10 results on '"Launay, Gaëtan"'
Search Results
2. Erratum to: Genetic relationship between greisenization and Sn–W mineralizations in vein and greisen deposits: Insights from the Panasqueira deposit (Portugal)
- Author
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Launay Gaëtan, Sizaret Stanislas, Lach Philippe, Melleton Jérémie, Gloaguen Éric, and Poujol Marc
- Subjects
Geology ,QE1-996.5 - Published
- 2021
- Full Text
- View/download PDF
3. Genetic relationship between greisenization and Sn–W mineralization in vein and greisen deposits: Insights from the Panasqueira deposit (Portugal)
- Author
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Launay Gaëtan, Sizaret Stanislas, Lach Philippe, Melleton Jérémie, Gloaguen Eric, and Poujol Marc
- Subjects
vein and greisen sn–w deposits ,panasqueira ,white-mica chemistry ,quartz trace chemistry ,u–pb dating of apatite ,magmatic-hydrothermal evolution ,Geology ,QE1-996.5 - Abstract
The W–Sn Panasqueira ore deposit is a magmatic-hydrothermal system, which includes a high-grade quartz-vein type mineralization and a disseminated greisen-type mineralization occurring in the upper part of the Panasqueira two-mica granite. We investigated the genetic and chronological relationships between the greisenization of the Panasqueira granite and the formation of ore-bearing quartz veins by monitoring major and trace elements variations in quartz-white mica assemblages composing the two-mica granite, greisen and W–Sn-bearing quartz veins. The greisen is characterized by an overall depletion in Mg, Ti, Ca, Na, Ba, Sr, REE and enrichment in Fe, Li, Rb, Cs, Sn, W which reflect the breakdown of feldspars and fluid-rock interactions with W–Sn-bearing fluids. White-mica from greisen and mineralized quartz veins are enriched in granophile elements (F, Rb, Cs, Li, Sn, W and Zn) compared to magmatic muscovite from the two-mica granite. Trace elements contents in quartz depict trends which show the progressive enrichment in Ge and B and depletion in Al, Ti and Li from magmatic to hydrothermal quartz that emphasize the progressive evolution and cooling of the magmatic-hydrothermal system of Panasqueira. Geochemical similarities between quartz-white mica assemblages from greisen and wolframite-bearing veins suggest that greisenization and the formation of mineralized veins result from the same hydrothermal event and derived from the same source of hydrothermal fluids. Apatite from greisen and quartz vein yielded U–Pb ages of 292 ± 10 Ma and 295 ± 5 Ma respectively confirming that greisenization and the formation of mineralized veins occurred roughly at the same time. These ages also overlap with the emplacement age of the Panasqueira granite (296 ± 4 Ma), indicating a temporal link between greisenization, W–Sn mineralization and granite crystallization. Temperatures of the magmatic-hydrothermal system constrained by Ti-in quartz thermometry depicts a cooling trend from magmatic quartz of granite (700–600 °C) to hydrothermal quartz of greisen (500–400 °C) and veins (450–350 °C). These results suggest that greisenization and the formation of W–Sn bearing quartz veins occurred at the magmatic-hydrothermal transition, during which orthomagmatic fluids rich in volatils, incompatible elements and W–Sn were exsolved during the final solidification stage of the Panasqueira two-mica granite.
- Published
- 2021
- Full Text
- View/download PDF
4. On the morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones
- Author
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Guillou-Frottier, Laurent, primary, Duwiquet, Hugo, additional, Launay, Gaëtan, additional, Taillefer, Audrey, additional, Roche, Vincent, additional, and Link, Gaétan, additional
- Published
- 2020
- Full Text
- View/download PDF
5. On morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones
- Author
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Guillou-Frottier, Laurent, primary, Duwiquet, Hugo, additional, Launay, Gaëtan, additional, Taillefer, Audrey, additional, Roche, Vincent, additional, and Link, Gaétan, additional
- Published
- 2020
- Full Text
- View/download PDF
6. Hydrodynamique des systèmes minéralisés péri-granitiques : étude du gisement à W-Sn-(Cu) de Panasqueira (Portugal)
- Author
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Launay, Gaëtan, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Métallogénie - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université d'Orléans, and Stanislas Sizaret
- Subjects
Panasqueira ,dynamic permeability ,greisenisation ,Sn-W deposits ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,circulation hydrothermal péri-granitique approches expérimentales ,peri-granitic fluid flow ,hydrodynamique ,magmatic-hydrothermal transition ,gisement à Sn-W ,transition-magmatique hydrothermale ,perméabilité dynamique ,numerical modeling ,modélisation numérique ,greisenization ,veine et greisen ,hydrodynamics ,experimental approaches ,vein and greisen - Abstract
The vein and greisen Sn-W deposits are magmatic-hydrothermal systems that provide an important part of the world W production and represent an important source of Sn. The formation of these deposits involves continuum of magmatic-hydrothermal processes and implies the transfer and the focusing of a large amount of mineralizing fluids. This study aims to improve understanding of hydrodynamic and geological processes involved during the transport and the deposition of metals leading to the formation of these deposits. We have performed a complete study combining (i) field works (geological and structural studies), (ii) fluid flow reconstruction via the textural analysis of tourmaline growth bands, (iii) experimental determination of permeability changes during greisenization, and (iv) numerical modeling of peri-graniticfluid flow accounting for magmatic fluid production and dynamic permeability related to fluid-rock interactions. This methodology was applied in the case of the world-class W-Sn-(Cu) Panasqueira deposit, which represents a referencesite to study magmatic-hydrothermal processes leading to the formation of large vein and greisen deposit. Our resultsdemonstrate that the releasing and the expulsion of ore-bearing magmatic fluids triggered greisenization of the apicalpart of granite intrusion, which caused generation of porosity (~8.5%) and therefore a significant increase of permeability(from 10-20 to 10-17 m²) in massive greisen composing the granite’s roof. The development of this permeable pathwayconstitutes an important drain promoting the expulsion and the focusing of magmatic fluids produced during thecrystallization of the underlying granite. This enhancement of magmatic fluids expulsion (i) promotes significantly fluidflux and transfer of metals, and (ii) the establishment of high fluid pressure conditions, which coupled with the regionalcompressive crustal regime, triggered the opening of mineralized veins above the granite roof. Finally, this studyemphasizes that reactive hydrothermal fluids are able to generate their own pathways in initially impermeable rocks. Thisprocess represents an important mechanism to enhance fluid flow and promote the formation of large hydrothermaldeposits.; Les gisements à Sn-W de type veine et greisen sont des systèmes magmatiques-hydrothermaux dont l’exploitation fournit une part importante de la production mondiale de tungstène et qui représentent également une source importante d’étain. La formation de ces gisements résulte d’un continuum de processus magmatiques et hydrothermaux et implique un transport efficace et la focalisation des fluides minéralisateurs. Cette étude vise à améliorer la compréhension des processus hydrodynamiques et géologiques impliqués lors du transport et du dépôt de métaux conduisant à la formation de ces gisements. Nous avons réalisé une étude pluridisciplinaire combinant (i) travail de terrain (étude géologique et structurale), (ii) reconstruction des paléo-circulations hydrothermales via l’analyse texturale des bandes de croissance des tourmalines, (iii) détermination expérimentale des changements de perméabilité induits par la greisenisation et (iv) modélisation numérique des écoulements péri-granitiques prenant en compte l’évolution de la perméabilité dynamique lors des interactions fluide-roche. Cette méthodologie a été appliquée au cas du gisement W-Sn-(Cu) de Panasqueira, qui constitue un site de référence pour étudier les processus magmatiques et hydrothermaux conduisant à la formation de gisements à Sn-W de classe mondiale. Les résultats obtenus démontrent que l’expulsion des fluides magmatiques minéralisés a déclenché la greisenisation des parties apicales (coupoles et apex) de l’intrusion granitique, entraînant la création de porosité (~ 8,5%) qui améliore significativement la perméabilité (de 10-20 à 10-17m²) au sein du greisen massif composant le toit de l’intrusion. Le développement de ce niveau perméable constitue un drain important favorisant l'expulsion et la focalisation des fluides magmatiques minéralisateurs exsolvés lors de la cristallisation du granite sous-jacent. Cette focalisation des décharges hydrothermales (i) améliore significativement le transport des métaux, et (ii) favorise l'établissement de conditions de pression de fluide élevées qui couplées aux contraintes régionales compressives causent l'ouverture des veines minéralisées au toit de l’intrusion. Cette étude souligne l’importance des rétrocontrôles entre perméabilité dynamique et altération hydrothermale. Ces derniers constituent des mécanismes majeurs permettant d’améliorer significativement la circulation des fluides minéralisateurs et donc la formation de gisements hydrothermaux de grandes tailles.
- Published
- 2018
7. Hydrodynamics of peri-granitic mineralized systems: study of the W-Sn-(Cu) Panasqueira ore deposit
- Author
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Launay, Gaëtan, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Métallogénie - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université d'Orléans, and Stanislas Sizaret
- Subjects
Panasqueira ,dynamic permeability ,greisenisation ,Sn-W deposits ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,circulation hydrothermal péri-granitique approches expérimentales ,peri-granitic fluid flow ,hydrodynamique ,magmatic-hydrothermal transition ,gisement à Sn-W ,transition-magmatique hydrothermale ,perméabilité dynamique ,numerical modeling ,modélisation numérique ,greisenization ,veine et greisen ,hydrodynamics ,experimental approaches ,vein and greisen - Abstract
The vein and greisen Sn-W deposits are magmatic-hydrothermal systems that provide an important part of the world W production and represent an important source of Sn. The formation of these deposits involves continuum of magmatic-hydrothermal processes and implies the transfer and the focusing of a large amount of mineralizing fluids. This study aims to improve understanding of hydrodynamic and geological processes involved during the transport and the deposition of metals leading to the formation of these deposits. We have performed a complete study combining (i) field works (geological and structural studies), (ii) fluid flow reconstruction via the textural analysis of tourmaline growth bands, (iii) experimental determination of permeability changes during greisenization, and (iv) numerical modeling of peri-graniticfluid flow accounting for magmatic fluid production and dynamic permeability related to fluid-rock interactions. This methodology was applied in the case of the world-class W-Sn-(Cu) Panasqueira deposit, which represents a referencesite to study magmatic-hydrothermal processes leading to the formation of large vein and greisen deposit. Our resultsdemonstrate that the releasing and the expulsion of ore-bearing magmatic fluids triggered greisenization of the apicalpart of granite intrusion, which caused generation of porosity (~8.5%) and therefore a significant increase of permeability(from 10-20 to 10-17 m²) in massive greisen composing the granite’s roof. The development of this permeable pathwayconstitutes an important drain promoting the expulsion and the focusing of magmatic fluids produced during thecrystallization of the underlying granite. This enhancement of magmatic fluids expulsion (i) promotes significantly fluidflux and transfer of metals, and (ii) the establishment of high fluid pressure conditions, which coupled with the regionalcompressive crustal regime, triggered the opening of mineralized veins above the granite roof. Finally, this studyemphasizes that reactive hydrothermal fluids are able to generate their own pathways in initially impermeable rocks. Thisprocess represents an important mechanism to enhance fluid flow and promote the formation of large hydrothermaldeposits.; Les gisements à Sn-W de type veine et greisen sont des systèmes magmatiques-hydrothermaux dont l’exploitation fournit une part importante de la production mondiale de tungstène et qui représentent également une source importante d’étain. La formation de ces gisements résulte d’un continuum de processus magmatiques et hydrothermaux et implique un transport efficace et la focalisation des fluides minéralisateurs. Cette étude vise à améliorer la compréhension des processus hydrodynamiques et géologiques impliqués lors du transport et du dépôt de métaux conduisant à la formation de ces gisements. Nous avons réalisé une étude pluridisciplinaire combinant (i) travail de terrain (étude géologique et structurale), (ii) reconstruction des paléo-circulations hydrothermales via l’analyse texturale des bandes de croissance des tourmalines, (iii) détermination expérimentale des changements de perméabilité induits par la greisenisation et (iv) modélisation numérique des écoulements péri-granitiques prenant en compte l’évolution de la perméabilité dynamique lors des interactions fluide-roche. Cette méthodologie a été appliquée au cas du gisement W-Sn-(Cu) de Panasqueira, qui constitue un site de référence pour étudier les processus magmatiques et hydrothermaux conduisant à la formation de gisements à Sn-W de classe mondiale. Les résultats obtenus démontrent que l’expulsion des fluides magmatiques minéralisés a déclenché la greisenisation des parties apicales (coupoles et apex) de l’intrusion granitique, entraînant la création de porosité (~ 8,5%) qui améliore significativement la perméabilité (de 10-20 à 10-17m²) au sein du greisen massif composant le toit de l’intrusion. Le développement de ce niveau perméable constitue un drain important favorisant l'expulsion et la focalisation des fluides magmatiques minéralisateurs exsolvés lors de la cristallisation du granite sous-jacent. Cette focalisation des décharges hydrothermales (i) améliore significativement le transport des métaux, et (ii) favorise l'établissement de conditions de pression de fluide élevées qui couplées aux contraintes régionales compressives causent l'ouverture des veines minéralisées au toit de l’intrusion. Cette étude souligne l’importance des rétrocontrôles entre perméabilité dynamique et altération hydrothermale. Ces derniers constituent des mécanismes majeurs permettant d’améliorer significativement la circulation des fluides minéralisateurs et donc la formation de gisements hydrothermaux de grandes tailles.
- Published
- 2018
8. Dynamic Permeability Related to Greisenization Reactions in Sn-W Ore Deposits: Quantitative Petrophysical and Experimental Evidence
- Author
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Launay, Gaëtan, primary, Sizaret, Stanislas, additional, Guillou-Frottier, Laurent, additional, Fauguerolles, Colin, additional, Champallier, Rémi, additional, and Gloaguen, Eric, additional
- Published
- 2019
- Full Text
- View/download PDF
9. Deciphering fluid flow at the magmatic-hydrothermal transition: A case study from the world-class Panasqueira W–Sn–(Cu) ore deposit (Portugal)
- Author
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Launay, Gaëtan, primary, Sizaret, Stanislas, additional, Guillou-Frottier, Laurent, additional, Gloaguen, Eric, additional, and Pinto, Filipe, additional
- Published
- 2018
- Full Text
- View/download PDF
10. On morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones.
- Author
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Guillou-Frottier, Laurent, Duwiquet, Hugo, Launay, Gaëtan, Taillefer, Audrey, Roche, Vincent, and Link, Gaétan
- Subjects
BUOYANCY-driven flow ,HOT springs ,FAULT zones ,FLUID flow ,HEAT conduction - Abstract
In the first kilometres of the subsurface, temperature anomalies due to heat conduction processes rarely exceed 20-30 °C. When fault zones are sufficiently permeable, fluid flow may lead to thermal anomalies much higher, as evidenced by the emergence of thermal springs or by fault-related geothermal reservoirs. Hydrothermal convection triggered by buoyancy effects creates thermal anomalies whose morphology and amplitude are not well known, especially when depth- and time-dependent permeability are considered. Exploitation of shallow thermal anomalies for heat and power production partly depends on the volume and on the temperature of the hydrothermal reservoir. This study presents a non-exhaustive numerical investigation of fluid flow models within and around simplified fault zones, where realistic fluid and rock properties are accounted for, as well as appropriate boundary conditions. 2D simplified models point out relevant physical mechanisms for geological problems, such as "thermal inheritance" or splitting plumes showing a pulsating behaviour. When permeability is increased, the classic "finger-like" upwellings evolve towards a "bulb-like" geometry, resulting in a large volume of hot fluid at shallow depth. In the simplified 3D models, where fault zone dip angle and fault zone thickness are varied, the anomalously hot reservoir exhibits a kilometre-sized "hot air balloon" morphology, or, when permeability is depth-dependent, a "funnel-shape" geometry. For thick faults, the number of thermal anomalies increases but not the amplitude. The largest amplitude (up to 80-90 °C) is obtained for vertical fault zones. At the top of a vertical, 100 m wide, fault zone, temperature anomalies greater than 30 °C may extend laterally over more than 1 km from the fault boundary. These preliminary results should motivate further geothermal investigations of more elaborated models where topography and fault intersections would be accounted for. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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