| Title | Using biotite composition of the Devonian Mount Elizabeth Intrusive Complex, New Brunswick, as a proxy
for magma fertility and differentiation in W-Mo-Au-Sb mineralized magmatic hydrothermal systems |
| Download | Downloads |
| |
| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Azadbakht, Z ;
Lentz, D R; McFarlane, C R M |
| Source | TGI 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. 535-546, https://doi.org/10.4095/296488  Open Access |
| Links | Canadian Database of Geochemical Surveys, downloadable
files
|
| Links | Banque de données de levés géochimiques du Canada,
fichiers téléchargeables
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| Image |  |
| Year | 2015 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This publication is contained in TGI 4 - Intrusion Related
Mineralisation Project: new vectors to buried porphyry-style mineralisation |
| File format | pdf |
| Province | New Brunswick |
| NTS | 21O |
| Lat/Long WENS | -68.0000 -66.0000 48.0000 47.0000 |
| Subjects | economic geology; igneous and metamorphic petrology; porphyry deposits; porphyry copper; mineral exploration; mineralization; biotite; granodiorites; hydrothermal deposits; hydrothermal alteration;
tungsten; molybdenum; gold; antimony; magmatic rocks; Mount Elizabeth Intrusive Complex; Paleozoic; Devonian |
| Illustrations | location maps; photomicrographs; ternary diagrams; plots |
| Program | Targeted Geoscience Initiative (TGI-4) Intrusion/Porphyry Ore Systems |
| Released | 2015 06 11; 2023 03 17 |
| Abstract | The Early Devonian (418 ± 1 Ma, monazite U-Pb) Mount Elizabeth intrusive complex, New Brunswick, Canada, is a multiphase metaluminous to weakly peraluminous, high K calc-alkaline body that shows within
plate affinity. The complex consists of apparently contemporaneous igneous suites including a mafic suite, an eastern peraluminous granite suite and a western alkali granite suite. The eastern part comprises compositionally and texturally homogenous
biotite granite, whereas the western part is mostly heterogeneous and contains five different units. The most abundant phase of the western suite is medium- to coarse-grained alkaline equigranular granite. This complex poorly exposed so that most of
the available data, including inferred contact relationships, is based on geophysical data. It should be added that no mineral occurrences have been reported so far from this complex.
Fresh biotite from this intrusion was analysed from core to rim
by electron microprobe, and laser ablation ICP-MS at the University of New Brunswick to test whether biotite preserves a record of magma evolution in terms of major and trace-element and halogen compositional variations. Subhedral to elongate biotite
phenocrysts are less than 700 ?m long and reddish brown in colour indicative of a reduced I-type source. A calc-alkaline affinity is also suggested by biotite major element classification schemes. Biotite is locally altered to chlorite along cleavage
planes, and typically contain iron oxides, monazite, ilmenite, apatite, xenotime, and zircon as mineral inclusions.
Results of electron microprobe and laser ablation ICP-MS studies indicate that biotite grains are homogenous in major elements;
however, they show variation in trace elements from core to rim. The biotite grains investigated have the highest Sn, W, Sb, and Mo concentrations recorded thus far among Devonian-related granitoid intrusions of New Brunswick (130, 40, 1, 3 ppm,
respectively). There is no systematic correlation between major elements including FeTot, or FeTot/Ti and any of these trace elements. To further study trace-element distribution, a biotite from each of the phases was mapped with laser-ablation
ICP-MS revealing patchy Ba, Rb, and Cs zoning. These patterns are interpreted to be a result of localized hydrothermal alteration and intracrystalline volume diffusion in these biotite grains. The intracrystalline distribution of Sn, W, Mo and Sb is
homogeneous. Furthermore, halogen contents analysed by EPMA indicate that hydroxyl is the dominant component of hydroxyl site followed by fluorine. It also showed that these biotites formed from strongly contaminated and reduced I-type granite.
As
a result, high concentration of Sn in biotite is interpreted to be caused by crustal contamination, and lowtemperature hydrothermal processes (sub-solidus) rather than being magmatic in origin. |
| Summary | (Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience
knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This volume summarises research activities completed under the TGI 4 Intrusion Related Mineralisation Project that
focused on porphyry-style ore systems related to the Cu- and Cu-Mo deposits of South-Central British Columbia and the Sn-W-Mo-In deposits in New Brunswick, Nova Scotia and Newfoundland. |
| GEOSCAN ID | 296488 |
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