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TitreMagmatic mica and its potential as an indicator of magma fertility in the granitoids of New Brunswick
TéléchargerTéléchargement (publication entière)
AuteurAzadbakht, Z; Lentz, D R; McFarlane, C R M
SourceTGI 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. 561-562, (Accès ouvert)
LiensCanadian Database of Geochemical Surveys, downloadable files
LiensBanque de données de levés géochimiques du Canada, fichiers téléchargeables
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Rogers, N; (2015). TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation, Commission géologique du Canada, Dossier public 7843
Référence reliéeCette publication est reliée Azadbakht, Z; Lentz, D; McFarlane, C; (2014). Magmatic mica and its potential as an indicator of magma fertility in the granitoids of New Brunswick, L'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 37
SNRC21G; 21H; 21I; 21J; 21O; 21P
Lat/Long OENS -68.0000 -64.0000 48.0000 45.0000
Sujetsgisements porphyriques; cuivre porphyrique; prospection minière; minéralisation; biotite; granodiorites; gisements minéraux hydrothermaux; altération hydrothermale; tungstène; molybdène; or; antimoine; roches magmatiques; roches intrusives; roches ignées; gisements filoniens; magmatisme; méthodes analytiques; amphibole; differentiation magmatique; gîtes magmatiques; uranium; mica; tantale; lithium; Orogenèse Acadienne; géologie économique; pétrologie ignée et métamorphique; géochimie; Paléozoïque; Dévonien
Illustrationslocation maps; plots; photomicrographs
ProgrammeInitiative géoscientifique ciblée (IGC-4), Étude des gîtes porphyriques
Diffusé2015 06 11
Résumé(disponible en anglais seulement)
The mineralized intrusions of New Brunswick are related to crustal growth processes that occurred during Acadian Orogeny, post Acadian uplift, and Neo-Acadian Orogeny. They were emplaced pre-, syn-, late-, and post-tectonically between 423 and 360 Ma. These intrusions have affinities ranging from primitive to highly evolved A-, S-, and I-types granitoids, and are associated with Sn, Ta, Li, Sb, W, Mo, Cu, and Au, as well as basemetals and U mineralization.
Biotite crystallizes over a wide range of conditions and reacts very sensitively to physiochemical conditions of the magma; this sensitivity makes mica a great mineral for identifying the petrogenetic, mineralization, and alteration processes of the host granitic rocks. The following features make biotite a valuable probe of magma composition: 1) it is the most important reservoir of any excess aluminium in granites that do not contain modal garnet, cordierite, or the Al2SiO5 polymorphs; therefore, it directly reflects the peraluminosity of the host magma in such rocks; 2) it is the most readily available indicator of oxidation state; and 3) it can provide information about the F and Cl content of the magma. Mineralized and barren rocks are characterized by different chemical variations in biotite. For instance, mineralized biotite is characterized by lower Mg and Ti contents relative to biotite from barren rocks; they also have higher amount of Al comparing to biotite from barren phases.
Several studies have shown that biotite, continuously equilibrates with the host liquids. Therefore, core-to-rim study of this mineral and its compositional zoning may provide a record of magma evolution so that the origin and evolution of granitoids can be discerned. Furthermore, the chemical composition and the colour of this mineral strongly reflects the tectonic origin of its host. For instance, the bright red colour of biotite indicates peraluminous collisional granitic pluton and reflects a high total Fe content with low Fe3+/(Fe2+ + Fe3+) and probably the presence of Ti4+. In part this study aims to calculate fluoride and chloride activity of aqueous fluids based on F and Cl contents in the minerals containing hydroxyl and halogens determined by combined electron microprobe and LA ICP-MS analysis. The final data will be compared to the whole rock geochemistry. These results are expected to help constrain crystallization conditions, volatile exsolution and fluorine-chlorine activity of fluids associated with these intrusions.
They should also indicate the degree of subsolidus re-equilibration via various geothermobarometry techniques.