WorldCat Identities

André-Mayer, Anne-Sylvie

Overview
Works: 26 works in 27 publications in 2 languages and 33 library holdings
Roles: Thesis advisor, Other, Author, Opponent, Editor
Publication Timeline
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Most widely held works by Anne-Sylvie André-Mayer
Erratum to Boiling and vertical mineralization zoning: a case study from the Apacheta low-sulfidation epithermal gold-silver deposit, southern Peru by Anne-Sylvie André-Mayer( )

1 edition published in 2002 in English and held by 2 WorldCat member libraries worldwide

Discussion: age of the Zambian Copperbelt by Philippe Muchez( )

1 edition published in 2017 in English and held by 2 WorldCat member libraries worldwide

Diagenetic origin of the stratiform Cu-Co deposit at Kamoto in the Central African Copperbelt by Philippe Muchez( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Fluides et fracturations dans les gisements de type porphyre et épithermal by Anne-Sylvie André-Mayer( Book )

2 editions published between 2000 and 2006 in French and held by 2 WorldCat member libraries worldwide

In 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
Hypersaline fluids generated by high-grade metamorphism of evaporites: fluid inclusion study of uranium occurrences in the Western Zambian Copperbelt by Aurélien Eglinger( )

1 edition published in 2014 in English and held by 2 WorldCat member libraries worldwide

Boiling and vertical mineralization zoning: a case study from the Apacheta low-sulfidation epithermal gold-silver deposit, southern Peru by Anne-Sylvie André-Mayer( )

1 edition published in 2001 in English and held by 2 WorldCat member libraries worldwide

Intrusion-related affinity and orogenic gold overprint at the Paleoproterozoic Bonikro Au-(Mo) deposit (Côte d'Ivoire, West African Craton) by Quentin Masurel( )

1 edition published in 2019 in English and held by 2 WorldCat member libraries worldwide

Métasomatose sodique et Minéralisations uranifères associées : Exemples du district de Kirovograd-Novoukrainsk (Ukraine), du batholite du Kurupung (Guyana), et du gisement d'Espinharas (Brésil) by Sandrine Cinelu( )

1 edition published in 2008 in French and held by 1 WorldCat member library worldwide

Les gisements uranifères Protérozoïques du batholite du Kurupung (2041 ± 29 Ma) situés au Nord-Ouest du Guyana et du district de Kirovograd - Novoukrainsk (granite de Novoukrainsk daté à 2047 ± 19 Ma) situés en Ukraine sont des occurrences où la minéralisation (présente sous la forme d'uraninite, pechblende, oxyde de U-Ti) est associée à une métasomatose sodique. Elles semblent appartenir à un évènement métallogénique Paléoprotérozoïque majeur nouvellement caractérisé dans le cadre de ce travail, et auquel appartiendraient aussi des minéralisations similaires du Sud marocain et de Lagoa Real au Brésil. Le gisement d'Espinharas situé au Brésil, associé aussi à une métasomatose sodique, présente une minéralisation uranifère principalement visible sous la forme de cristaux de coffinite, d'oxyde d'uranium et d'uranothorite. Cette altération hydrothermale se développe selon différents stades : (i) une albitisation avec remplacement isomorphique de l'orthose et du plagioclase par de l'albite puis une dissolution complète du quartz de la roche ; (ii) une cristallisation d'albite automorphe dans les cavités laissées par le quartz suivie par (iii) une cristallisation de minéraux calciques (calcite, épidote, pyroxène), de minéraux d'uranium (uraninite et/ou pechblende et/ou brannérite et/ou oxyde de U-Ti selon les gisements), de zircons hydrothermaux, de chlorite, et parfois de quartz secondaire. Les études isotopiques (delta18Oalbite compris entre 2,2 et 2,9 ‰ pour les albitites d'Ukraine et delta18Oalbite et delta18Ocalcite compris entre 2,8 et 5,3 ‰ pour des albitites du Guyana) et microthermométriques (Th > 350°C) ont permis de montrer que le fluide hydrothermal responsable de cette altération hydrothermale et de la minéralisation est peu salé et d'origine superficielle. Le fluide hydrothermal est de plus sous-saturé en silice mais sursaturé en Na, U et Zr
Les minéralisations aurifères de Yaou et Couriège (Bouclier Guyanais) : des modalités de l'enrichissement primaire aux processus secondaires by Vincent Combes( )

1 edition published in 2020 in French and held by 1 WorldCat member library worldwide

Les minéralisations aurifères situées en Guyane (France, Amérique du Sud) sont localisées au sein de terrains d'âge rhyacien (2.3-2.05 Ga), témoins de l'orogenèse Transamazonienne. Ces gisements du Bouclier Guyanais sont masqués par une forêt dense sous laquelle des profils latéritiques bien développés laissent peu d'affleurement de roche non altérée. Considérant ce contexte spécifique, cette thèse s'intéresse à définir (i) quels sont les processus de minéralisation d'or primaire et (ii) quel est leur préservation et enrichissement (ou non) au cours des processus supergènes secondaires et se base sur deux sites d'étude : le gisement de Yaou et le prospect de Couriège. À Yaou, des corps intrusifs (quartz monzodiorite), encaissant principalement la minéralisation aurifère, sont alignés le long d'une zone de cisaillement à cinématique sénestre affectant un ensemble volcano-sédimentaire. Une évolution tectono-magmatique polyphasée, impliquant 5 phases de déformation, est proposée à l'échelle du camp minéralisé. Sont associés à cette séquence de déformation, deux événements aurifères qui contrôlent le budget aurifère global du gisement. L'intrusion porteuse de la minéralisation est datée à 2130,6 ± 5,8 Ma (U-Pb sur zircon). Les modalités des processus supergènes sont étudiées dans le prospect de Couriège, qui comportent plusieurs indices aurifères associés soit à des veines de quartz riches en pyrite au sein de profils latéritiques en place, soit à des colluvions et alluvions. Le profil du site d'Achman Giraud est caractérisé par un profil d'altération authigénique développé sur un protolithe d'amphibolite avec des veines de quartz aurifères. La dispersion verticale et latérale de l'or peu importante, le caractère principalement primaire des grains d'or et les preuves limitées de reprécipitation de l'or supergène, plaident en faveur d'une faible remobilisation supergène sans preuve évidente d'enrichissement au cours de la latéritisation. Le profil du site de Lupe expose un horizon colluvionnaire aurifère tronquant un profil latéritique stérile. L'or est présent sous forme d'inclusions d'électrum dans des cristaux de pyrite détritiques centimétriques partiellement goethitisés et sous forme de grains d'or libres qui présentent une forme subarrondie, des marques de transport mécanique et des bordures appauvries en Ag, suggérant un transport significatif ainsi qu'une altération supergène
Dynamique du système diagénétique/hydrothermal du bassin de McArthur (Australie) : nature des fluides, datations et contraintes sur la distribution des ressources métalliques (U, Cu, Pb-Zn) by Joséphine Gigon( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

The sedimentary McArthur Basin (Northern Territory and Queensland, Australia) is associated with numerous diagenetic/hydrothermal uranium, copper, lead and zinc concentrations, including some world-class deposits (e.g., Ranger and HYC). Some deposits correspond to styles of mineralisation well defined such as unconformity-type for uranium and Sediment-Hosted Massive Sulphide (SHMS) for lead-zinc, but others are not linked to a specific type. A major mineralising event at around 1650-1600 Ma is recorded in the uranium deposits in the North (Alligator Rivers Uranium Field - ARUF) and South (Westmoreland) parts of the basin and in lead-zinc deposits in the centre (Batten Fault Zone), and accounted for the exceptional metalliferous stock of the basin. In addition, even if it has not been established that the fluids responsible for uranium and lead-zinc mineralisation share a common origin, their characteristics in terms of temperature and salinity are similar. This PhD focused on the major factors controlling metals resources distribution at a large scale in this intracratonic sedimentary basin by studying the mineralisation with a geochronological and geochemical approach, and by characterising the associated fluids in order to define its age, temperature and emplacement conditions. In addition to the major event at 1650-1600 Ma, the metallogenic history of the basin shows numerous other evidences for crystallisation or remobilisation of the metalliferous stock. Some of the fluid circulation stages are linked with geodynamic events such as basin inversions or orogeneses located a few hundreds of kilometres from the studied area. It seems that the large scale migrations of mineralising fluids (i.e., overall horizontal in the large sandstone aquifers, and vertical in the major faults zones) allowed the metal mobilisation in different reservoirs from the basin and the basement, and their selective precipitation within favourable zones
Cycle de l'uranium et évolution tectono-métamorphique de la ceinture orogénique Pan-Africaine du Lufilien (Zambie) by Aurélien Eglinger( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

Uranium is an incompatible and lithophile element and can be used as a geochemical tracer to discuss the generation and the evolution of continental crust. This thesis, focused on the Pan-African Lufilian belt in Zambia, characterizes the U cycle for this crustal segment. Silici-clastic and evaporitic sediments have been deposited within an intracontinental rift during the dislocation of the Rodinia supercontinent during the early Neoproterozoic. U-Pb ages on detrital zircon grains in these units indicate a dominant Paleoproterozoic provenance. The same zircon grains show subchondritic epsilonHf (between 0 and -15) and yield Hf model ages between ~2.9 and 2.5 Ga. These data suggest that the continental crust was generated before the end of the Archean associated with U extraction from the mantle. This old crust has been reworked by deformation and metamorphism during the Proterozoic. U has been remobilized and re-concentrated during several orogenic cycles until the Pan-African orogeny. During this Pan-African cycle, U-Pb and REY (REE and Yttrium) signatures of uranium oxides indicate a first mineralizing event at ca. 650 Ma during the continental rifting. This event is related to late diagenesis hydrothermal processes at the basement/cover interface with the circulation of basinal brines linked to evaporites of the Roan. The second stage, dated at 530 Ma, is connected to metamorphic highly saline fluid circulations, synchronous to the metamorphic peak of the Lufilian orogeny. These fluids are derived from the Roan evaporite dissolution. Some late uranium remobilizations are described during exhumation of metamorphic rocks and their tectonic accretion in the internal zone of the Lufilian orogenic belt
Réservoirs fluides et transferts en contexte d'exhumation orogénique : implications sur la position structurale des minéralisations Cu-Pb-Zn-Fe-Ag dans la région Lavrion-Eubée (Grèce) by Christophe Scheffer( )

1 edition published in 2016 in French and held by 1 WorldCat member library worldwide

This thesis is focused on the Attico-Cycladic orogenic wedge formed during the Alpine orogeny. From a multi-method and multi-scale approach using structural geology, petrography, mineral thermobarometry, element and isotope geochemistry, and PVTX data of associated fluid inclusions, this study deciphers the relationships between fluid circulation, fluid-rock interactions and mobilisation-transport-deposits of metals. Marbles and schists from the Evia Island and the Lavrion peninsula testify to a complex orogenic history marked by an Eocene burial phase followed by syn- and post-orogenic exhumation. Cu-Pb-Zn-Fe-Ag mineralisations from the Lavrion area are synchronous with the formation of the low-angle post-orogenic detachment and the emplacement of granodioritic magmas. The structural position of the deposits attests of an emplacement during ductile to brittle deformation conditions. Deposits associated with ductile to ductile-brittle deformation (skarn, carbonate replacement) are related to a marble decarbonation and magmatic fluid circulation. The progressive exhumation of the orogenic wedge allows the transition toward brittle conditions and opens the system to surficial meteoritic fluids. This meteoritic fluid circulation is responsible to remobilisation of metals from primary deposits allowing thus a second phase of deposition in a pure brittle deformation (epithermal veins)
Métallogénie de l'or et de l'uranium dans le cadre de la croissance et de la différenciation de la croûte au Néoprotérozoïque : exemple du massif du Mayo-Kebbi (Tchad) dans la Ceinture Orogénique d'Afrique Centrale by Diondoh Mbaguedje( )

1 edition published in 2015 in French and held by 1 WorldCat member library worldwide

The Mayo Kebbi massiflocated in southwestern Chad between the Congo craton in the South, the West African craton in the west and the Sahara metacraton to the east exposes a segment of Neoproterozoic juvenile crust accreted in the Central African orogenic belt during the Pan African orogeny. It consists of two greenstone belts (Zalbi and Goueygoudoum) separated by the May Kebbi calc-alkaline batholith complexes and intruded by calc-alkaline high-K granitic plutons. The whole is covered by Phanerozoic sedimentary formations. The greenstone belts contain sulphide zones hosted mainly by metaplutonic rocks (granodiorites) and metabasalts and metavolcaniclastics. The mineralization comprises pyrite, pyrrhotite, arsenopyrite, chalcopyrite, pentlandite, pentlandite silver, pentlandite cobaltiferous, sphalerite, cobaltite. These sulphides are disseminated, aggregated in form of layers or are filling veins and cracks. The greenstones also contain quartz veins with calcite and chlorite comprising a mineralization made of pyrite, chalcopyrite, galena and gold. Gold is present both as native crystals and as electrum. The high-K calc-alkaline Zabili granitic pluton hosts uranium mineralization related to a superposition of: (1) ductile deformation and metasomatic alteration implying the interaction between magmatic minerals with a Na-rich fluid, of potential magmatic origin, coeval to the main deposition of uranium oxides, followed by (2) brittle deformation and deposition of secondary hydrated uranium silicates involving a Na-Ca-rich fluid. We propose that these uranium mineralizations represent the extreme expression of crustal differentiation as a result of Pan-African reworking of a Neoproterozoic juvenile crustal segment
Métallogenèse de l'uranium dans la région de Litsa (Péninsule de Kola, Russie) by Léonid Serov( )

1 edition published in 2011 in English and held by 1 WorldCat member library worldwide

The Litsa district is one of the most interesting areas of the Kola Peninsula with respect to uranium metallogenesis. Presenting all the features of uraniferous province, it endured a protracted geological history with several successive uranium enrichments. There are over 30 uranium occurrences and manifestations, totally estimated at 102,000 tons in Speculative Resources (IAEA nomenclature), with an average grade of Uranium 0.01%. They occur at different stratigraphic levels of the geological succession in the district: Archean, Paleoproterozoic, Mesoproterozoic and Paleozoic. Uranium content in the geological formations gradually increases during the geological evolution of the Litsa district from Archean to Paleozoic. The most abundant and probably prospective for the economic-grade uranium mineralization is Paleozoic pitchblende vein type, located around the Litsa-Araguba granitoid complex, where favorable protoliths, structures and epigenetic processes are encountered
Les granites pegmatitiques enrichis en éléments de terres rares légères marqueurs des processus de croissance et de différenciation crustale : exemple de la Province Protérozoïque de Grenville, Québec by François Turlin( )

1 edition published in 2017 in French and held by 1 WorldCat member library worldwide

The Rare Earth Elements (REE) are of great economic interest and first order geological tracers. However, their metallogenic cycle remains poorly defined. The Grenville Province exposes its orogenic root and shows numerous REE occurrences that are especially associated with pegmatitic granite dykes (“PGD”) in the central Grenville. Two hypotheses can account for the genesis of these PGD, whether (i) the partial melting of the orogenic root composed of reworked Archean and/or Proterozoic pre-existing continental crust, or (ii) the extreme differentiation of mantle melts produced during post-orogenic extension. A multi-method approach (field geology, petrogeochemistry, geochronology and isotopy) allow to characterize the PGD and discuss their petrogenesis during the geodynamic evolution of the province. They intruded at ca. 1005-1000 Ma (U-Pb on monazite and zircon) metaplutons (mineralization hosted in allanite) or metasedimentary sequences (mineralization hosted in monazite) from the mid-pressure allochthonous crustal segment. U-Pb dating on monazite and apatite from a single leucosome of these migmatitic paragneisses evidence for a peak of metamorphism at ca. 1080-1050 Ma that was followed by a slow cooling at a rate of 2 to 6°C/Ma, first under suprasolidus conditions until the close to wet-solidus intrusion of PGD, and then under subsolidus conditions down to the 450-500°C isotherm dated at ca. 970-950 Ma. The intrusion of the PGD is coeval with the initiation as early as ca. 1005 Ma of the protracted (> 20 Ma) partial melting of underlying parautochthonous paragneisses. The peraluminous character of the PGD, the investigation of pristine magmatic zircon of the PGD (U-Pb-Hf-O isotopes and trace elements), and the petrogeochemical investigations of parautochthonous Paleoproterozoic-Archean metapelites that derive from the Laurentian margin's erosion, points to the derivation of the PGD from their partial melting. To the contrary, one PGD derived from the reworking of allochthonous plutonic units is poorly mineralized in REE, and confirms that REE from the central Grenville occurrences are issued from crustal rocks of the Superior Craton
Minéralisations uranifères de la ceinture orogénique Pan-africaine du Damara (Namibie) : implication de la fusion partielle, de la migration et de la mise en place des magmas sur le remaniement de la croûte continentale by Wilfried Antoine Bassou Toé( )

1 edition published in 2012 in French and held by 1 WorldCat member library worldwide

La chronologie de la formation de la croûte continentale est débattue mais la plupart des modèles convergent sur le fait qu'une bonne partie de la croûte continentale présente à la surface de la Terre aujourd'hui est présente depuis le Protérozoïque (2,5 - 0, 54 Ga) et qu'elle a essentiellement subit un remaniement au cours d'orogénèses. L'uranium, qui est un élément incompatible, est un traceur de cette évolution depuis son fractionnement initial par fusion partielle du manteau jusqu'à son remaniement dans les niveaux crustaux supérieurs. La ceinture orogénique Néoprotérozoïque Pan-africaine (0,5 ± 0,1 Ga) du Damara en Namibie constitue une cible géologique pour tester les relations entre croissance / évolution crustale et métallogénie de l'uranium. Elle s'est formée suite à la collision des cratons archéens du Congo et du Kalahari (plaque subductante). Ce travail de thèse montre que l'évolution de la croute continentale de la ceinture du Damara durant l'orogènese Pan-africaine au Néoprotérozoïque se fait par remaniement de roches ayant été extraites du manteau depuis l'Archéen et que leur fusion partielle est le mécanisme prépondérant pour la minéralisation uranifère primaire associée à la cristallisation de granites intrusifs. Les granites in-situ issus de la fusion partielle des sédiments dans les niveaux crustaux supérieurs sont peu ou pas propices à de fortes concentrations d'uranium du fait 1) de la faible préconcentration de leur protolithes et 2) de leur migration relativement limitée. Les granites intrusifs minéralisés correspondent à des injections tardi- à post-collision (ca. 520 - 480 Ma dans la zone centrale) et sont liés aux phases de relaxation thermique et d'effondrement gravitaire subséquentes à l'épaississement crustal de l'orogène dans un contexte de convergence de plaques
Mineral resources in a sustainable world 13th Biennial SGA Meeting 24-27 August 2015, Nancy, France : proceedings by Society for Geology Applied to Mineral Deposits( Book )

1 edition published in 2015 in English and held by 1 WorldCat member library worldwide

Distribution et contrôle cristallographique des éléments Ge, Ga et Cd dans les sphalérites des gisements de type Mississippi Valley dans les districts de Central et East Tennessee, USA by Julien Bonnet( )

1 edition published in 2014 in French and held by 1 WorldCat member library worldwide

Mississippi Valley-type Type deposits (MVT) in central and eastern Tennessee, respectively MTM (Middle Tennessee Mine) and ETM (East Tennessee Mine), contain large reserves of zinc in the form of sphalerite, but also germanium in substitution of zinc in sphalerite. However, only the deposits District MTM contain economic concentrations of germanium. These two mining districts hosted in the same geological formations and with a comparable mineralogy, are compared in order to understand the distribution of germanium and other trace elements in MVT. Analyses at atomic scale by atomic absorption spectroscopy X, XANES and EXAFS, revealed several of germanium configurations in sphalerites: germanium can substituted to zinc in ZnS under 2 + and 4+ form, but it can be under the form of nanoscale inclusions of germanium oxide associated with sphalerite. Analyses at mineral scale by electron microprobe, LA-ICP-MS and Raman spectroscopy showed two groups of trace elements: i) the first group composed by Fe and Cd is preferentially incorporated following (110) faces of sphalerite, ii) the second group composed by Cu, Ga and Ge, is preferably incorporated following (010) faces of sphalerite. The coupling of Raman spectroscopy with laser ablation ICP-MS revealed a partitioning of trace elements between the cubic and hexagonal forms of ZnS: the elements Cd and Fe are more concentrated in the cubic form, while Cu, Ga and Ge are more concentrated in the hexagonal ZnS
Les gisements d'or comme témoins de l'histoire géologique du craton oues-africain : apports de la datation by Élodie Le Mignot( )

1 edition published in 2014 in French and held by 1 WorldCat member library worldwide

The West African craton is a region enriched in gold deposits and occurrences which are hosted in Paleoproterozoic terrains. These Birimian terrains formed during the Eburnean orogeny which took place between 2.25 and 1.98 Ga. Six gold deposits situated in Burkina Faso and Ghana were studied in order to define a correlation between the different orogenic phases and the mineralizing event(s). The detailed study of the mineralization of the six deposits confirmed the importance of the orogenic gold deposits in the West African craton. Moreover, the existence of a Cu (±Au) porphyry deposit was revealed in the mining district of Gaoua, southwestern Burkina Faso. Our observations highlighted the polyphased character of gold mineralization within nearly all of the studied deposits. Re-Os dating performed on sulfides directly linked to the gold mineralization permitted two main metallogenic periods to be distinguished. The first period was coincident with the D1 and D2 orogenic phases, occurring between 2200 and 2120 Ma, and representing respectively magmatic accretion and transition towards a collisional regime. This period was characterized by low grade disseminated gold mineralization. The second metallogenic period took place during the later brittle deformational phases of the orogeny, ca. 2050-2040 Ma. This secondary mineralization contains visible gold concentrated in veins, breccias and shear zones, and displays higher gold grades. Geochronological evidence for the existence of early gold mineralization could have consequences for the understanding of paleoplacer-type deposits, observed primarily in Ghana. Indeed, this primary mineralization could represent a potential source for gold found in Tarkwaian paleoplacers, which formed after 2130 Ma, and for which the provenance of the gold remains unidentified
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 by Olivier Cardon( )

1 edition published in 2007 in French and held by 1 WorldCat member library worldwide

Many porphyry-type and neutral epithermal ore deposits related to a neogene andesitic volcanism are encountered in the Apuseni Mountains. To study possible genetic relationships between the porphyry-type and neutral epithermal deposits, the Bolcana porphyry has been investigated since it is surrouded by a number of epithermal low-sulfidation veins with a Pb-Zn ± Au mineralization (Troita and Magura). In order to establish the temporal relationship between the different ore deposits, a Re-Os dating method has been developped and applied on pyrite. This method enabled us to assign an age of 10.9 ± 1.9 Ma for the porphyry-hosted mineralization. The ages obtained for the epithermal systems are somewhat approximative as perturbations of the Re-Os system are observed for these environements. A fractionation of rhenium and arsenic responsible for a significant enrichment in these elements for the apical zone of the porphyry has been demonstrated. This enrichment is most probably related to a maximum boiling event. The sources for the metals have been characterized by combining two isotopic systems (Re-Os and Pb-Pb) on both pyrite and galena. The osmium data indicate that the Troita deposit has composition which is similar to that of the Bolcana porphyry. In constrast the results obtains for the Magura deposits indicates the Re-OS system has in this case been perturbed due to a weathering of nearby ophiolites which probably contributed some osmium to the pyrite at Magura. Additional results obtained for common lead seem to confirm the osmium data, with an osmium isotopic composition which has a more important mantle-derived component than at Troita
 
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