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1
Ash, Philip John. "A review of the sediment-hosted, disseminated precious metal deposits of Nevada : geological setting, classification, genesis and exploration." Thesis, Rhodes University, 1986. http://hdl.handle.net/10962/d1001566.
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Carlin-type, fine-grained, "invisible" or Disseminated Replacement Type gold-silver deposits are all different names for a major new type of ore deposit that is currently being extensively developed in the Western United States. This type of deposit is now being found elsewhere. Thus a descriptive empirical model that emphasizes the geological and geochemical environment of formation is needed to assist the mining industry in the search for similar deposits. These deposits are typically formed in carbonaceous, silty dolomites and Iimestones or mineralization calcareous siltstones rocks and is exceedingly fine-grained is disseminated in the and claystones. host sedimentary Gold-silver , ore. Primary alteration usually less than one micron in size in unoxidized types include decalcification, argillitization, silicification resulting in the and pyritization. Silicification is commonly intense formation of jasperoid bodies which may be the host to higher grade ore. Supergene alteration is dominated by oxidation resulting in the formation of numerous oxides and sulphates and the release of gold from its association with sulphides and organic carbon. elements are As, Ba, Hg, Sb, and TI. Commonly associated trace Available geological, geochemical, fluid inclusion and stable-isotope studies lead to the conclusion that a circulating hydrothermal system is the important factor necessary for gold-silver concentration and deposition. A direct genetic or only casual relation between are deposition and discrete igneous formations remains unclear. However, it is considered that volcanism provided the source of heat necessary for the generation of a circulating hydrothermal system. High angle faults and fold structures facilitate transport and are of prime importance in directing are fluids to favourable host lithologies. The host rocks, overwhelmingly carbonate - rich, include those whose original and/or altered compositions and resulting permeability provide favourable sites for the precipitation of disseminated gold. The processes specialized. resulting Any th ick in the formation of these deposits are section of carbonate rocks has the potential not to produce Disseminated Replacement Type deposits wherever underlying igneous activity has developed a hydrothermal system
2
Harris, Anthony Charles. "The genesis of a porphyry Cu-Au deposit, farallon negro volcanic complex, NW Argentina /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17494.pdf.
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Adams, Garry J. "Structural evolution and ore genesis of the granites gold deposits, Northern Territory /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09pha2128.pdf.
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Cooper, Mark. "The Sudbury igneous complex : insights into melt sheet evolution and ore genesis." Thesis, Open University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340675.
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Hochman, Mark Brett McEwen. "The application of artificial thermoluminescence to uranium exploration and uranium ore genesis studies." Title page, abstract and contents only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phh6825.pdf.
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Choi, Wing-sang Vincent, and 崔穎生. "Geology and ore genesis of the Ma On Shan iron deposit, Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/192993.
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Ma On Shan Iron Mine was a only few economic deposit in Hong Kong for which have been closed for more than decades. There is lack of modern geological study of the mine. In order to understand the origin of the iron mine formation, microscopic and macroscopic study of underground were used in terms of field observation, thin section, Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS). In this study, ore formation is due to granitic magma contact with dolomitic marble which formed the Ma On Shan magnetite Skarn. Moreover, the mineral forming sequence is proposed. Magnetite and magnesium humite subgroup form in the early stage. Then the retrograde minerals are dominated by actinolite, tremolite fluorite and magnesium humite subgroup. In the late stage, some metallic minerals and rare earth mineral are disseminated within late stage vein, they are pyrite, cassiterite, scheelite and thorium/yttrium compound. Sellaite, cassiterite, scheelite, thorium/yttrium compound are newly discovered in Ma On Shan Iron Mine thanks to the modern technology. However, some common minerals have been mentioned by pervious authors are not found, e.g. garnet, this may due to the zonation and spatial distribution of mineral formation.published_or_final_version
Applied Geosciences
Master
Master of Science
7
Dünkel, Ines. "The genesis of east Elba iron ore deposits and their interrelation with Messinian tectonics /." Tübingen : Institut und Museum für Geologie und Paläontologie, 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967986257.
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Dünkel, Ines. "The genesis of East Elba iron ore deposits and their interrelation with Messinian tectonics." [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10405671.
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Williams, Richard James. "Karst-associated bauxite deposits of Parnassos-Ghiona, Central Greece : ore genesis and structural evolution." Thesis, University of Brighton, 2014. https://research.brighton.ac.uk/en/studentTheses/2b04d019-0696-4544-a13d-b2de8971a69b.
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The karst-associated bauxites of the Parnassos-Ghiona zone in Central Greece are part of the large Mesozoic age Mediterranean Karst Bauxite belt. Greece is responsible for around 50% of European bauxite production, and has an estimated 600 million tonnes of bauxite reserves. This investigation focuses on the bauxites of Mount Iti and Mount Ghiona, two mountains in the west of the Parnassos-Ghiona zone that are currently being explored and mined by Greek bauxite producer, Elmin S.A. The aim was to develop a better geological understanding of the ore genetic history and regional structural evolution to aid ore deposit science and bauxite exploration. Within the Parnassos-Ghiona zone the bauxites were deposited as three separate ore horizons intercalated with thick limestone layers during the early Jurassic, late Jurassic and late Cretaceous. Only the upper two bauxite horizons are economic and therefore formed the focus of this investigation.
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Devlin, Barry David. "Geology and genesis of the Dolly Varden silver camp, Alice Arm area, northwestern British Columbia." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26243.
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The Dolly Varden camp, Alice Arm area, northwestern British Columbia, is characterized by stratiform and volcanogenic silver-lead-zinc-barite deposits in Early to Middle Jurassic calc-alkaline volcanic rocks of the Hazelton Group. These deposits, containing exceptional silver and significant base metal values, are in andesitic tuffaceous rocks, and occur typically as layers of quartz, carbonate, barite and jasper, with lesser amounts of pyrite, sphalerite and galena, and sparse chalcopyrite. Production from three deposits, the Dolly Varden, Northstar and Torbrit mines, totaled 1,284,902 tonnes of ore that averaged 484g silver per tonne, 0.38 percent lead and 0.02 percent zinc.
The Hazelton Group is a thick, widespread assemblage of basaltic to rhyolitic volcanic flow rocks, their tuffaceous equivalents, and derived sedimentary rocks. Dolly Varden camp is underlain by more than 3,000m of Hazelton Group rocks comprised of one major volcanic and one major sedimentary formation. Volcanic rocks underlie sedimentary rocks and have been subdivided into footwall and hangingwall units based on stratigraphic position relative to the mineralized stratiform horizon. Footwall volcanic rocks consist of green ± maroon basaltic-andesite tuff, green ± maroon porphyritic andesite and green andesite shard tuff. Stratiform mineralization rests conformably upon the underlying green andesite shard tuff. Hangingwall volcanic rocks above the stratiform layer consist of pale grey basaltic-andesite ash tuff, maroon basaltic-andesite ash-lapilli tuff, grey-green porphyritic andesite, and pale green andesite ash tuff. Hangingwall volcanics are unconformably capped by sedimentary rocks consisting of maroon siltstone, calcareous and fossiliferous wacke, and black siltstone and shale; black siltstone and shale form the youngest rock unit of the Hazelton Group in the Dolly Varden area. Basalt and lamprophyre dykes intrude all rocks of the Hazelton Group. The rocks of the Hazelton group exposed in the Dolly Varden camp are folded into a series of anticlines and synclines with gentle, northwestern plunges. Two major sets of nearly vertical block faults cut all rock units; earlier faults trend northwest and younger faults trend north-northeast.
Geological mapping, combined with petrologic, petrographic and isotopic data, indicate that the stratiform deposits probably formed as submarine exhalative deposits associated with andesitic volcanism of the Hazelton Group during the Early to Middle Jurassic. Evidence for a volcanogenic origin is the conformity of layered mineralization with stratigraphy, lateral and vertical mineral zonation patterns, consistent hangingwall versus footwall contact relationships, fragments of stratiform ore within tuffaceous volcanic rocks of the hangingwall, consistent differences in the stable isotopic compositions between the sulfides versus barite, quartz and carbonate gangue, and the Jurassic "fingerprint" for the lead-bearing deposits of the Dolly Varden camp.
The Dolly Varden deposits display criteria for classification of a new, previously unrecognized, stratiform and volcanogenic, deposit type, named here, the "Dolly Varden type", and is characterized by silver-rich, low sulfide and high oxide stratiform mineralization within andesitic volcanic rocks.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
11
Potra, Adriana. "Isotopic Studies of the Guerrero Composite Terrane, West-Central Mexico: Implications for Provenance of Crustal Rocks and Genesis of Ore Metals." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/371.
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A variety of world-class mineral deposits occur in Mesozoic and Tertiary rocks of the Guerrero terrane. New Pb isotope analyses of various crustal units and ores from distinct subterranes of the Guerrero terrane are presented to trace metal sources in these deposits and infer source reservoirs. New Sr and Nd isotope results are provided to gain insight into the provenance of the crustal rocks from the Guerrero terrane.
Triassic schist samples from the Arteaga Complex and Triassic-Jurassic phyllite and slate samples from the Tejupilco metamorphic suite contain radiogenic Pb (206Pb/204Pb = 18.701-19.256) relative to bulk earth models. Cretaceous sedimentary rocks of the Zihuatanejo Sequence are more radiogenic (206Pb/204Pb = 18.763-19.437) than samples from the Huetamo Sequence (206Pb/204Pb = 18.630-18.998). Tertiary intrusive rocks from La Verde, Inguaran, La Esmeralda, and El Malacate plot to the right of the average Pb crust evolution curve of Stacey and Kramers (206Pb/204Pb = 18.705-19.033). Ores from the La Verde and La Esmeralda porphyry copper deposits yield isotopic ratios (206Pb/204Pb = 18.678-18.723) that are generally less radiogenic than the host igneous rocks, but plot within the field defined by the sedimentary rocks from the Huetamo Sequence.
Tertiary intrusive rocks from the Zimapan and La Negra districts in the Sierra Madre terrane plot above and to the right of the Stacey-Kramers reference line (206Pb/204Pb = 18.804-18.972). Lead isotope ratios of ore minerals from the Zimapan and La Negra skarn mines (206Pb/204Pb = 18.775-18.975) resemble those of the associated igneous rocks, implying a magmatic Pb input in the skarn deposits.
New Sr and Nd isotope data on metamorphic rocks (87Sr/86Sr = 0.707757-0.726494 and 143Nd/144Nd = 0.512109-0.512653) suggest that the basement of the Guerrero terrane originated from sources that had been derived from an old cratonic area. The narrow ranges and generally low 87Sr/86Sr ratios (0.704860-0.705755) and 143Nd/144Nd values (0.512765-0.512772) above that of bulk earth for igneous rocks from Inguaran, El Malacate, and La Esmeralda suggest a relatively low degree of crustal contamination. However, the isotopic values for the La Verde site (87Sr/86Sr = 0.708784 and 143Nd/144Nd = 0.512640) may indicate the involvement of a more evolved crustal component.
12
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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Rojas, Martínez Paula Amanda. "Genesis of the El Romeral iron ore: New contributions to the understanding of iron oxide-apatite deposits." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/146513.
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Magíster en Ciencias, Mención Geología.
GeólogaLos depósitos denominados de tipo magnetita-apatito o iron oxide-apatite (IOA) son una importante fuente de Fe, P y REE a nivel mundial. Sin embargo, el origen de estos depósitos sigue siendo tema de debate, en donde predominan tres teorías: una hipótesis magmática que involucra inmiscibilidad de líquidos, un origen hidrotermal por reemplazo de la roca hospedante y una teoría magmático-hidrotermal por flotación de pares magnetita-burbuja. Con el fin de dilucidar el origen de estos depósitos, el presente trabajo se centra en el estudio del yacimiento El Romeral, principal depósito tipo IOA de la IV Región, ubicado en la Franja Ferrífera de la Cordillera de la Costa. Este depósito se emplaza en andesitas de la Formación La Liga, limitado al oeste por la Diorita Romeral. La mineralización está conformada por cuerpos subverticales de magnetita maciza con intercrecimiento de actinolita, relacionados con el sistema de Falla Romeral. A través de estudios petrográficos, combinado con microscopio electrónico de barrido, análisis de microsonda electrónica y micro-Raman en inclusiones minerales se han definido y estudiado los distintos eventos de mineralización. Se define (i) un primer evento con magnetita (I), rica en inclusiones minerales, la cual presenta altos contenidos de V (~2500-2800 ppm) y Ti (~80-3000 ppm). A mayores profundidades se observan inclusiones de alta temperatura (e.g. Ti-pargasita, ilmenita y clinocloro) que van gradando a inclusiones de menor temperatura en zonas someras (e.g. α-cuarzo). Por otro lado, se define un (ii) segundo evento caracterizado por magnetita prístina, sin inclusiones (II), con altas concentraciones de V (~2300-2700 ppm) y menor contenido de Ti (~50-400 ppm). Esta misma variación termal se evidencia con la química de minerales accesorios. La presencia de cristales de actinolita con bajos #Fe, asociados a la magnetita II, sugiere una cristalización a altas temperaturas (hasta 840°C), al igual que la presencia de F-apatito, los cuales se detectaron a mayores profundidades. En contraste, a menores profundidades predominan los apatitos ricos en OH, con mayor contenido de Cl. Asimismo, mayores razones de Co:Ni (>1) se midieron en sulfuros de eventos primarios, asociados a la mineralización de magnetita II, a diferencia de menores razones Co:Ni (<0.5) asociadas a sulfuros tardíos. En vista de los resultados anteriores y de la estrecha relación temporal entre la actinolita relacionada con la mineralización (~128 Ma, 40Ar/39Ar) y la Diorita Romeral (~129 Ma, U-Pb en circones) se establece un primer evento de origen magmático, posiblemente relacionado con la cristalización de este cuerpo intrusivo, que va gradando a un sistema hidrotermal en superficie, influenciado por la acción de la Falla Romeral.
Este trabajo ha sido financiado por el proyecto FONDECYT - 1140780 y Núcleo Milenio Trazadores de Metales NC130065
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Duff, Shamus. "Ore Types of the Auriferous Lalor VMS Deposit, Snow Lake, Manitoba: Implications for Genesis and Post Depositional Processes." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34586.
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The Lalor deposit is a newly discovered Paleoproterozoic volcanogenic massive sulphide (VMS) deposit located at the east end of the Flin Flon-Snow Lake belt within the Snow Lake arc assemblage. Lalor is the largest of 11 VMS deposits in the Snow Lake arc assemblage, with combined resources and reserves of 25.3 Mt and average grades of 2.9 g/t Au, 25 g/t Ag, 5 wt% Zn and 0.79 wt% Cu, including 8.8 Mt at 4.6 g/t Au. Lalor and all other deposits in the Snow Lake arc assemblage have been affected by intense polyphase deformation and amphibolite facies metamorphism. As a result, both the original hydrothermal alteration assemblages and the ore mineral assemblages have been completely recrystallized. However, a variety of different ore types have been preserved, allowing the partial reconstruction of the hydrothermal system, including massive Fe-Zn sulphide lenses, discordant Cu-Au stringer zones, and distinctive precious metal-rich Au-Ag-Pb-Cu zones. The different ore types occur in a series of stratigraphically and structurally “stacked” ore lenses that partly overlap but still largely preserve the original architecture of the deposit.
The ore is distributed in 12 discrete lenses or zones of mineralization that are interpreted to be the result of several distinct and overlapping hydrothermal events. Type 1 Fe-Zn massive sulphide ore is the most common ore type in six ore lenses and consists of massive coarse-grained pyrite and sphalerite with trace galena in dominantly quartz-muscovite±kyanite-biotite schist (K alteration association). Type 2 Cu-Au mineralization consists of semi-massive and stockwork chalcopyrite and pyrrhotite in garnetiferous quartz-biotite±staurolite-amphibole-cordierite gneisses (footwall Mg-Fe alteration association). Despite extensive recrystallization and local remobilization, these two ore types are interpreted to represent the (metamorphosed) low- and high-temperature ore assemblages, respectively, of a typical volcanogenic massive sulphide deposit. Type 3 Au-Ag-Pb-Cu-rich ore consists of stringer and disseminated sulphides and sulphosalts mainly hosted in chlorite-carbonate-actinolite schist (Mg-Ca and Ca alteration associations). Galena is an important indicator of Au mineralization and occurs in this ore type as fine-grained blebs in a matrix of chlorite, dolomite, calcite, anthophyllite, Ca-plagioclase, and calc-silicates (epidote, grossular, diopside, Ca-amphibole ± scapolite). Where abundant, the galena is associated with chalcopyrite, pyrite, pyrrhotite and minor to trace sphalerite, Ag-Sb-Pb sulphosalts, electrum and native gold. Type 4 low-sulphide ore contains ≤10 vol% disseminated pyrite in quartz-biotite-anthophyllite gneiss, with minor chlorite, staurolite, and coarse almandine garnet, and has variable Au grades. The sulphides and sulphosalts in ore types 3 and 4 are interpreted to be metamorphically remobilized from pre-existing disseminated mineralization.
The hydrothermal system developed during two main episodes of seafloor volcanism. Type 1 massive sulphides in the 10 and 11 lenses and in the 20, 30, 31, and 40 lenses were formed at the paleoseafloor. These lenses are underlain by Type 2 Cu-Au stockwork mineralization (27 Lens) and originally conformable zones of Type 3 Au-Ag-Pb mineralization (21, 24, 25, 26, and 28 lenses). The large Cu-Au stockwork zone (27 Lens) may have been the main feeder of the deposit and is partly continuous with disseminated Au-Ag-Pb-Cu galena-sulphosalts mineralization below the 20 base metal Lens. The Au-Ag-Pb-Cu mineralization is thought to have formed in the subseafloor from late-stage, lower-temperature hydrothermal fluids (ca. <300°C). In this model, significant Au was introduced first by high-temperature (>300°C) fluids responsible for the Type 2 Cu-Au mineralization and then by lower-temperature (possibly boiling) hydrothermal fluids responsible for Type 3 Ag-Au-Pb-Cu mineralization. Although all the ore types are extensively recrystallized and partly remobilized, their distribution strongly supports primary hydrothermal Au enrichment at Lalor. The lead isotopic compositions of the ore galena show no evidence of post-magmatic disturbance that would be expected if Au had been introduced during deformation and metamorphism (e.g., as in the nearby New Britannia orogenic Au deposit), and the Au-rich assemblages are very similar to those that commonly occur in unmetamorphosed Au-rich volcanogenic massive sulphide deposits.
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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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Lipson, Rael Desmond. "Lithogeochemistry and origin of metasediments hosting the Broken Hill Deposit, Aggeneys, South Africa, and implications for ore genesis." Doctoral thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/23684.
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Bullen, Warwick David. "Gold mineralization in an archaean granite-greenstone remnant west of Melmoth, Natal ore genesis and implications for exploration." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1005579.
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The previously undifferentiated, "Melmoth Granite-Greenstone Remnant" (MGGR¹) crops out over an area of about 360 km² in northern Natal, South Africa. The greenstone sequence is comprised mainly of mafic metalavas with lesser serpentinite, talc schist, dacitic tuff, quartz-muscovite schist, quartzite and calc-silicate rocks. The greenstones are intruded by syntectonic trondhjemitic gneisses, late-tectonic granodioritic gneisses and post-tectonic granite dykes. Four phases of deformation and metamorphism are recognized. Epigenetic, disseminated and quartz vein-hosted gold mineralization is associated with D₂ shearing - a positive correlation existing between the intensity of the shearing, the thickness of the shear zone and the grade of ore it contains. Auriferous quartz veins are distinguished from an earlier generation of barren vein quartz on the basis of mineralogy, texture and relationship to the s-fabric. The mineralization occurs in zones of dilation associated with shear zone refraction. Associated wall rock alteration includes sericitization, argillization and chloritization. An ore genesis model based on the aforementioned parameters, is proposed. Finally, an exploration programme has been devised in order to locate undiscovered gold deposits in the MGGR. The programme could probably be applied, with minor modifications, to shear zone-hosted gold deposits in other granite-greenstone remnants in northern Natal. ¹- Name suggested by writer.
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Gapara, Cornwell Sine. "A review of the deposition of iron-formation and genesis of the related iron ore deposits as a guide to exploration for Precambrian iron ore deposits in southern Africa." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005610.
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Iron-formations are ferruginous sedimentary rocks which have their source from fumarolic activity associated with submarine volcanism, with deposition of iron as oxides, hydroxides, and hydrous oxide-silicate minerals in shallow and/or deep marine sedimentary systems. The Precambrian ironformations of southern Africa have a wide age range, but are more prominently developed before 1.SGa. These iron formations occur in greenstone belts of the Kaapvaal and Zimbabwean cratons, in the Limpopo mobile belt, in cratonic basins and in the Damara mobile belt. The Archaean-Proterozoic sedimentary basins and greenstone belts host iron ore deposits in iron-formation. Iron formations have a lengthy geological history. Most were subjected to intense, and on occasions repeated, tectonic and metamorphic episodes which also included metasomatic processes at times to produce supergene/hypogene high grade iron ores. Iron-formations may be enriched by diagenetic, and metamorphic processes to produce concentrating-grade ironformations. Uplift, weathering and denudation, have influenced the mineral association and composition of the ores, within which magnetite, haematite and goethite constitute the major ore minerals. The iron resources of the southern Africa region include the Sishen deposits, hosting to about 1200 Mt of high grade direct shipping ore, at >63% Fe. Deposits of Zimbabwe have more than 33 000 Mt of beneficiable iron-formation. The evaluation of an iron ore prospect involves many factors which must be individually assessed in order to arrive at an estimate of the probable profitability of the deposit. Many of these are geological and are inherent in the deposit itself. Other factors are inherent aspects of the environment in which the ore is formed. Although the geological character of the ore does not change, technological advances in the processing techniques may have a great effect on the cost of putting the ore into marketable form. Geochemical, geophysical and remote sensing methods would be used for regional exploration. Chip sampling and drilling are useful for detailed exploration. Purely geological exploration techniques are applicable on a prospect scale in the exploration of iron ore deposits. Regional exploration targeting should choose late Archaean greenstone belts containing oxide facies iron-formation or Early Proterozoic basins located at craton margins as they are both known to host high-grade haematite orebodies formed by supergene/hypogene enrichment. Most types of iron ore deposits in southern Africa are described and classified. An attempt is made to emphasize the major controls on mineralisation, in the hope that these may be applicable to exploration both in the southern African region and within analogous settings around the world.
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Haggerty, Randolph. "An isotopic investigation of the mineralizing fluids and ore genesis of the Llanrwst and Llanfair-Talhaiarn orefields, North Wales." Thesis, University of Leeds, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247041.
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Van, Huyssteen Darryn Ashley. "Mineralogical variation in the basal Upper Zone, Bushveld Igneous Complex, South Africa: implications for ore genesis and mineral extraction." Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/5060.
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Stalder, Marcel. "Petrology and mineral chemistry of sulphide ores and associated metalliferous rocks of the Gamsberg Zn-Pb deposit, South Africa : implications for ore genesis and mineral exploration." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16072.
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Thesis (PhD)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The Gamsberg Zn-Pb deposit is a metamorphosed and multiply deformed sediment-hosted base metal deposit in the central Namaqua Province of South Africa. The deposit is hosted by the Bushmanland Group, a late Palaeoproterozoic (2000-1600 Ma) supracrustal succession of quartzite, metapelitic schist and interbedded metavolcanic rocks. Mineralisation occurs within the central part of the Gams Formation, a heterogeneous sequence of metamorphosed metalliferous sediments and fine-grained organic-rich shales. The ore horizon is subdivided into a lower unit of metapelite-hosted ore, an intermediate layer of phosphorite-hosted ore, and an upper unit of banded garnet-apatite ore. The ore body is enveloped by unmineralised silicate-, carbonate- and oxide-facies metalliferous rocks, which originally represented mixtures of Fe-Mn-rich hydrothermal precipitates, authigenic carbonate, and variable concentrations of detrital material. Based on mineralogical and geochemical characteristics, the metalliferous host rocks are subdivided into iron formations, coticules, Fe-Mn silicates, impure marbles and barite/Ba-rich quartzite. Minerals of the Gams Formation mostly represent solid solution between the Fe and Mn end-members of garnet, pyroxene, pyroxenoid, amphibole, olivine, spinel and ilmenite. Calcium-rich rock types are a typical feature and characterized by the occurrence of manganoan calcite, clinopyroxene, andradite-rich garnet and titanite. A successive increase in the (Mn+Ca):Fe value of rocks and minerals is evident with increasing distance from the ore horizon. Amphibole is restricted to Fe-rich ore-bearing assemblages, whereas orthopyroxene, clinopyroxene, Fe-rich pyroxenoid and olivine are present in intermediate assemblages, and Mn-rich rhodonite and pyroxmangite in the most manganiferous assemblages. These variations are mimicked by an increase in the Mn:Fe value of coexisting garnet and ilmenite group minerals with increasing distance from ore. LA-ICP-MS analyses have been used to constrain the REE patterns of garnet and apatite. In the ore-body, these minerals display a positive Eu anomaly, which is interpreted to reflect a distinct hydrothermal signature. In contrast, garnet and apatite in unmineralised metalliferous rocks display nil or a negative Eu anomaly. Primary features of the Gams Formation, such as REE patterns, the banded nature of garnet-apatite ore, the presence of diagenetic apatite nodules, and the distribution of the redox-sensitive elements Ba and Mn have been used to constrain palaeo-environmental conditions. The results indicate that metapelitehosted ore has been deposited in a stratified ocean that was characterised by anoxic bottom waters and precipitation of Fe and Zn sulphides into organic matter-rich shales. These rocks were superceded by phosphorite-hosted ore, garnet-apatite ore and metalliferous host rocks that developed in a suboxic to oxic environment. The large size of the deposit, the internal lamination of the ores and the predominance of sphalerite and barite are consistent with a vent-distal setting and precipitation of the ore-forming constituents from dense and reduced hydrothermal fluids, which originated due to reactivation of dormant growth faults. Collectively, the geological evidence indicates that Gamsberg is bridging the gap betweenthe SEDEX and BHT classifications. The relationships demonstrate that differences between these two classes of sediment-hosted Zn-Pb deposits are predominantly related to environmental conditions within localised third order basins and not to fundamental differences in ore-forming processes.
AFRIKAANSE OPSOMMING: Die Gamsberg Zn-Pb afsetting is ‘n meerfasig vervormde en gemetamorfiseerde sedimentgesetelde onedel metaal afsetting in die sentrale Namakwa Provinsie van Suid Afrika. Die afsetting word geherberg deur die Boesmanland Groep, ‘n laat Paleoproterosoïse (2000 – 1600 Ma) bokors-opeenvolging van kwartsiet, metapelitiese skis en tussengelaagde metavulkaniese gesteente. Mineralisasie word gevind in the sentrale deel van die Gams Formasie. Die Gams Formasie is ‘n heterogene opeenvolging van gemetamorfiseerde metaalhoudende sediment en fynkorrelrige organiese skalie. Die erts horison word onderverdeel in ‘n onderste laag van metapeliet-gesetelde erts, n sentrale laag van fosforiet-gesetelde erts, en ‘n boonste laag van gebande granaat-apatiet erts. Die erts-liggaam word omhuls deur ongemineraliseerde silikaat-, karbonaat- en oksied-fasies metal-ryke rotse. Hierdie gesteentes word geinterpreteer as oorspronklike mengsels van Fe-Mn-ryke hidrotermale partikels, outigeniese karbonaat, en verskeie hoeveelhede detritale materiaal. Gebaseer op mineralogiese en geochemiese kenmerke word hierdie rotse onderverdeel in ysterformasies, „coticules“, Fe-Mn silikate, onsuiwer marmer en barite/Ba-ryke kwartsiet. Minerale van die Gams Formasie form meestal soliede oplossingsreekse tussen die Fe en Mn endlede van granaat, pirokseen, piroksenoid, amfibool, olivien, spinel en ilmeniet. Kalsium-ryke rots tipes is ‘n tipiese kenmerk van die Gams Formasie en word gekenmerk deur mangaan-ryke kalsiet, klinopirokseen, andradiet-ryke granaat en sfeen. Daar word ‘n stapsgewyse vergroting van die (Mn+Ca):Fe verhouding in gesteentes en minerale gevind met toeneemende afstand van die erts horison. Amfibool is beperk tot Fe-ryke ertsdraende gesteentes, ortopirokseen, klinopirokseen, Fe-ryke piroksenoid en olivien tot intermediêre gesteentes, en Mn-ryke rodoniet en piroksmangiet tot Mn-ryke gesteentes. Hierdie variasies gaan gepaard met vergroting van die Mn:Fe verhouding in granaat en ilmeniet-groep minerale met toeneemende afstand van die erts. LA-ICP-MS analises was gebruik om die skaars-aarde element patrone van granaat en apatiet te bepaal. In die erts-liggaam wys hierdie minerale ‘n positiewe Eu anomalie, wat geinterpreteerd word as ‘n hidrotermale kenmerk. In ongemineraliseerde gasheer gesteentes wys granaat en apatiet geen of ‘n negatiewe Eu anomalie. Primêre kenmerke van die Gams Formasie, soos skaars-aarde patrone, the gebande voorkoms van granaat-apatiet erts, die teenwoordigheid van diagenetiese apatiet knolle, en die verspreiding van die redox-sensitiewe elemente Ba en Mn, was gebruik om afleidings oor die paleo-omgewing te maak. Die resultate het gewys dat metapeliet-gesetelde erts afgeset was onder anoksiese bodem water deur presipitasie van Fe en Zn sulfiedes in organiese skalie. Hierdie erts gaan oor in fosforiet-gesetelde erts, granaat-apatiet erts en metaal-ryke gasheer gesteente wat in ‘n suboksiese tot oksiese omgewing ontstaan het. Die grootte van die afsetting, die interne gelaagdheid van die erts, asook die teenwoordigheid van sfaleriet en bariet dui op ‘n distale omgewing relatief tot die hidrotermale bron en presipitasie van die ertsuit digte en gereduseerde hidrotermale vloeistowwe, wat ontstaan het deur die heraktiveering van rustende groeiverskuiwings. Gesaamentlik bewys die geologiese kenmerke van Gamsberg dat gemetamorfiseerde SEDEX en Broken Hill-tipe mineralisasie binne die perke van ‘n enkele afsetting kan voorkom. Die geologiese verhoudings dui aan dat verskille tussen hierdie twee tipes van sedimentgesetelde afsettings meestal veroorsaak word deur omgewings-toestande binne in gelokaliseerde derde orde komme en nie deur fundamentele verskille in ertsvormende prosesse nie.
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Misiewicz, Julian Edward. "The geology and metallogeny of the Otavi mountain land, Damara orogen, SWA/Namibia, with particular reference to the Berg Aukas Zn-Pb-V deposit a model of ore genesis." Thesis, Rhodes University, 1988. http://hdl.handle.net/10962/d1005571.
Full textAbstract:
The Olavi Mountain Land is a 10 000 km2 mineral province located at the eastern extremity of the exposed Northern Platform of the Damara Pan African orogenic belt. The Olavi Mountain Land is tbe most important mineral province on the Northern Platform. Exploitation of tbe Cu-Pb-Zn-V province has been on-going since the possession of the territory by the German colonial authority in 1890. Production has been mostly from four mines which in order of importance are Tsumeb, Kombat, Berg Aukas and Abeoab. A second mineral province on the Northern Platform located in the west is centred on Sesfontein where as yet only insignificant mineralization has been noted. Besides these localities, the Northern Platform is conspicuously devoid of notable mineralization. The aim of this thesis has been to document tbe Berg Aukas deposit, an important end-member type of mineralization in the Otavi Mountain Land. The basic premise bas been to show tbat the derivation and localization of the mineralization is a consequence of two broad controls which can be simply summarised as features of the basement and of the carbonate sequences. The geodynamic evolution of the Damara Belt commenced with intra-continental rifting approximately 900 Ma ago. Rift grabens trending north-east were filled by the Nosib Group which comprises mostly clastic lithologies but also some volcanics. The earliest and largest rift is referred to as the Northern Rift. Separation of the Congo, Kalahari, and proto-South American cratons resulted in rifting and rapid downwarping so that an encroaching sea and an Olavi Group carbonate shelf developed along the northern margin of the Northern Rift. Significantly, the carbonates only covered the Northern Rift in the area of the Otavi Mountain Land where a basinal dome, referred to as the Grootfontein Basement High, marked the basin edge. In the west, the carbonates covered the less important Sesfonfein Rift, and it is only in these two areas where Nosib sequences underlie the carbonate platform. Carbonate sedimentation was interrupted by a major period of crustal readjustment and the deposition of an extensive mixtite throughout the geosynclinal Swakop Trough and Northern Platform. This is referred to as the Chuos Formation and subdivides the Olavi Group into a lower Abenab and an upper Tsumeb Subgroup. Reversal of spreading led to plate collision and subduction of tbe Kalahari craton beneath the Congo craton. It was accompanied by orogenesis which resulted in F1 folding of the Northern Platform into a series of north-easterly trending intermontane basins into which a molasse sequence known as the Mulden Group was unconformably deposited. Following this major north-south deformation mild east-west compression initiated F2 folding and the formation of doubly plunging synclines. The Berg Aukas Syncline represents a primary depositional basin which was subsequently folded. The original basin was formed by late Nosib rifting wben spreading caused the Swakop geosynclinal Trough to form. Carbonates of the basal Berg Aukas Formation were deposited in a lagoonal setting typified by reef and fore-reef facies witb peri-platform conditions. Rapid subsidence caused these sediments to be overlain by deep water carbonates of the Gauss Formation. Two styles of mineralization known as the Tsumeb-type and Berg Aukas-type are stratigraphically, isotopically, and mineralogically distinct. The Tsumeb-type is a cupriferous variety of discordant bodies confined to the upper sequences beneath the Mulden unconformity. The Berg Aukas-type is a Zn-Pb variety confined to tbe basal unconformity. The Berg Aukas deposit comprises three ore bodies known as the Northern Ore Horizon, the Central Ore Body, and the Hanging Wall Ore Body. Sphalerite and galena constitute the bypogene ore. Willemite, smithsonite, cerussite, and descloizite are important supergene ores. A review of genetic models concludes that a magmatic origin initially proposed for tbe Tsumeb deposit is entirely rejected and a basin dewatering model in line with Mississippi Valley-type deposits is proposed. The syntectonic nature of mineralization at Berg Aukas and elsewhere in the Otavi Mountain Land indicates that orogenesis encouraged dewatering and leaching of metals from a broad mineralizing front along the margin of the Swakop Trough. These were transported by acidic saline brines which migrated along the clastic aquifers and structural conduits provided by the Northern Rift. Fluid inclusion studies indicate that the hydrothermal fluids at Berg Aukas were very saline (23% TDS) and were transported at temperatures ranging between 92° to 210°C. Hydrothermal fluids which mineralized Berg AukaS-type deposits migrated along the basal unconformity towards the basement high and were responsible for hydrothermally altering the basement granites and gabbros and the Nosib clastic rocks. Tsumeb-type deposits resulted by migration of fluids through the carbonate pile and along north-easterly trending basement geofractures. As a consequence of variation in transport, the Berg Aukas-type and Tsumeb-type fluids leached different sources and therefore derived mineralogically and isotopically seperable characteristics. The localization of the Berg Aukas ores was controlled by the carbonate stratigraphy and structure. Hydrothermal karsting and ore deposition took place on the contact between Massive Grey and Light Grey Dolostones which represents a permeability contrast. The movement of the hydrothermal fluids was controlled by north-south trending vertical fractures caused by F2 folding which resulted in a peric1inal structure. Hydrothermal karsting was accompanied by ca1citic, dolomitic and silicic alteration. The heated acidic fluids initiated solution collapse and a variety of breccia types. Supergene processes resulted in oxidation and upgrading of the ore. Vanadium derived indirectly from gabbros in the basement complex were transported as calcium metavanadate complexes and deposited on contact with the oxidizing base metal sulphides.
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Mäkisalo, A. (Anssi). "Geological characterization of anorthositic rocks in the Otanmäki intrusion, central Finland:constraints on magma evolution and Fe-Ti-V oxide ore genesis." Master's thesis, University of Oulu, 2019. http://jultika.oulu.fi/Record/nbnfioulu-201903201346.
Full textAbstract:
Abstract. The 2.06 Ga Otanmäki intrusion in central Finland is a differentiated mafic intrusion hosting stratabound Fe-Ti-V oxide ore. The ore occurs as <1–200-m-wide lenses in a heterogeneous zone comprising different gabbro varieties and anorthosite. Anorthosite forms ubiquitous amoeboid-shaped inclusions a few meters in diameter, constituting a significant component in the ore-bearing part of the intrusion. The anorthositic rocks have not been studied earlier in detail and their role in the geological history of the intrusion is not well understood. The purpose of this Master’s thesis is to characterize the anorthositic rocks by means of mapping and geochemical and minerochemical methods, compare them to other mafic rocks in the Otanmäki intrusion and corresponding mafic intrusions globally and study their role in the magmatic evolution and Fe-Ti-V oxide ore genesis. A total of 20 thin sections were prepared for petrographic microscopy and 64 EPMA analyses were made to determine the plagioclase composition. The geochemical data include 18 ICP-OES/ICP-MS analyses and 58 portable XRF measurements. Pre-existing data, which include 941 bedrock observation points, 139 thin sections, 197 geochemical analyses and 110 electron microanalyses, were utilized as well as historical maps and drill core logs by the mining company Rautaruukki Oy.
Based on the mapping campaign carried out in 2017–2018, a 1:50 000 geological map of the Otanmäki intrusion covering 20 km² and a related stratigraphical column are presented. Detailed maps in 1:200 scale, which are based on aerial drone photography from anorthosite-bearing areas, were also compiled. A revised nomenclature for the Otanmäki intrusion is presented, in which the intrusion is divided into three tectonic blocks: Otanneva, Otanmäki, and Vuorokas. All these blocks comprise three major stratigraphical units: the Lower Zone, Ore Zone and Upper Zone. Furthermore, fine-grained marginal amphibolites are reported from two locations.
Based on the mineralogical observations and major and trace element data, the anorthositic rocks represent strongly differentiated plagioclase adcumulates and are cognate to the Otanmäki intrusion. Crystallization of the Ore and Upper Zones has likely included one or several periods of plagioclase buoyancy, enabling accumulation of plagioclase crystals in the roof part of the magma chamber. Parts of the massive roof anorthosite sank gravitationally into the lower parts of the magma chamber as variably solidified autoliths and were deposited on a semi-solidified substratum. The sinking was likely affected by Fe-Ti-oxide crystallization and subsequent decrease in the density of the residual melt. The genesis of the Fe-Ti-V oxide ore is suggested to have been affected by gravitational movements of partially solidified cumulate slurry towards a subsided magma chamber center. At least parts of these movements postdate the deposition of the anorthositic autoliths. The occurrence of anorthositic autoliths bears many similarities with the Skergaard and Sept Iles mafic intrusions.Otanmäen intruusion anortosiittisten kivien geologinen karakterisointi ja merkitys magmaattisessa evoluutiossa sekä Fe-Ti-V-oksidimalmin synnyssä. Tiivistelmä. Kainuussa sijaitseva Otanmäen intruusio on differentioitunut mafinen intruusio, jossa esiintyy kerrosmyötäistä Fe-Ti-V-oksidimalmia. Malmi ilmenee <1–200 metriä leveinä linsseinä heterogeenisessä vyöhykkeessä, joka koostuu eri gabrotyypeistä sekä anortosiitista. Anortosiitti muodostaa muutamia metrejä halkaisijaltaan olevia runsaslukuisia, muodoltaan vaihtelevia sulkeumia. Sulkeumat ovat merkittävä komponentti intruusion malmia sisältävässä osassa, mutta niitä ei ole tutkittu tarkasti ja niiden merkitys intruusion geologisessa historiassa on osin epäselvä. Tämän pro gradu -tutkielman tarkoitus on karakterisoida anortosiittiset kivet geologisen kartoituksen sekä kokokivi- ja mineraalikemiallisten menetelmien avulla, verrata niitä intruusion muihin mafisiin kiviin sekä vastaaviin intruusioihin globaalisti ja tutkia niiden merkitystä magmaattisen evoluution ja Fe-Ti-V-oksidimalmin synnyn kannalta. Työtä varten valmistettiin 20 ohuthiettä, joista tehtiin mikroskooppisten tutkimusten lisäksi 64 elektronimikroanalyysiä plagioklaasin koostumuksen selvittämiseksi. Geokemiallinen aineisto sisältää 18 ICP-OES/ICP-MS analyysiä sekä 58 kannettavalla XRF-analysaattorilla tehtyä koostumusmittausta. Lisäksi hyödynnettiin aikaisempien tutkimusten aineistoja, joihin kuuluu 941 kallioperähavaintopistettä, 139 ohuthiettä, 197 kokokivigeokemiallista analyysia, 110 elektronimikroanalyysia sekä Rautaruukki Oy:n laatimia karttoja ja kairasydänraportteja
Otanmäen intruusiosta laadittiin vuosina 2017–18 suoritetun kartoitustyön perusteella 20 km²:n kattava, 1:50 000-mittakaavainen geologinen kartta sekä stratigrafiapylväs. Lisäksi laadittiin 1:200-mittakaavassa yksityiskohtaisia geologisia karttoja anortosiittisia sulkeumia sisältäviltä alueilta hyödyntäen drone-ilmakuvausta. Työssä esitetään uusi, yhtenäistetty nimistö Otanmäen intruusiolle. Intruusio jaetaan kolmeen tektoniseen lohkoon: Otanneva, Otanmäki ja Vuorokas. Intruusiolohkot sisältävät kolme magmaattisen stratigrafian pääyksikköä: alavyöhyke, malmivyöhyke ja ylävyöhyke. Lisäksi intruusion reunoilla esiintyy kahdessa kohtaa hienorakeisia amfiboliittisia kiviä.
Mineralogisten havaintojen sekä pää- ja hivenalkuainekoostumuksen perusteella anortosiittiset kivet ovat voimakkaasti differentioituneita plagioklaasiadkumulaatteja, jotka ovat syntyneet samasta magmasta muiden intruusion kivien kanssa. Malmi- ja ylävyöhykkeiden kiteytymisen aikana plagioklaasi on ainakin ajoittain kellunut magmassa. Tämä on mahdollistanut plagioklaasikiteiden kasautumisen magmasäiliön yläosaan. Osa tästä yläosan massiivisesta anortosiitista upposi takaisin magmasäiliön alempiin osiin vaihtelevasti kiinteytyneinä autoliitteina, jotka kerrostuivat osin jähmettyneeseen kumulaattikerrokseen. Oksidimalmin kiteytyminen ja siitä seurannut tiheyden lasku jäännössulassa ovat todennäköisesti vaikuttaneet autoliittien uppoamiseen. Fe-Ti-V-oksidimalmin syntyyn on vaikuttanut osittain kiteytyneiden kumulaattien valuminen kohti magmasäiliön vajonnutta keskustaa. Malmivyöhykkeessä tapahtuneet magmaattiset liikunnot ovat tapahtuneet ainakin osittain anortosiittisten autoliittien kerrostumisen jälkeen. Autoliittien osalta Otanmäen intruusiolla on merkittäviä yhteneväisyyksiä Skaergaardin ja Sept Ilesin intruusioihin.
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Land, Jarred. "Genesis of BIF-hosted hematite iron ore deposits in the central part of the Maremane anticline, Northern Cape Province, South Africa." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1020905.
Full textAbstract:
The Paleoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa is host to high-grade BIF-hosted hematite iron-ore deposits and is the country’s most important source of iron to date. Previous work has failed to provide a robust and all-inclusive genetic model for such deposits in the Transvaal Supergroup; in particular, the role of hydrothermal processes in ore-genesis has not been adequately clarified. Recent studies by the author have produced evidence for hydrothermal alteration in shales (Olifantshoek Supergroup) stratigraphically overlying the iron-ore intervals; this has highlighted the need to reassess current ore-forming models which place residual supergene processes at the core of oregenesis. This thesis focuses on providing new insights into the processes responsible for the genesis of hematite iron ores in the Maremane anticline through the use of newly available exploration drill-core material from the centre of the anticline. The study involved standard mineralogical investigations using transmitted/reflected light microscopy as well as instrumental techniques (XRD, EPMA); and the employment of traditional whole-rock geochemical analysis on samples collected from two boreholes drilled in the centre of the Maremane anticline, Northern Cape Province. Rare earth element analysis (via ICP-MS) and oxygen isotope data from hematite separates complement the whole-rock data. Iron-ore mineralisation examined in this thesis is typified by the dominance of Fe-oxide (as hematite), which reaches whole-rock abundances of up to 98 wt. % Fe₂O₃. Textural and whole-rock geochemical variations in the ores likely reflect a variable protolith, from BIF to Fe-bearing shale. A standard supergene model invoking immobility and residual enrichment of iron is called into question on the basis of the relative degrees of enrichment recorded in the ores with respect to other, traditionally immobile elements during chemical weathering, such as Al₂O₃ and TiO₂. Furthermore, the apparently conservative behaviour of REE in the Fe ore (i.e. low-grade and high-grade iron ore) further emphasises the variable protolith theory. Hydrothermally-induced ferruginisation is suggested to post-date the deposition of the post-Transvaal Olifantshoek shales, and is likely to be linked to a sub-surface transgressive hydrothermal event which indiscriminately transforms both shale and BIF into Fe-ore. A revised, hydrothermal model for the formation of BIF-hosted high-grade hematite iron ore deposits in the central part of the Maremane anticline is proposed, and some ideas of the author for further follow-up research are presented.
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Andersson, Stefan. "Deformation, metamorphism and remobilisation in the Hornkullen polymetallic deposit, western Bergslagen, Sweden." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-223246.
Full textAbstract:
The polymetallic Hornkullen deposit is situated in the western part of the Bergslagen ore province, Sweden. It is hosted by an inlier of approximately 1.90-1.88 Ga Svecofennian volcanic and sedimentary metasupracrustal rocks enclosed in a significantly younger, c. 1.8 Ga TIB granitoid (Filipstad granite). Although being mined intermittently for silver during the last 100s of years in addition to been the subject for more recent exploration work, the genesis of this deposit and others in a similar geological position is poorly understood. The hypothesis is that the Hornkullen deposit represents a metamorphically overprinted, syn-volcanic Svecofennian mineralisation. The main ore assemblage comprises magnetite, pyrrhotite, galena, chalcopyrite and arsenopyrite with subordinate pyrite, sphalerite, ilmenite and löllingite. Pb-Fe-Ag-Sb sulphosalts include boulangerite, meneghinite, jamesonite, freibergite-tetrahedrite, pyrargyrite, and stephanite, which mainly occur in trace amounts. Gudmundite and molybdenite are rare accessories. Generally, galena, chalcopyrite and pyrrhotite have accommodated strain in a ductile manner. Locally, this can also be seen in boulangerite, meneghinite and sphalerite. Magnetite, arsenopyrite and pyrite frequently have been deformed in a brittle way. The contrast in competence resulted in the remobilisation of the more ductile minerals into fractures in the more competent minerals. In massive parts, this contrast also resulted in more fragmented clasts of competent minerals within a less competent matrix, similar to “ball ore” texture. Recrystallisation is particularly evident in magnetite and pyrrhotite but also seen in coarser aggregates of ilmenite. Additionally, these minerals and also pyrite and arsenopyrite frequently exhibit euhedral morphology when occurring within less ductile minerals. Inclusions of ore minerals in porphyroblastic garnet are abundant. Geothermobarometry of arsenopyrite and sphalerite suggests temperatures and pressures of 525°C (between 440°C and c. 590°C) and c. 300-400 MPa, consistent with regional Svecokarelian amphibolite facies metamorphism, albeit with some caveats. Fluid inclusion entrapment conditions were determined to c. 440°C (between 400°C and 600°C) and c. 280 MPa. The observed textures are a result of deformation and remobilisation of diverse ore minerals during the Svecokarelian orogeny. Remobilisation was possibly initiated during prograde metamorphism, followed by additional and more extensive modification during retrograde conditions, at least to temperatures below 200°C. Sulphosalt formation is considered to reflect an evolution from prograde through retrograde metamorphism, although most of them formed during the retrograde stage, including the Ag-minerals. No evidence for any additional introduction of elements from later TIB magmatism is present. The combined observations can most easily be reconciled with a metamorphically overprinted syn-volcanic Svecofennian mineralisation.Den polymetalliska mineraliseringen vid Hornkullen är belägen i västra Bergslagen i Mellansverige. Den uppträder i ca. 1,90-1,88 miljarder år gamla Svekofenniska metavulkaniska- och sedimentära ytbergarter inneslutna i en yngre, ca. 1,8 miljarder år gammal intrusiv bergart, så kallad Filipstadsgranit. Trots att mineraliseringen ganska nyligen varit ett mål för prospektering samt tidigare brutits på silver, saknas fortfarande information om dess malmmineralogi och hur den bildats. Hypotesen är att Hornkullen utgörs av en metamorft överpräglad synvulkanisk Svekofennisk mineralisering. Den domineras av magnetit, magnetkis, blyglans, kopparkis och arsenikkis och i mindre mängd pyrit, zinkblände, ilmenit och löllingit. Pb-Fe-Ag-Sb-sulfosalter finns lokalt och inkluderar boulangerit, meneghinit, jamesonit, freibergit-tetrahedrit, pyrargyrit, och stephanit. Gudmundit och molybdenglans är andra sällsynta accessoriska malmmineral. Blyglans, kopparkis och magnetkis har deformerats plastiskt men lokalt också boulangerit, meneghinit och zinkblände. Magnetit, arsenikkis och pyrit har deformerats sprött. Denna tydliga skillnad i kompetens har resulterat i att inkompetenta mineral ommobiliserats och kommit att fylla sprickor i de mer kompetenta mineralen. I massiva delar av mineraliseringen har denna skillnad även resulterat i en textur av kulmalmstyp. Granoblastisk omkristallisering är särskilt tydligt i magnetit och magnetkis, men även i grovkorniga aggregat av ilmenit. Vidare så förekommer dessa mineral liksom pyrit och arsenikkis ofta som euhedrala kristaller i mindre kompetent matrix. Inneslutningar av malmmineral i porfyroblastisk granat är vanligt förekommande. Geotermobarometri på arsenikkis och zinkblände gav temperatur och tryck på 525°C (mellan 440°C och ca. 590°C) och ca. 300-400 MPa, vilket överensstämmer med regional Svekokarelsk amfibolitfaciesmetamorfos. Förhållandena vid infångandet av synmetamorfa vätskeinneslutningar har uppskattats till en temperatur på ca. 440°C (mellan 400 och 600°C) och tryck på ca. 280 MPa. Merparten av de observerade texturerna är resultat av deformation och ommobilisering relaterad till de förhållanden som rådde under den Svekokarelska orogenesen. Ommobiliseringen av vissa mineral startades förmodligen redan under prograd metamorfos, vilket sedan följdes av mer omfattande modifikation under retrograda förhållanden, åtminstone till temperaturer under 200°C. Bildningen av sulfosalter reflekterar en utveckling från prograd till retrograd metamorfos där de flesta bildats under den senare, retrograda fasen, däribland de olika silvermineralen. Alla observationer resulterar sammantaget i tolkningen att Hornkullen är en regional-metamorft överpräglad och deformerad synvulkanisk Svekofennisk mineralisering.
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Cruz, Victor Muniz Alves. "Metalogenia em terrenos de alto grau metamórfico: as mineralizações tungstaníferas da área de Monumento/Cacaria RJ." Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8155.
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Conselho Nacional de Desenvolvimento Científico e TecnológicoEm trabalho de prospecção geoquímica regional por concentrado de bateia (PEREIRA e SANTOS, 1983) foi evidenciado na região de Cacaria, município de Piraí, ocorrências de scheelita. Com o objetivo de investigar a possível fonte litológica desta ocorrência, foram realizadas amostragens de sedimentos de corrente e concentrado de bateia além de investigações de campo para sua fonte. Elaborouse ainda um mapa geológico em escala de detalhe 1:25.000. As unidades estratigráficas base utilizadas no mapa foram definidas em trabalhos da empresa RIOFINEX (1977) durante pesquisas para mineralizações de Pb-Zn na região de Rio Claro. Ensaios laboratoriais envolvendo descrição de lâminas petrográficas, difratometria de raios X, fluorescência de raios X, espectrometria Raman, microscopia eletrônica de varredura e o auxílio do mineralight de ondas curtas. As mineralizações scheelitíferas encontradas foram classificadas segundo um modelo do tipo sedimentar exalativo, localmente com possíveis contribuições de atividades metassomáticas tardias, concentrando a mineralização, assim como proposto para algumas ocorrências já descritas no nordeste brasileiro.
In a mineral exploration panning concentrate programme PEREIRA AND SANTOS (1985) identified in the Cacaria region, near the Piraí City, occurences of scheelite. With the objective to investigate the lithological origin of this mineral a nonsystematic sampling by stream sediments and panning concentrate, was carried out to identify the tungsten mineralization source. A geological map was also executed at detailed scale of 1:25.000. The stratigraphic division applied to this map was defined in projects of RIOFINEX (1977) company during investigation of Pb-Zn mineralization in Rio Claro. Laboratorial trials involving description of petrography, Xray diffraction, X-ray fluorescence, Raman spectroscopy, electronic microscopy scanning and short wave mineralight. The scheelite-bearing mineralization was classified according to a exhalative sedimentary model with possible contributions of a late metasomatic activities concentrating the mineralization as proposed for some occurrences observed in northeast part of Brazil.
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Dünkel, Ines [Verfasser]. "The genesis of East Elba iron ore deposits and their interrelation with Messinian tectonics / [Hrsg.: Institut und Museum für Geologie und Paläontologie der Universität Tübingen]. Ines Dünkel." Tübingen : Inst. und Museum für Geologie und Paläontologie, 2003. http://d-nb.info/967986257/34.
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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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Zehni, Addi. "Geologie, mineralogie et geochimie du gisement de pb(zn-cu) de beddiane (district de touissit-boubeker, maroc oriental)." Toulouse 3, 1988. http://www.theses.fr/1988TOU30145.
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Le gisement de beddiane appartient au district de touissit-bou beker, "chaine des horsts", maroc oriental. Il est encaisse dans la serie alleno-bajocienne, discordante sur le socle paleozoique, et se caracterise, par rapport aux gisements voisins, par sa richesse exceptionnelle en plomb, des concentrations exploitables de cuivre et peu de zinc. L'analyse sedimentologique de la formation carbonatee encaissante a permis de mettre en evidence des sequences transgressives et regressives, traduisant un environnement geologique instable: subsidences saccadees et emersions temporaires, suivies de phenomenes de dissolution-karstification pendant et apres le depot de la formation. L'examen petrographique a permis de distinguer plusieurs types de dolomies et de mettre en evidence deux phases principales de dolomitisation: un diagenetique precoce et une autre epigenetique, tardive. La lithogeochimie, effectuee a partir des carottes de sondages, a montre que toutes les assises carbonatees, sont fortement anormales en pb, zn et cu et plus particulierement les facies micritiques. Trois phases de mineralisations zn, pb et cu ont ete distinguees. La zonalite verticale et horizontale des mineralisations au sein du gisement et la geometrie des karsts mineralises suggerent que les solutions salines hydrothermales (100**(o)c) aient circule d'ouest en est dans cette couverture carbonatee. La presence dans le socle sous-jacent de filons a pb-cu pourrait temoigner d'une origine plus profonde des fluides mineralisateurs
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Creach, Monique. "Accumulation supergène de cuivre en milieu latéritique : étude pétrologique, cristallochimique et géochimique de l'altération du skarn de Santa Blandina (Itapeva, Bresil)." Poitiers, 1988. http://www.theses.fr/1988POIT2344.
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On etudie l'indice cuprifere de santa blandina (bresil) provenant de l'alteration d'un skarn porteur d'une mineralisation sulfuree a chalcopyrite et bornite. Les produits argilomorphes provoquent l'epigenie des mineraux du skarn et des solutions percolantes provoquent l'evolution mineralogique de ces produits. Les analyses mineralogiques et cristallochimiques determinent la nature exacte de ces phases argilomorphes et montrent la difficulte de l'incorporation du cuivre dans un reseau regulier d'argile
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Lardeau, Maria. "Mineralogie et petrogenese du minerai sulfure du gisement volcano-sedimentaire a zn-cu-ba-(pb-ag) de chessy-les-mines (rhone) : application a l'etude des amas sulfures metamorphises." Orléans, 1987. http://www.theses.fr/1987ORLE2053.
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L'etude petrogenetique des minerais de chessy-les-mines a permis de preciser la nature de la mineralisation et l'etude des deformations, de retracer l'evolution geologique complexe. Il est apparu que les metamorphismes ont amene une homogeneisation et une purification chimique des mineraux du minerai alors que leur recristallisation lors de la mise en place du granite a entraine un rajeunissement chimique. Cette approche petrogenetique et geochimique renforce la parente genetique entre chessy-les-mines et saint bel
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Birve, Anna. "Suppressor of zeste 12, a Polycomb group gene in Drosophila melanogaster; one piece in the epigenetic puzzle." Doctoral thesis, Umeå University, Molecular Biology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-98.
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In multicellular organisms all cells in one individual have an identical genotype, and yet their bodies consist of many and very different tissues and thus many different cell types. Somehow there must be a difference in how genes are interpreted. So, there must be signals that tell the genes when and where to be active and inactive, respectively. In some instances a specific an expression pattern (active or inactive) is epigenetic; it is established and maintained throughout multiple rounds of cell divisions. In the developing Drosophila embryo, the proper expression pattern of e.g. the homeotic genes Abd-B and Ubx is to be kept active in the posterior part and silenced in the anterior. Properly silenced homeotic genes are crucial for the correct segmentation pattern of the fly and the Polycomb group (Pc-G) proteins are vital for maintaining this type of stable repression.
As part of this thesis, Suppressor of zeste 12 (Su(z)12) is characterized as a Drosophila Pc-G gene. Mutations in the gene cause widespread misexpression of several homeotic genes in embryos and larvae. Results show that the silencing of the homeotic genes Abd-B and Ubx, probably is mediated via physical binding of SU(Z)12 to Polycomb Response Elements in the BX-C. Su(z)12 mutations are strong suppressors of position-effect-variegation and the SU(Z)12 protein binds weakly to the heterochromatic centromeric region. These results indicate that SU(Z)12 has a function in heterochromatin-mediated repression, which is an unusual feature for a Pc-G protein. The structure of the Su(z)12 gene was determined and the deduced protein contains a C2-H2 zinc finger domain, several nuclear localization signals, and a region, the VEFS box, with high homology to mammalian and plant homologues. Su(z)12 was originally isolated in a screen for modifiers of the zeste-white interaction and I present results that suggests that this effect is mediated through an interaction between Su(z)12 and zeste. I also show that Su(z)12 interact genetically with other Pc-G mutants and that the SU(Z)12 protein binds more than 100 euchromatic bands on polytene chromosomes. I also present results showing that SU(Z)12 is a subunit of two different E(Z)/ESC embryonic silencing complexes, one 1MDa and one 600 kDa complex, where the larger complex also contains PCL and RPD3.
In conclusion, results presented in this thesis show that the recently identified Pc-G gene, Su(z)12, is of vital importance for correct maintenance of silencing of the developmentally important homeotic genes.
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Whitfield, Derek. "The genesis and controls of gold mineralization south of Rehoboth, Namibia." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1005560.
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Gold mineralization is hosted within gossanous quartz-haematite veins in volcano-sedimentary lithologies of the Klein Aub - Rehoboth basin of the Irumide Belt, Namibia. Mineralization and hydrothermal alteration are restricted to deformed lithologies particularly the metasediments. Lithological relationships, geochemistry and metallogenic characteristics of the Irumide Belt suggest an intra-continental rift setting. Copper mineralization is well known along the length of the belt, from Klein Aub in the southwest to Ghanzi in the northeast, whereas gold mineralization appears restricted to the Klein Aub Rehoboth basin. The gold is envisaged as having being leached initially from graben fill sequences during rift closure and basin dewatering. Location of the mineralization is strongly controlled by structure and lithological contact zones. Such zones are percieved as having acted as conduit zones for escaping mineralized fluids during basin closure and deformation. Apart from the lack of an effective mineralizing trap, all features consistent with the development of an ore deposit are present. The largest mineralization traps within the area studied are shear zones followed by lithological contact zones. The Mebi and Blanks gold mines are developed over large shear zones while the Swartmodder and Neuras gold mines are situated over mineralized lithological contacts. The Swartmodder copper mine yielded ore from a mineralized schist enclave within granite. Copper and gold occurrences are attributed to two contrasting styles of mineralization. Copper mineralization is suggested to have developed during initial rifting of the belt (ie. stratabound sedimentary exhalative type), while the gold and minor copper resulted from rift closure and basin dewatering. Although no economical orebody was realized during the course of this study a model is proposed for the development of mineralization within the Irumide basement lithologies as a working hypothesis for future exploration.
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Bruchon, Isabelle. "Etude geologique, mineralogique et geochimique des mineralisations polymetalliques a sb-zn-w(pb, cu, ag, as. . . ) du secteur brassac-lacaune (tarn, montagne noire)." Toulouse 3, 1988. http://www.theses.fr/1988TOU30144.
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Quatre parageneses successives decrivent la mise en place des mineralisations sulfurees de cambounes. Les 3 premieres sont dues a la remobilisation in situ d'une mineralisation stratiforme cambrienne lors de la deformation hercynienne majeure. La paragenese a antimoine, tardihercynienne est associee a des fluides hydrocarboniques et hypersalins. La paragenese a cu-pb est complexe et depend de la temperature de formation et de la proximite des mineralisations preexistantes
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Li, Ning. "Depositional controls and genesis of the Jinding sandstone-hosted Zn-Pb deposit, Yunnan Province, Southwest China /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Thesis (Ph. D.)--University of Texas at Austin, 1998.Vita. One folded ill. in pocket. Includes bibliographical references (leaves 222-235). Available also in a digital version from Dissertation Abstracts.
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Halter, Ghislaine. "Zonalite des alterations dans l'environnement des gisements d'uranium associes a la discordance du proterozoique moyen (saskatchewan, canada)." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13078.
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Cette etude porte sur les conditions des gisements d'uranium du saskatchewan de la region de waterbury lake, qui sont associes a la discordance entre le socle archeen/aphebien et la couverture sedimentaire helikienne. Deux episodes tardi-hudsoniens gouvernent la remobilisation in situ de l'uranium: une retromorphose (facies schiste vert) et une alteration hydrothermale affectant les zones tectonisees du socle. Les donnees isotopiques des phyllites revelent que la diagenese des gres est realisee en presence d'une saumure qui est egalement a l'origine du fluide mineralisateur
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Latorre-Muzzio, Gina. "The influence of geological, genetic and economic factors on the ore reserve estimation of Kwaggashoek east iron ore deposit." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005584.
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Tectonics plays an important role in the genesis and subsequent mlnlng development of the Kwaggashoek East ore body. Lithological key units control the effectiveness of the ore forming processes, affecting the in situ ore reserve, The Kwaggashoek East deposit is the product of primary and secondary processes. A genetic model focussed on the source, migration and deposition of iron suggests a possible original source of iron as the product of very dilute hydrothermal input into deep ocean waters, with subsequent migration through structural conduits. Supergene processes account for the upgrading of the ore and the phosphorus redistribution. A good correlation between samples in a preliminary geostatistical study reflects the effectiveness of this process in the high grade ore zone. A broad overview of the economic issues which affect the commercialization of iron, indicates a balanced supply-demand situation for the five next years. The reserve estimation procedure requires accurate scientific terminology and appropriate methodology. Documentation is essential and should be detailed enough to allow for future reassessment. The results of three estimation methods in Kwaggashoek East differ by less than 5%. The accuracy of the final results depends more on geological interpretation and assumptions than on the method applied. Although optimization of grade and tonnage in the Kwaggashoek East deposit seems to be met with the actual cut-off grade used in the Thabazimbi mine district, the grade-quality concept introduced in this thesis indicates a decrease in the estimated reserves for the deposit
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Tazari, Mahmood. "A Meta-Analysis of Association Between One-Carbon Metabolism Gene Polymorphisms and Risk of Prostate Cancer." ScholarWorks, 2015. https://scholarworks.waldenu.edu/dissertations/406.
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Prostate cancer is the most common cancer among men. The purpose of this quantitative, meta-analysis study was to examine one-carbon metabolism gene polymorphisms in a group of genes to determine their association with prostate cancer risk. The genetic epidemiology theory provided the framework for the study. The data collected were from published articles. From over 2,800 individual studies, 20 articles were retained for results and data abstraction, following the title, abstract screen, and full text screening in the second phase. The data were analyzed by a meta-analysis statistical method, combining the results from selected studies to estimate the overall association. According to study results by the adjusted p-values of fixed model, there was a significant association between decreased risk of prostate cancer and the variant of Allele T, Genotype TT, and the recessive model of C667T polymorphism. In the random model, the adjusted p-values show a significant association between decreased risk of prostate cancer, the variant of Genotype TT, and recessive model. There was an increased risk of prostate cancer in A1298C polymorphism by adjusted p-value on the variant of Genotype AC, in the fixed model. This study leads to positive social change by providing information on an optimization surveillance strategy to ensure valid screening test for prostate disease reporting. Future studies with a greater number of samples are needed, including gene-gene and gene-environment interaction to verify study results.
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Biotti, Alessandro. "Elektronische Marktplätze auf Basis einer Serviceorientierten Architektur am Beispiel Genesis /." St. Gallen, 2008. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/01299809001/$FILE/01299809001.pdf.
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Tarence, Paul Edward. "Teaching Genesis chapters one through twelve on the Internet by testing and assessment." Online full text .pdf document, available to Fuller patrons only, 2001. http://www.tren.com.
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Wilson, Margaret Taylor. "Developing a nurturing model of pastoral care in the hospice setting based on "restored image" in Genesis 1:27 /." Free full text is available to ORU patrons only; click to view:, 2002. http://wwwlib.umi.com/cr/oru/fullcit?p3079970.
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Reed, Patricia. "Function of bacteriophage Orf recombinases in genetic exchange." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/4917/.
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Recombination events in bacteriophages frequently occur by illegitimate exchange at short tracts of sequence homology, enabling these viruses to acquire novel genes and serve as vehicles for horizontal gene transfer. The emergence of new pathogenic organisms due to the acquisition of virulence determinants from bacterial viruses has stimulated considerable interest in the mechanisms of phage recombination. Bacteriophage λ encodes its own recombination system, consisting of Exo, β and γ proteins. An additional λ recombinase, Orf, participates in the early stages of exchange, supplying a function equivalent to the Escherichia coli RecFOR complex. The host enzyme complex promotes the loading of the RecA strand exchange protein onto SSB-coated ssDNA. This thesis describes the purification and biochemical analysis of the λ Orf protein, in parallel with two distantly related homologs from E. coli cryptic prophage DLP12 and Staphylococcus aureus phage ɸETA.X Orf was found to belong to a family of proteins originating from diverse lambdoid phage and prophage sources. Members of this family reside within a conserved genetic module located between phage replication and cell lysis functions. Orf exists as a homodimer, arranged as a toroid with a shallow cleft running perpendicular to the central cavity. K binds preferentially to DNA containing single- stranded regions, and associates with E. coli SSB protein in the presence of ssDNA. The Orf homolog from E. coli DLP12 displayed similar properties. This work suggests that members of the Orf family function as recombination mediator proteins, stimulating the assembly of strand exchange proteins onto ssDNA, and highlights the importance of overcoming the barrier presented by SSB proteins during lambdoid phage recombination.
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Veselinović, Milica. "Genetic models for epithermal gold deposits and applications to exploration." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005562.
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Epithermal gold deposits are the product of large-scale hydrothermal systems in tectonically active regions. They form at shallow crustal levels where the physico-chemical conditions change abruptly. Two major groups of epithermal gold deposits can be distinguished based on their genetic connection with: A) Copper-molybdenum porphyry systems and B) Geothermal systems related to volcanic centres and calderas. Epithermal gold deposits connected with geothermal systems encompass three major types: adularia-sericite, acid-sulphate and disseminated replacement (the Carlin-type). Their essential ingredients are: high heat source which leads to convection of groundwater in the upper crust; source of hydrothermal fluid, metals and reduced sulphur; and high-permeability structures which allow fluid convection and metal deposition. Mixing of these ingredients leads to the formation of epithermal gold deposits throughout crustal history, without any restriction on age. The ores were deposited from near-neutral (adularia-sericite type and some of the Carlin-type) to acidic (acid-sulphate type and porphyry-related epithermal gold deposits), low-salinity, high C0₂ and high H₂S fluids, which were predominantly meteoritic in origin. The transport capability of deep fluids in epithermal hydrothermal systems may be shown to be dependent largely on their H₂S content and, through a series of fluid mineral equilibria, on temperature and on C0₂ content. The most common mechanisms of ore deposition are boiling (phase separation), mixing of fluids of different temperatures and salinities, reaction between them and wall rocks, dilution and cooling. An understanding of genetic models for epithermal gold deposits provides the basis for the selection of favourable areas for regional to prospect-scale exploration.
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Charlier, Johan. "Monitoring gene level biodiversity - aspects and considerations in the context of conservation." Doctoral thesis, Stockholms universitet, Zoologiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-62796.
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The objectives of this thesis relate to questions needed to be addressed in the context of genetic monitoring for implementing the Convention on Biological Diversity for the gene level. Genetic monitoring is quantifying temporal changes in population genetic metrics. Specific goals of this thesis include i) synthesizing existing information relevant to genetic monitoring of Swedish species, ii) providing a genetic baseline for the Swedish moose, iii) evaluating the relative performance of nuclear versus organelle genetic markers for detecting population divergence, iv) actually monitoring the genetic composition, structure, level of variation, and effective population size (Ne) and assessing the relation between Ne and the actual number of individuals for an unexploited brown trout population. The concept of conservation genetic monitoring is defined and Swedish priority species for such monitoring are identified; they include highly exploited organisms such as moose, salmonid fishes, Norway spruce, Atlantic cod, and Atlantic herring. Results indicate that the Swedish moose might be more genetically divergent than previously anticipated and appears to be divided into at least three different subpopulations, representing a southern, a central, and a northern population. The relative efficiency of nuclear and organelle markers depends on the relationship between the degree of genetic differentiation at the two types of markers. In turn, this relates to how far the divergence process has progressed. For the monitored brown trout population no indication of systematic change of population structure or allele frequencies was observed over 30 years. Significant genetic drift was found, though, translating into an overall Ne-estimate of ~75. The actual number of adult fish (NC) was assessed as ~600, corresponding to an Ne/NC ratio of 0.13. In spite of the relatively small effective population size monitoring did not reveal loss of genetic variation.
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Hong, Seung-Pyo School of Biochemistry & Molecular Genetics UNSW. "Transcriptional regulation of one-carbon metabolism genes of Saccharomyces cerevisiae." Awarded by:University of New South Wales. School of Biochemistry and Molecular Genetics, 1999. http://handle.unsw.edu.au/1959.4/22503.
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The glycine decarboxylase complex (GDC) of Succharomyces cerevisiae composed of four subunits (P, H, T and L) and plays an important role in the interconversion of serine and glycine and balancing the one-carbon unit requirements of the cell. It also enables the cell to use glycine as sole nitrogen source. This study was concerned with characterising the molecular mechanism of transcriptional regulation of the GCVgenes encoding the subunits of the GDC. The important findings of this work can be summarised as follows: i) Transcription of the GCV genes are regulated by glycine and rich nitrogen sources, which are mediated by different cis-acting elements. The LPDl gene did not show a glycine response since its transcriptional regulation is distinct from that of the other genes encoding the GDC subunits. ii) Glycine analogues or serine did not affect expression of GCV2, and therefore glycine probably needs to be metabolised to effect the glycine response of the GCV genes. iii) The repression of the GCV2 gene expression by rich nitrogen sources is mediated by a sequence between -227 and -205 of GCV2, and NCR-regulatory mutant studies showed that repression is not directly controlled by the known NCR system. iv) The glycine response of GCV2 is mediated by a motif (the glycine regulatory region; GRR; 5'-CATCN7CTTCTT-3') with CTTCTT at its core. Additional sequence immediately 5' of this motif (between -310 to -289) plays a minor role for the gene's full glycine response. v) The GRR of the GCV genes can mediate the glycine response by either activation or repression, indicating that the transcription factor(s) mediating the glycine response is/are dual-functional in nature. vi) Studies of GCV2 gene expression using different regulatory mutants showed that expression of the gene is further modulated by other transcription factors such as and Baslp which are distinct from the glycine response and possibly involved in setting up the basal expression level. vii) I n vitro studies of the GRR-protein interaction revealed THF affects the affinity of the DNA-binding protein(s) for the GRR. The importance of THF in regulation of the GCV2 gene was also shown in vivo using a foll mutant that is unable to synthesise any folates. THF or a C1-bound derivative of it acts as a ligand for the transcription factor, thus influencing transcription of the GCV genes in the appropriate physiological manner. viii) Using heparin-Sepharose chromatography fractions, four complex formations (complex I to IV) were observed with the GRR. The protein responsible for one of these was separable from the others. EMSA profiles using the GRR of the GCVI and GCV2 genes (in the presence or absence of THF) were very similar, indicating that these genes bind the same proteins and are regulated in a similar manner. ix) Mutation of the CTTCTT motif within the GRR caused significant reduction in in vitro DNA-protein complex formation, however, THF addition overcame this reduction. x) Only complex II formation was observed with a DNA fragment spanning -322 to -295, and THF affected this complex formation. xi) Footprinting analyses of complex I revealed that the binding protein protected the GRR of the GCV2 gene from DNaseI activity. This protein is an excellent candidate for the glycine response regulatory protein. Titration experiments using EMSA showed that this protein can dimerise. A preliminary genome-wide analysis of the S. cerevisiae transcriptome was carried out using miniarray membrane hybridisation. This investigated the global transcriptional changes within the cell in response to the addition of glycine into the medium. Identification of genes related to various cellular processes including onecarbon metabolism gave an insight into the regulation of the cellular metabolic flow, especially that of one-carbon metabolism. The results indicated that: xii) Glycine is transported into mitochondria to be used as substrate for the GDC which (with mitochondria1 SHMT) produces serine that is subsequently utilised for the various one-carbon metabolic pathways, such as methionine synthesis and purine synthesis. xiii) A gene of unknown function (YER183C) which showed homology to the gene for human 5,lO-CH-THF synthetase was identified from gene-array analysis to be upregulated on glycine addition, indicating the protein encoded by this gene may be involved in balancing the metabolic flow between methionine and purine synthesis when THF pools are disturbed by glycine addition. xiv) Addition of glycine to the medium also triggers the expression of other metabolic genes related to amino acid biosynthetic pathways and that of many other genes which are not directly related to one-carbon metabolism. This may be due to prolonged culturing with glycine in the medium resulting in altered expression of genes mediated by one or more secondary factors. These may reflect an adaptive response rather than a direct consequence of glycine induction. On the basis of the above data, a model for the mechanisms regulating glycine response is presented.
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Linklater, Michael Anthony Leonard Flanders. "The exploration for and possible genesis of, some Archaean granite/gneiss-hosted gold deposits in the Pietersburg granite-greenstone terrane." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005557.
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Abstract The gold mineralization event within Archaean granite-greenstone terranes occurred during the late Archaean, and followed the intrusion of syn- to late-tectonic granitic plutons into previously deformed greenstone belts. An Archaean granite/gneiss-hosted gold deposit, in terms of this project, is classified as having a gold-assay cutoff of 1g/metric ton over widths of at least several metres, or higher grades over narrower widths and/or verbal descriptions that indicate such values. Fluid inclusion studies and isotopic data identify two possible origins for the auriferous fluids; namely magmatic and metamorphic. The exploration target according to the magmatic model, is a late-Archaean, hydrothermally altered, mineralized and fractured granitic intrusion preferably with a granodioritic or quartz-dioritic composition. The exploration target according to the metamorphic replacement model is a granitic stock that has intruded a zone of crustal weakness such as a shear zone, active during the late Archaean. Alternatively, the granitic intrusion should be affected by regionally extensive late-Archaean shearing. It should be hydrothermally altered, deformed and mineralized. Five areas within the Pietersburg granite-greenstone terrane were selected for the 'Regional Area Selection' phase of exploration for Archaean granite/gneiss-hosted gold deposits; namely Roodepoort, Waterval, Ramagoep, Moletsie and Matlala. Roodepoort contains a known granodiorite-hosted gold deposit; the Knight's Pluton, and served as an orientation survey for this project. The use and interpretation of LANDSAT images formed an integral part of exploration techniques; to assess their usefulness in the exploration of Archaean granite/gneiss-hosted gold deposits. Area selection criteria for granite/gneiss-hosted gold mineralization at Roodepoort are the major ENE-trending shear zone, the NNW-trending lineament and hydrothermal alteration, shearing, quartz-stockworks and sulphide mineralization within the Knight's Pluton. The origin of the gold within the Knight's Pluton is uncertain; both magmatic and metamorphic models are possibilities. Ongoing exploration is in progress at Roodepoort. The only area selection criterion for granite/gneiss-hosted gold mineralization at Waterval is the sericitized, subcropping granites located within trenches. Gold mineralization is insignificant. No area selection criteria for Archaean granite/gneiss-hosted gold mineralization were located at Ramagoep, Matlala and Moletsie. No further exploration is recommended for all these areas. The MES image interpretations were successful in identifying lineaments, granitic outcrops, greenstones, vegetation and soil cover. The Clay-iron images adequately differentiated betweeen iron-rich and clay-bearing areas. However, not all clay-bearing areas were associated with hydrothermal alteratian; field checks were necessary to discriminate between weathered granites and hydrothermally altered granites. The Wallis images served to locally enhance the contrasts of the MES and Clay-iron images.
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Steiger, David. "Systematischer Vergleich von Ansätzen zur Modellierung von organisationsübergreifenden Geschäftsprozessen am Beispiel von ITAIDE und GENESIS." St. Gallen, 2007. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/04607628001/$FILE/04607628001.pdf.
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Bowers, Laura Yvonne. "Orf protein modulates phage and bacterial pathways of genetic recombination." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2345/.
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The emergence of novel pathogenic organisms due to the acquisition of virulence determinants from bacteriophages has generated significant interest in the pathways responsible for genomic rearrangements. Phageλ encodes its own recombination system, the Red system, comprising Exo, β and γ proteins. In addition,λ encodes another recombinase, Orf, which participates in the initial stages of genetic exchange and supplies a frmction equivalent to that of the Escherichia coli RecFOR proteins. This thesis focuses on determining the function of Orf in phage and bacterial recombination pathways by analysing its impact on recombinases encoded by λ and E. coli. Experiments revealed that Orf interacts with bacterial and phage recombination proteins in the initial exchange step of recombination, modulating the activities of both Exo and RecA. Orf, along with β, attenuates the 5'-3' exonuclease activity of Exo, a feature that depends largely on the ability of Orf to bind DNA. Orf also facilitates loading of RecA onto ssDNA pre-coat SSB but only if a ssDNA:dsDNA intersection is incorporated in the substrate. A motif similar to that found at the BRCA2-Rad51 interface may be responsible for Orf mimicking a RECA monomer to initiate nucleoprotein filament formation. Significantly, this would direct recombination down the bacterial RecA pathway of break restoration rather than the phage Red pathway with potentially important consequences for the outcome of the exchange reaction.
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Farré, de Pablo Júlia. "Genesis and evolution of chromitites in ophiolite complexes from a mineralogical perspective." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673632.
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The finding of a suite of unusual minerals associated to ophiolitic chromitites questions traditional model for the formation of these rocks. These findings include minerals typically considered indicators of ultra-high pressure and super-reducing conditions (i.e., diamond). Several authors proposed new genetic models for ophiolitic chromitites which involved their formation and/or evolution in the deep mantle (>410 km), opening an intense debate that is still active. This Ph.D. thesis contributes to this debate by studying four examples of ophiolitic chromitites from different geodynamic settings (fore-arc, back-arc, and supra-subduction mantle interacted with mantle plume) in order to evaluate the origin of these “exotic” minerals in ophiolitic chromitites and their possible meaning into the evolutionary history of these enigmatic rocks.
The studied examples of chromitites formed in fore-arc settings include chromitite veins from Havana-Matanzas ophiolite (Cuba) and chromitite pods from Loma Las Cabirmas hill in Loma Caribe peridotite (Dominican Republic). The chromitites from Havana-Matanzas are characterized by abundant platinum-group mineral (PGM) inclusions and by being associated with orthopyroxenite in ophiolitic mantle section. Chromite studies reveal that the chromitites and orthopyroxenites formed coetaneously from Si- and Mg-rich andesitic melts with boninitic affinity originated in the fore-arc mantle of an intra-oceanic arc. The melts infiltrated the pre-existing harzburgite, dissolving olivine while precipitating orthopyroxene and chromite. The abundance of PGM is interpreted to result from the “collector” effect of chromite during the chromitite formation, which was enhanced due to the small volume of chromitites formed.
The Loma Las Cabirmas chromitites display unusually high platinum-group elements (PGE) contents and hydrothermal PGE mineralizations. The study of these chromitites suggests that hydrothermal fluids infiltrated the chromitites during serpentinization of the rocks and gave place to the in situ alteration of magmatic PGM in the chromitites and the precipitation of hydrothermal Pt-rich mineralization in uvarovite- and chromian clinochlore-filled fractures, within the thermal range of 350–150 ºC. Therefore, the PGE bulk geochemistry and mineralogy of these chromitites was largely impacted by post-magmatic processes.
Microdiamonds were found in situ in ophiolitic chromitites from Tehuitzingo serpentinite (Mexico), interpreted as an ophiolitic mantle section formed in a back-arc geodynamic setting. Micrometric diamonds were located within healed fractures crosscutting the chromite grains. These diamonds were associated with amorphous C bearing O-species and with a low-pressure and low-temperature mineral assemblage. Thermodynamic calculations show that the chromite from the healed fractures recrystallized at 670–510 ºC. Consequently, the diamonds are inferred to be metastable and form from C undersaturated CO2–H2O–CH4 fluids infiltrating the chromitite during serpentinization processes. The diamond formed due to the super-reducing conditions achieved within the sealed inclusions. The formation of microdiamonds in (ultra)reduced low-pressure and low-temperature environments during serpentinization challenges the idea that diamond in ophiolitic rocks constitutes an unequivocal indicator of ultra-high pressure conditions.
Chromitites from the northern and central part of the Loma Caribe peridotitic belt (Dominican Republic) were studied as an example of chromitites hosted in an ophiolite with geochemical fingerprints of deep-seated plume activity. These chromitites display unusual compositions, different from other ophiolitic chromitites. Instead, the analyzed chromite grains exhibit major and trace element composition that overlaps the field of komatiitic chromite. Moreover, the composition of parental melts of these chromitites is similar to plume derived products of the Dominican Republic. Therefore, I inferred that these chromitites formed in the lithospheric mantle after parental melts derived from an enriched peridotite source influenced by the Caribbean mantle plume.
Altogether, my results show the importance of differentiating features resulting from magmatic primary processes from those resulting from alteration processes. Only then it will be possible to reconstruct the genetic story and evolution of the chromitites and propose accurate models.En els darrers anys s’han trobat una sèrie de minerals considerats “exòtics” en cromitites ofiolítiques que han fet replantejar a la comunitat científica internacional els models de formació d’aquestes roques. Aquests minerals inusuals són sovint considerats indicadors de condicions d’ultra-alta pressió i súper reductores (i.e. diamant), de manera que els models proposats a partir d’aquestes troballes inclouen un origen i/o una evolució de les cromitites a nivells profunds mantèl·lics (>410 km), contraposant-se a la formació en el mantell litosfèric proposada pels models tradicionals. Aquesta tesi doctoral estudia quatre exemples de cromitites ofiolítiques que pertanyen a diferents contexts geodinàmics amb l’objectiu d’identificar minerals o trets inusuals en les cromitites i/o en les seves roques associades per tal d’avaluar-ne el seu origen i el seu possible significar en el marge de la historia evolutiva d’aquestes roques. Els casos estudiats són: (1) les venes de cromitita de l’ofiolita d’Habana-Matanzas (Cuba), pertanyents a un context de avant-arc; (2) els pods de cromitites de Loma Las Cabrimas (peridotita de Loma Caribe, República Dominicana), també pertanyents a un context d’avant-arc i caracteritzades per les seves mineralitzacions hidrotermals de baixa temperatura de Pt; (3) les cromitites de la serpentina de Tehuitzingo (Mèxic), interpretada com una secció mantèl·lica ofiolítica formada en un context de rere-arc; per últim, (4) les cromitites del nord i del centre del cinturó peridotític de Loma Caribe (República Dominicana), que constitueixen un exemple de cromitites encaixades en una ofiolita amb evidències geoquímiques d’activitat de ploma mantèl·lica. En conjunt, els resultats demostren la importància de diferenciar els efectes de processos magmàtics primaris d’aquells derivats de processos d’alteració per tal de fer una interpretació correcta de la història evolutiva d’aquestes roques.
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Meyer, Louis J. "Tissue-specific orf and gene expression analysis in maize mitochondria /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422943.
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