Magmatic biotite and its use to distinguish barren and mineralized granitic systems in New Brunswick, Canada
Notice bibliographique
Résumé
Forty-two different Devonian granitoid intrusions in New Brunswick were studied for this project. They formed by crustal growth processes during the Acadian orogeny, post-Acadian uplift, and Neoacadian orogeny and most are associated with granophile element deposits, such as Sn, W, Mo, Cu, Bi, In, Sb, Au, and possibly Ta and Li, as well as base-metals and U mineralization. These intrusions were emplaced pre-, syn-, late-, and posttectonically between 423 and 360 Ma with affinities ranging from primitive to highly evolved A-, S-, and I-types granitoids. The aim of this study is to find a way to differentiate barren and mineralized granitic systems using biotite compositional systematics since it is highly sensitive to physico-chemical changes of its host, and continuously reequilibrates with host and derivative fluids. Therefore, core to rim studies of this mineral and analysis of its compositional zoning may reveal the origin and evolution history of the hosting granitoid and the different types of associated mineralization. Mineralized and barren granitoids are characterized by different chemical variations in biotite. For instance, biotite from a mineralized granitoid is characterized by lower Mg and Ti, and higher Al content relative to biotite from a barren granitoid. A combination of electron microprobe (EPMA) and laser ablation ICP-MS (LA-ICP-MS) was used to identify major, minor, trace elements, and halogen contents of biotite; these results were used to calculate fluoride and chloride activity of aqueous fluids associated with these intrusions, based on F and Cl contents in the mineral.*** Microprobe studies indicated homogeneous intragranular major element composition; crystallization temperature was calculated using Ti-In-biotite geothermometer, which gave a range of 670 to 750 ± 25°C . However, hydroxyl exchange biotite-apatite thermometer confirmed sub-solidus processes disturbed these systems resulting in a lower temperature around 300. Biotite grains from the highly fractionated bodies of the Pleasant Ridge, Mount Pleasant, and Kedron granites show the highest fluorine contents, ranging from 4.5 wt.% to 6.5 wt.%. Trace element changes within the biotite lattice were measured using LA-ICP-MS. Interestingly, almost all of studied grains show Cs, Ba, and Rb zoning relative to K. These patterns were followed by Co, Cu, K, Li, Be, Sn, W, Ti, Sc, Ni, B, and V. Large ionic charge and radius make it difficult for elements to join or leave any crystalline structure; therefore, any Cs or Ba zoning could be of an igneous origin. As a result, any other elemental pattern following those could be a result of magmatic evolution, which has been recorded by the biotite crystal growth. Based on the results of this project, the concept of using biotite composition to help identify fertile Acadian magma systems has been established; however, more work needs to be done to define characteristics of different magmatic processes.
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 machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| 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 | 0,004 | 0,004 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| 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 source (Gemma direct ou Codex distillé), 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 ».