Experimental and field investigations of serpentinization and rodingitization
Notice bibliographique
Résumé
The chemical evolution of peridotites and felsic rocks included in or adjacent to them, and fluids during the hydrothermal alteration of these rocks is the subject of this study. Experiments using a flow-through hydrothermal apparatus, and studies of natural samples from the JM Asbestos chrysotile deposit in the Asbestos ophiolite, Quebec, were the means by which the various topics of this thesis were investigated. Open-system fluid-rock interaction was studied by flowing deionized water or a 0.1 m CaCl2 solution through olivine (Fo91) and lherzolite at a temperature of 300°C and a pressure of 300 bars. During these experiments, the original minerals (olivine, orthopyroxene and clinopyroxene) were altered to an assemblage, which consisted of serpentine-group minerals (conical, polygonal, and cylindrical fibers, and plates), brucite and magnetite. Reaction of lherzolite with deionized water and thermodynamic modelling indicate that the highest pH and calcium concentration are attained when pyroxenes are present in the unaltered rock, and that these parameters are at maximum in the presence of the buffering assemblage serpentine + brucite + diopside. Alteration of olivine by 0.1 m CaCl2 aqueous solution does not lead to the formation of secondary calcium phases. These results, supported by thermodynamic calculations, suggest that calcium-rich fluids can circulate through forsteritic olivine-rich lithologies without inducing calcium metasomatism. In the JM Asbestos mine, these Si-Al lithologies are largely felsic dykes, which, based on geological relationships, are interpreted to have been emplaced after serpentinization of the host peridotites began, but before obduction of the Asbestos ophiolite onto the Laurentian continental margin. Slates underlying and in thrust contact with serpentinite are also locally rodingitized. Mass balance calculations suggest that the calcium responsible for the rodingitization of the slates may have been derived locally, whereas the calcium responsible for the rodingitization of the felsic dykes was most probably derived from a source remote from the dykes. The strong dilution in rodingites and nephrites of the low-solubility minor and traces elements P, Cr and Zr suggests that very large amounts of fluids were involved in calc-silicate metasomatism of the felsic dykes and adjacent serpentinites. The absence of CO2 and presence of hydrocarbons (alkanes from methane to pentane) in the fluid inclusions of both episodes is an indication that the fluids responsible for calc-silicate alteration were derived from the serpentinites. (Abstract shortened by UMI.)
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.
Comment cette classification a été obtenuedéplier
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 | 0,000 | 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 | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».