - 450°C and pressures of less than 5 kbars. The BIF generally strikes approximately 3400 and dips from 60 to 75°E. Brittle-ductile deformation is evidenced by small-scale isoclinal folds, brecciation, extension fractures and boudinaging of cherty BIF units. Fold axial planes are sub-parallel to the foliation orientation with sub-vertical plunges parallel to prominent rodding and mineral lineation in the footwall. Gold mineralization at the Kalahari Goldridge deposit is associated with two generations of subhorizontal quartz-carbonate veins dips approximately 20 to 40°W. The first generation consists of ladder vein sets (Group lIA) preferentially developed in Fe-rich meso bands, whilst the second generation consists of large quartz-carbonate veins (Group lIB), which crosscut the entire ore body extending into the footwall and hanging-wall in places. Major structures that control the ore body are related to meso-scale isoclinal folds with fold axes subparallel to mineral elongation lineations, which plunge approximately 067°E. These linear structures form orthogonal orientation with the plane of the mineralized shallowdipping veins indicating stretching and development of fluid - focusing conduits. A second-order controlling feature corresponds to the intersection of the mineralized veins and foliation planes of host rock, plunging approximately 008°N and trending 341°. G0ld is closely associated with sulphides, mainly pyrite and pyrrhotite and to a lesser extent with bismuth tellurides, and carbonate gangue. The ore fluid responsible for the gold deposition is in the C-O-H system with increased CH₄ contents attributed to localized hydrolysis reaction between interbedded carbonaceous sediment and ore fluid. The fluid is characterized by significant C0₂ contents and low salinities below 7.0 wt % NaCl equivalent (averages of 3.5 and 3.0 wt % NaCl equivalent for the first and second episodes of the mineralization respectively) . Calculated values of f0₂. ranging from 10⁻²⁹·⁹⁸ to 10⁻³²·⁹⁶ bars, bracket the C0₂-CH₄ and pyrite-pyrrhotite-magnetite buffer boundaries and reveal the reducing nature of the ore fluid at deposition. Calculated total sulphur content in the ore fluid (mΣs), ranges from 0.011 to 0.018M and is consistent with the range (10⁻³·⁵ to 10⁻¹M) reported for subamphibolite facies ore fluids. The close association of sulphides with the Au and nature of the fluid also give credence that the Au was carried in solution by the Au(HS)₂ - complex. Extensive epigenetic replacement of magnetite and chlorite in BIF and other meta-pelitic sediments in the deposit by sulphides and carbonates, both on meso scopic and microscopic scales gives evidence of an interaction by a CO₂- and H₂S-bearing fluid with the Fe-rich host rocks in the deposit. This facilitated Au precipitation due to changes in the physico-chemical conditions of the ore fluid such as a decrease in the mΣs and pH leading to the destabilization of the reduced sulphur complexes. Local gradients in f0₂ may account for gold precipitation in places within carbonaceous sediments. The fineness of the gold grams (1000*Au/(Au + Ag) ranges from 823 to 921. This compares favourably with the fineness reported for some Archaean BIFhosced deposits (851 - 970). Mass balance transfer calculations indicate that major chemical changes associated with the hydrothermal alteration of BIF include enrichment of Au, Ag, Bi, Te, volatiles (S and CO₂), MgO, Ba, K and Rb but significant depletion of SiO₂ and minor losses of Fe₂O₃. In addition, anomalous enrichment of Sc (average, 1247%) suggests its possible use as an exploration tool in the ferruginous sediments in the Kraaipan greenstone terrane. Evidence from light stable isotopes and fluid inclusions suggests that the mineralized veins crystallized from a single homogeneous fluid source during the two episodes of mineralization under the similar physicochemical conditions. Deposition occurred at temperatures rangmg from 350 to 400°C and fluid pressures ranging from 0.7 to 2.0kbars. Stable isotope constraints indicate the following range for the hydrothermal fluid; θ¹⁸H₂O = 6.65 to 10.48%0, 8¹³CΣc = -6.0 to -8.0 %0 and 8³⁴SΣs = + 1.69 to + 4.0%0 . These data do not offer conclusive evidence for the source of fluid associated with the mineralization at the Kalahari Goldridge deposit as they overlap the range prescribed for fluid derived from devolatization of deep-seated volcano-sedimentary piles near the brittle-ductile transition in greenstone belts during prograde metamorphism, and magmatic hydrothermal fluids.
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26

Calapa, Kayla. "Hydrologic alteration and enhanced microbial reductive dissolution of Fe(III) (hydr)oxides under flow conditions in Fe(III)-rich rocks: contribution to cave-forming processes." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619628782604003.

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27

Blake, Kevin L. "The petrology, geochemistry and association to ore formation of the host rocks of the Kiirunavaara magnetite-apatite deposit, northern Sweden." Thesis, Cardiff University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321483.

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28

Beck, Kimberly D. "Investigation of the Lead Isotope Signatures of Marine Sediments in Relation to the Lead Isotope Signatures of Northern Andean Ores." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2201.

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Lead isotope ratios of ores and igneous rocks in the Central and Southern Andes show a large-scale geographic pattern related to magmatic source processes. This pattern changes in the Northern Andes for reasons that are not well understood; this study is an investigation of potential causes of this change. Deep ocean sediment samples from the Nazca Plate were analyzed for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb, and the data were compared with published data on central Andean ores and ores and igneous rocks from Ecuador. Lead isotopic compositions of the Nazca Plate sediments are quite homogenous and are a close match with Andean ore lead in the coastal arc from central Perú through south-central Chile. However, the lead isotope ratios of the sediment samples are much lower than northern Perú and Ecuador ores. Variations in sediment composition are probably not the source of the northern Andean ore lead isotope pattern.

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Dunbar, Alyssa C. "Using Surficial Geochemical Methods to Detect Anomalies of Ore Indicator Metals in a Peat Bog at McIlvenna Bay, Saskatchewan, Canada, as a Method for Blind VMS Deposit Exploration." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35833.

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Surficial geochemistry, particularly selective leach technology, has proven effective in revealing anomalous concentrations of ore indicator metals overlying zones of buried mineralization. This study focuses on the buried Zn-Cu-Au-Ag VMS deposit at McIlvenna Bay in the Flin Flon Greenstone Belt to determine whether the peat swamp at the surface contains any anomalies of ore indicator metals using simple surficial geochemical techniques. Three selective leaches were performed, ammonium acetate pH 5.0, hydroxylamine, and sodium pyrophosphate. The hydroxylamine leach, which selects for metals in the reducible phase often associated with Mn and Fe oxides, has the clearest anomaly for multiple metals observed simultaneously, at the greatest magnitude. The pyrophosphate leach, which selects for metals that are oxidizable, often associated with organics showed a clear anomaly only for Cu, despite the abundance of organic matter and its great affinity for binding metals, likely because the organic-metal complexes formed in this system are easily exchangeable and highly soluble, not allowing for the formation of clear anomalies. The use of selective leach technology on surficial soil or peat has shown to be effective for delineating ore indicator metal anomalies, giving surface projections of buried mineralization in various types of systems, as long as the dynamics of the system are well understood in order to determine the phase the metals are associated with.

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Harnois, Luc Carleton University Dissertation Geology. "Geochemistry of the ore chimney formation and associated metavolcanic rocks and gold deposits in the Flinton-Harlowe area, Grenville province, southeastern Ontario." Ottawa, 1987.

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31

John, Kangeze Biteme. "Ore forming potential of the Atchiza Suite and Sustainable management of mineral deposits in Mozambique : "Petrology, geochemistry and sustainable management of mineral deposits"." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for geologi og bergteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20380.

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Part 1- Abstract This research study presents detailed petrographic- and geochemical- analysis of 63 rock samples from the Atchiza Suite. The Suite is a layered mafic-ultramafic pluton located in the Tete Suite, of NW Mozambique. At present, the Atchiza comprises a group of three main types of rock that are classified based on their mineralogy, textures, geochemical composition. These are ultramafic cumulates (dunite and pyroxenites), mafic cumulates (medium-grained cumulate gabbro) and coarse-grained gabbro (non-cumulate gabbro). Compared to the rest of other rocks, coarse-grained gabbro shows high enrichment of Ti (0.64-3.46 wt% TiO2), Zr (5.9-296.1 5ppm), Sr (253.7-1268.4ppm) and V (224-952.3ppm), but relatively low depleted in compatible elements (Ni = 48.7-235.7ppm , Cr = below detection limit to 410.5ppm). Cumulate ultramafics are highly enriched in compatible elements (Ni up to 4636.2ppm, Cr up to 4721ppm). A high Mg# in ultramafic cumulates (0.59-0.86) suggests an Mg-rich primitive parental magma, whereas a low Mg# in coarse-grained gabbro (0.23-0.37) suggests a relatively high-differentiated magma. Cumulate gabbro shows Mg# ranging from 0.40-0.72, suggesting a moderately evolved magma source (derivative magma subsequent to fractionation of ultramafic cumulates). The Ni/Zr, Cr/Zr, Sr/Zr and Ti/Zr ratios are generally the lowest in coarse-grained gabbro when compared to cumulate rocks. The same applied; this suggests that coarse-grained gabbros were probably formed from a relatively high-differentiated magmatic liquid. In addition, the presence of an uninterrupted cryptic differentiation trend with these ratios implies that the Atchiza igneous lithologies were derived from one and the same parental melt. Apparently, Atchiza shows great variability of Fe2O3, SiO2 and SO3 during magmatic differentiation. There is significant decrease in Fe2O3, an increased SiO2 and SO3 contents in residual magma during progressive magma fractionation. It is true that all these geochemical changes will lower down the solubility of S in the system, thus providing a favourable condition for silicate-sulfide immiscibility. Theoretically, therefore, the Atchiza may have a potential to host Ni-Cu-(PGE) sulfide deposits. Part 2- Abstract Unlike water and forests, minerals are finite resources; they cannot be replaced back to their natural forms once they are depleted. For that reason, sustainable management of mineral resources is very important so that stakeholders in the extractive sector are guaranteed the same opportunities in sharing benefits. As part of this study, and with respect to Atchiza Suite, this section is discussing sustainable management of mineral deposits in Mozambique. Investment in Mozambican extractive industry should primarily be done with the main objective of poverty reduction for Mozambican citizens. Thus, the Mozambican Government needs to realize that proper management of mineral deposits will provide sufficient income for the country, enough to fund other development projects. Rather than being mismanaged, this massive collection of mineral revenues needs to be appropriately re-invested back to diversify other economic sectors. If this mineral revenue is managed wisely, the national annual budgets will be sufficiently supported. Most importantly, the country’s reliance on international loans and aids will be reduced significantly. Decision-making for development of the country’s mineral projects should not be central-governed; rather it should be transparent to the public and open for opinions and suggestions. As the main stakeholder in Mozambican extractive sector, local communities and civil societal groups should also be given opportunities to participate in decision-making, important for the development of mining projects. Mineral agreements for which the Mozambican State has been signing with multinational companies for development of the country’s mineral projects need to be published and be available publicly. In addition, negotiation of mining agreements must be transparent and involve all stakeholders. Investment and development of the country’s mineral projects must be performed through partnerships and Joint ventures between multinational mining companies, national-based companies and the Mozambican State. Development of mineral deposits must incorporate environmental sustainability. Despite its high mineral potential (e.g. Ni-Cu-PGE-Ti-V), Atchiza also is surrounded by a wide range of other natural resources. The Cahora Bassa Dam, which is located just adjacent to Atchiza Project, is the main source of clean energy not only for Mozambique domestic market, but also for the majority of Sub-Saharan countries. All of these natural resources require good practice of Environmental sustainability in mining activities.

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Howarth, Geoffrey Hamilton. "Petrogenesis and metallogenesis of the Panzhihua Fe-Ti oxide ore-bearing mafic layered intrusion, SW China." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001810.

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The Panzhihua intrusion is one of several large Fe-Ti oxide ore bearing intrusions related to the major flood volcanism of the Emeishan Large Igneous Province (ELIP), SW China. The Panzhihua intrusion in particular has recently become the focus of numerous studies owing to the excellent exposure in large open pit mining operations. The formation of Fe-Ti oxide ore layers has been the focus of these studies and has become a somewhat controversial topic with three separate models currently proposed for ore formation. The gabbroic Panzhihua intrusion extends for ± 19 km along strike, has a maximum thickness of 3000 m and hosts extensive (up to 60 m thick) Fe-Ti oxide ore layers in the lower portions of the intrusion. The intrusion has been divided into five zones: marginal zone (MGZ), lower zone (LZ), middle zone A (MZa), middle zone b (MZb) and the upper zone (UZ). The gabbroic rocks are comprised of plagioclase, clinopyroxene and interstitial Fe-Ti oxides with minor olivine. Apatite is present within the MZb only and shows no correlation with Fe-Ti oxide ore layers. Fe-Ti oxides are present throughout the stratigraphy of the intrusion. This is unlike typical layered intrusions where significant Fe-enrichment through fractionation of Fe-poor silicate phases (i.e. plagioclase) is required before Fe-Ti oxide saturation. There are no oxide-free cumulate rocks at the Panzhihua intrusion, implying either an evolved parent magma or very high Fe content of the source rocks. I present here new mineral composition data, whole-rock major and trace element geochemistry along with whole-rock Sr-Nd isotopes and PGEs in order to constrain the evolution of the Panzhihua parent magma en route from source to chamber and the formation of Fe-Ti oxide ore layers. Furthermore an initial pilot study using O-isotope data is conducted on Ti-magnetite and plagioclase separates from gabbroic vs. ore rocks. Results are coupled with detailed thermodynamic modeling using the software PELE in order to further constrain Fe-Ti oxide ore layer formation. The intrusion is characterised by extreme depletion of PGEs relative to the coeval flood basalts and picrites. High Cu/Pd and Pd/Pt imply two separate stages of S-saturated and S-undersaturated depletion of PGEs. Pd is highly compatible in sulphide and is quickly scavenged by sulphide liquids resulting in an increase in Cu/Pd of the residual liquid. Furthermore decoupling of Pd and Pt can be achieved by either late stage hydrothermal alteration or through S-undersaturated stage of PGE depletion where Pt is scavenged by Pt-rich alloys or oxide minerals. I show that the latter is more likely. Fractionation modeling suggests that the Panzhihua parent magma formed at depth from original picritic magma. This is consistent with several other recent studies on other layered intrusions of the ELIP. Sr-Nd isotopic ratios indicate very little crustal contamination has occurred en route to the current chamber. Sr and Nd concentrations of footwall rocks are too low to produce any significant change in initial Sr and Nd isotopic ratios of the intruding basaltic magmas, indicating that crustal contamination will not be indicated by Sr-Nd isotopic ratios. Gradational change in the Sr-Nd isotope ratios across the MGZ provides strong evidence for formation in an open system by multiple replenishments of progressively less contaminated magmas from depth. Contamination is difficult to constrain but must be occurring prior to emplacement at the current level (low Sr and Nd contents of footwall). A gradational upward decrease in highly incompatible element across the MGZ can then be explained by continuous magma flow, which effectively removes the evolved intercumulus liquids from the growing cumulate pile at the base of the chamber. The initial stages of formation of the Panzhihua intrusion are interpreted to result from prolonged low volume pulses of magma into a slowly opening chamber. The timing of Fe-Ti oxide crystallisation is fundamental in the understanding of the petrogenesis of ore layers. Distinct geochemical variation in whole-rock Fe2O3/TiO2 and Zr/Nb indicates that Timagnetite is the dominant oxide within the lower ± 270 m of the intrusion whereas above this level both Ti-magnetite and ilmenite are present as cumulus phases. This is interpreted to indicate a variation in the fO2 where the lower intrusion crystallises at higher fO2 relative to that above this level. Silicates within the ore layers, in particular plagioclase, are highly embayed and resorped where in contact with Fe-Ti oxides. This characteristic of the silicate grains implies early crystallisation prior to Fe-Ti oxides with subsequent disequilibrium conditions resulting in resorption. Furthermore distinct reaction rims of kaersutite amphibole, Fo-enriched olivine, An-enriched plagioclase and pleonaste are observed. The abundance of amphibole suggests H2O involvement in this reaction and consumption of silicates. A model for parent magma crystallisation at various H2O contents indicates that plagioclase crystallisation temperature is very sensitive to H2O content of the parent magma. Plagioclase crystallises early for “dry” compositions but significantly later for “wet” compositions. Fe-Ti oxide ore layers are generally well layered, contain gabbroic xenoliths and are observed raversing/cross-cutting the cumulate stratigraphy. I present here a new model for ore layer formation in order to account for these distinct features of the ore layers. A model invoking multiple replenishments of magma with variable oxide microphenocryst content, H2O content and volume is proposed. Magma evolving in the plumbing system and fed to the Panzhihua chamber is variably enriched in H2O, which results in significantly different crystallisation paths. High H2O magmas (> 2 wt %) crystallise Fe-Ti oxides early whereas low H2O magmas (< 1 wt %) crystallise oxides late. Early pulses of H2O-poor magma crystallise a sequence of plag+cpx+Fe-Ti oxide (±ol). Later pulses of H2Orich magma subsequently intrude the partially crystallised cumulate sequence incorporating and consuming previously crystallised silicates with subsequent early crystallisation of Ti-magnetite and formation of ore layers. H2O-rich magmas likely have suspended Ti-magnetite microphenocrysts as well, which crystallise at depth in the plumbing system. This model can account for the various characteristic features of the Fe-Ti oxide ore layers at the Panzhihua intrusion as well as other Fe-Ti oxide ore bearing intrusions in the region.

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Green, Bradley. "A study of the Wilkins and Green and Gold Copper-gold prospects, Olary Block, South Australia with emphasis on petrology, geochemistry and ore mineralogy /." Title page, contents and abstracts only, 1996. http://web4.library.adelaide.edu.au/theses/09SB/09sbg811.pdf.

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Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1998.
Australian National Grid Reference (SI 54-2) 1:250 000. Four folded maps in pocket pasted onto back cover. Includes bibliographical references (leaves 62-68).

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Chhun, Eath. "Ordovician igneous rocks of the central Lachlan Fold Belt : geochemical signatures of ore-related magmas /." University of Sydney. Geosciences, 2004. http://hdl.handle.net/2123/610.

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The majority of economic gold deposits in NSW are associated with Ordovician-aged igneous rocks and are examples of the Cu-Au porphyry-skarn-epithermal association commonly developed in convergent margin to orogenic settings. They are among the oldest porphyry Cu-Au deposits in the Pacific Rim region. They are similar to younger deposits in terms of tectonic setting and structure, but the largest are chemically distinct, being associated with shoshonite magmas (Cadia, Ridgeway and Northparkes). The Lachlan Fold Belt (LFB) porphyries are subdivided into four sub-groups based mainly on their age relative to development of the Lachlan Transverse Zone (LTZ) structure. Two subgroups pre-date the LTZ, one group is syn�LTZ and one group post-dates the LTZ. No mineralisation has been found or reported among pre-I.TZ porphyries. but it is common in post- . l Z_ porphyries. Petrographic analysis and microprobe results establish a wide range of primary and secondary features within the Ordovician rocks examined in this study. Cale alkaline to shoshonitic affinities are supported by the variable abundance of primary K-feldspars. Primary mineral phases such as pyroxenes and igneous magnetite provide an indication of fractioning mineral assemblages responsible for igneous trends in magma chemistry. The hydrothermal mineral assemblages documented in these LFB study areas are characteristic of younger Cu-Au Porphyry style mineralisation. As expected, the most pervasive alteration is associated with highly mineralised shoshonitic Ordovician rocks at Ridgeway, and Cadia. the less strongly mineralised calc alkaline Ordovician rocks at Cargo. Copper Ilill and Fairholme. are correspondingly less strongly altered overall. although secondary mineral assemblages are locally abundant. Many varieties of oxides and carbonates are observed at the different study localities. Most of the studied samples conform to igneous chemical trends because they are weakly altered, although post magmatic processes, such as veining, are detectable in certain trends. The K2O enrichment of the studied samples is consistent with subductionmoditied mantle wedge sources. A few effects, such as the high Fe203 contents of some Ridgeway samples, probably reflect porphyry-style hydrothermal alteration processes. Host rocks at the Cadia and Ridgeway are entirely alkalic on the K2O versus SiO2 plot and shoshonitic on the Total Alkalies versus SiO2 plot. Igneous rocks at the other deposits display a range of compositions between low K tholeiites to shoshonites that in some cases reflects multiple igneous suites. The LREE and L1LE enrichments, and HFSE depletions (Nb, Ta and Ti) of the magmas associated with these deposits are characteristics of a subduction-related tectonic setting. They all fall in the volcanic-arc granite and syn-collisional granite field of the Nb-Y tectonic discrimination diagram. Several magma types are identified by differences in the HFSE and REE trends. Differences in the extent and style of magma fractionation are evident in the trace element data. The Ridgeway samples define a wider range of trace element concentrations than the Cadia samples that may indicate a greater extent of fractionation during emplacement of the Ridgeway magmas. Fairholme samples display a high Nh and /If trends that are distinct from the main fields on Zr variation diagrams. Compositional differences between larger Cu-Au deposits, Cadia-Ridgeway and smaller deposits, Copper Ifill, Cargo and Fairholme are evident in terms of Nb-Ta depletion and variation. The smaller deposits show constant Nb/Ta or negative Nb/Ta trends that extend to high Nb. The larger deposits display positive Nb/Ta trends that do not extend to high Nb. This distinction reflects a difference of preferential incorporation of Nb in a mineral phase (magnetite). Comparisons between Cadia-Ridgeway and other shoshonite (altered samples of Bajo de la Alumbrera, Argentina), calc alkaline magmas from New Zealand and rocks from other areas indicate that Nb/Ta is not directly correlated with the shoshonitic classification, K2O vs. SiO2, and that the Cadia-Ridgeway Nb and Ta variation is not the result of alteration. The fact that the weakly altered LFB Capertee shoshonites exhibit a narrow range of Nb and low Nb/Ta suggest the shoshonite trend for the LFB as a whole is a steep one on the Nb/Ta versus Nb plot. The results of this study could provide important information for exploration within the LFB. Only the Cadia and Ridgeway deposits display a wide range of Nb/Ta values and lack the near-horizontal trend seen for other localities associated with smaller deposits. The tectonic evolution of the LFB is a major factor contributing to occurrence of large porphyry Cu-Au deposits. The sequence of important events, however, commences with sub-crustal generation of oxidised magma and finishes with efficient Cu-Au accumulation by hydrothermal processes at favourable structural sites. The increase in Au-Cu deposit size from small (Copper Hill-Cargo) to world class (Cadia-Ridgeway) indicates the importance of magma composition during this process. The most obvious differences between the Cadia-Ridgeway and New Zealand rocks is that the latter are volcanic in origin and associated with an arc-back arc system. Therefore, they did not form in a tectonic regime suitable for the evolution of porphyries and the focussed movement of hydrothermal fluids during dilatant episodes. As a result, they are not linked to mineralisation despite having Nb-Ta and Nb/Ta variations that are typical of the high oxidation states in Au-prospective magmas of the LFB.

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Michaud, Michael Julien. "The geology, petrology, geochemistry and platinum-group element-gold-copper-nickel ore assemblage of the Roby Zone, Lac des Iles mafic-ultramafic Complex, northwestern Ontario." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0027/MQ52068.pdf.

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Burkhard, Dorothee J. M. "Ore minerals and geochemistry in the serpentinites of the Eastern Central Alps (Davos to the Val Malenco) compared to occurrences in the Klamath Mountains (California and Oregon)." Heidelberg : Ruprecht-Karls-Universität, 1987. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=016704785&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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Halder, Stefan Verfasser], and Bernd [Akademischer Betreuer] [Lehmann. "Genesis of BIF-hosted iron ore deposits in the Carajás mineral province, Brazil : constraints from in-situ Fe isotope analysis and whole-rock geochemistry / Stefan Halder ; Betreuer: Bernd Lehmann." Clausthal-Zellerfeld : Technische Universität Clausthal, 2018. http://d-nb.info/1231364297/34.

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Kokh, Maria. "Rôle du CO2 dans les transferts des métaux d'intérêt économique par les fluides géologiques." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30006/document.

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Le CO2 est le deuxième après l'eau constituant des fluides de haute température (T) et haute pression (P) qui opèrent dans la lithosphère, transportent la matière et forment des dépôts économiques des métaux. Cependant, son effet sur la mobilisation et la précipitation des métaux reste quasiment inconnu faute de données directes et de modèles physico-chimiques. Dans ce travail de thèse, nous avons mis en œuvre des méthodes expérimentales et des analyses chimiques et spectroscopiques sur des fluides modèles riches en CO2, couplées à une modélisation thermodynamique, afin de quantifier, pour la première fois de manière systématique, la solubilité, le partage et la spéciation de divers métaux d'intérêt économique (Fe, Cu, Au, Mo, Pt, Sn, Zn) dans les systèmes eau-gaz-sels typiques des fluides hydrothermaux métallifères. Des mesures de solubilité des principaux minéraux de ces métaux (sulfures, oxydes et métaux natifs) et de leurs coefficients de partage ont été effectuées dans des fluides supercritiques H2O-CO2-S-KCl à 450°C et 500-700 bar et dans des systèmes liquide-vapeur H2O-CO2-S-KCl-NaCl à 350°C, 130-300 bar, à l'aide d'autoclaves à cellule flexible et de réacteurs à séparation de phase que nous avons mis au point. Les conditions d'acidité, de redox et de fugacité de soufre ont été contrôlées par des équilibres entre les minéraux sulfures et oxydes de fer et alkali-aluminosilicates ou entre le sulfate et le sulfure en solution. Les données ont été analysées dans le cadre d'un modèle thermodynamique couplé à une révision critique des données sur la spéciation des métaux en phase fluide. Ce modèle électrostatique ne requière pas de paramètres ajustables; il utilise la constante diélectrique du solvant H2O-CO2 et le paramètre de Born des espèces dominantes en phase aqueuse. Nos résultats montrent que la mobilité des métaux dans les fluides riches en CO2 est contrôlée par la nature et la charge de leurs complexes principaux. La présence du CO2 favorise la stabilité des complexes neutres (FeCl20, AuHS0, CuHS0, ZnCl20, KMoO40, Pt(HS)20) alors que celle des espèces chargées de ces métaux (FeCl42-, Au(HS)2-, CuCl2-, ZnCl42-, HMoO4-, PtCl3-) est considérablement affaiblie. Il en résulte un fractionnement important de certains métaux selon la composition du fluide et le contexte géologique. Notre modèle explique bien l'enrichissement en Fe et l'appauvrissement en Cu des gisements métamorphiques d'or (orogéniques) formés par des fluides riches en CO2. Le transport de l'or par ces fluides est favorisé à faible teneur en soufre (Au(HS)0 est dominante), alors que dans les fluides riches en soufre, typiques des gisements porphyres cuprifères où les complexes chargés sont dominants (Au(HS)2-, Au(HS)S3-), la présence du CO2 aura pour effet d'abaisser la solubilité de l'or. Cependant, même à fortes teneurs en CO2 (>50 wt%), la capacité des fluides à transporter l'or sous forme d'espèces neutres (~100s ppb) reste comparable à celle d'un fluide aqueux, ce qui explique les associations de minéralisations aurifères avec des fluides riches en CO2. L'effet du CO2 sur la mobilité de Mo, Zn et Si qui forment des espèces neutres, est faible dans la plupart des contextes géologiques, alors que celle de Sn pourrait être favorisée par des complexes carbonatés et celle de Pt par des complexes carbonyles (CO). Le rôle direct du CO2 sur le partage liquide-vapeur pour la plupart des métaux est relativement faible devant celui du soufre réduit (H2S) dont la présence favorise fortement l'enrichissement de la phase vapeur en Au, Pt, Mo et Cu. Ainsi le CO2 intervient dans ces processus de démixtion de manière indirecte, en élargissant le domaine T-P d'immiscibilité du fluide. Cette étude démontre que, contrairement aux modèles métallogéniques actuels, la présence du CO2 peut favoriser la mobilité de certains métaux et engendrer des fractionnements importants entre différents métaux lors de l'évolution des fluides dans la croûte terrestre
Carbon dioxide is the second component after water of geological fluids that operate at high temperature (T) and pressure (P) in the lithosphere, transport the metals and form economic deposits. However, its effect on the mobilization and precipitation of metals remains virtually unknown owing to a lack of direct data and physical-chemical models. In this thesis, we have developped experimental methods and chemical and spectroscopic analyzes of CO2-rich fluids, coupled with thermodynamic modeling, to systematically quantify, for the first time, the solubility, distribution and speciation of various metals of economic interest (Fe, Cu, Au, Mo, Pt, Sn, Zn) in gas-water-salt systems typical of metalliferous hydrothermal fluids. Measurements of the solubility of the major minerals of these metals (sulfides, oxides and native metals) and of metal partition coefficients were carried out in supercritical fluids H2O-CO2-S-KCl at 450°C and 500-700 bar and in two-phase vapor-liquid systems H2O-CO2-NaCl-KCl-S at 350°C, 130-300 bar, using flexible-cell and phase-separation reactors that we have set up. The conditions of acidity, redox potential and sulfur fugacity were controlled by equilibria among iron sulfide and oxide minerals and alkali-aluminosilicate minerals or between sulfate and sulfide in the fluid. The data obtained were analyzed in the framework of a thermodynamic model coupled with a critical review of the literature on the metal speciation in the fluid phase. The electrostatic model that we used does not require any adjustable parameters; it is based on the dielectric constant of the CO2-H2O solvent and the Born parameter of the dominant species in the aqueous phase. Our results show that the mobility of metals in CO2-rich fluids is controlled by the nature and electrical charge of their main aqueous complexes. The presence of CO2 favors the stability of the neutral complexes (FeCl20, AuHS0, CuHS0, ZnCl20, KMoO40, Pt(HS)20) whereas that of the charged species of these metals (FeCl42-, Au(HS)2-, CuCl2-, ZnCl42-, HMoO4-, PtCl3-) is largely weakened. This results is significant fractionations between some metals, depending on the composition of the fluid and the geological context. Our model accounts for the enrichment in Fe and depletion in Cu observed in metamorphic orogenic gold deposits formed by CO2-rich fluids. The transport of gold by these fluids is favored at low sulfur content (Au(HS)0 is dominant), whereas in S-rich fluids typical of porphyry copper deposits and high T orogenic gold deposits where the charged complexes are dominant (Au(HS)2-, Au(HS)S3-), the presence of CO2 leads to lowering the solubility of gold. However, even at high CO2 content (> 50 wt%), the ability of fluids to carry gold as neutral species (~100s ppb) remains comparable to that of an aqueous fluid, which explains the associations of gold mineralizations with fluids rich in CO2. The effect of CO2 on the mobility of Mo, Zn and Si, which form neutral species, is weak in most geological situations, whereas that of Sn could be promoted by carbonate complexes and that of Pt by carbonyl (CO) complexing. The direct role of CO2 in the vapor-liquid partitioning of most metals is relatively small compared to that of reduced sulfur (H2S) whose presence strongly favors the enrichment of the vapor by Au, Pt, Mo and Cu. Thus, the main impact of CO2 in these demixing processes is to expand the fluid T-P domain of immiscibility. This study demonstrates that, contrary to common belief, the presence of CO2 can promote the mobility of certain metals and cause significant fractionations between different metals during the evolution of fluids in the crust

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Polteau, Stéphane. "The early proterozoic Makganyene glacial event in South Africa : its implication in sequence stratigraphy interpretations, paleoenvironmental conditions and iron and manganese ore deposition." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1007612.

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The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup in the Griqualand West Basin. It consists of diamictites, sandstones, banded iron-formations (BIFs), shales, siltstones and carbonates. It is generally accepted that the Makganyene Formation rests on an erosive regional unconformity throughout the Northern Cape Province. However this study demonstrates that this stratigraphic relationship is not universal, and conformable contacts have been observed. One of the principal aims of this study is to identify the nature of the Makganyene basal contact throughout the Griqualand West Basin. Intensive fieldwork was carried out from Prieska in the south, to Danielskuil in the north. In the Sishen and Hotazel areas, only borehole material was available to assess the stratigraphy. The Griquatown Fault Zone delimits the boundary between the deep basin and platform facies. The Koegas Subgroup is only present south of the Griquatown Fault Zone, where it pinches out. However, the transition Griquatown BIFs-Koegas Subgroup occurs in lacustrine deposits on the Ghaap platform (Beukes, 1983). The Griquatown Fault Zone represents the edge of the basin, which corresponds to a hinge rather than a fault zone. The Makganyene Formation rests with a conformable contact on the Koegas Subgroup south of the Griquatown Hinge Zone, and north of it the Makganyene Formation lies unconformably on the Asbestos Hills Subgroup. The Makganyene Formation displays lateral facies changes that reflect the paleogeography of the Griqualand West Basin, and the development of ice sheets/shelves. The Ghaap platform is characterised by coarse immature sand interbedded with the diamictites. The clasts in this area contain local Asbestos Hills material and no dropstones are present. Such settings are typical of sediments that are being deposited below a grounded ice mass. At the Griquatown Hinge Zone, the sandstone lenses are smaller, and the clasts consist of chert, of which a great number are striated and faceted. In the Matsap area, the presence of dropstones is strong evidence for the presence of a floating ice shelf that released its material by basal melting. Further south, the Makganyene Formation contains stromatolitic bioherms that only form if clastic contamination is minimal and therefore the ice that transported the detritus to the basin did not extend far into open sea conditions. The base of the Hotazel Formation also contains diamictite levels. Dropstones have been identified, implying a glacial origin. The Hotazel diamictites are interbedded with hyaloclastites and BIFs. The Makganyene glacial event, therefore, was not restricted to the Makganyene Formation, but also included the Ongeluk Formation, through to the base of the Hotazel Formation. Petrographic studies of the Makganyene Formation and the base of the Hotazel Formation reveal mineral assemblages that are diagnostic of early to late diagenetic crystallisation and of low-grade metamorphism not exceeding the very low green-schist facies. The facies identified display the same sense of basin deepening, from shallow high-energy Hotazel area on the Ghaap platform, to the deep basin in the Matsap area. Whole-rock geochemical analyses reveal that the elemental composition of the Makganyene Formation is very similar to that of the Asbestos Hills BIFs, which were the most important source of clastic detritus for the Makganyene Formation. However, minor amounts of carbonates of the Campbellrand Subgroup, as well as a felsic crustal input from the Archean granitoid basement, made contributions. On the Ghaap platform, the Makganyene diamictite is enriched in iron, calcium, and magnesium, while in the deeper parts of the basin the diamictites are enriched in detrital elements, such as titanium and aluminium, which occur in the fine clay component. The Hotazel diamictite displays a distinct mafic volcanic input, related to the extrusion of the Ongeluk basaltic andesites, which was incorporated in the glacial sediments. Sequence stratigraphy is based on the recognition of contacts separating the different systems tracts that compose a depositional sequence. However, because the basal contact of the Makganyene Formation has not been properly identified in previous work, no correct model has been proposed so far. Therefore correlations between the Griqualand West and the Transvaal basins, based on lithostratigraphic similarities and extrapolations of unconformities, have to be reviewed, especially since the publication of new radiometric ages contradict all previously proposed correlations. It is proposed here that the Transvaal Supergroup in the Griqualand West Basin represents a continuous depositional event that lasted about 200 Ma. The Makganyene glacial event occurred during changing conditions in the chemistries of the atmosphere and ocean, and in the continental configuration. A Snowball Earth event has been proposed as the causative process of such paleoenvironmental changes. However, evidence presented here of less dramatic glacial conditions, with areas of ice-free waters, implies an alternative to the Snowball Earth event. The paleoenvironmental changes are thought to represent a transition from an anaerobic to aerobic atmosphere, that was responsible for the global cooling of the surface of the Earth, Such a glacial event may have aided in the large-scale precipitation of iron and manganese in areas of intense upwellings.

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40

Taylor, Mackenzie C. "GOLD FROM THE TYPE 4 ORE OF ROUND MOUNTAIN, NEVADA: A TEXTURAL AND MINERALOGICAL STUDY OF MACROCRYSTALLINE GOLD VS. DISSEMINATED GOLD." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1512407677037903.

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Zhao, Xinfu. "Paleoproterozoic crustal evolution and Fe-Cu metallogeny of the western Yangtze Block, SW China." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43572261.

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Lu, Jun. "Inorganic and organic geochemistry of the zinc ores of the Idol Mine, East Tennessee." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06162009-063123/.

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Keller, Allison Lynn. "Preliminary High-Resolution Time-Lines Through the Cenomanian-Turonian (Late Cretaceous) Oceanic Anoxic Event (OAE 2)." Thesis, University of California, Riverside, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1602646.

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Rapid changes in Earth?s marine environment are sufficiently rare that the scope and consequences of these events cannot be inventoried without recourse to the stratigraphic record of deep pre-historic time. Traditional stratigraphy divides geologic time into a succession of coarse biozones ? uneven time bins, each recognized by distinctive index fossils and spanning several hundred thousand to even a few million years. This thesis uses the CONOP software to resolve sequences of global appearance and disappearance events at the species level across the late Cenomanian oceanic anoxic event (OAE 2) at a much finer resolution than traditional biostratigraphy. The resulting time-lines include information for the Aptian to Maastrichtian from 501 locations, 4,962 taxa, and 25,112 local last occurrences. This dataset is large enough to represent the global environment and to compensate for the inevitably patchy and incomplete record preserved at any one location. Six geographically widespread clades ? ammonites, calcareous nannofossils, dinocysts, benthic forams, planktonic forams, and radiolaria ? were analyzed; they span a range of trophic levels, composition and preferred habitat. Extinction pulses and intervals of falling diversity are not unique to OAE 2 or even uniquely severe. Several occur throughout the Albian-Santonian interval. The key is to monitor trends in diversification rate. OAE 2 is distinguished as a boundary between more positive (or equal in the ammonite case) and more negative diversification regimes. It may have been part of a general habitat deterioration or disturbance, but it would be too simplistic to describe it as a coordinated pelagic extinction event.

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Mach, Craig J. "Tectonic controls, timing and geochemistry of supergene enrichment of the Tyrone porphyry copper deposit, Grant County, New Mexico /." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3342621.

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Thesis (Ph. D.)--University of Nevada, Reno, 2008.
"December, 2008." Accompanying CD-ROM contains appendices C and D. Appendix C: AutoCAD files with drill hole log; Appendix D: excel spreadsheet with copper mass balance calculations. Includes bibliographical references (leaves 206-215). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

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Giovenazzo, Danielle. "Géologie et caractéristiques géochimiques des minéralisations Ni-Cu-EGP de la région de Delta, ceinture de Cape-Smith, Nouveau-Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1991. http://theses.uqac.ca.

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Olivo, Gema Ribeiro. "Les gites d'or palladifères des mines de Caue et de Conceicao, dans les formations de fer du type lac Supérieur du district d'Itabira, Craton Sao Francisco, Bresil : structure, minéralogie, géochronologie et métallogenie = (Palladium-bearing gold deposits of the caue and conceicao mines, hosted by lake superior-type iron-formations of the Itabira district, Sao Francisco craton, Brazil : structure, mineralogy, geochronology and metallogeny) /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1994. http://theses.uqac.ca.

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Schmauder, Gretchen C. "Thermal and chemical profiling of the Bald Mountain District, White Pine County, Nevada /." abstract and full text PDF (free order & download UNR users only), 2005. http://0-wwwlib.umi.com.innopac.library.unr.edu/dissertations/fullcit/1433099.

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Thesis (M.S.)--University of Nevada, Reno, 2005.
"August, 2005." Includes bibliographical references. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

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Doyle, Jessica B. "Geology and structure of Winters Creek, Jerritt Canyon District, Elko County, Nevada." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447627.

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Chi, Guoxiang. "Contrôle polygénétique sur la localisation des gisements proximaux et distaux dans le champ polymétallique-stannifère à Xinlu, Guangxi, Chine méridionale /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1992. http://theses.uqac.ca.

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Voicu, Gabriel. "Géologie, géochimie et métallogénie du gisement d'or Omai, Bouclier Guyanais, Amérique du Sud = Geology, geochemistry and metallogeny of the Omai Gold Deposit, Guiana Shield, South America /." Thèse, Montréal : Chicoutimi : Université du Québec à Montréal ;. Université du Québec à Chicoutimi, 1999. http://theses.uqac.ca.

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Dissertations / Theses on the topic 'Ore geochemistry'

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