WorldCat Identities

Vanderhaeghe, Olivier

Works: 24 works in 28 publications in 2 languages and 48 library holdings
Roles: Cartographer, Thesis advisor, Other, Opponent, Editor
Publication Timeline
Most widely held works by Olivier Vanderhaeghe
Carte géologique de la France à 1/50/000 by François Prognon( )

1 edition published in 2012 in French and held by 11 WorldCat member libraries worldwide

Partial melting of crust and flow of orogens( Book )

3 editions published in 2001 in English and held by 7 WorldCat member libraries worldwide

Saint-Germain-Lembron by Bureau de recherches géologiques et minières (France)( )

1 edition published in 2012 in French and held by 3 WorldCat member libraries worldwide

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

Protracted, coeval crust and mantle melting during Variscan late-orogenic evolution: U-Pb dating in the eastern French Massif Central by Oscar Laurent( )

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

Croissance et remobilisation crustales au Pan-Africain dans le sud du massif du Ouaddaï (Tchad) by Félix Djerossem Nenadji( Book )

2 editions published in 2018 in French and held by 2 WorldCat member libraries worldwide

Cette thèse est consacrée à la croissance et à la remobilisation crustales au Pan-Africain dans le Sud du massif du Ouaddaï au Tchad, situé à la marge Sud du Métacraton du Sahara et au Nord du Craton du Congo. La cartographie du secteur d'étude a permis de distinguer des roches métasédimentaires comprenant des niveaux d'amphibolites et intrudées par des roches plutoniques de composition intermédiaire à felsique. Les amphibolites correspondent à des basaltes tholeiitiques dérivés de la fusion partielle d'un manteau appauvri (ƐNd540= 4). Les roches felsique, représentées par des leucogranites de type-S, donnant des âges U-Pb sur zircon de 635 ± 3 Ma et 612 ± 8 Ma, sont issues de la fusion partielle des métasédiments. Les granitoïdes potassiques calco-alcalin de type-I, donnant un âge U-Pb sur zircon à 538 ± 5 Ma, incluant une monzonite à pyroxène de nature shoshonitique datée autour de ca. 540 Ma, sont caractérisées par des signatures isotopiques radiogéniques (ƐNd620= -4 et -15) et sont attribuées à la fusion partielle d'un manteau enrichi plus ou moins contaminé. Les roches métasédimentaires sont caractérisées par une foliation composite S0 /S1-2 de direction NE-SW qui est associée à des plis isoclinaux P1 et P2 d'échelle centimétrique à hectométrique et qui porte une linéation L1-2 plongeant faiblement vers le NW. Cette foliation est également affectée par des plis droits ouverts P3 associés à une schistosité de plan axial S3 fortement pentée vers le NNW ou le NW. La présence de grains de zircon détritiques et leurs signatures Hf comprenant une composante héritée Archéenne à Paléoprotérozoique indique que les roches métasédimentaires sont issues de l'érosion des cratons voisins et un dépôt au début du Néoprotérozoique.[...]
Evolution of the mineralizing fluids and possible genetic links between Miduk porphyry copper and Latala vein type deposits, Kerman copper belt, South Iran by F Padyar( )

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

Formation des minéralisations aurifères du massif du Canigou (Pyrénées orientales) : caractérisation d'un système de circulation de fluides hydrothermal tardi-varisque by Gaétan Link( Book )

2 editions published in 2020 in French and held by 2 WorldCat member libraries worldwide

Shear zones are markers of localized and heterogeneous deformation of the continental crust. They are also considered to represent drains where the fluids present within the crust preferentially flow. Although many markers of fluid flow are present in the petrological and geochemical record, tracing the entire hydrothermal circulation system, including its source, remains a challenge. In orogenic belts, gold mineralizations are mainly located along shear zones and can be tracers of the hydrothermal fluid circulation. In the eastern Pyrenees, the Canigou massif exposes a late-orogenic Variscan metamorphic dome. The former migmatitic middle crust is exhumed in the core. Vein-type gold mineralizations are localized at its rim, which corresponds to the former upper crust. The dome and its rim have been affected by a succession of 3 deformation phases. The first phase is indistinguishable, generally transposed by the foliation of the second phase, contemporary with a HT/BP metamorphic event that caused a partial melting of the middle crust and a heating of the upper crust. The third phase is synchronous with a rapid isobaric cooling of the upper crust. The deformation of this phase is characterized by a dynamic that is first pervasive, with the doming of the Canigou, and then increasingly localized, resulting in the formation of shear zones that cross the upper and middle crust. Auriferous ore-bodies are localized along these shear zones. The gold-bearing veins show markers of alternating brittle and ductile deformation. Gold-bearing sulphides crystallized under temperature conditions of more than 450°C. Geochemical data from sulphides in the orebodies and from disseminated sulphides in the host rocks indicate that the gold contained in the gold-bearing veins is derived from the carbonate and black schist levels of the underlying Ediacaran meta-sedimentary series. The disseminated sulphides in this series, of diagenetic origin and pre-enriched in gold, were leached during HT/BP metamorphism. The gold-bearing shear zones are also characterized by localized thermal anomalies superimposed on the regional thermal signal. The values of these anomalies, 50 to 100°C above those of the regional thermal signal, are consistent with those estimated from the petro-structural record of the gold-bearing veins. Numerical modelling of fluid flow coupled with heat transfer confirmed that such thermal anomalies could have been generated by a concentrated fluid flow along the vertical shear zones for a duration of less than 1 Ma. These fluids, at the origin of the gold mineralization, would come from the base of the upper crust, or even the middle crust. The detection and quantification of such thermal anomalies generated by former hydrothermal fluid flow within the crust is one of the first reported cases of this type and. This method could also provide a guide for mineral exploration. The vein-type gold mineralization is evidence of a very rapid fluid circulation phase, probably catalyzed by seismic events. This phase could be the marker of a change in dynamics within the orogenic belts, as the crust begins to cool and deformation shifts from a less and less pervasive to an increasingly localized dynamic
Zircon dating and mineralogy of the Mokong Pan-African magmatic epidote-bearing granite (North Cameroon) by R Tchameni( )

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

Modélisation d'instabilités gravitaires au sein de la croûte partiellement fondue par une méthode de Volume-Of-Fluid by Aurélie Louis-Napoléon( )

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

Gravity instabilities within partially molten orogenic roots may form migmatite domes. Not only can these domes concentrate materials of economic interest, but they also bring a better understanding of the evolution and differentiation of Earth's crust. Although horizontal forces can be involved in the formation of domes, the objective of this thesis was to look only at the influence of vertical forces by studying convection and diapirism. We had at our disposal two numerical codes based on Volume-Of-Fluid methods (VOF): JADIM (IMFT code) and OpenFOAM (open-source). We first showed that the VOF method is suitable for the modeling of gravity instabilities. Therefore we compared the results obtained with JADIM and OpenFOAM with i) theoretical, experimental and numerical results from the literature of RayleighTaylor and Rayleigh-Bénard instabilities and with ii) the results of the geodynamic code ASPECT . We found that JADIM and OpenFOAM provide results in good agreement with those in the literature and conserve mass better than ASPECT. We chose OpenFOAM for the rest of this work because it is faster than JADIM. Then, we applied the VOF method to the context of the migmatite domes from Naxos island (Greece). These domes were formed between 24 and 16 Ma and feature nested structures of 2 km sub-domes in a 10 km major dome. Zircon dating has shown that the rocks have undergone a temperature alternation with a 2 Ma period. These domes are interesting because they are recent and thus better preserved than older domes. We have tried to show that they can result from a combination of convective and diapiric episodes. We first considered the hot orogenic crust as a system made of 3 horizontal layers with temperature dependent viscosity. We showed that both in 2D and 3D, we cannot reproduce nested domes: the simulated domes are destroyed by convection when it appears. Therefore we made the system more complex. We took into account internal heating and partial melting which allow to achieve low viscosities. In addition, we added the strain-rate dependency of the rheology, as well as compositional heterogeneities (inclusions). All these factors were subjected to parametric tests, which finally allow us to propose two scenarios explaining the formation of the Naxos domes. The first scenario takes into account a nonlinear rheology and heavy and light inclusions, making it possible to generate local convection: convection and diapirism are then simultaneous, and diapirs emerge above the convective cells. The second scenario takes into account partial melting, but the progressive cooling of the system is the key mechanism that allows light inclusions to rise and form domes. However, both these scenarios do not exclude the role of external lateral forces at the end of the orogen on the remaining exhumation. More generally, we have found that the characteristics of the domes (size and homogeneity) are determined by their mode of formation (presence of inclusions, convection ...) The dimensional analysis of systems with partial melting allows us to distinguish several convective regimes and to determine the parameters necessary for the sedimentation (upwards and downwards) of inclusions during crustal convection
Évolution géodynamique d'un arc insulaire néoprotérozoïque de l'Anti -Atlas marocain : caractérisation des processus de croissance intra-océanique et d'accrétion by Antoine Triantafyllou( )

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

Relics of an intra-oceanic arc system are exposed in the Anti-Atlas in southern Morocco, in the Sirwa and Bou Azzer windows. Both of these areas form a highly tectonized patchwork made of a back-arc ophiolitic sequence to the north thrusted onto accreted arc complexes to the south. These arc complexes (Tachakoucht, Tazigzaout and Bougmane complexes) are made of granodioritic gneisses and amphibolites with typical oceanic arc signature and for which igneous ages range from 750 to 730 Ma. These magmas were buried, deformed and metamorphosed under MP-MT conditions in Tachakoucht (700°C - 8kbar) and HP-MT in Bougmane (750°C - 10 kbar) prior to several magmatic events dated at 700 and 650 Ma and the intrusion of hydrous basic magmas (hornblende gabbros, hornblendites) with oceanic arc signatures. This episodic magmatism strongly perturbed the thermal regime of the arc leading to the granulitization of the host rocks at different levels of the arc crust and to the genesis of intermediate to felsic magmas (granodioritic to granitic). These ones have been segregated through the crustal section intruding both stacked paleo-arc and ophiolitic remnants. This field, petrological, geochemical and geochronological study established that oceanic arc magmatism in the Anti-Atlas occurred in three flare-ups on a 120 Ma long time span (760 to 640 Ma). The growth of the arc was controlled and driven both by successive magmatic inputs and intra-oceanic tectonic thickening processes while final collision of the intraoceanic system with the West African Carton occurred later, around 630-600 Ma
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
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
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
Croissance et différenciation crustales au Néoprotérozoique : exemple du domaine panafricain du Mayo Kebbi au Sud-Ouest du Tchad by Moussa Isseini( )

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

The Mayo Kebbi massif (south-western Chad) is located between the Congo craton, the West African craton and the Saharan Metacraton. It consists of two greenstone belts (Zalbi and Goueygoudoum), three magmatic complexes (Gauthiot falls, Lere, Figuil) and post-tectonic intrusions distinguished on the basis of their structural, petrological, geochemical and geochronological characteristics. The geodynamic evolution of this massif includes the following phases:Phase 1: Emplacement of a Mafic to Intermediate Plutonic (MIP) complex. Boloro metadiorite, which belongs to this complex, is dated at 748 ± 4 Ma (U-Pb zircon age). This metadiorite is enriched in REE and characterized by LaN/YbN ~ 12, Sr/Y > 32, high LILE, Cr and Ni contents but negative anomalies in Nb-Ta. These features are attributed to partial melting of the slab followed by interaction of the produced magmas with the mantle wedge during their ascent.Phase 2: Emplacement of metagabbros and metabasalts (700 ± 10 Ma: U-Pb zircon age) of the Zalbi metavolcanic-sedimentary group. These rocks are characterized by a decoupling of LILE and HFSE, negative Nb-Ta anomalies, weak to moderate LREE fractionation relative to HREE. In particular, their geochemical characteristics are similar to modern back-arc basins. The isotopic compositions of Sr and Nd of these rocks preclude contamination by old continental crust of the related magmas during their emplacement. Accordingly, the MIP complex and the Zalbi metavolcanic-sedimentary group are associated to juvenile accretion in an island arc/back-arc basin tectonic setting.Phase 3: The syntectonic quartz metadiorite of Gauthiot Falls magmatic complex (665 ± 1 Ma: U-Pb zircon age, Penaye et al., 2006) is emplaced during a first collision event, which involves the Mayo Kebbi massif and the Adamaoua-Yade domain to the east. This event marks the beginning of the closure of the Zalbi back-arc basin and crustal thickening.Phase 4: The thickening is responsible of intra-crustal differentiation by partial melting of rocks accreted during the previous phases at the base of the arc. During this phase, several tonalitic intrusions are emplaced, including hornblende-biotite tonalites of Gauthiot Falls and Guegou tonalite (Lere magmatic complex). The latter is dated at 647 ± 5 Ma (U-Pb zircon age). The produced magmas have typical features of TTG magmas, leaving a garnet bearing residue at the base of the continental crust.Phase 5: The syntectonic tonalite of Figuil magmatic complex dated at 618 ± 6 Ma (U-Pb zircon age), is characterized by initial ?Nd = -3 and initial 87Sr/86Sr = 0.7073 attesting for the involvement of pre-Neoproterozoic crust on its origin. It marks a second collision event between the Mayo Kebbi massif and the Western domain of the Central African Orogenic Belt to the west.Phase 6: The Zabili A-type granite emplaced at 567 ± 10 Ma (U-Pb zircon age) and is related to the last magmatic events of the Pan-African orogenic cycle (post-tectonic intrusions). The geochemical (low Sr, Eu, Ca, Mg, Ni) and isotopic compositions (initial ?Nd = +3 à +7) of this granite point to an origin involving extreme fractionation of mantle-derived magmas which interacted with an old crustal component during their emplacement in the upper continental crust
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)
Circulations fluides au cours de l'effondrement d'un prisme d'accrétion crustal : l'exemple du "Metamorphic Core Complex" de l'île de Naxos (Cyclades, Grèce) by Luc Siebenaller( )

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

The aim of this thesis is to characterize fluid circulations in the context of the collapse of a crustal accretionary belt. The Naxos Metamorphic Core Complex comprises a detachment/decollement system characterized by mylonites, ultramylonites, cataclasites and normal faults with structural relationships reflecting the rheological layering at the crustal scale. Fluid inclusion chemistry is determined by microthermometry, Raman spectroscopy; laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), crush-leach and stable isotopes (C and H) analyses. These data characterize three different types of fluids: (1) high salinity fluids with a high metal content and high Th, (2) aqueous-carbonic fluids in equilibrium with the wall rocks and (3) aqueous probably surface-derived fluids. These data indicate that the crust is subdivided into two crustal reservoirs separated by the brittle/ductile transition. Surface-derived aqueous fluids circulate in association with the brittle deformation within the upper crust whereas aqueous-carbonic and high salinity fluids circulate in relation with ductile deformation. The characteristics of the trapped fluids indicate that as rocks have passed through the ductile/brittle transition they undergo a drastic change in geothermal gradient from 60 to 100°C/km within a lithostatic pressure regime to 35-60°C/km within a hydrostatic pressure regime. This implies that the fluid circulations are closely related to the rheological layering within the crust and its evolution during crustal extension. The ductile/brittle transition corresponds to a rheological boundary correlated to a thermal boundary and impermeable cap
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
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

The Proterozoic uranium ore deposits of Kurupung batholith (2041 ± 29 Ma, North-West of Guyana) and of Kirovograd - Novoukrainsk (granite dated at 2047 ± 19 Ma, Ukraine) are two occurrences where the mineralization (occurring as uraninite, pitchblende, U-Ti oxide) is associated to sodium metasomatism. These occurrences and also the similar mineralizations of South Morocco and of Lagoa Real (Brazil) seem to belong to a major Paleoproterozoic metallogenic event characterized in this study. The uranium ore deposit of Espinharas (Brazil) is also associated to a sodium mineralization and presents a uranium mineralization mainly occurring as coffinite crystals, uranium oxide and uranothorite. This hydrothermal alteration has different stages: (i) albitization with an isomorphic replacement of orthoclase and plagioclase by albite, following by a complete dissolution of the quartz; (ii) crystallization of euhedral albite in cavities left by quartz leaching, following by (iii) the crystallization of calcic minerals (calcite, epidote, pyroxene), uranium minerals (uraninite and/or pitchblende and/or brannerite and/or U-Ti oxide according the ore deposits), hydrothermal zircons, chlorite, and sometimes secondary quartz. The isotopic study (delta18Oalbite between 2.2 and 2.9 ‰ for Ukraine albitites; delta18Oalbite and delta18Ocalcite are between 2.8 and 5.3 ‰ for Guyana albitites) and the microthermometric study (Th > 350°C) have permit to show that the hydrothermal fluid responsible of this hydrothermal alteration and the mineralization is a surface derived fluid with a less salinity. The hydrothermal fluid is silica under-saturated but over-saturated in Na, U and Zr
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Alternative Names
Olivier Vanderhaeghe wetenschapper

Vanderhaeghe, O.

French (15)

English (9)