| Titre | Using biotite composition of the Devonian Lake George granodiorite, New Brunswick, as a case study for W-Mo-Au-Sb mineralized magmatic hydrothermal systems |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Azadbakht, Z ;
Lentz, D R; McFarlane, C R M |
| Source | TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation; par Rogers, N (éd.); Commission géologique du Canada, Dossier public 7843, 2015 p. 459-474, https://doi.org/10.4095/296483  Accès ouvert |
| Liens | Canadian Database of Geochemical Surveys, downloadable files
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| Liens | Banque de données de levés géochimiques du Canada,
fichiers téléchargeables
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| Image |  |
| Année | 2015 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/296483 |
| Media | en ligne; numérique |
| Référence reliée | Cette publication est contenue dans TGI 4 -
Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation |
| Référence reliée | Cette publication est reliée à les
publications suivantes |
| Formats | pdf |
| Province | Nouveau-Brunswick |
| SNRC | 21G |
| Région | Lake George |
| Lat/Long OENS | -68.0000 -66.5000 46.0000 45.0000 |
| Sujets | gisements porphyriques; cuivre porphyrique; prospection minière; minéralisation; biotite; granodiorites; gisements minéraux hydrothermaux; altération hydrothermale; tungstène; molybdène; or; antimoine;
roches magmatiques; Dépôt de Mount Pleasant ; géologie économique; pétrologie ignée et métamorphique; Paléozoïque; Dévonien |
| Illustrations | cartes de localisation; photomicrographies; diagrammes ternaires; graphiques; photographies; tableaux |
| Programme | Initiative géoscientifique ciblée (IGC-4) Étude des gîtes porphyriques |
| Diffusé | 2015 06 11; 2023 03 17 |
| Résumé | (disponible en anglais seulement)
The granodioritic Lake George polymetallic deposit is located approximately 35 km southwest of Fredericton, New Brunswick. This intrusion is a metaluminous to
weakly peraluminous, calc-alkaline body that shows an evolved I-type, volcanic arc affinity. Based on an Early Devonian age determination, (412 +5/-4 Ma, zircon U-Pb) it is related to the Hakshaw granite phase of the Pokiok Batholith. The Lake George
stock is cut by Hibbard stibnite -quartz veins and quartz-scheelite-molybdenite veinlets that contain significant amounts of gold. Fresh biotites from this intrusion were analyzed at both the core and rim by electron microprobe, and along rim to rim
transects by laser ablation ICP-MS at the University of New Brunswick to build an understanding of the halogens responsible for mineralization and trace element distribution within this deposit.
Biotites of this intrusion are reddish brown in
colour (indicative of reduced I-type source) and mostly altered to chlorite. They usually contain apatite, zircon, titanite, ilmenite, rutile, and sulphide minerals as mineral inclusions. Temperature was calculated with the Ti-In-biotite
geothermometer, in which the results showed a variation between 583 and 745°C.
Two depths of emplacement were determined based on the Al in hornblende and biotite geobarometries confirming the porphyritic texture of this intrusion (4.3 and 1.5
km, respectively). Forming amphiboles at that depth clearly indicates a high water content of the source magma; in addition, hydroxyl is the most dominant component of the hydroxyl site (Average 1.89 wt%) in biotites. The limited range of IV(F/Cl)
values of the Lake George biotites suggested that they all equilibrated with one fluid.
Even though there is no noticeable difference in major elements from core to rims, evidence of magma evolution is recorded by biotite grains by their trace
elements. For instance, Cu, Rb, Cr, K, Mo, Sn, Cs and W increase from core to rims, whereas Ba, Ni, Mn, and Li act inversely. Sb has a negligible variation from core to rim. Interestingly, the partition coefficient (biotite/whole-rock) is
significantly small for Sb, W, and Mo (main associated mineralization) with 0.06, 0.28 and 0.13 in pure magmatic biotites and increase to 0.77, 1.93 and 0.20 in more altered biotites reflecting enrichment of these elements towards the late stage
fluid.
Based on these observations, the concept of using mica composition to help identify fertile Acadian magma systems was proved; this method may be a useful tool to indicate the difference between barren and mineralized granophileelement rich
systems. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'Initiative géoscientifique ciblée (IGC-4) est un programme géoscientifique fédéral de collaboration qui fournit à l'industrie les
connaissances géoscientifiques et les techniques novatrices de prochaine génération dont elle a besoin pour mieux détecter les gîtes minéraux enfouis, réduisant ainsi certains risques liés à l'exploration. Ce volume résume les activités de recherche
effectuées dans le cadre du projet de minéralisation lié à des intrusions de l'Initiative géoscientifique ciblée 4 qui était axé sur des systèmes minéralisés porphyriques associés aux dépôts de Cu et de Cu-Mo dans le centre-sud de la
Colombie-Britannique et aux dépôts de Sn-W-Mo-In au Nouveau-Brunswick, en Nouvelle-Écosse et à Terre-Neuve-et-Labrador. |
| GEOSCAN ID | 296483 |
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