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408 results on '"Beaudoin, Georges"'

15. Fluid sources and mineralizing processes in greenstone belts: a stable isotope (O, H) comparison between the weakly mineralized Moly-Desgagne--Guercheville system and Val-d'Or orogenic gold deposits, Canada

Author

Kieffer, Marie A., Scheffer, Christophe, Quesnel, Benoît, Bedeaux, Pierre, Beaudoin, Georges, Mathieu, Lucie, and Gaboury, Damien

Subjects
Hydrothermal systems (Geology) -- Environmental aspects, Ore deposits -- Environmental aspects -- Canada, Geological research, Gold -- Environmental aspects, Orogeny -- Research, Earth sciences
Abstract

In orogenic gold systems, the source of the fluids and the processes leading to mobilization, transport, and deposition of gold remain debated. Most studies focus on endowed rather than on gold-poor orogenic systems to unravel the 'key' parameters of gold mineralizing processes. Here, we present stable isotope (O, H) data from the Moly-Desgagne--Guercheville fault system (gold-free to low gold endowment) in the Chibougamau area, Abitibi greenstone belt, Canada. The gold-free Moly-Desgagne showing and nearby poorly endowed Hazeur showing and Monster Lake deposit share similar features typical of orogenic systems. The stable isotope compositions of tourmaline and quartz from the Moly-Desgagne--Guercheville fault system also display similar characteristics, such as (1) temperature of vein formation of 345 [+ or -] 86 [degrees]C (1[sigma]); (2) fluid mixing between an upper crustal reservoir (low T - high [delta]D - low [delta][.sup.18]O) and a metamorphic water reservoir (high T - low [delta]D - high [delta][.sup.18]O); and (3) positive [delta][D.sub.fluid] values consistent with multiple boiling-condensation cycles related to fault-valve processes. These characteristics are similar to those from the gold-endowed Val-d'Or vein field. The difference in gold endowment between the Moly-Desgagne--Guercheville and Val-d'Or vein fields may be related to the nature of the fault system (i.e., terrane-bounding or 'intragreenstone belt') and the volume and (or) composition (i.e., gold, its ligands, C[O.sub.2]) of the fluid source rocks. Key words: Abitibi greenstone belt, Chibougamau, orogenic vein systems, mineralizing processes, hydrothermal fluid, stable isotopes (O, H) La source des fluides et les processus menant à la mobilisation, au transport et au dépôt de l'or dans les systèmes aurifères orogéniques font toujours débat. La plupart des études s'intéressent aux systèmes orogéniques riches en or plutôt qu'aux systèmes pauvres en or afin de cerner les paramètres << clés >> des processus de minéralisation. Nous présentons des données sur les isotopes stables (O, H) du système de failles Moly-Desgagné--Guercheville (sans or ou à faible teneur) dans la région de Chibougamau de la ceinture de roches vertes de l'Abitibi (Canada). L'indice exempt d'or de Moly-Desgagné et l'indice Hazeur et le gisement du lac Monster, tous deux à faible teneur, situés à proximité, présentent tous des caractères semblables typiques de systèmes orogéniques. Les compositions d'isotopes stables de la tourmaline et du quartz du système de failles Moly-Desgagné--Guercheville présentent également des caractéristiques semblables telles que 1) des températures de formation de veines de 345 [+ or -] 86 [degrees]C (1[sigma]), 2) le mélange de fluides provenant d'un réservoir dans la croûte supérieure (faible T - [delta]D élevé - [delta][.sup.18]O faible) et d'un réservoir d'eau métamorphique (haute T - [delta]D faible - [delta][.sup.18]O élevé) et 3) des valeurs positives du [delta][D.sub.fluide] concordant avec plusieurs cycles d'ébullition-condensation associés à des processus de << soupape de faille >>. Ces caractéristiques sont semblables à celles du champ filonien riche en or de Val-d'Or. La diférence des teneurs en or entre les champs filoniens de Moly-Desgagné--Guercheville et de Val-d'Or pourrait être reliée à la nature du système de failles (c.-à-d. bordant des terranes ou à l'intérieur d'une ceinture de roches vertes) et au volume ou à la composition (c.-à-d. or, ligands de l'or et C[O.sub.2]) des roches sources des fluides. [Traduit par la Rédaction] Mots-clés : ceinture de roches vertes de l'Abitibi, Chibougamau, champs filoniens orogéniques, processus de minéralisation, fluide hydrothermal, isotopes stables (O, H), 1. Introduction The term 'orogenic gold deposit' (or orogenic vein system) was introduced by Groves et al. (1998) to designate quartzcarbonate lode gold deposits formed in active convergent (synorogenic) tectonic [...]

Published
2022
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48. Passive Mineral Carbonation of Mg-rich Mine Wastes by Atmospheric CO2

Author

Beaudoin, Georges, Nowamooz, Ali, Assima, Gnouyaro Palla, Lechat, Karl, Gras, Antoine, Entezari, Ali, Kandji, El Hadji Babacar, Awoh, Akué-Sylvette, Horswill, Micha, Turcotte, Sara, Larachi, Faïçal, Dupuis, Christian, Molson, John, Lemieux, Jean-Michel, Maldague, Xavier, Plante, Benoît, Bussière, Bruno, Constantin, Marc, Duchesne, Josée, Therrien, René, and Fortier, Richard

Published
2017
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50. Trace Element Composition of Chalcopyrite from Volcanogenic Massive Sulfide Deposits: Variation and Implications for Provenance Recognition

Author

Caraballo, Enzo, Beaudoin, Georges, Dare, Sarah, Genna, Dominique, Petersen, Sven, Relvas, Jorge M. R. S., Piercey, Stephen J., Caraballo, Enzo, Beaudoin, Georges, Dare, Sarah, Genna, Dominique, Petersen, Sven, Relvas, Jorge M. R. S., and Piercey, Stephen J.

Abstract

Chalcopyrite from 51 volcanogenic massive sulfide (VMS) and sea-floor massive sulfide (SMS) deposits from six lithostratigraphic settings was analyzed for trace elements by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to evaluate its potential as an indicator mineral for exploration. Partial least squares discriminant analysis (PLS-DA) results reveal that chalcopyrite from different lithostratigraphic settings has different compositions reflecting host-rock assemblages and fluid composition. Three random forest (RF) classifiers were developed to distinguish chalcopyrite from the six lithostratigraphic settings with a divisive approach. This method, which primarily classifies according to the major host-rock affinity and subsequently according to VMS settings, yielded an overall accuracy higher than 0.96 on test data. The model validation with literature data having the same elements required by the models yielded the highest accuracies (>0.90). In validation using published data with missing elements, the accuracy is moderate to high (0.60–1); however, the performances decrease significantly (<0.50) when the most important elements are missing. Similarly, RF regression models developed using all sets of analyzed elements to determine ccp/(ccp + sp) ratio (ccp = chalcopyrite; sp = sphalerite) in chalcopyrite within a single VMS setting reported high performances, thus showing a potential to predict the Cu/Zn ratio (Cu-rich vs. Zn-rich) of the mineralization based on chalcopyrite composition. This study demonstrates that trace element concentrations in chalcopyrite are primarily controlled by lithotectonic setting and can be used as predictors in an RF classifier to distinguish the different VMS subtypes.

Published
2023
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