Letteratura scientifica selezionata sul tema "Gîtes minéraux – Analyse"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Gîtes minéraux – Analyse".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Tesi sul tema "Gîtes minéraux – Analyse":
Amponsah, Prince Ofori. "Etude comparative des structures et des altérations associées aux minéralisations aurifères de la région de Wa-Lawra, NW Ghana". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30012/document.
The objective of this thesis was to perform a detailed structural, mineralization and associated alteration studies of three gold deposits located in northwest Ghana, on the eastern margin of the West African Craton. Thus, the Kunche and Bepkong deposits, located in the Wa-Lawra belt and Julie deposit located in the Julie belt. These three deposits have multiple differences interms of geological, structural, tectonic and geochemical characteristics but gold mineralization in these deposits are all associated with a green schist facies metamorphism. In Julie, the gold mineralization is hosted in granitoids with its composition akin to tonalite-granodiorite-trondhjemite (TTG) where as in the Kunche and Bepkong deposits, the gold mineralization are localized within volcaniclastic sedimentary formations and strongly silicified graphitic schists. The gold mineralization is associated with a network of quartz veins often boudinaged and formed in connection with a shear zones, oriented E-W in the Julie deposit and N to NNW at Kunche and Bepkong deposits. The dominant alteration in the mineralized zone is sericite, quartz, carbonate and sulfides with influences from the host rock. For example, the granitoid is influenced by tourmaline and chlorite in the schists or in themetavolcanic rocks. At Julie, gold is closely associated with pyrite whereas Kunche and Bepkong gold is associated with arsenopyrite. Two generations of gold are distinguished; the first corresponds to the invisible gold associated with primary growth areas in the pyrite crystals in Julie and arsenopyrite in Kunche and Bepkong, and late visible gold inclusions which are frequently found in fracture fillings. In Julie, the mineralizing fluid is rich in CO2, and has low to moderate salinity (NaCl-H2O-CO2 system), trapped in P / T conditions around 220 ° C and <1 kbar; whilst in Bepkong, the mineralizing fluid is associated with quartz are rich in CH4, with a low salinity (CH4-CO2-SO2-H2O system) which indicates that the visible trapping temperatures is around 320°C
Deloule, Etienne. "Analyses isotopiques à l'échelle intra-cristalline : une contribution à l'étude des systèmes géologiques". Vandoeuvre-les-Nancy, INPL, 1991. http://docnum.univ-lorraine.fr/public/INPL_T_1991_DELOULE_E.pdf.
Kim, Yonghwi. "Near real-time reconciliation of geochemical data acquired with handheld spectroscopic devices : Application to volcanogenic massive sulphide (VMS) deposit from the Iberian Pyrite Belt". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0027.
Mineral exploration focused on deeply concealed targets at depth requires effective techniques applicable in the field in order to identify ore-forming systems on a large scale and pathfinders to locate ore on a smaller scale. According to the rapid development of portable equipment in recent years, the importance of near real-time analysis in the field has been increasing by helping fast decision-making support before laboratory requests.Spectroscopic analysis using individual equipment has been widely used in the exploration of mineral resources, but it is rare to apply integrated data from several techniques to characterize “vectors”, which provide variations in lithology, geochemistry, mineralogy, and mineral chemistry. In addition, it is even rarer if the combination of spectral data is obtained from various portable instruments. Therefore, this study aims at reconciling geochemical data acquired from portable spectroscopic devices in order to determine the best geochemical information from each technique applied by combining the mineralogical and elemental information. Elemental and mineralogical data are provided in this study by six portable techniques: (i) elemental analyses such as XRF and LIBS for major, trace, and light elements, and (ii) mineralogical analyses such as Raman, VNIR-SWIR, MIR, and XRD to constrain rock-forming, ore, and alteration minerals.The final objective of this study is to identify vectors to the ore by applying the reconciled multi-spectral data obtained from the “real” sample in the Elvira volcanogenic massive sulfide (VMS) deposit. To achieve this, step-by-step procedures were carried out: (i) methodological understanding of each technique, (ii) establishment of a spectral database consisting of naturally monomineralic minerals, (iii) design of a decision tree to classify by mineral or mineral classes based on diagnostic bands, and mineral identification and quantification of (iv) carbonate and (v) phyllosilicate minerals (i.e., trioctahedral chlorites and dioctahedral micas), which are indicators of the target deposit.Several limitations of portable spectroscopy were confirmed based on the device itself and the geological environment in the Elvira deposit. Nevertheless, portable spectroscopy is effective in identifying the presence and compositional changes of various minerals from heterogeneous rock samples. Therefore, spectroscopic analysis on-site can be one of the vectoring tools to determine the implication for ore mineralization in hidden ore explorations
Vélasquez, German. "Étude des minéralisations aurifères du district d'El Callao, Venezuela : rôle de la remobilisation de l'or invisible dans la formation du gisement". Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1827/.
The Colombia Mine is localized in the El Callao Mining District Venezuela. It has Au reserves of 23 million ounces (= 740 t Au), which make it the largest gold mine in Guayana Craton, and grant it the label of giant gold deposit (i. E. > 500 t Au). The mineralization is hosted by the Paleoproterozoic El Callao formation, which is constituted by Fe-rich tholeiitic basalts that were formed in a plateau oceanic setting. Exploitation in the mine is focused on three "vein systems", known as América, Colombia and Hansa quartz veins. These veins systems are actually constituted by a network of interconnected quartz, albite and ankerite veins, which form a large stock enclosed between a hanging wall and a footwall. These interconnected veins include a large number of centimeter- to meter-size altered metabasaltic fragments, rich in pyrite and containing most of the gold mineralization. In the fragments, gold is always closely related to pyrite, either as inclusions, or filling fractures within it. We interpret these vein systems as a shear-fracture hosted mesh, formed in a fragileductile transitional deformation regime by a succession of micro-seisms. Each of these micro-seisms was accompanied by crystallization of a new core/rim pyrite sequence. Furthermore, local change in confining pressure from supra-lithostatic to near-hydrostatic accompanied each pressure drop causing boiling of the hydrothermal fluid, which, in turn, promoted precipitation of "invisible" gold. Later, during pyrite deformation, fluids reacted with pyrite crystals causing coupled dissolution-reprecipitation reactions. In this case, Au and others metals (i. E. , Cu, Te, Bi, Pb, Sb) were lixiviated from pyrite and reprecipitated as visible gold grains, found either in inclusions or in fractures within pyrite, and are almost always accompanied by inclusions of chalcopyrite, tellurobismuthite, sphalerite and ankerite. We conclude that all visible gold in the Colombia Mine is secondary, and that it originated from remobilization of primary, invisible gold. For this reason, we consider that economic gold mineralization in the Colombia mine was favored by the brittle deformation that that took place relatively late in the genesis of the vein network, after hydrothermal pyrite precipitation
Lebret, Noëmie. "Contexte structural et métallogénique des skarns à magnétite des Beni Bou Ifrour (Rif oriental, Maroc) : apports à l’évolution géodynamique de la Méditerranée occidentale". Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2005/document.
The Beni Bou Ifrour massif is a basement window surfacing among Neogene basins in the oriental Rif. It includes the biggest iron deposits of Morocco (> 60 Mt mined from 1915 to 1976). Identified as magnetite skarn deposits, a multi-scale integrated study allows to use them as tracers of the crustal evolution of this orogenic segment. At massif scale, field and microscopic observations display a diversity of geologic and morphologic features among the deposits. They appear to be linked to different emplacement conditions rather than genetic considerations. A dyke and sill inter-connected network (“christmas tree”) can thus explain those differences, determined by the structural position of each deposit. Outcropping of the mineralizations is related to the uplift of the Beni Bou Ifrour massif. Extended field observations and new chronological constraints (Ar-Ar and U-Pb datings, biostratigraphy…) allow to define an avant-pays thrust and fold model. Resulting translations and major deformations are restricted to a short time span between 8 and 6 Ma. At the Rif scale, this model of the Beni Bou Ifrour fits the regional history and attests the compression preeminence since 8 Ma, despite normal faults which accommodate the general uplift of the massif. At a geodynamic scale, Pb isotopic compositions have been performed on the epithermal Pb-Zn mineralizations associated to the iron skarn deposits. The combined study of Neogene Trans-Alboran and Mediterranean Maghreb margin and comparison of Pb isotopic compositions with associated deposits allow to constrain a slab breakoff event in western Mediterranean. We estimate its average velocity at about 7-8 cm/yr between 20 and 8 Ma