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TitleMagmatic mica and its potential as an indicator of magma fertility in the granitoids of New Brunswick
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AuthorAzadbakht, Z; Lentz, D R; McFarlane, C R M
SourceTGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation; by Rogers, N (ed.); Geological Survey of Canada, Open File 7843, 2015 p. 561-562, https://doi.org/10.4095/296491 (Open Access)
LinksCanadian Database of Geochemical Surveys, downloadable files
LinksBanque de données de levés géochimiques du Canada, fichiers téléchargeables
Year2015
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Rogers, N; (2015). TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation, Geological Survey of Canada, Open File 7843
RelatedThis publication is related to Azadbakht, Z; Lentz, D; McFarlane, C; (2014). Magmatic mica and its potential as an indicator of magma fertility in the granitoids of New Brunswick, Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 37
File formatpdf
ProvinceNew Brunswick
NTS21G; 21H; 21I; 21J; 21O; 21P
Lat/Long WENS -68.0000 -64.0000 48.0000 45.0000
Subjectseconomic geology; igneous and metamorphic petrology; geochemistry; porphyry deposits; porphyry copper; mineral exploration; mineralization; biotite; granodiorites; hydrothermal deposits; hydrothermal alteration; tungsten; molybdenum; gold; antimony; magmatic rocks; intrusive rocks; igneous rocks; vein deposits; magmatism; analytical methods; amphibole; magma differentiation; magmatic deposits; uranium; mica; tantalum; lithium; Acadian Orogeny; Paleozoic; Devonian
Illustrationslocation maps; plots; photomicrographs
ProgramIntrusion/Porphyry Ore Systems, Targeted Geoscience Initiative (TGI-4)
Released2015 06 11
AbstractThe 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.
GEOSCAN ID296491