Mass transfer during gold precipitation within a vertically extensive vein network (Sigma deposit - Abitibi greenstone belt - Canada). Part II. Mass transfer calculations
Pourquoi ce travail est dans la base
Une base qui oublie comment elle a trouvé un travail ne peut pas être vérifiée. Voici les voies qui ont admis celui-ci.
Notice bibliographique
Résumé
A companion work (Garofalo, this issue) shows that along the Archean, Au-mineralized quartz-tourmaline veins of the Sigma deposit of Canada, fluid-rock interaction generated two types of hydrothermal alteration during gold deposition, one tourmaline-rich and another albite-rich. This work combines petrographic and mass transfer studies to monitor the chemical exchange occurring between the Au-bearing hydrothermal fluid within the veins and a porphyritic diorite wall rock in which two alteration envelopes of the different types developed. Tourmaline-rich alteration consists of replacement of the host rock by tourmaline-calcite-quartz-pyrite-pyrrhotite at the vein walls. In these haloes, components like SiO2, B, Al2O3, Na2O, CO2, CaO, S, andAu were transferred from the vein fluid to the host rock, while other components like K2O and FeO were transferred from the rock to the fluid. Albite-rich alteration consists of progressive replacement of biotite, chlorite, epidote, and quartz of the host rock by the assemblage albite-pyrite-pyrrhotite, and the trends of gains and losses are opposite of those calculated for the tourmaline-rich haloes. Only B, S, and Au are transferred from the fluid to the rock in both alteration types. Progressive mineralogical and chemical changes of thewall rock during alteration indicate that diffusion metasomatism was important for generating the two alteration types. These results underscore some key characteristics of the hydrothermal alteration at Sigma. First, the distinct alteration types formed most probably from chemically distinct hydrothermal fluids, in agreement with independent fluid inclusion data (Garofalo et al., 2002b). These two fluids reacted with the wall rocks, producing the contrasting mineralogical and chemical modifications recorded within the albite-rich and tourmaline-rich haloes. The trends of mass transfers are peculiar because the components given by the albite-rich haloes to the vein fluid are those given by the vein fluid to the tourmaline-rich haloes. Hence, albite-rich alteration was functional to the generation of tourmaline-rich haloes in the wall rocks and to tourmaline precipitation with the veins. Second, the combined transfers into and out of the veins caused modifications in the concentration ofmajor components in the fluid, like SiO2 and Al2O3. The concentration ratios of other major fluid components like Na and K remained unchanged because of buffering from the vein mineral assemblage, while that of some minor and trace components like REE, Rb, Sr, and high field strength elements varied significantly. A comparison between the mass transfer data presented here and that of other vein-hosted Au deposits with alteration characteristics similar to Sigma shows that, with the exception of Au, S, and CO2, inconsistent mass transfer trends are typical in these deposits and include the so-called “immobile” components (i.e. Al2O3, TiO2, and Zr). This shows that mass transfer data cannot be used for formulating genetic models of vein hosted Au deposits at the global scale, but mainly for constraining models for single deposits, where the background geological and geochemical information are in general well defined.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découle