| Titre | Petrographic observations and evaporate mound analysis of quartz-hosted fluid inclusions: applications to assess metal fertility in granites |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Tweedale, F; Hanley, J J; Kontak, D J; Rogers, N |
| 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. 369-381, https://doi.org/10.4095/296477  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/10.4095/296477 |
| 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 Petrographic
observations and evaporate mound analysis of quartz-hosted fluid inclusions: Applications to assess metal fertility in granites |
| Formats | pdf |
| Province | Nouvelle-Écosse |
| SNRC | 21A; 11D; 11E |
| Lat/Long OENS | -66.0000 -63.5000 45.0000 43.0000 |
| Sujets | gisements porphyriques; cuivre porphyrique; prospection minière; minéralisation; altération; tungstène; molybdène; étain; bismuth; gisements minéraux; roches intrusives; roches granitiques; inclusions
fluides; quartz; métallogénie; analyses pétrographiques; granodiorites; pétrogenèse; cuivre; or; Batholite de South Mountain ; géologie économique; pétrologie ignée et métamorphique; géochimie; Paléozoïque; Dévonien |
| Illustrations | cartes de localisation; photomicrographies; diagrammes ternaires |
| Programme | Initiative géoscientifique ciblée (IGC-4) Étude des gîtes porphyriques |
| Diffusé | 2015 06 11; 2023 03 17 |
| Résumé | (disponible en anglais seulement)
The 380 Ma South Mountain Batholith (SMB), Nova Scotia, is a large (~7300 km2), contiguous, mesozonal granitoid intrusion consisting of 13 coalesced plutons
hosting a variety of mineralized zones (e.g., Sn-Zn-Cu- Ag, Mn-Fe-P, U, Cu-Ag). Given the hydrothermal nature of this mineralization, it is expected that a geochemical fingerprint of the mineralizing fluids might be preserved both petrographically
and as secondary fluid inclusions (FIs) in the granites on a scale equal to or larger than the mineralized zones. In this unique study, we investigate the possibility of integrating petrographic observations that reflect fluid:rock interaction and
the chemistry of secondary, quartz-hosted FIs in samples from the SMB to assess granite fertility and also the scale of this potential vectoring tool. The protocol involved: (1) detailed petrographic study of >500 archived samples and focused on the
extent and degree of alteration (e.g., perthite textures, chlorite alteration of biotite, plagioclase alteration, percent of secondary muscovite, abundance of FI in quartz); and (2) determining fluid chemistry of quartz- hosted FIs in >100 samples
collected from a 10 x 10 km grid superimposed on the SMB. The petrographic data record highly variable degrees of alteration and the results are being used to design an alteration algorithm that can be used to map the extent of fluid:rock interaction
throughout the batholith. The chemistry of FIs, determined using the evaporate mound method, is being used as a proxy for both the mineralizing and altering fluids. At present, results for >600 mounds determined for 68 samples indicate the fluids are
dominated by Na-K-Ca-Cl-F, with traces of Fe, Mn, and S, and that two distinct types are present, one Na-rich and the other Ca-rich. Two intriguing results to date include: (1) the pervasive occurrence of F in the mound analysis with up to 40 wt%
when normalized to 100%, even in samples distal to known mineralization; and (2) elevated Ca in many samples, including those from chemically evolved, hence Ca-depleted rocks. This latter feature may reflect extensive albitization of plagioclase,
hence liberation of Ca, during fluid-mediated alteration. Thus, our preliminary findings clearly indicate that mappable variation in the degree and extent of alteration is retained in the main mineral phases of the granites and that fluid chemistry,
preserved as secondary FIs in quartz, is a potential proxy for fluid:rock interaction and hence a measure of metal fertility. |
| 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 | 296477 |
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