Thèses sur le sujet « Porphir »
Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Porphir.
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleures thèses pour votre recherche sur le sujet « Porphir ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les thèses sur diverses disciplines et organisez correctement votre bibliographie.
1
Lecerf, Adrien. « Ordre et variation : essai sur le système de Jamblique ». Thesis, Paris, EPHE, 2015. http://www.theses.fr/2015EPHE5071.
Texte intégralRésumé :
Cette thèse se propose de donner une synthèse générale du système du néoplatonicien Jamblique de Chalcis, acteur important de l’évolution de la métaphysique grecque durant l’âge antique tardif. Elle reconstruit tour à tour sa doctrine psychologique, sa hiérarchie des êtres et quelques-uns de ses concepts fondamentaux, en mettant l’accent sur l’histoire des idées entre le fondateur de l’école, Plotin, et la naissance de l’école néoplatonicienne d’Athènes. L’ensemble des œuvres laissées par Jamblique est exploité, ainsi que les quelque 800 fragments et témoignages sur sa vie et sa doctrine laissés par les auteurs postérieurs. Les influences subies sont analysées et replacées en contexte : néoplatonisme de Plotin et Porphyre, qui donne à Jamblique les principaux niveaux de son ontologie, qu’il analyse et fractionne ; médio-platonisme, dont le néoplatonisme hérite des topiques philosophiques ; aristotélisme, qui lègue une conception dynamique de l’âme et une hiérarchie des puissances cognitives consacrant la transcendance de l’intellect ; pythagorisme, qui permet à Jamblique de concevoir les mathématiques comme un langage valable pour la description de toutes les parties de la philosophie. Par l’ampleur de son œuvre ainsi que l’originalité et la fermeté des solutions apportées aux problèmes traités, Jamblique crée une synthèse puissante qui sert de base doctrinale aux écoles néoplatoniciennes tardives d’Athènes et Alexandrie, et est profondément représentative d’un âge théocentrique, où l’âme humaine n’est qu’un principe dérivé, qui doit prendre sa place dans l’ordre universel des choses : une métaphysique de l’unité, reposant sur la dualité dynamique de l’ordre et de sa variationThis thesis strives to provide modern research with a synthesis of the system of Iamblichus of Chalcis, an important figure in the development of later Greek metaphysics. It reconstructs in turn his psychology, his hierarchy of being and some of his most basic concepts and philosophical laws, with a stress on the continuity between Plotinus, founder of the Neoplatonic school, and the beginnings of the school of Athens. The whole of Iamblichus’ body of work is exploited, as well as the 800 fragments and testimonia on his life and doctrine handed down to us by later authors. Influences received are analysed and set in context: Plotinus’ and Porphyry’s Neoplatonism, which provides the general levels of reality which Iamblichus tried to analyse and enrich; Middle Platonism, whose topics are debated in Neoplatonism; Aristotelianism, which accounts for a dynamic conception of the human soul and a hierarchy of cognitive powers beginning with the transcendent Intellect; Pythagoreanism, which allows Iamblichus to depict mathematics as a universal language, able to take the mark of all parts of philosophy. By the scope of his work and the originality and neatness of the solutions he provided to problems which nascent Neoplatonism had to confront, Iamblichus is able to create a powerful synthesis which acts as a doctrinal basis for the later schools of Athens and Alexandria: it is profoundly representative of a theocentric era, in which human soul is but a derived principle that has to keep its place in the grand scheme of being. It is a metaphysics of unity, founded on the dual dynamic of order and variation
2
Hannach, Gabriela. « Phenotypic plasticity in the red alga Porphyra abbottae : environmental factors influencing light harvesting ability / ». Thesis, Connect to this title online ; UW restricted, 1990. http://hdl.handle.net/1773/5210.
Texte intégral
3
Li, Yang. « Geochronology and fluid evolution of the Qulong porphyry system : implications for porphyry deposit formation ». Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11869/.
Texte intégralRésumé :
Understanding the metal enrichment process and rate in porphyry Cu systems (PCS) is critical to underpin the genetic model of PCS and refine the template for exploration, of which robust temporal constrain is the key. In addition, fluid evolution paths constrained by bulk analysis potentially suffer problems of contamination. Based on detailed field geology and petrographic study, this PhD thesis addresses the timescales and fluid evolution process of the world class Qulong porphyry Cu-Mo deposit, Tibet, China, by applying high precision geochronology and high spatial resolution isotope analysis. A fluid inclusion study indicates that the bulk mineralization at Qulong was deposited between 425 and 280 oC under hydrostatic pressure conditions. The depth of formation of the Qulong porphyry Cu-Mo system is estimated at ~2.7 km, which implies ~2.3 km of erosion has occurred since its formation. Zircon CA-ID-TIMS U-Pb geochronology constrains the emplacement ages of the Rongmucuola pluton, the P porphyry and quartz aplite to 17.142 ± 0.014/0.014/0.023 (analytical/plus tracer/plus decay constant uncertainty), 16.009 ± 0.016/0.017/0.024 and 15.166 ± 0.010/0.011/0.020 Ma, respectively. Molybdenite ID-NTIMS Re-Os geochronology suggests that the bulk mineralization at Qulong was deposited through multiple shorted lived pulses (~ tens of kyrs) between 16.126 ± 0.008/0.060/0.077 and 15.860 ± 0.010/0.058/0.075 Ma, with a duration of 266 ± 13 kyrs. Quartz SIMS oxygen isotope analysis indicates a periodic interplay between meteoric and magmatic fluids and continuing increase of meteoric water from ~10 to ~25 % volume percent during the ore-forming process. As a result meteoric water is invoked as the main trigger for metal deposition at Qulong. The major conclusions of this study from Qulong are supported by numerical modelling, titanium diffusion and high precision studies, and have implications for understanding porphyry systems worldwide, for example, multiple and cyclic magmatic-hydrothermal fluid pulses cooled by meteoric water are fundamental for ore formation.
4
Pizarro, Martínez Héctor Orlando. « Les traceurs minéralogiques comme indicateurs de porphyres cuprifères dans les remplissages sédimentaires des bassins adjacents, désert d'Atacama, Chili ». Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30105.
Texte intégralRésumé :
Les gisements de cuivre porphyrique (PCDs) sont liés au magmatisme calco-alkalins produit le long d'une marge tectonique convergente et résultent de la circulation de fluides hydrothermaux dérivés de magmas felsiques oxydés, hydratés et à faibles profondeurs. Au cours de l'évolution des systèmes magmatiques et hydrothermaux, les interactions fluide-roche génère des minéraux de l'altération hydrothermale typiques et peut également modifient ou génèrent des minéraux accessoires avec des signaux différents qui peuvent être associés à chaque étape de l'évolution du système, ce qui pourraient être distinguées par les caractéristiques physico et chimiques des minéraux accessoires hérités (zircon), des minéraux modifiés (apatites) ou des minéraux nouvellement formés (oxydes de Fe-Ti). Dans le désert d'Atacama, les bassins hydrographiques exposés le long de l'avant-arc occidental sont remplis de dépôts de gravier provenant de l'érosion de la Cordillère de Domeyko, en réponse à la phase tectonique éocene Incaique. On peut émettre l'hypothèse que certains de ces bassins contiennent des preuves minéralogiques qui qui vient de la dénudation des systèmes minéralisés en cuivre-porphyre situés en amont. L'objectif principal de cette thèse est donc de trouver des preuves magnétiques, minérales et chimiques qui permettront de relier la dénudation des PCDs aux sédiments déposés dans les bassins adjacents. Pour tester cette relation, nous comparons les caractéristiques magnétiques des roches et pétrographique et géochimique des minéraux accessoires (zircons et apatites) dans quatre PCDs situés dans la Cordillère de Domeyko (Chuquicamata, Mirador, Esperanza et Escondida), avec les mêmes caractéristiques des sédiments remplissant un bassin proche du district minier de Centinela. Dans ces PCDs, des caractéristiques pétrographique et géochimique distinctes des minéraux accessoires associées à la fertilité en cuivre ont été trouvés. Dans les zircons, la plus grande fertilité correspond aux signatures géochimiques : Hf > 8 750 (ppm), Eu / Eu* > 0,4, 10 000 x (Eu / Eu *) / Y> 1, (Ce / Nd) / Y> 0,01, Dy / Yb <0,3, Th / U < 1 -> 0,1), ce qui peut être lié à un état d'oxydation élevé et à une teneur élevée en eau magmatique dans le magma. Dans les apatites, les caractéristiques les plus distinctives de la fertilité en cuivre sont la couleur de luminescence verte, les valeurs élevées de Ca et la faible teneur en oligo-éléments, tels que Mg, Na, Cl, qui peuvent être liées à l'évolution des fluides hydrothermaux. Bien que le signal magnétique des PCDs soit contrôlé par la présence d'oxydes Fe-Ti d'origine hydrothermale et magmatique, il n'a pas été possible de différencier la contribution de ces deux composantes. Dans le bassin, il existe un dépôt de gravier (Tesoro) contenant un nombre important de zircons et d'apatites indicateurs de fertilité métallogénique des PCDs, qui coïncide avec une minéralisation de Cu exotique. On observe également une diminution des valeurs de susceptibilité magnétique des niveaux inférieurs aux niveaux supérieurs, qui est principalement contrôlée par la concentration en oxydes de Fe-Ti à grains grossiers d'origine détritique. La concentration la plus élevée en oxydes de fer pourrait être associée à un climat aride et à une influence tectonique, alors que la diminution de la concentration peut être liée à une tendance à l'aridification et / ou à un éloignement relatif des sources de ces oxydes. En conclusion, les apatites et les zircons détritiques des bassins ont le potentiel de documenter la dénudation des PCDs en amont. Par conséquent, l'utilisation de minéraux indicateurs représente une technique d'exploration potentiellement efficace qui peut facilement s'appliquer à la recherche de preuves concrètes de PCD contenues dans des dépôts de gravier. D'autre part, les propriétés magnétiques des sédiments nous renseignent sur les conditions paléo-climatiques et / ou tectoniques de leur dépôtPorphyry copper deposits (PCDs) are linked to calk-alkaline magmatism produced in a convergent tectonic margin and resulted from the circulation of hydrothermal fluids derived from oxidized and water rich felsic magmas emplaced at shallow depths. During the evolution of the magmatic and hydrothermal systems, the fluid-rock interaction generates typical hydrothermal alteration minerals and can also modify or generates accessories minerals with different properties that can be associated at each stage of the evolution of the system, which could be distinguished by the physico and geochemical characteristics of the inherited accessory minerals (zircon), the modified minerals (apatite) or the newly formed minerals (Fe-Ti oxides). In the Atacama Desert hydrographic basins exposed along the western forearc are filled by gravel deposits which were derived from the erosion of the Domeyko Cordillera in response to the Eocene Incaic tectonic phase. It can be hypothesized that some of these basins contain mineralogical evidences that come from the denudation of porphyry copper mineralized systems located upstream. Therefore, the main goal of this thesis is to find magnetic, mineral and chemical evidences that will help to link the denudation of PCDs with sediments deposited in adjacent basins, mainly by using heavy minerals and magnetic signals as tracers contained in the sedimentary record. To test this relationship, I compare the rock-magnetic properties and physical and geochemical characteristics of minerals (zircon and apatite) in four selected DPCs located in Domeyko Cordillera (Chuquicamata, Mirador, Esperanza and Escodida), with the same characteristics in detrital sediment filling a close basin in the Centinela Mining District. In the studied PCDs, accessory minerals with distinctive physical and geochemical characteristics associated with metallogenic fertility were identified. In zircons, the most fertile samples correspond to these geochemical signatures: Hf > 8,750 (ppm), Eu/Eu* > 0.4, 10.000 x (Eu/Eu*)/Y > 1, (Ce/Nd)/ Y > 0.01, Dy/Yb < 0.3, Th/U < 1 - > 0.1), which can be linked to high oxidation state and high content of magmatic water in the magma. In apatite, the most relevant features indicating fertility are the green luminescence color and high Ca values and low content of trace elements, such as Mg, Na, Cl, which can be related to the evolution of hydrothermal fluids. Although the magnetic signal from DPCs is controlled by the presence of Fe-Ti oxides of hydrothermal and magmatic origin, their characteristics could not be used to differentiate the contribution of these two components. In the stratigraphic record there is a gravel deposit (Tesoro) which contains an important number of zircons and apatite which can be signaled as indicators of metallogenic fertility, that coincides with exotic-Cu mineralization and abundant clasts coming from different hydrothermal alteration zones related to PCDs. In the gravel deposits, a decrease in the magnetic susceptibility values from lower to upper levels is observed, which is mainly controlled by coarse-grain Fe-Ti oxides concentration of detritic origin. In the gravel deposits, rock magnetic properties are mainly controlled by Fe-Ti oxides concentration of detritic origin, where the highest concentration of Fe-minerals could be associated to arid climatic conditions and a rapid tectonically-controlled denudation, whereas the decline in concentration can be related to an aridification trend and/or sources changes
5
Rappé, Charles J. « Porphyry and the Platonic-Aristotelian tradition ». [S.l. : s.n.], 2002. http://www.freidok.uni-freiburg.de/volltexte/599.
Texte intégral
6
McFall, Katie Anne. « Critical metals in porphyry copper deposits ». Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/412122/.
Texte intégralRésumé :
Critical metals are elements essential to high-tech industry and green technology which are associated with a significant supply risk. Diversifying supplies of these elements is therefore a high priority. Porphyry copper deposits contain potentially economic enrichments of some of these elements, namely rhenium, platinum group elements (PGEs), bismuth and tellurium. This thesis investigates the source, transport mechanism and distribution of these critical elements in two post-collisional Tethyan porphyry deposits. The Muratdere Cu-Mo (Au-Re) porphyry deposit, Turkey, described here for the first time, contains two generations of molybdenite with contrasting Re concentrations. The early, Re-poor molybdenites have magmatic δ34SCDT values, while the late, vein hosted Re-rich molybdenite has δ34SCDT values matching those of the surrounding country rock suggesting that the additional Re has been sourced from hydrothermal fluid-country rock interaction. The Skouries Cu-Au porphyry deposit, Greece, is PGE, Te and Bi enriched. In contrast to Muratdere, Skouries is shown to be an orthomagmatic system hosted by a series of overprinting dykes, with the metal enrichment hypothesised to have been provided by periodic mafic recharge of a deeper source magma chamber. The mineralising fluids in Skouries are shown to have been highly oxidised and hypersaline with complex cation chemistry (Na, K, Fe, Mn and Ca), and with the overall fluid evolution progressing from an early CO2 rich fluid to a later brine. The PGEs in the deposit are located in the main hypogene mineralising veinsets, associated with potassic alteration, and are found to be hosted in bismuth and tellurium complexes. A variety of platinum group minerals are identified, including sopcheite (Ag4Pd3Te4) and sobolevskite (PdBi). LA-ICP-MS of fluid inclusions, combined with microthermometry, has shown gold, bismuth and palladium to be hydrothermally transported by high temperature ( > 500°C), high salinity ( > 65 wt% NaCl+KCl) and highly oxidised fluids, and a bismuth-tellurium collector model is proposed to allow concentration of palladium from under-saturated fluids into platinum group minerals. High semi-metal (Te and Bi) contents in porphyries are therefore proposed to be an indicator of PGE enrichment.
7
Valencia, Victor A. « EVOLUTION OF LA CARIDAD PORPHYRY COPPER DEPOSIT, SONORA AND GEOCHRONOLOGY OF PORPHYRY COPPER DEPOSITS IN NORTHWEST MEXICO ». Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1085%5F1%5Fm.pdf&type=application/pdf.
Texte intégral
8
André-Mayer, Anne-Sylvie. « Fluides et fracturations dans les gisements de type porphyre et épithermal ». Nancy 1, 2000. http://www.theses.fr/2000NAN10176.
Texte intégralRésumé :
En métallogénie, il est admis depuis longtemps que les fluides sont les principaux vecteurs des métaux et que fluides et déformations sont étroitement associés dans le déroulement des processus minéralisateurs. Ce travail aborde ces deux principaux aspects en environnement porphyre et épithermal où de nombreuses inconnues subsistent en ce qui concerne les processus minéralisateurs, l'origine dès fluides minéralisateurs ainsi que le rôle joué par les drains de cas fluides à savoir les fractures. L'étude des fluides réalisée dans le district épithermal de Shila (SW Pérou) a permis de proposer un modèle de minéralisation pour l'ensemble des gisements du district. Les différences observées dans la nature des fluides et dans leurs propriétés PVT semblent expliquer les différents types et· styles de minéralisation. A Apacheta, l'étude de l'évolution verticale des paramètres physico-chimiques des fluides en parallèle de la minéralisation montre que la différence de minéralisation observée entre les niveaux profonds (Pb-Zn) et plus superficiels (Au-Ag) est lié à un fractionnement des gaz présents dans les fluides lors d'un phénomène d'ébullition. L'étude de la géochimie des fluides (crush-leach) associés à ce type de minéralisation dans différents districts (Shila, Pérou; Baia Mare et Monts Apuseni, Roumanie, Pongkor, Indonésie) montre que ces fluides présentent des chimies comparables quel que soit leur contexte géodynamique. Ces compositions sont également similaires aux fluides associés aux systèmes géothermiques. Des analyses des propriétés de réseaux de fractures ont été réalisé à échelle macroscopique sur des systèmes de veines qu'elle soient minéralisées ou non. Elles ont permis dans un premier temps d'établir une nouvelle méthode pour caractériser des paléocontraintes en tenant compte de l'influence de la présence de fluides. Appliquée sur le réseau de veines de Soultz-sous-Forêts, cette méthode donne des valeurs réalistes de paléocontraintes à l'origine de la réouverture d'un système de veines en présence de fluides. Différentes techniques d'études géométriques et statistiques permettant la caractérisation des propriétés d'un réseau de fractures ont également été appliquées sur le stockwerk minéralisé du porphyre cuprifère de Rosia Poienî (Roumanie). Les hétérogénéités constatées dans les caractéristiques du stockwerk (à l'échelle métrique) semblent se traduire directement pas des variations dans les teneurs en cuivre. La description statistique des propriétés du stockwerk minéralisé semble être un outil prospectif très intéressant. La caractérisation des propriétés hydrauliques des veines constitutives du stockwerk met également en évidence des hétérogénéités à l'échelle de la carrière. Les niveaux les plus profonds et les plus minéralisés sont dominés par des perméabilité de drains et une organisation de veines en clusters. Les niveaux les plus superficiels développent quant à eux de faible perméabilité de fissures, sans drains majeurs entraînant de ce fait une perméabilité pervasive dans la masseIn metallogeny, it is now obvious that fluids are the main vectors of metals and that fluids and deformations are closely associated in the mineralizing processes. This work deals about this two main aspects in the porphyry and epithermal environment. Fluid studies, realised in the epithermal district of Shila (SW Peru), allow to state a mineralizing model at the district scale. The differences observed in the PVT properties of the fluids seem to explain the different types and styles of mineralization. At Apacheta, studies of the vertical evolution of the physico-chemical parameters of the fluids in parallel to the mineralization show that differences, observed between deep levels (Pb-Zn) and shallower levels (AuAg), is directly linked to a fractionation of gases present in fluids during a boiling event. The geochemistry (crush-leach) of the fluids associated to this type of mineralization in various districts (Shila, Pero; Baia Mare and Apuseni Moutains, Romania; Pongkor, Indonesia) are similar whatever their geodynamic context and are comparable with the fluids associated to geothermal systems. Analyses of fracture networks has been realised at macroscopic scale on different (mineralized or not) vein systems. They allow in a first time to establish a new methodology to characterize paleostresses taking into account the influence of the fluid pressure. Applied on the Soultz-sous-Forêts vein system, this method gives realistic paleostress magnitudes linked to the reopening of quartz veins. The mineralized stockwerk of the Rosia Poieni porphyry copper (Apuseni Mts, Romania) has been chosen for a statistical and hydraulic characterization in order to understand how mineralized vein system evolve and grow. A 1D sampling of the stockwerk has been realized on 2000 fractures distributed on five levels of the open pit (910, 940, 1000, 1045 and 1060 ml. Various statistical analyses has been applied and heterogeneities observed in the stockwerk (metric scale) express directly variations in the copper content. Statistical description of the stockwerk properties seems thus to be a very powerful prospective tool. Estimation of hydraulic conductivities developed by veins has been realized and show equally heterogeneities at the quarry scale. The mean permeability developed by all the veins on each profile decrease from the deeper and more mineralized level (910m) to the highest level (1060m). High permeabilities developed on the 910 m profile are linked to the presence of major drains and the clustered organization of veins. The level 1060 m, characterized by numerous and thin veins with a homogeneous spatial repartition, develop a more pervasive permeability
9
Geißler, Marion, Anja Hartmann, Wolfram Heidenfelder et Tim Witzke. « Geotope - Einblicke in die Erdgeschichte ». Geopark Porphyrland. Steinreich in Sachsen e.V, 2019. https://slub.qucosa.de/id/qucosa%3A36070.
Texte intégralRésumé :
Naturschutz ist inzwischen tief in unserem Denken und Handeln angekommen. Aber
noch immer wird dabei zu allererst an den Schutz von Tieren und Pflanzen gedacht, gefolgt vom Schutz des oberirdischen und unterirdischen Wassers. Das ist verständlich, hat doch diese Art des Naturschutzes lange zurückliegende Wurzeln.
10
Dickinson, Jenni Michelle. « Jura-triassic magmatism and porphyry Au-Cu mineralization at the Pine Deposit, Toodoggone District, North-central British Columbia ». Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/3959.
Texte intégralRésumé :
The Pine, Fin, and Mex porphyry Au-Cu ± Mo systems are all located within a 10 km² area in the
Toodoggone district, along the eastern margin of the Stikine terrane in British Columbia. Multiple
episodes of porphyry-style mineralization are associated with these three magmatic centres. The Fin
monzogranite is the oldest dated pluton in the district, with a U-Pb zircon emplacement age of 217.8 ± 0.6
Ma. A cross-cutting main-stage quartz-pyrite-chalcopyrite ± molybdenite ± sphalerite vein gives an older
Re-Os molybdenite mineralization age of 221.0 ± 1.4 Ma. Hence the vein probably cross-cuts a slightly
older, undated magmatic phase. Lead isotope values for sulphide minerals from main-stage veins indicate
that magmatic-derived fluids interacted with country rocks and possibly other fluids.
The Pine quartz monzonite (U-Pb zircon emplacement age of 197.6 ± 0.5 Ma) intrudes, alters,
and locally mineralizes Toodoggone Formation Duncan Member andesite tuff (U-Pb zircon age of 200.9
± 0.4 Ma). High-grade (0.57 g/t Au and 0.15% Cu) mineralization occurs in main-stage quartz-magnetite
chalcopyrite-pyrite veins and disseminated throughout the potassic alteration zone in the Pine quartz
monzonite stock. Late-stage anhydrite-pyrite ± specular hematite ± chalcopyrite, quartz-pyrite ±
chalcopyrite, and pyrite ± chalcopyrite veins and related phyllic alteration cross-cut earlier veins.
Propylitic alteration occurs distal to the potassic core of Pine in the Fin monzogranite and Duncan
Member andesite. Limited fluid inclusion data, in combination with S and Pb isotope values for veins and
host rocks, suggest that the main-stage fluid was magmatic-derived and deposited metals at 430 to 550 °C
and depths of about 5.5 km. Late-stage fluids were also probably derived from the Pine quartz monzonite
but interacted with Takla Group country rock prior to metal deposition. Metals were deposited at
temperatures of 330 to 430 °C and depths of about 5.0 to 5.5 km.
The final mineralization phase of the Pine porphyry system is temporally constrained by the
emplacement of weakly mineralized syenite dykes (U-Pb zircon age of 193.8 ± 0.5 Ma). The final stage
of magmatism in the Pine-Fin-Mex area is defined by the emplacement of rhyolite dykes (U-Pb zircon
age of 193.6±0.4 Ma).
11
Puig-Pichuante, R. M. « Molybdeunum mineralization with emphasis on porphyry systems genesis and exploration ». Thesis, Rhodes University, 1986. http://hdl.handle.net/10962/d1006840.
Texte intégralRésumé :
Mo became very important in the last century, because of its sophisticated properties and its use in the new technology of alloys . Porphyry systems (porphyry Cu-Mo and Mo) contribute a significant proportion (90 - 95 per cent) to the Mo world's production. This type of deposit is associated mainly with Phanerozoic orogenic belts. Above 87per cent of the world resources are in the American Circumpacific belts , both Andean and Cordilleran . Ore grade in porphyry Cu-Mo range from 0,005 to 0,04per cent Mo, whereas in porphyry Mo grades range from 0,08 to 0,75per cent Mo . These deposits are associated with a magmatism which shows an evolution from calcic in island arcs, to calc-alkaline in magmatic back arcs, with an increase of the Mo content in the same direction. Porphyry Mo deposits display several features in common with porphyry Cu deposits. hydrothermal Similarities include nature of host alteration patterns and distribution of rock intrusives, ore minerals. An interesting difference is found in the Re contents of the molybdenite mineral. This element is higher in the molybdenites of porphyry Cu, than in those of the porphyry Mo. The ore genesis process begins involves partial melting, within enriched zones of the upper mantle and magma differentation, liquid state thermogravitational diffusion, magma convection and boiling. These processes progressively concentrate Mo in the fluids, which are released at some stage, into sulphidic hydrothermal systems, under complex geologictectonic conditions involving fracturing, brecciation and hydrothermal alteration. Major concentrations of the ore mineral are always associated with potassic alteration, and with late magmatic-early hydrothermal stages (Chilean and Western North American porphyries). Geological mapping and a close understanding of alteration and mineralization patterns, and lithogeochemistry are important tools for the exploration of porphyry Mo deposits. Geochemical prospecting, using soils, vegetation and water as sampling media, and regional aeromagnetic, gravity surveys, aerial photography and remote sensing, are us.
12
Curtis, Bruce Anthony. « A morphological and phylogenetic investigation of Porphyra linearis Greville and Porphyra purpurea (Roth) C. Agardh forms from Nova Scotia ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23688.pdf.
Texte intégral
13
Wolfe, RC. « The Dinkidi Cu-Au porphyry : geology of the Didipio region and paragenesis of the Dinkidi Cu-Au porphyry deposit ». Thesis, Royal Society of Tasmania, University of Tasmania Library Special and Rare Materials Collection, 2002. https://eprints.utas.edu.au/11283/2/Wolfe_-Whole.pdf.
Texte intégralRésumé :
The Dinkidi Cu-Au porphyry deposit is located in northern Luzon, Philippines. The 110 Mt deposit is characterised by high gold grades (ave. 1.2 g/t Au and 0.5% Cu) and is one of only a few alkaline porphyry deposits to have been discovered outside British Columbia.
Alkaline magmatism in northern Luzon is related to the Late Oligocene rifting event that formed the Cagayan Valley Basin, and to the final stages of west-directed subduction along the East Luzon trench. Subalkaline andesitic and trachytic lavas and minor volcaniclastic rocks of the Mamparang Formation were emplaced along the southwest margin of the Cagayan Valley Basin, and have been intruded by a series of alkaline plutons and stocks. The Dinkidi deposit is hosted within the multi phase Dinkidi Stock, which is in turn part of a larger alkaline intrusive body, the Didipio Igneous Complex.
The Didipio Igneous Complex consists of: (I) an early composite clinopyroxene-gabbro-diorite-monzodiorite pluton; (2) the Surong clinopyroxene to biotite monzonite pluton; (3) the Cu-Au mineralised Dinkidi Stock, which comprises an early equigranular biotite-monzonite stock (Tunja Monzonite), a thin, variably-textured clinopyroxenesyenite (the Balut Dyke), and a monzosyenite porphyry (Quan Porphyry) that grades, in its core, into a crystal-crowded leucocratic quartz-syenite (Bufu Syenite); and (4) postmineralisation andesite dykes.
Whole-rock chemistry indicates that the volcanic formations in the Didipio region become progressively more alkaline up stratigraphy, indicating that Late Oligocene rifting intermittently tapped an LILE-enriched mantle source that became progressively more LILE-enriched over time. Whole rock and mineral compositions indicate that all intrusions in the Didipio region were sourced from a common magma chamber, and were related by shallow level fractional crystallisation.
Five main hydrothermal events are recognised in the Didipio region: (I) contact metamorphism and weak biotite-cordierite alteration is associated with emplacement of the early diorite phase; (2) K-silicate magnetite-biotite alteration, and subeconomic Cu-Au mineralisation associated with the emplacement of the Surong monzonite pluton; (3) intensely developed porphyry-style alteration and ore-grade Cu-Au mineralisation which is spatially and temporally associated with emplacement of the Dinkidi Stock; (4) an advanced argillic alteration assemblage, which has overprinted the Didipio Igneous Complex and is associated with subeconornic high-sulphidation style Cu-Au mineralisation; (5) late-stage unmineralised zeolite-carbonate veins, which are associated with post-mineral strike-slip faulting.
At Dinkidi, emplacement of the Tunja Monzonite was temporally and spatially associated with the formation of a pervasive biotite-magnetite K-silicate alteration assemblage in the pre-mineral diorites. Emplacement of the Balut Dyke was associated with a calc-potassic style diopside-actinolite-K-feldspar-bornite alteration assemblage and associated vein stockwork. This quartz-free mineral assemblage is associated with high gold grades (2-8 g/t Au) and is typical of alteration assemblages found in quartz-undersaturated alkaline porphyry systems. Intrusion of the Bufu Syenite led to the formation of a quartz-sericite-calcite-chalcopyrite stockwork vein and alteration assemblage, which has overprinted the calc-potassic assemblage. The quartz stock work hosts the bulk of low grade mineralisation (1-2g/t Au) at Dinkidi and is typical of silica-saturated alkaline porphyry systems. A coarse-grained assemblage of quartz-actinolite-perthite (the 'Bugoy Pegmatite') formed as an apophysis on the Bufu Syenite, and was subsequently brecciated by late-stage faulting. High-level argillic and late-stage fault-related zeolite mineral assemblages have overprinted the porphyry-style hydrothermal assemblages.
The calc-potassic assemblage is inferred to have formed at temperatures in excess of >600°C from a silica-undersaturated K-Ca-Fe brine. Fluid inclusion studies indicate that the quartz stockwork was emplaced at submagmatic temperatures (>600°C) from a quartz-saturated Na-K-Fe brine (>68 wt. % eq. NaCI) that contained up to 0.6 wt. % Cu and 4 wt. % Fe. Cooling to ~420°C and neutralisation by wall rock interaction lead to the precipitation of sulphides within the quartz stockwork. The quartz-bearing assemblage was emplacement at 2.9 to 3.5 km paleodepth, and was associated periods of overpressurisation and quartz growth disrupted by episodic depressurisation to near hydrostatic pressure conditions.
The hydrothermal mineral assemblages at Dinkidi reflect the composition and degree of fractionation of the associated intrusions. Extensive fractionation within a feldspathoid-normative dioritic magma chamber is interpreted to have ultimately caused quartz saturation and the development of the late-stage syenite intrusions and related quartz stockwork mineralisation. The calcic, silica-undersaturated Balut Dyke (associated with the calc-potassic stockwork) does not fit this fractionation trend, and is interpreted to have formed by interaction between the late-stage syenitic melt and a co-magmatic mafic melt that underplated the siliceous magma chamber prior to formation of the Balut Dyke. A reversion to fractionation-dominated magmatic processes in the silicic magma chamber then lead to the intrusion of the quartz-saturated Quan Porphyry and Bufu Syenite. Ultimately, the residual mafic melt was emplaced as a series of late-stage andesite dykes.
The Dinkidi porphyry Cu-Au deposit shows that it is possible for silica-undersaturated and silica-saturated styles of alkaline porphyry mineralisation to form in the same magmatic-hydrothermal system, given the right conjunction of geological processes. Exploration models for alkaline porphyry systems therefore need to be flexible enough to accommodate the possibility of silica-undersaturated and saturated mineralised zones forming in the same deposit. The strongly mineralised, variably textured Balut Dyke shares textural and genetic similarities with mineralised pegmatite dykes from midcrustal granitic environments. Highly Cu-Au mineralised 'pegmatitic' dykes should therefore also be considered as a viable exploration target in alkaline porphyry systems.
14
Lampadaridi, Anna. « La Vie de Porphyre de Gaza par Marc le Diacre (BHG³ 1570) : Édition critique, traduction, commentaire ». Thesis, Paris 4, 2011. http://www.theses.fr/2011PA040140.
Texte intégralRésumé :
La Vie de Porphyre de Gaza (BHG³ 1570) se présente comme un texte hagiographique de l’époque protobyzantine écrit par Marc le Diacre. Ce personnage se désigne lui-même comme le disciple du saint qui raconte la vie de son maître après sa mort en 420. Pourtant, à cause d’un emprunt à l’Histoire Philothée de Théodoret de Cyr, la Vie dans son état actuel est certainement postérieure à l’année 444 et ne peut pas provenir de la plume de Marc, qui n’est que le narrateur. Selon l’hypothèse des éditeurs Grégoire et Kugener, la Vie actuelle est le fruit du remaniement d’un texte plus ancien. Le texte nous offre un témoignage unique sur l’histoire du paganisme et du christianisme à Gaza à la fin du IVe et au début du Ve s. Ordonné évêque de Gaza en 395, Porphyre contribue activement à la christianisation de la ville, qui était alors majoritairement païenne. Le point culminant de son activité est la démolition du Marneion et la fondation sur ses débris de la « Grande Église » de Gaza. Cependant, outre les problèmes concernant l’identité de son auteur et sa datation, la Vie s’est trouvée dès l’époque de Tillemont au centre d’un grand débat concernant sa valeur historique, à cause des anachronismes qui ont été relevés. Dans le cadre de notre thèse, nous avons entrepris une nouvelle édition critique du texte, accompagnée d’une traduction française. La brève étude littéraire du texte est suivie par un commentaire historique guidé par le problème d’authenticité que pose la Vie. L’édition critique est précédée d’un examen de la tradition directe et indirecte du texte. Finalement, les notes de la traduction visent à faire ressortir sa valeur documentaireThe Life of Porphyry of Gaza (BHG³ 1570) is a hagiographical text of the protobyzantine period written by Mark the Deacon. He introduces himself as the saint’s loyal disciple, who narrates his master’s life after his death in 420. However, due to the plagiarism of Theodoret of Cyrrhus’s Philotheos History, the current form of the Vita dates certainly later than 444 and cannot have been written by Mark, who is just the narrator. According to the hypothesis of the editors Grégoire and Kugener, the current form of the Vita is the result of the revision of an older text. The text provides us with a unique account of the history of paganism and christianism in Gaza at the end of the 4th and the beginnings of the 5th century. Appointed bishop of Gaza in 395, Porphyry contributes actively to the christianisation of the city, which was largely pagan. The peak of his activity is the demolition of the Marneion and the erection of the “Great Church” of Gaza on the site of the former temple. However, in addition to the problems concerning its authorship and its datation, the Vita was found in the centre of a great debate concerning its historical value since the time of Tillemont. In the frame of our PhD thesis, we undertook a new critical edition, accompanied by a french translation. The brief literary study of the text is followed by a historical commentary guided by the problem of the Vita’s authenticity. The critical edition is preceded by an examination of the direct and the indirect text tradition. Finally, the notes of the translation aim to reveal its documentary value
15
Huh, Min-Jun. « Le premier commentaire de Boèce à l’Isagogè de Porphyre : introduction, traduction et commentaire ». Thesis, Paris 4, 2013. http://www.theses.fr/2013PA040145.
Texte intégralRésumé :
Notre thèse en deux volumes vise à donner une traduction inédite du premier commentaire de Boèce à l’Isagogè de Porphyre à partir de l’édition critique de Samuel Brandt publiée en 1906. De fait, Boèce s’appuie sur la traduction latine de Marius Victorinus et non, comme le suggère le titre, sur le texte grec de Porphyre. Le premier volume contient une introduction générale articulée en quatre parties: examen critique des études secondaires; les sources matérielles du premier commentaire de Boèce à l’Isagogè; le traitement des questions de Porphyre sur les universaux; et l’Isagogè de Marius Victorinus et la tradition rhétorique latine. Les thèses que nous défendons sont les suivantes : le commentaire perdu de Porphyre sur les Catégories (A Gédalios) pourrait avoir été la source principale de ce traité logique de Boèce ; historiquement, les trois questions de Porphyre ont été apparentées à la réfutation porphyrienne de la position anti-aristotélicienne de Plotin ; et, contrairement à Victorinus qui considère l’Isagogè comme une introduction aux Topiques de Cicéron, Boèce la conçoit dans la perspective néoplatonicienne qui fait d’elle une introduction aux Catégories d’Aristote. Cette introduction est suivie de la traduction française accompagnée du texte latin de l’édition de Brandt. Notre commentaire à la traduction est développé dans le second volume qui contient également une traduction française inédite du commentaire d’Ammonius à l’Isagogè de Porphyre et une réfutation de la thèse soutenue par Brandt dans ses prolegomena de son édition critique à propos des parallèles textuels attestés dans les commentaires à l’Isagogè de Boèce et d’Ammonius (cf. appendices 1 et 2)Our thesis in two volumes aims to give an original French translation of Boethius’s first commentary on Porphyry’s Isagoge based on the critical edition published by Samuel Brandt in 1906. Actually, Boethius commentary deals with the Latin translation of Marius Victorinus and not, as the title seems to suggest, with the greek treatise of Porphyry. The first volume contains a general introduction divided into four parts : a critical studies of the secondary sources; the material sources of the Boethian first commentary on Isagoge; the Boethian analysis of Porphyry’s three questions about universals; and Marius Victorinus’ Isagoge and the Latin rhetorical tradition. The thesis we defend in the introduction can be summarized as follows : Porphyry’s lost commentary on Categories (Ad Gedalium) may have been the main source of the first Boethian commentary on Isagoge ; historically, the three questions on universals had been related to the Porphyrian refutation of anti-Aristotelian position of Plotinus ; and, unlike Victorinus which considers Isagoge as an introduction to Cicero’s Topica, Boethius adopts the Neoplatonic perspective which makes it an introduction to Aristotle’s Categories. This introduction is followed by the French translation accompanied by the latin text edited by Brandt. Our commentary on the Boethian treatise is developed in the second volume, which also contains an original French translation of Ammonius’ commentary on Porphyry’s Isagoge and a full refutation of the thesis supported by Brandt in his prolegomena to his critical edition about the textual parallels attested in the Boethian and Ammonian commentaries on Isagoge (cf. appendix 1 and 2)
16
Carlier, Jeanne. « Recherches sur la lettre à Anébon, de Porphyre ». Paris 4, 1995. http://www.theses.fr/1995PA040028.
Texte intégralRésumé :
Le présent travail propose une recherche approfondie sur le rôle et le statut des êtres intermédiaires dans la philosophie religieuse de Porphyre (tome I); une édition et une traduction des fragments de la lettre à Anébon de Porphyre, auquel on a joint la traduction du Traité sur le Styx et des Summikta zetemata (tome II); pour la partie de la lettre qui concerne la divination et la hiérarchie des êtres supérieurs, un commentaire portant à la fois sur l'établissement du texte et sur les concepts. On se pose quatre questions : les sources légitimes de la connaissance sur dieu selon Porphyre (révélation, philosophie, "notions innées"); le statut de l'homme, de dieu, et des intermédiaires entre l'homme et dieu : l'homme est-il consubstantiel au père? ; l'attitude de Porphyre vis-à-vis des rituels de la religion positive, et en particulier en face de la théurgie, dont on soutient qu'elle a, dès Jamblique, une vocation œcuménique; enfin, les cibles visées par la lettreThis thesis offers detailed research on the status and functions of the intermediate beings in Porphyry's religious philosophy (vol. 1); an edition and translation of Porphyry's fragmentary letter to Anebo, including a translation of De Styge and Summikta zetemata (vol. 2); a commentary (textual and conceptual) on the part of the letter concerning divination and the hierarchy of superior beings. Four problems are dealt with : the legitimized sources of knowledge according to Prophyry (revelation, philosophy, "innate notions"); the status of man, of god, of the intermediate beings : are god and man consubstantial?; Porphyry's attitude toward the rituals of positive religion, especially towards theurgy, which is proved to include a good deal of common religion; the targets of porphyry's criticism in the letter to Anebo
17
Griffin, Neil John. « Harvest ecology and biodiversity of South African Porphyra ». Doctoral thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/10564.
Texte intégralRésumé :
Bibliography: 140-161 leaves .Porphyra (Bangiales, Rhodophyta) is the world's most valuable maricultured seaweed, due to its high value as a food crop. The vast majority of Porphyra in South Africa belongs to P. capensis, a morphologically and ecologically plastic taxon apparently endemic to the region. There is no demand for P. capensis as a food crop, as it is unsuitable for the market, and there are no records of its customary use locally. Porphyra capensis is however a potentially highly valuable fodder for the mariculture of abalone (Haliotis midae), and pressure to harvest it has recently increased. This study aims to assess the potential for harvest of Porphyra on the south-western shores of South Africa. There are two main thrusts to this work. The fIrst thrust examines Porphyra as an ecological entity in the region. The second thrust reassesses the taxonomy of Porphyra species in the region.
18
Carle, Jacques. « Porphyre "contre les chrétiens" : édition, traduction et commentaire ». Aix-Marseille 1, 2008. http://www.theses.fr/2008AIX10014.
Texte intégralRésumé :
Porphyre, philosophe néoplatonicien, a composé un pamphlet en 15 livres intitulé : "Contre les chrétiens". Son oeuvre commencée vers 270 aurait pu s'échelonner jusqu'au début du quatrième siècle, au moment de la grande persécution de Dioclétien à laquelle il s'associa probablement. Réfutée abondamment, l'oeuvre semble essentiellement d'intérêt exégétique, mais hérite d'une partie de la critique antichrétienne qui l'a précédée. L'essentiel nous est parvenu par Eusèbe de Césarée en grec, Jérôme ou Augustin en latin ; plus implicitement, par Arnobe ou Lactance (même s'ils n'ont pas cité nommément Porphyre), et très approximativement sans doute par Macaire de Magnésie. D'autres oeuvres de Porphyre semblent indispensables toutefois pour compléter l'approche de sa polémique et on ne peut guère considérer aujourd'hui comme suffisant le seul recours au "Contre les chrétiens". Le corpus proposé s'articule en trois temps essentiels : il s'efforce de reconstituer d'abord les objections antichrétiennes de Porphyre, attribuables à la "Philosophie tirée des Oracles", au traité "Sur le Retour de l'Ame" ou encore à d'autres oeuvres plus difficiles à situer. Il s'agit enfin de proposer une restitution un peu différente du "Contre les chrétiens" en changeant un peu la perspective que A. Von Harnack avait donnée à la première édition.
19
Nickerson, Phillip Anson. « Post-Mineral Normal Faulting in Arizona Porphyry Systems ». Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242354.
Texte intégralRésumé :
In the Basin and Range province of southwestern North America, Oligocene and Miocene normal faults are superimposed upon the Late Cretaceous-early Tertiary magmatic arc. This study examines tilted fault blocks containing dismembered pieces of porphyry systems, including pieces below and peripheral to ore bodies, that are exposed at the modern surface. Features in the magmatic-hydrothermal porphyry systems are used to place constraints on the style of extension in Arizona, and reconstructions of extension are used to examine the deep and peripheral portions of porphyry systems to provide a more complete understanding of porphyry systems as a whole. The Eagle Pass, Tea Cup, and Sheep Mountain porphyry systems of Arizona are examined in this study. In all the study areas, previous interpretations of the style of extension involved strongly listric normal faults. However, similar amounts of tilting observed in hanging wall and footwall rocks, as well as structure contour maps of fault planes, require that down dip curvature on faults was minimal (<1°/km. Instead, extension is shown here to have occurred as sets of nearly planar, "domino-style" normal faults were superimposed upon one another, including in the Pinaleño metamorphic core complex. Reconstructions of Tertiary extension reveal that sodic (-calcic) alteration is occurs 2-4 km peripheral to, and greisen alteration is found structurally below and overlapping with, potassic alteration. In addition, a preliminary reconstruction of extension across the Laramide magmatic arc reveals that the geometry, as revealed by known porphyry systems, is of similar scale to that of other magmatic arcs. These results help further the debate surrounding competing models of continental extension, and combine with previous work to provide a more complete understanding of the geometries of Arizona porphyry systems at the district and arc scale.
20
Mathur, Ryan Dilip. « Rhenium-osmium isotopes of base metal porphyry deposits ». Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289216.
Texte intégralRésumé :
This study uses Re-Os isotopes from sulfide minerals (molybdenite, pyrite, chalcopyrite, bornite, sphalerite, arsenopyrite, and galena) and magnetite from high (400-500°C) and low and low ( < 300°C) temperature mineralization assemblages associated with the intrusion of igneous rocks to trace the source of Os and by inference the other metals. The source of Os is used as a proxy for the source of copper and gold in these systems. Concentrations of Re-Os for all sulfides except molybdenite in various deposit types vary from 0.005-2 ppb Os and 0.120-500 ppb Re. Initial ¹⁸⁷Os/¹⁸⁸Os ratios derived from isochron plots ranges from 0.15-50. These data show interesting relationships among deposits of different styles within the district, region, and worldwide scales. On the district-deposit scale, Re-Os isotopes illustrate a complex behavior for the source of Os and by inference other transition and noble metals. The source of Os can be linked to one intrusive event, multiple intrusive events, and the sedimentary rocks into which the magmas intersect. On a regional scale, in the Andean Cordillera, Re-Os isotopes reveal a correspondence between the initial ¹⁸⁷Os/¹⁸⁸Os ratios from sulfides of the ore deposit and amount of copper present in porphyry copper deposits. Eleven deposits sampled from different crustal blocks and different mineralization ages form a trend in which deposits that contain large amounts of copper have less radiogenic ¹⁸⁷Os/¹⁸⁸Os initial ratios, suggesting a greater mantle component. Smaller deposits have more radiogenic Os suggesting greater crustal components. On a global scale, the significant observation for the deposits that form in arc environments is that all of the calculated initial ¹⁸⁷Os/¹⁸⁸Os ratios are greater then the chondritic mantle. This indicates that there must be a crustal source (recycled in a metasomatized mantle, lower/upper continental crust, or subducting slab) that contributes Os and by inference other metals present in porphyry coppers. Another feature of the data set is that gold-bearing systems in arc environments associated with porphyry intrusions have crustal signatures (0.5-2.5) regardless of the style of the related ore body. For instance, the low/high sulfidation epithermal gold systems in Bucaramanga Columbia (¹⁸⁷Os/¹⁸⁸Os initial 1.2), the massive sulfide ores of the Grasberg, Irian Jaya (¹⁸⁷Os/¹⁸⁸Os initial 0.7--1.2), and Cu-Au skarns in the Hedley District, British Columbia (¹⁸⁷Os/¹⁸⁸Os initial 1.7-2.5) all have large crustal components.
21
Tomlinson, David Harris. « Nature and Origin of Fissure Ore at the Porphyry-Epithermal Transition Zone of the Bingham Canyon Porphyry Cu-Au-Mo Deposit, Utah ». BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7544.
Texte intégralRésumé :
Late-stage fissure-filling ore at the world class Bingham Canyon, Utah, porphyry copper deposit has long been recognized, but poorly studied. Physical and chemical characterization of the Pb-Zn-Cu-Ag-Au mineralized fissures in the porphyry-epithermal transition zone provides insight into the origin, timing, and controls of ore deposition. These sheared sulfide-rich fissures are dominated by pyrite and multiple generations of quartz, with lesser amounts of other sulfides and gangue minerals. Au (0.27 to 4.61 ppm) provides the most value to the ore in the transition zone. Host rocks include Eocene monzonite and Paleozoic limestone and quartzite"”all of which can contain economic ore bodies. Associated alteration is predominantly sericitic and argillic. Mineralization into the wall rocks is restricted, not exceeding 1.5 m from the fissure margins. Mineral assemblages vary with distance from the center of the main Cu-Mo deposit and the modal abundances are dependent on host rock. The appearance of both galena and sphalerite (and tennantite to an extent) mark the transition from a porphyry to an epithermal environment. This is accompanied by an increased concentration of chalcophile trace elements in sulfides as determined by EMPA and LA-ICP-MS. Significant hosts of Ag include galena and tennantite, while Cu is hosted primarily in chalcopyrite, tennantite, and sphalerite. Gold does not appear to be hosted in solid solution, but may be focused along fractures or inclusions in pyrite. δ3434S values of fissure pyrite has a narrow range (+2.3 to 3.4‰), while δ18O of quartz is more variable and high (+11.5 to 14.0‰) relative to typical hydrothermal quartz. This can be explained by increased fractionation at lower temperatures in the magmatic fluids, which could have additionally mixed with exchanged 18O-rich meteoric water. Ore grades improve with distance from the center of the deposit; however, this is accompanied by higher concentrations of elements (Pb, As, Bi, etc.) undesirable for downstream processing. The mineralized fissures were created sequentially throughout the formation of the deposit. Initial joints probably formed as a result of the intrusion of a barren equigranular monzonite. The NE orientation of the joints was controlled by the regional stress field, which is more apparent distal to the center of the deposit. A quartz monzonite porphyry then intruded, dilating the joints to allow precipitation of quartz and then pyrite during the Cu-Au-stage of mineralization in the main ore body. After dike-like intrusions of latite porphyry and quartz latite porphyry intruded, galena, sphalerite, and pyrite precipitated to form the Pb-Zn-Ag mineralization. This was followed by late precipitation of chalcopyrite and tennantite (and likely Au mineralization).
22
Schweikert, Katja, et n/a. « The functional biology of Porphyra sp. in New Zealand ». University of Otago. Department of Botany, 2007. http://adt.otago.ac.nz./public/adt-NZDU20080910.114121.
Texte intégralRésumé :
The intertidal red algal genus Porphyra is found on rocky shores worldwide. In the Northern Hemisphere the genus is well studied but there is a paucity of data on southern hemisphere Porphyra and even less on New Zealand Porphyra. The species� taxonomy has been undergoing revision since the late 1990�s, when it was discovered that the main species P. columbina and P. lilliputana reported for New Zealand were a combination of several endemic species. These species are found from the low to the high intertidal watermark; hence they are exposed to fluctuating stresses such as desiccation, temperature, high light and UV radiation. Algae have evolved a number of mechanisms to adapt to naturally changing increasing abiotic conditions, such as accumulation of screening pigments and changes in antioxidant metabolism during light stress. For terrestrial plants, polyamines (small aliphatic amines) have been shown to be involved in protecting cells from damage under conditions of stress including UV-B radiation; such mechanisms have yet to be identified in algae.
The overall aim of this study was to determine the importance of cellular processes in shaping the community structure of Porphyra on a wave-exposed shore on the east coast of the South Island, New Zealand. Porphyra distribution and community structure was assessed by regular monthly monitoring of presence and absence of Porphyra along four transect lines at the site. Enviromnental information was recorded to determine the effects of temperature, light, UV radiation, humidity and wind on Porphyra�s spatial and temporal distribution. Regular tissue samples were taken for species identification by the application of primers, which were specifically designed during this study. P. cinnamomea and Porphyra spec. "ROS 54" were identified as dominant species present almost throughout the year with a pronounced maximum in presence during late winter and spring, and some weeks of absence during April or May. The two dominant species were recorded from the low to the high intertidal shore, but the mid intertidal was identified as the preferred habitat. Other species that were found were rare and only present for a few months in a very restricted area. It was hypothesised that free radical generation and antioxidant metabolism are associated with desiccation tolerance in Porphyra. An attempt was made to investigate the impact of desiccation stress on Porphyra. The extraction process of antioxidants was problematic and no reproducible results could be obtained. It was attempted to investigate the spatial distribution of spores and conchocelis of different Porphyra species in the field, and determine if those found at Brighton Beach are species-specific in their morphology. This indicated that the two main Porphyra species at Brighton Beach not only prefer to occupy the same habitat but that they also have a morphologically similar conchocelis phase.
Mechanisms on a cellular level such as polyamine metabolism affected by environmental (abiotic) stresses are related to the alga�s ability to adapt to stress and therefore can have an effect on Porphyra�s distribution along the shore and its presence throughout the year. The depletion of the ozone layer has become an important issue as the effects of increased UV radiation on the environment, especially the intertidal habitat, are revealed. Marine macrophytes possess the main three. polyamines: putrescine, spermidine and spermine of varying levels. For the few species studied, Rhodophyta generally contain higher levels of polyamines than Chlorophyta, while polyamine levels for the one heterokontophyte analysed were between Chlorophyta and Rhodophyta. Levels of the three most common polyamines (putrescine, spermidine, spermine) were determined in P. cinnamomea under controlled UV exposure. Tissue discs were exposed to visible light (PAR), PAR and UV-A or PAR, UV-A and UV-B radiation. Discs exposed to PAR and PAR and UV-A showed little change in polyamine levels over a six day trial period, while discs exposed to PAR, UV-A and UV-B showed a significant increase in free, bound soluble and bound insoluble polyamines over the same period of time. Correspondingly levels of ADC and ODC, two enzymes involved in polyamine synthesis, were measured. ODC levels changed little while ADC levels increased significantly during UV-B treatment, indicating that under UV-B stress polyamines are mainly synthesized via the ADC pathway. The experimental set-up and process of this study has not been applied in macroalgal polyamine research and results obtained are the first indication that increased levels of polyamines are involved in protection and/or protection mechanisms in macrophytic algae to prevent UV-B damage.
23
Gingras, Delphine. « L'influence du stoïcisme sur le De Abstinentia de Porphyre ». Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/33305.
Texte intégralRésumé :
Le traité De l’abstinence est écrit par Porphyre dans le but de convaincre son ami de revenir à la pratique du végétarisme, qu‟il a récemment abandonnée. Dans ce texte, l‟auteur présente une série d‟arguments anti-végétariens, qu‟il réfutera tout en défendant la pertinence de ce mode de vie pour le philosophe. Parmi les opposants, les stoïciens occupent une place importante, le troisième livre du traité leur étant presque entièrement consacré. En réfutant les arguments anti-végétariens des stoïciens, Porphyre développe ses positions avec un vocabulaire qu‟il leur emprunte. Ce faisant, il teinte son traité de l‟influence stoïcienne. Ce mémoire a pour objectif d‟analyser de quelle manière le dialogue entre Porphyre et les stoïciens influence l‟auteur du De abstinentia. L‟argument anti-végétarien attribué aux stoïciens consiste à dire qu‟il est impossible de demander à ce que les êtres humains épargnent la vie des animaux, puisque ceux-ci ne nous sont pas familiers (oikeion), du fait de leur absence de raison. Or, puisque dans la théorie stoïcienne la justice prend sa source dans les relations de familiarité qui lie les êtres rationnels entre eux, on ne peut considérer que la mise à mort des animaux dans le but de consommer leur chair est un acte injuste, voire impie, comme le soutient Porphyre. Les trois termes de ce débat feront chacun l‟objet d‟un chapitre : oikeiôsis, justice et logos. Ces trois notions permettront d‟approfondir la teneur du désaccord de Porphyre avec les stoïciens et de comprendre de quelle manière ce néoplatonicien se réapproprie le vocabulaire stoïcien pour le pousser à des conclusions qui sont conformes à sa métaphysique. On trouvera que derrière la question du végétarisme, c‟est le thème plus complexe du mode de vie qui anime le débat.The treatise On Abstinence is written by Porphyry in order to convince his friend to return to the practice of vegetarianism, which he recently abandoned. In this text, a series of anti-vegetarian arguments are presented, which the author refutes while defending the relevance of this way of life for the philosopher. Among the opponents, the Stoics have an important place, the third book of the treaty being almost entirely devoted to them. Refuting the anti-vegetarian arguments of the Stoics, Porphyry develops his positions with a vocabulary borrowed to them. In doing so, he gives his treatise a Stoic flavour. This dissertation aims to analyze how the dialogue between Porphyry and the Stoics influences the author of the De abstinentia. The anti-vegetarian argument attributed to the Stoics says that it is impossible to ask of human to spare the life of animals, since they are not rational and, thus, not appropriate (oikeion) to us. Because, in the Stoic‟s theory, justice is rooted in the relations of appropriation between rational beings, we could not say that killing animals to eat their flesh is unjust, or impious, like Porphyry argues. One chapter will be dedicated to each of the terms of this debate: oikeiôsis, justice and reason. These three notions will allow us to further the analysis of the disagreement of Porphyry towards the Stoics and to understand how this neoplatonic philosopher uses the Stoics vocabulary to pursue his own metaphysical goals. We will find that behind the question of vegetarianism lies the more complex theme of the way of life.
24
Diaz, Acevedo Nelson Simon. « Exotic deposits derived from porphyry copper systems in Chile ». Thesis, Rhodes University, 1996. http://hdl.handle.net/10962/d1011149.
Texte intégralRésumé :
The exotic orebodies related to cal-alkaline porphyry copper deposits. are sub-horizontal lenticular bodies of secondary copper minerals that impregnate Tertiary gravels and bedrock of different ages. They lie immediately downslope of the porphyry copper deposits, that is to say. they are related to the propylitic halo of the main deposits, and are considered to have originated with the deposition of copper minerals from solutions that overflowed during the secondary enrichment process. Supergene alteration took place between the late Oligocene and Miocene, by which time both orehodies (exotic and porphyry copper) were established. The paucity of tile denudation since the Miocene in the Andean segment from 21º to 26º latitude S. due to the dominance of a hyperarid climate explains the remarkable preservation of the shallow porphyry copper systems, supergene enriched blankets and associated deposits. This is reflected in the limonites, where the typical boxworks have been partially or totally destroyed on surface by the superleaching. As a result of the lateral migration of the copper-bearing solutions, the exotic deposits show a zonation. alteration and mineralization whose characteristics depend among other factors. on the reactivity of the bedrocks and the Cu/S ratio of the mother deposit. In these deposits three zones can be recognized: Proximal (0 to 2 km Intermediate (2 to 3) and Distal (3 to 8-14 km) with palaeodrainage control. The associations and mineralogical abundance are related to the climate (rain. temperature). In some deposits two important units are detected and they are the Cu-phosphates and Cu-lixiviable (to sulphuric acid) units. The size of tile Chilean exotic deposits varies between 100 and 3.500.000 tons of copper, with a total known resource of 8 M tons of copper. The large exotic deposits are comparable to the resources of a medium-sized porphyry copper- type deposit. The discovery of the exotic deposits is related to the exploration of porphyry copper deposits, where a mass balance of the leached column must be done. Moreover the lithology and alteration of the propylitic halo. permeability, structures, geophysics and geochemistry should be considered. The diorite model is not compatible with a supergene enrichment process, expressed by the absence of colour anomalies, exotic deposits and in the presence of secondary minerals like jarosite, which is coherent with the pyrite deficiency of the system. The projects are for exploitation of reserves by open pit methods. The projects plan to extract and to crush copper oxide ore which will he pre-treated with concentrated sulphuric acid prior to heap leaching, solvent extraction and electrowinning. The copper output varies between 10,000 and 50,000 ton per year of catilode copper. The total investment varies between 20 and 100 millions dollars. For project calculations, estimation of 65 % - 82 % copper recovery and 37 - 40 kg/ton net acid consumption can be used due to the nature of ore. The leaching time is estimated as 30 to 180 days for heaps of 4,5 to 30 metres high. As a result of this, the plant capacity is determined by an annual equivalent of 10,000 to 25,000 ton Cu per year. Pit planning has heen carried out using diverse software on the basis of 5 x 5 x 5 m and 10 x 10 x 10 m block models, evaluated using a kriging package built into the program, giving an overall waste/ore ratio (induding pre-stripping) of 0: I (in an outcrop) to 3: I. The location of the mine and plant sites are associated with the porphyry copper in production, for this the already installed facilities can be used. So there is no need to build a new mine camp or access. The environmental impact is summarized relating to the characterization of the physical, biological and socio-cuitural effects, using the framework of the Base Line study and the Impact evaluation derived from the construction and project operation phases. The conclusions and recommendations will diminish, mitigate and/or eliminate impact derived from the specific activities.
25
Rasmussen, Henrik. « Caractérisation des intrusions porphyriques du secteur du Lac Ackerman, ceinture de roches vertes de Swayze, Ontario / ». Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1999. http://theses.uqac.ca.
Texte intégral
26
Schumer, Benjamin Nathan, et Benjamin Nathan Schumer. « Mineralogy of Copper Sulfides in Porphyry Copper and Related Deposits ». Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626163.
Texte intégralRésumé :
Porphyry copper deposits represent one of the largest copper reserves on Earth. They typically contain large, low-grade reserves of primary ore and higher-grade, supergene enrichment blankets of sulfide and oxide ores. Understanding the mineralogy of porphyry copper ores and ores related to porphyry copper systems is exceedingly important for several reasons, foremost of which are the information provided by ore mineral parageneses, assemblages, and mineral chemistry on evolution of these magmatic-hydrothermal systems, and information on mineral processing characteristics of the ores. The focus of this work is to better understand the mineralogy of supergene copper sulfides in porphyry copper systems and hypogene base metal lodes related to porphyry copper systems, and use this mineralogical knowledge to improve our understanding of the processes responsible for ore formation.
The objectives of this study are accomplished by two means: focusing on the crystallography and crystal chemistry of minerals, and then applying this mineralogical knowledge to a supergene sulfide enrichment blanket and hypogene massive sulfides from base metal lodes in southeastern Arizona. The discovery of a new mineral, natropalermoite, NaSr2Al4(PO4)4(OH)4, provided the opportunity to use single-crystal X-ray diffraction to solve a crystal structure, and electron-probe microanalysis (EPMA) to study the crystal chemistry of natropalermoite and how the accommodation of Na in the structure changes lengthens the unit cell along [010] and shortens it along [100] and [001] compared to its lithium analogue, palermoite. Solution of the crystal structure of the mineral nickelskutterudite, (Ni,Co,Fe)As3, allowed for the investigation of anion deficiency in minerals of the skutterudite group, a problem whose solution has eluded researchers for nearly 100 years. Two skutterudite (CoAs3) and two nickelskutterudite samples were analyzed using single-crystal X-ray diffraction, EPMA, and procrystal electron density. The results showed fully-occupied anion sites and a cation surplus, which was accommodated in the icosahedral site, proving that minerals of the skutterudite group are not anion deficient.
This mineralogical knowledge was applied to the supergene enrichment blanket in the Western Copper section of the Morenci mine, Greenlee County, and hypogene massive sulfide deposits associated with a porphyry copper deposit at Bisbee, Cochise County, Arizona. This is one of very few studies of supergene sulfide blankets ever completed. One drill hole through the supergene blanket at Western Copper was examined using ore microscopy and EPMA. Results showed dominant (Cu+Fe):S ratios of 1.80 ± 0.05, 1.92 ± 0.03, and 1.10 ± 0.10, with higher (Cu+Fe):S dominant high in the blanket and low ratios dominant near the base of the blanket. These values were interpreted to be controlled by activity of Cu2+, Fe2+, and Fe3+ in solution.
Massive sulfide deposits at Bisbee were investigated using ore microscopy and EPMA in order to correct the previous conflicting reports of the mineralogy and paragenesis of this famous district and interpret constraints on conditions of ore-forming fluids. Results show four types of ore: chalcopyrite-rich with hematite and/or pyrite, bornite-rich, chalcocite-rich, and a Zn-Pb association. Chalcopyrite-rich ores formed first, followed by bornite-rich and chalcocite-rich ores. All ores were formed at relatively shallow depths from oxidized, moderately sulfur-rich fluids; early fluids were higher temperature and later fluids were lower temperature and considerably more sulfidized. Zinc-lead ores formed early and were continuously dissolved and reprecipitated distal to Cu-mineralization. These patterns are similar to many other base-metal lode districts worldwide, however Bisbee contains more Zn-Pb ore than other districts with hematite-containing ores and less than those without hematite.
27
Spencer, Edward. « The transport and deposition of molybdenum in porphyry ore systems ». Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/27402.
Texte intégralRésumé :
Approximately 99% of Mo is obtained from porphyry deposits (e.g. Sillitoe, 2010), representing the strongest association of any metal with a single deposit type. Despite this, the controls on the formation of Mo-rich porphyries and the spatial-temporal decoupling of Mo from Cu in these systems remain poorly understood. By combining fieldwork, Re-Os molybdenite dating and a fluid inclusion study at one of the world's largest Cu-Mo porphyries (El Teniente, Chile), this project assesses the magmatic-hydrothermal evolution of the system to help constrain the processes controlling Mo enrichment. Results indicate that deposit-wide Mo grades of < 0.06 wt.% are principally controlled by the abundance of main mineralisation-type quartz-molybdenite veins, that develop outwards and upwards into Cu-rich vein types. Parental ore fluids had low salinities (~6.5 wt.% NaCleq) and were exsolved at depth following the emplacement of multiple intrusions that acted as short-lived (< 100,000 years) conduits for mineralising fluids between 6.3 and 4.6 Ma. The decoupled deposition of Mo and Cu surrounding each temporally separate intrusion is attributed to the sequential deposition of Mo then Cu in response to decreasing temperature followed by intermittent fluid boiling and increasing fluid pH in response to sericitic alteration of the mafic host-rocks. Mo grades > 0.06 wt.% correspond to the presence of late mineralisation-type veins and breccias produced by the exsolution of Mo-rich brines ±aqueous fluids from a highly fractionated magma source. Mineralisation in this stage was short-lived and occurred in all parts of the deposit at ~4.6 Ma. The relatively Cu-poor nature of this stage is attributed to the prior preferential extraction of Cu from the underlying magma chamber in earlier mineralising events. In accordance with data from other Mo-rich porphyry systems, results indicate that Mo-Cu decoupling is controlled by both changes in magma chemistry as well as by the evolving P-T-X properties of hydrothermal fluids.
28
Gendall, Ian Richard. « The porphyry copper system and the precious metal-gold potential ». Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1005604.
Texte intégralRésumé :
It has been established that porphyry copper/copper-gold deposits have formed from I Ma to 2 Ga ago. Generally, they are related to the Mesozoic-Cenozoic interval with few reported occurrences from the Palaeozoic or Precambrian. A reason cited is the erosion of these deposits which are often related to convergent plate margins and orogenic belts. Observations of the alteration and mineralisation within and around porphyry copper/copper-gold systems have been included in numerous idealised models. These alteration and mineralisation patterns are dependent on the phases of intrusion, the tectonic setting and rock type, depth of emplacement and relationship to coeval volcanics, physiochemical conditions operative within and surrounding the intrusive and many other mechanical and geochemical conditions. Island arc and cratonic arc/margin deposits are generally considered to be richer in gold than their molybdenum-rich, intra-cratonic counterparts. Metal zonation may occur around these copper/copper-gold deposits, e.g. copper in the core moving out to silver, lead, zinc and gold. This zonation is not always present and gold may occur in the core, intermediate or distal zones. Examples of gold-rich porphyry deposits from British Columbia, Chile and the SW Pacific Island regions suggest gold is closely associated with the potassic-rich zones. Generally these gold-rich zones have greater than 2% magnetite and a high oxygen fugacity is considered to be an important control for gold deposition. High Cl contents within the magma are necessary for gold mobility within the host intrusive centres. Beyond this zone HS₂ becomes an important transporting ligand. Exploration for porphyry copper-gold deposits includes an integrated geological, geophysical and geochemical approach. Petrographic work through to Landsat imagery may be used to determine the chemical conditions of the system, ore association, favourable structural zones and alteration patterns, in order to focus exploration activities.
29
Nelson, James Baird 1967. « Analysis of trace element distributions distal to porphyry copper deposits ». Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/278566.
Texte intégralRésumé :
Enrichment and depletion of trace elements occurs in host rocks distal to porphyry copper deposits as a result of hydrothermal metasomatism. Subtle geochemical distributions in weakly propylitized host rocks is sufficient to indicate proximity to a mineralized system and may be applied to porphyry copper exploration. Samples collected adjacent to four porphyry copper deposits were analyzed for a multi-element suite, then normalized to the elemental concentrations of the fresh host rocks. The probability that an element has been enriched or depleted is determined by using concentrations in the unaltered host in conjunction with a calculated standard deviation. The probabilities have distinct zoning that is related to alteration around the deposits. Contribution lateral to deposits was observed with: Ag, As, Au, Bi, Br, Ca, Cu, Hg, Mn, Mo, Pb, Sb, Se, V, and Zn. Proximal to the mineralized portion of the systems elemental removal was observed with: Ba, Br, Ca, Mg, Mn, P, Pb, Ti, V, Y, and Zn.
30
Clarke, Emma Catherine. « Iamblichus' De Mysteriis : a manifesto of the miraculous ». Thesis, Royal Holloway, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327055.
Texte intégral
31
Miller, Owen David William. « Precious metal mineralization associated with the Coed-y-Brenin porphyry copper system, North Wales ». Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=236945.
Texte intégralRésumé :
The Coed-y-Brenin system is a diorite-hosted porphyry copper deposit of early Ordovician age (Tremadoc) situated on the south eastern side of the Harlech Dome: a thick sequence of Cambrian and Ordovician sediments and volcaniclastics that were subject to greenschist facies metamorphism during the Caledonian Orogeny. The copper mineralization occurs as disseminations, coatings on hairline fractures and in late-stage quartz-sulphide-calcite veinlets. Pyrite and chalcopyrite are the main opaque phases but sulphosalts, tellurides and electrum are also present. The copper mineralization is largely confined to the diorite and micro-tonalite dykes and sills associated with the Rhobell Fawr Volcanic centre. This study has shown that epithermal style precious-metal mineralization is also developed in the Coed-y-Brenin area in the shales and siltstones of the Maentwrog and Ffestiniog Flags Formations. It is characterised by pyritization, sericitization and silicification. The gold and silver occur as electrum in fractures and also as tellurides in late stage quartz-pyrite veins. Both styles of mineralization share a close spatial association and are characterised by propylitic and phyllic alteration. Argillic and potassic assemblages are not developed. Geochemical analysis of mineralized and unmineralized material has shown that the diorite-hosted mineralization is enriched in Cu, Au and Ag and depleted in Zn while the epithermal mineralization displays enrichments in Au, Ag, As, Sb and the base metals. Rb:Sr ratios increase with increasing alteration in both styles of mineralization. Sulphur isotope studies have shown that both styles of mineralization have a common, probably magmatic, sulphur source. Fluid inclusion data and 0 and H isotope studies indicate that following magma emplacement and development of the porphyry copper mineralization a low temperature-low salinity meteoric hydrothermal system was established. Fluid inclusion data and 0 and H isotope studies indicate that following magma emplacement and development of the porphyry copper mineralization a low temperature-low salinity meteoric hydrothermal system was established. This was responsible for the late-stage quartzsulphide-calcite veins in the diorites and for all the sediment-hosted mineralization. The association between epithennal and porphyry deposits has become apparent in recent years but the Coed-y-Brenin system is unusual due to its Lower Palaeozoic age and because both styles of mineralization are developed at the same structural level. This study of the Coed-y-Brenin porphyry system demonstrates the potential for the development and preservation of epithermal mineralization in porphyry systems and also in older orogenic belts.
32
Cardon, Olivier Leroy Jacques André-Mayer Anne-Sylvie. « Datation Re-Os sur pyrite et traçage des sources des métaux dans des gisements de type porphyre et épithermal neutre exemple des gisements de Bolcana, Troita et Magura, Monts Apuseni, Roumanie / ». S. l. : S. n, 2007. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2007_0130_CARDON.pdf.
Texte intégral
33
Rich, Shane Daniel. « Geochemical mapping of porphyry deposits and associated alteration through transported overburden ». Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58704.
Texte intégralRésumé :
Discoveries of porphyry copper deposits (PCDs) in British Columbia have declined over the past 20 years. Undiscovered PCDs are predicted to occur in the Intermontane Belt, an assemblage of volcanic arc terranes considered important for hosting large porphyry deposits. The Deerhorn Cu-Au porphyry, located within this belt, is covered with up to 60 m of undisturbed moraine. Detailed regolith mapping based on a new classification scheme for BC, combined with aqua regia and deionised water assays, sequential leaching, physicochemical measurements and hydrocarbon analysis, was undertaken to determine the response in the till to buried mineralisation. Geochemical relationships dependent on the regolith type were identified and are particularly evident in organic rich areas. To minimise background noise, data analysis was constrained to the dominent regolith unit: the undisturbed moraine (DrM), resulting in enhanced anomaly identification. Regolith mapping in advance of a soil survey can therefore allow targeted efficient sampling. Normalisation to organic carbon (Corg) to counteract the influence of organic matter on trace element variability resulted in anomalous response for elements As, Cs, Cu, Mo, Tl, U and W by conventional aqua regia on a 180-micron fraction B-upper-horizon soil. The response for six of these elements is peripheral to mineralisation in the surface environment. Multi-element evaluation is superior for mineralisation detection than individual element evaluation. Light hydrocarbon results indicate a surface response with a distinct depletion over mineralisation. Sequential leaching on selected anomalous Cu samples indicates that an aqua regia extraction was the optimal first choice for anomalous Cu detection. Copper-Fe-oxide-bearing grains interpreted as oxidised sulphides were recovered from an anomalous Cu-bearing sample and confirm a contribution of glacial clastic transport. Visual screening for clastic fragments allows a reprioritisation of anomalous response. Copper isotope results do not support Cu-ion migration from the buried mineralisation, but instead support a clastic contribution. Anomaly formation is interpreted as a combination of clastic transport, ionic migration of H⁺, vegetation uptake and surface redistribution.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
34
Magny, Ariane. « Porphyry in fragments : Eusebius, Jerome, Augustine and the problem of reconstruction ». Thesis, University of Bristol, 2010. http://hdl.handle.net/1983/d105292c-dfd6-4210-b53c-db5d1c4003f9.
Texte intégralRésumé :
Everyone working on Porphyry's 'Against the Christians' refers to the fragment collection compiled by Adolf von Harnack in 1916. Harnack's scholarship was impressive, but his work is difficult to use, and needs revision in the light of new approaches to the collection and interpretation of fragments. This dissertation draws mainly on the methodological work of Most et al. (1997) to argue that a fragment should not be read apart from its contextual framework. The dissertation analyses the fragments preserved in Eusebius, Jerome, and Augustine, and explains how each author's agenda, as well as their religious and intellectual contexts, influence the way in which they refer to Porphyry. Ultimately, this study aims at proposing a new fragment collection.
35
Chase, John Michael. « Etudes sur le commentaire de Porphyre sur les "Catégories" d'Aristote adressé à Gédalios ». Paris, EPHE, 2000. http://www.theses.fr/2000EPHEA001.
Texte intégralRésumé :
La présente thèse donne le texte grec, la traduction française, et le commentaire historique et philosophique des fragments 49, 56, 58, 59,60 ,61, 62, 63, 64, 65, 66, 67 Smith du Commentaire du philosophe néoplatonicien Porphyre de Tyr (c. 234-310 de notre ère) aux « Catégories » d’Aristote, adressé à Gédalios. Ce commentaire est aujourd’hui perdu, mais il en reste des fragments cités dans les « Commentaires sur les Catégories » des philosophes néoplatoniciens Dexippe (4e siècle) et Simplicius (6e siècle). Dans l’ « Ad Gedalium », Porphyre défendait le traité aristotélicien des « Catégories » contre les critiques qui avaient été formulées aux deux premiers siècles de notre ère par des philosophes académiciens, platoniciens, et même péripatéticiens. Surtout, Porphyre y essayait de réfuter les objections que Plotin avait formulées contre la doctrine aristotélicienne des Catégories dans ses traités « Sur les genres de l’être » (Ennéades VI 1-3). A cette occasion, nous analysons les rapports entre Plotin, Dexippe, Porphyre et Simplicius et nous étudions le modus operandi de Simplicius dans son « Commentaire sur les Catégories ». Dans une Introduction, nous esquissons la vie et l’œuvre de Porphyre. Par la suite, nous consacrons un chapitre à chaque fragment, donnant le texte grec, en donnant notre traduction française en regard. Dans le commentaire à chaque fragment, nous essayons de reconstituer l’histoire du problème philosophique auquel Porphyre fait face, et nous situons celui-ci par rapport à la tradition des commentateurs sur les Catégories.
36
Runyon, Simone Elizabeth, et Simone Elizabeth Runyon. « Deep Hydrothermal Alteration in Porphyry Copper Systems : Insights from the Laramide Arc ». Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625856.
Texte intégralRésumé :
Multiple generations of normal faults dismembered, tilted, and exposed thicknesses of up to 15 km of the upper crust in portions of central and southern Arizona. This extension, variable in distribution and magnitude, was superimposed on the axis of the Laramide magmatic arc and dismembers many porphyry copper systems, allowing for detailed study of vertical and lateral zonation of alteration around these centers. This study examines tilted fault blocks containing portions of porphyry systems across Arizona, focusing on hydrothermal alteration deep and distal in these systems (3+ km paleodepth) to develop a more complete understanding of porphyry occurrences as larger geochemical systems.
This study focuses on Na-Ca and coarse muscovite alteration in the roots of Laramide porphyry copper systems across Arizona (Ajo, Sierrita, Kelvin-Riverside, Mt. Grayback, Granite Mountain, Charleston, Globe-Miami, Sycamore Canyon, Copper Basin, Texas Canyon, and Copper Creek), provides a detailed study of Middle Jurassic coarse muscovite alteration at Luhr Hill in the Yerington district, Nevada, and documents the structural and hydrothermal evolution of the Ajo mining district in southwestern Arizona. Most areas in this study are interpreted to be highly extended, highly eroded, or both, allowing for study of deep hydrothermal alteration. Na-Ca alteration has been previously documented extensively along the Jurassic arc of the southwestern United States but less widely known in younger plutons, notably of Laramide age in Arizona. Coarse muscovite alteration previously has rarely been documented in porphyry copper systems, and this study shows that coarse muscovite alteration is likely present in systems where root zones are exposed at surface. Na-Ca alteration also is present in many in Laramide porphyry systems, though volumetrically minor, as no Laramide system contains more than a few volume perfect Na-Ca alteration in a given hydrothermal system. Na-Ca alteration in Laramide systems can include Ca, Na-Ca and Na alteration but is dominated by Na alteration (epidote-albite-chlorite ± actinolite). At Ajo, both Na-Ca and coarse muscovite alteration are present within the district due to superposition of temporally unrelated hydrothermal alteration, coupled with complex extensional deformation.
This study shows that both Na-Ca and coarse muscovite alteration are more common in Laramide porphyry copper systems than previously recognized, that Na-Ca alteration is most commonly developed as shallower Na alteration (albite-epidote-chlorite ± actinolite), common deeper Na-Ca alteration (oligoclase-actinolite-epidote), and rare, deep Ca alteration (oligoclase-diopside-actinolite ± garnet ± epidote). Na-Ca alteration is commonly less voluminous in Laramide systems than documented in systems along the Jurassic arc.
Coarse muscovite alteration, commonly termed greisen, occurs structurally below and commonly postdates potassic alteration and likely formed from late-stage, low-temperature, magmatic-hydrothermal fluids. Coarse muscovite alteration associated with more silicic magmatic compositions is developed at shallower depths and contains muscovite with higher trace element contents, coarse muscovite alteration with more variable mineral assemblages, and coarse muscovite veins that are better mineralized. Coarse muscovite alteration (greisen) occurs as the main mineralized veins at the tops of evolved metaluminous to peraluminous granites in W-Sn systems, as well mineralized veins in the cores and tops of Mo-Cu porphyry systems, and as poorly mineralized veins in the roots of porphyry copper systems. Detailed understanding of coarse muscovite alteration in a given district can, therefore, can be an indicator of depth or petrologic affiliation of a system. These results provide a better understanding of late-stage magmatic-hydrothermal alteration and hydrothermal alteration associated with the incursion of external fluids into the root zones of porphyry copper systems.
37
Greenlaw, Lauren. « Surface lithogeochemistry of the Relincho porphyry copper-molybdenum deposit, Atacama region, Chile ». Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50752.
Texte intégralRésumé :
Porphyry copper deposits (PCDs) typically have large alteration haloes that extend several kilometers from economic mineralization providing a geochemical footprint potentially an order of magnitude larger than the deposit. The Paleocene (64±2 Ma) Los Morteros batholith comprises four granodiorite units and hosts four syn-mineralization porphyry units. These units are interpreted as the product of four magmatic differentiation cycles with three magmatic recharges. Alteration assemblages observed within the system include potassic, propylitic and phyllic, with intensities varying between weak to moderate for potassic and phyllic alteration, and weak to strong for propylitic.
Lithogeochemical characterization and quantification of alteration is an important exploration tool that has the potential to lead to exploration success. Two hundred and ninety-six surface rock samples were collected in a grid covering 65 km² centered over the Relincho PCD in the Atacama region, Chile to assess the suitability of surface rock lithogeochemistry as a medium for lithological and alteration characterization. Aqua regia ICP-MS, pressed pellet XRF, and fusion-ICP results, combined with shortwave infrared (SWIR) spectra, alkali feldspar staining, petrography and field observations were used to classify lithological units and identify and quantify alteration.
Data evaluation and modeling is completed through the use of exploratory data analysis, simple mass balances and molar element ratios (MER) complimented by hand and thin-section observations and SWIR analyses. Gain-loss variations are consistent with spatial element distributions indicating: the addition of SiO₂, K₂O, Ag, Cu and Mo and loss of CaO, Na₂O during potassic alteration; and the addition of Na₂O and loss of SiO₂ during propyltic alteration. Wavelengths of SWIR chlorite features indicate that chlorite is more Fe-rich proximal to mineralization and Mg-rich distally.
Simple and molar element ratios are used as proxies for the potassic, propylitic and phyllic alteration assemblages. From these ratios, alteration indices are calculated. The potassic index (K₂O/Th) and propylitic-phyllic index ((18Ca + 14Na + 25K)/(2Si + 7Al + 4(Fe + Mg)) identify and quantify potassic, phyllic and propylitic alteration. Alteration thresholds derived from probability plots indicate that these indices would identify the Relincho deposit as a potential PCD exploration target at a sample spacing of up to 2000 m. Supplementary materials: http://hdl.handle.net/2429/50971Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
38
Hollis, Lucy. « Cretaceous porphyry magmatic-hydrothermal systems in the Tchaikazan River area, southwest B.C ». Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/15291.
Texte intégralRésumé :
The Hub, Charlie and Northwest Copper are spatially related mineral showings
(Cu ± Mo) located in the Tchaikazan River area of southwest British Columbia. The
Tchaikazan River area is located on the boundary between the Intermontane Belt and
southeast Coast Belt (SECB). Evidence of magmatic-hydrothermal alteration is
preserved throughout the study area.
Multiple episodes of magmatic-hydrothermal activity are associated with these
three centres of porphyry-style mineralization. The Hub diorite is the oldest dated pluton in the area, with a U-Pb zircon emplacement age of 81.19 ± 0.78 Ma. ZFT/AFT data suggests an emplacement depth of> 4km for the Hub diorite. The Hub diorite is crosscut by a biotite ± magnetite (± quartz) matrix/cemented hydrothermal breccia. A feldspar hornblende dyke crosscuts both the diorite and hydrothermal breccia and gives a U-Pb zircon age of 79.9 ± 1.5 Ma. Copper, molybdenite ± galena occurs in quartz veining and cement to the hydrothermal breccia. ZFT/U-Pb and Ar-Ar ages for the Hub diorite are within error of each other. AFT data suggests an average erosion rate of 40 m/myr for intrusive rocks in the Taseko Lakes area. Field relationships, geophysical anomalies, geochronology, and stable isotope
data suggest that there are three centres for magmatic-hydrothermal activity in the
Tchaikazan River area: The Hub, Northwest Copper pluton, and Ravioli Ridge. The area
displays evidence for multiple, temporally-distinct intrusive, alteration and mineralizing events.
39
Wareham, Christopher Desmond. « Isotopic and geochemical studies of a Pliocene porphyry-mo system, Rico, Colorado ». Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304968.
Texte intégralRésumé :
The historic mining district of Rico in the southern Colorado Mineral Belt contains a Pliocene porphyry-Mo deposit and peripheral epithermal Pb-Zn-Ag deposits, and hot-springs. The porphyry-Mo mineralisation is confined almost exclusively to Precambrian greenstone. The epithermal mineralisation is hosted by a Palaeozoic and Mesozoic sequence dominated by carbonates, but containing evaporites. The system is geologically complex and focused on a resurgent dome which is cored by a horst of Precambrian strata, and cut by reactivated Precambrian basement shears. The shears have controlled the emplacement of the Laramide and Pliocene granitoids in area. The mineralisation is associated with more evolved members of the latter suite. Sr-Nd-Pb-O isotope and minor element data on the granitoid intrusions indicate that they are not simply differentiates of mantle magmas. However, Nd model ages indicate that they are not purely remelts of 1800Ma Precambrian crust. Realistically it is impossible to quantify the relative proportions of crust and mantle material involved in the genesis of the intrusions. Notwithstanding this, the Rico granitoids are isotopically distinct from those associated with Climax-type porphyry-Mo deposits in Colorado. Sr-Nd-Pb isotope and trace element data on a lamprophyre suite in the area suggest two episodes of mafic magmatism; a period whereby the source was predominantly subduction modified lithospheric mantle, and a period whereby the source was predominantly, OIB-type, asthenospheric mantle. δ-34S data and ore deposit paragenesis indicate that the sulphide S has an igneous origin and that the sulphate S was derived by mobilisation of Pennsylvanian evaporites. Modelling of the S isotopic data indicates a common S source for the epithermal and porphyry mineralisation. The sulphate and sulphide S reservoirs remained essentially decoupled during mineralisation. δ13C data are compatible with the hydrothermal C having been derived by the dissolution and re-precipitation of host sequence carbonate. Pb and Sr isotope analyses of ore and gangue minerals support the conclusions reached in the stable isotope study. The Sr isotope study indicates that the Sr isotopic composition of the hydrothermal fluids varies considerably. Pb isotope ratios measured on molybdenite, pyrite, and galena indicate that the mineralisation at Rico derived its Pb from source with a higher Th/U ratio than that involved in the genesis of Climax-type porphyry-Mo deposits. Sr and O isotope analyses of Laramide sills present throughout the Rico area indicate that the Sr isotopic composition of the hydrothermal fluids varied and that the Sr isotopic composition of altered sills is not solely a function of alteration temperature; the proportion of altered primary feldspar and the growth of Sr-rich secondary minerals is also important. REE data on these sills indicate that hydrothermal alteration mobilised and fractionated these elements, but that mobility is not simply a reflection of alteration temperature. [SO4]4- appears to have been an important REE complex in the near surface oxidising environment.
40
de, Sousa Eudes Alves 1959. « Impact of geology on ore grade estimation of a porphyry copper deposit ». Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277264.
Texte intégralRésumé :
Accurate ore estimation processes are of crucial importance in the mining scenario. Over the last 20 years, one practical approach to improve ore grade estimation has encouraged the need to incorporate the geology of the ore deposit being estimated in the estimation process. The objective of this study is to investigate the impact of the geology on the kriging estimation of the ore grade of a portion of a porphyry copper deposit. Preliminary data analysis demonstrates the need to perform a subsequent variogram modeling and kriging estimation of the ore grade by rock type separation. Global and local estimations were done to assess the influence of the geology on the ore grade estimation at a global and local scales. The results obtained in this study demonstrated that for the portion of the deposit studied the incorporation of the geology does not produce substantial improvement on the ore grade estimation.
41
Valencia-Moreno, Martin Andres 1961. « Geochemistry of Laramide granitoids and associated porphyry copper mineralization in northwest Mexico ». Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282731.
Texte intégralRésumé :
The present study investigates the effects of basement variations on the geochemical composition of the Laramide plutonic belt of northwestern Mexico, and implications for the development of the associated porphyry copper mineralization. In the north part, the belt intruded rocks of the North America and Caborca terranes representing cratonic basements juxtaposed by Mid-Jurassic strike-slip faulting. The central part of the belt was emplaced in the Cortes terrane which contains Paleozoic eugeoclinal sequences accreted to North America between Mid-Permian and Late Triassic times. The southern part of the belt intruded island arc-related sequences of the Guerrero terrane, accreted to North America during the Late Cretaceous. A suite of 30 samples of granitoids were studied to characterize the geochemical composition of the belt. The samples range from 56% to 75% SiO₂ and have mid to high-K calc-alkaline and mostly metaluminous compositions. REE results show more evolved chondrite-normalized plots in the north part of the belt, characterized by higher ΣREE and La(N)/Yb(N) ratios, and more pronounced negative Eu anomalies. Southward, the samples show a progressive flattening, eventually with almost no Eu anomalies in the Guerrero terrane. ⁸⁷Sr/⁸⁶Sr initial ratios higher than 0.7062 and initial εNd below -4 characterize the granitoids from the north part of the belt. Slightly less evolved isotope signatures occur in the central part, whereas ⁸⁷Sr/⁸⁶Sr ratios below 0.7063 and more positive εNd values characterize the samples from the south. The data suggest a garnet-bearing source for the granitoids emplaced in the north and central parts of the belt, whereas much less garnet fractionation is needed in the southern part. The effect of different crustal domains on the porphyry copper mineralization is less obvious. Hypogene Cu grades do not vary much along the belt, but the associated metals such as Mo, W, and Au show a certain degree of spatial control. Higher Mo grades are associated with the North America and Caborca terranes. Tungsten deposits are not terrane-constrained, but the more conspicuous mineralization occurs in central Sonora, mainly associated to the Caborca terrane. Higher Au values seem to occur in porphyry copper and associated breccia deposits in the Guerrero terrane. In general, the associations Cu-Mo-WO₃ in terranes of North America affinity, and Cu-Au in the Guerrero terrane suggest basement control.
42
Tala, Fadia. « Fenologia e ecofisiologia das macroalgas Porphyra spp. (Bangiales, Rhodophyta) e Lessonia spp. (Laminariales, Phaeophyceae) na costa norte e central do Chile : variações latitudinais e sazonais ». Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/41/41132/tde-31032014-110235/.
Texte intégralRésumé :
O propósito dos estudos fenológicos é descrever e compreender como o desenvolvimento dos organismos ocorre em resposta às variações ambientais que mudam ciclicamente e como certos fatores estimulam a geração de uma cascata de sinais e reações que abrangem desde mudanças moleculares, bioquímicas e fisiológicas, os que acabam se manifestando como padrões anuais de abundância e reprodução. As mudanças ambientais ocorrem em escalas temporais (diárias, sazonais, interanuais) e espaciais (latitudinal, em profundidade, em altitude) e têm um forte impacto no crescimento e desenvolvimento das espécies, em especial de aquelas com características sésseis. O objetivo deste estudo foi caracterizar os padrões fenológicos (sazonais e latitudinais) de abundância, reprodução, fotossíntese e capacidade antioxidante de dois gêneros de macroalgas de importância ecológica e econômica, Porphyra spp. (rodofícea) e Lessonia spp. (feofícea), distribuídas ao longo da costa norte e centro (25° - 34°S) do Chile. Os resultados mostram que variações sazonais de radiação e latitudinais de temperatura influenciam significativamente as respostas fenológicas e ecofisiológicas das espécies estudadas. No caso de Porphyra spp., o ajuste temporal mais notório envolve um desenvolvimento fenológico anual para a população do norte e perene para as do centro e sul. As características fisiológicas mostraram diminuição na eficiência fotossintetizante, pigmentos (clorofila α, carotenoides e ficobiliproteínas) e proteínas solúveis em primavera-verão, acompanhados por aumento da capacidade antioxidante. No caso de Lessonia e embora a abundância não tenha mostrado uma mudança sazonal nas populações, o ajuste temporal mais notório aconteceu nas características fisiológicas, com diminuição na eficiência fotossintetizante, pigmentos (clorofilas α e c, carotenoides), fenois e capacidade antioxidante durante o verão, acompanhado por aumento na absorptância do talo, ETRmax e NPQ. Estudos sobre as identidades taxonômicas das populações de Porphyra são necessários para distinguir entre possíveis padrões devido à caraterísticas da espécie de possíveis variações morfológicas ou ecotípicas. Estudos das espécies de Lessonia próximas aos seus limites de distribuição biogeográfica poderiam elucidar se as diferenças fenológicas e fisiológicas são devido a padrões dependentes das espécies ou são mascaradas por características ambientais locais. Os estudos fenológicos e as mudanças em nível bioquímico/fisiológico podem subsidiar novos destinos da biomassa produzida ou da matéria prima proveniente de organismos de importância econômica. Além disso, alterações nos padrões fenológicos e ecofisiológicos típicos podem direcionar a compreensão sobre os impactos de câmbios ambientais tais como os câmbios climáticos globais, contaminação e poluição, sobrexploração e as interações e dinâmica entre as populaçõesThe purpose of phenological studies is to describe and understand how the development of the organisms occurs in response to environmental variations which change cyclically and how certain factors stimulate the generation of signals and a cascade of reactions from molecular, biochemical and physiological levels, which at the end manifests annual patterns of abundance and reproduction. Environmental changes occur in time scale (daily, seasonal, interannual) and spatial scale (latitudinal, depth, altitude) and have a strong impact on growth and development of the species, especially those with sessile characteristics. The purpose of this study was to characterize the phenology (seasonal and latitudinal) of abundance, reproduction, photosynthesis and antioxidant capacity of two macroalgae with ecological and economic importance, Porphyra spp. (Rhodophyta) and Lessonia spp. (Phaeophyceae), distributed along the coast north and center (25° - 34°S) in Chile. The results show that seasonal changes in radiation and latitudinal temperature significantly influence the phenological and ecophysiological responses of the species studied. For Porphyra spp., the most notorious temporal adjustment involves an annual phenological development from north population in contrast to perennial populations from central and south. The physiological characteristics showed decrease in photosynthetic efficiency, pigments (chlorophyll a, carotenoids and phycobiliproteins) and soluble proteins in spring-summer, accompanied by increasing in antioxidant capacity. For Lessonia spp., although the abundance showed no seasonal changes between the populations, the most notoriously temporal adjustment occurs in physiological characteristics with decrease in photosynthetic efficiency, pigments (chlorophylls a and c, carotenoids), phenols and antioxidant capacity during the summer, followed by increase in thallus absorptance, ETRmax and NPQ. Studies on the taxonomic identity of Porphyra populations are required to distinguish between possible characteristics due to species-specific patterns from morphological or ecotypes variations. Studies in the species Lessonia near their limits of biogeographical distribution could elucidate whether the phenological and physiological differences are due to patterns species-specific or are masked by local environmental characteristics. The phenological studies and changes in the biochemical/physiological levels can subsidize new destination of biomass production and raw material from organisms economically important. Moreover, changes in typical phenological and ecophysiological patterns can give a light about environmental impacts of alterations such as global climate changes, contamination and pollution, overexploitation and interactions and dynamics between populations.
43
Astudillo, Leyton Natalia. « Minéralogie magnétique et paléomagnétisme des grands gisements type porphyre cuprifère de Chuquicamata et El Teniente, Chili ». Toulouse 3, 2008. http://thesesups.ups-tlse.fr/292/.
Texte intégralRésumé :
L'objectif principal de cette recherche a été de déterminer les effets de l'altération hydrothermale sur la minéralogie magnétique et les enregistrements paléomagnétiques de deux méga-gisements de type porphyre cuprifère au Chili. Le gisement de Chuquicamata (Eocène-Oligocène), dont la minéralisation est hébergée dans des roches granodioritiques est limité longitudinalement par une faille majeure (Falla oeste) et les minéralisations d'intérêt économique sont principalement concentrées à l'est de la faille. La susceptibilité magnétique et l'intensité de l'aimantation rémanente diminuent fortement en fonction de l'altération quartz-séricite qui augmente à l'approche de la faille. A l'ouest de la Falla Oeste, des rotations antihoraires de petits blocs confirment l'hypothèse d'un mouvement sénestre de ~35km ayant permis la juxtaposition du porphyre cuprifère de Chuquicamata avec la granodiorite Fiesta. Dans le gisement EL TENIENTE (Miocène supérieur - Pliocène inférieur). , les contrastes magnétiques sont forts entre les dacites et quartz-diorite (k <0. 001 SI) et le complexe d'andésites minéralisées (<0. 01 < k < 0. 2 SI). Une aimantation rémanente très stable de polarité normale ou inverse, est portée par la magnétite en grains fins. Compte tenu des fréquentes inversions de polarité du champ magnétique terrestre au cours de la période 4. 5-5Ma, la zonation spatiale de la polarité magnétique observée au niveau de la mine suggère une acquisition d'aimantation et de minéralisation très rapide (~0. 1-0. 2Ma) au cours d'épisodes successifsThe principal objective of this research was to determine the effects of hydrothermal alteration on the magnetic mineralogy and the paleomagnetic records in two Chilean porphyry copper mega deposits. The Chuquicamata orebody (Eocene-Oligocene) where the mineralization is hosted in granodioritic rocks is longitudinally limited by a master fault (West fault) and the economic mineralization is concentrated on the eastern side. Magnetic susceptibility and remanent magnetization strongly decrease, while quartz sericite alteration increases when getting closer to the fault. In the western block of the mine, counterclockwise rotation of small blocks associated with deformation along the West Fault, support the hypotesis of 35 km of sinistral strike-slip movement, leading to the juxtaposition of Chuquicamata porphyry copper deposit with the Fiesta granodiorite. In El Teniente orebody (late Miocene- early Pliocene), the magnetic contrasts are strong between weakly magnetic dacites and quartz-diorites (k <0. 001 SI) and the mineralized andesite complex (<0. 01 < k < 0. 2 SI). A very stable remanent magnetization of normal or reverse polarity is carried by fine grained magnetite. Considering the frequent polarity reversals of the earth magnetic field in the time interval 4. 5-5Ma, the spatial zonation of magnetic polarity within the mine suggests that mineralization and subsequent cooling occurred within short time intervals (~0. 1-0. 2Ma)
44
Rempel, Kirsten U. « The solubility and speciation of molybdenum in aqueous liquid and vapour : an experimental study ». Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115874.
Texte intégralRésumé :
We have conducted an experimental investigation of the solubility and speciation of Mo in HCl-, NaCl-, and NaOH-bearing water vapour, and of the partitioning of Mo between coexisting aqueous liquid and vapour at 300 to 370°C and up to saturated pressure. Our results indicate that Mo concentration is enhanced in HCl-bearing water vapour at fHCl > 0.1 bar, and in NaOH-saturated water vapour, but is unaffected by the presence of NaCl. This suggests that Mo speciates as MoO3·nH2O in water vapour at equilibrium with NaCl or fHCl < 0.1 bar. The dependence of SigmafMo on fHCl at higher acidity points to the formation of Mo oxychloride (MoO2Cl 2). For the system MoO3-NaOH-H2O, log Sigma fMo increases with increasing fH2O, and with log SigmafNa in a ratio of 0.28+/-0.4, but Sigma fNa does not change with increasing fH2O. This suggests the formation of a small proportion of sodium molybdate (Na 2MoO4) in addition to MoO3·nH2O. Our partitioning experiments show that at lower temperature and fluid density, Mo partitions more strongly into the liquid than the vapour, but the Mo concentration in the vapour increases as the temperature-pressure conditions approach those of the critical point of water (374°C and 221 bar), surpassing that in the liquid at ∼360°C. The results of our experiments indicate that both the liquid and vapour phases may be important for the transport of Mo in porphyry ore-forming systems, and that vapour-phase solubility is enhanced in high fHCl magmatic gases.
45
Mach, Craig J. « Tectonic controls, timing and geochemistry of supergene enrichment of the Tyrone porphyry copper deposit, Grant County, New Mexico / ». abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3342621.
Texte intégralRésumé :
Thesis (Ph. D.)--University of Nevada, Reno, 2008."December, 2008." Accompanying CD-ROM contains appendices C and D. Appendix C: AutoCAD files with drill hole log; Appendix D: excel spreadsheet with copper mass balance calculations. Includes bibliographical references (leaves 206-215). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
46
Stavast, William James Andrew. « Three-Dimensional Evolution of Magmatic Hydrothermal Systems, Schultze Granite and Ruby Star Granodiorite, Arizona ». Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/194841.
Texte intégralRésumé :
The biotite bearing Schultze Granite (Globe-Miami district) and the biotite-hornblende bearing Ruby Star Granodiorite (Pima district) compose two intrusive centers that produced multiple porphyry copper deposits during the Laramide orogeny. Both magmatic-hydrothermal systems were dismembered and tilted by Tertiary extension, as indicated by tilted Tertiary sedimentary rocks, paleomagnetic data, and geobarometry, thereby producing extraordinary exposures of these magmatic-hydrothermal systems: ~ 1 to ~10 km (Globe-Miami district) and <1 to>12 km (Pima district). Ages of emplacement range from 68 to 61 Ma for the Schultze Granite and 64 to 58 Ma for the Ruby Star Granodiorite. The plutons were formed by rapid accumulation of magma within short periods of time (~1 m.y.). The Schultze Granite is a high-silica granite and did not evolve chemically with time, except during formation of late porphyry and aplite dikes. Phases of the Ruby Star pluton range from granodiorite to granite, but appear to be distinct intrusive events separated in time by several million years. Each pluton is chemically homogenous with depth, probably due to convection. The low iron contents of biotites suggest that magmas related to porphyry copper deposits have higher oxidation states than typical granitic bodies. Hydrothermal alteration was associated with most phases of each pluton, with multiple alteration types overlapping to create complex centers. Veins persist to >10 km beneath porphyry copper deposits. Deep styles of alteration differ in the two plutons. The Schultze Granite contains biotite veins and greisen veins (coarse-grained muscovite) (~10 km). The Ruby Star Granodiorite contains sodic-calcic alteration (4-8 km) and greisen veins (4-12 km). The sodic-calcic alteration is asymmetrically distributed on the eastern side of the Sierrita deposit and is interpreted to have been created by influx of external sedimentary brines from Paleozoic sedimentary rocks that only are present on the eastern side of the pluton. Greisen alteration occurs late in the hydrothermal history and may be the last fluids that were exsolved from the magma as the magma chamber completely crystallized. These deep alteration styles can be used to predict where porphyry copper deposition may have occurred, which can lead to discoveries in extended terranes.
47
Niese, Siegfried. « Der Porphyrfächer in Mohorn-Grund - ein sehenswertes Naturdenkmal in der Umgebung interessanter erdgeschichtlicher Zeugnisse ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-160625.
Texte intégralRésumé :
Das in einem ehemaligen Steinbruch im Rhyolith des Tharandter Waldes in Mohorn-Grund befindliche Naturdenkmal Porphyrfächer und eine Anzahl in seiner Umgebung befindlicher Aufschlüsse der verschiedensten Gesteinsarten aus unterschiedlichen geologischen Zeitaltern werden beschrieben. Sie sind zum großen Teil auf einem Rundweg in einem geologischen Freilichtmuseum zu besichtigen. Darüber hinaus wird auf das Interesse hingewiesen, das Geologen und Wanderer bereits in den vergangenen zwei Jahrhunderten an diesen Vorkommen zeigtenThe Porphyrfächer in a former quarry in the forest of Tharandt in Saxonia in Mohorn-Grund and a number of further geological outcrops with different types of rocks from different geological ages in his vicinity are described. Most of them can be seen at a round in a geological open-air museum. Many geologists and visitors have shown their interest in these rocks in the last two century, too
48
McGregor, Bruce Jonathan. « Aspects of the biology of Porphyra (Bangiales, rhodophyta) of the Isle of Man ». Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317182.
Texte intégral
49
Yalo, Masande Nicholas. « An investigation of the natural products composition of Porphyra capensis (a red seaweed) ». University of the Western Cape, 2017. http://hdl.handle.net/11394/6354.
Texte intégralRésumé :
Magister Scientiae - MSc (Chemistry)Plants have been widely used in traditional medicine for a number of ailments, among which may be included infectious diseases such as colds, influenza, chicken pox, TB, etc. as well as lifestyle diseases such as diabetes and cancer. Seaweeds have also been shown to contribute to the maintenance of health through their nutritional and medicinal properties and recently, a great deal of interest has developed towards the isolation of bioactive compounds from marine sources due to their numerous health benefits. Furthermore, marine algae are valuable sources of structurally diverse metabolites with scientifically proven therapeutic claims. Chemical constituents of red seaweed, Porphyra capensis was investigated in this present study along with subsequent brine shrimp lethality assay analysis of the crude extracts. The compounds isolated from the plant were from the hexane (6) and butanol (2) extracts. These compounds were all isolated and purified by various chromatographic techniques, namely silica gel chromatography, Sephadex LH-20 gel as well as C18 reversed phase silica gel. The structures of the isolated compounds were analysed and characterised by NMR, GC-MS, ESI MS and FTIR spectroscopy. Eight compounds were isolated and identified as phytol, desmosterol, 9-eicosenoic acid, 5,8,11,14,17-eicosapentanoic acid, palmitic acid, methyl (E)-hexadec-9-enoate, glycerol and compound 1 (novel compound). All the compounds were isolated from Porphyra capensis for the first time. The hexane, butanol and methanol extracts were found to be non-toxic with the brine shrimp test LC50 value at least two times greater than ?g/ml.
50
Gilmer, Amy K. « Petrogenesis of the Don Manuel igneous complex and porphyry copper system, central Chile ». Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702924.
Texte intégralRésumé :
Porphyry copper deposits (PCDs) are associated with shallow-level, subvolcanic intrusions. While PCDs have been studied extensively, the petrology of the host intrusions have received relatively little attention because hydrolytic alteration often destroys the primary petrologic features. However, these features are key to understanding the trans-crustal arc magmatic processes that result in PCDs. The Don Manuel porphyry copper system of the Miocene-Pliocene PCD belt of central Chile, contains significant alteration, but it is localized, allowing investigation of the primary petrology in relatively fresh portions. Fieldwork and examination of drill cores enabled characterization of the Don Manuel igneous complex (DMIC). The DMIC consists of six intrusive units ranging from 53-74 wt.% Si02. Highresolution CA-ID-TIMS U-Pb and whole-rock 40Ar/39Ar dating indicate that the intermediate to felsic units were emplaced in pulses between 4.0-3 .6 Ma, making it the youngest documented PCD system in the Andes. The episodic emplacement of this igneous complex occurred on a timescale similar to eruption and degassing events in arc volcanic systems. Petrographic, geochemical and isotopic data establish the origin and assembly of the diverse magmas that comprise the DMIC. The magmas have undergone polybaric differentiation from parents with varying initial water contents. Mineral chemistry, coupled ~ith thermobarometry, constrain the petrogenesis of the DMIC, indicating that wet magmas began differentiating in the lower to middle crust and continued to evolve in shallow crustal reservoirs. Intermediate porphyry dikes associated with copper mineralization contain diverse crystal cargos that represent mush entrained from different depths, crystals originating in different magmas, and crystals grown in-situ from hybridized magmas. The petrologic complexity and episodic timescale observed in the porphyry copperrelated magmas is analogous to the open system, trans-crustal processes indicated arid observed in arc volcanic systems. Examination of other PCDs through this framework could provide additional information about key ore ingredients such as volatiles, metals, and sulfur.