| Title | Magmatic evolution in Devonian granitic rocks and relation to granophile mineralization in New Brunswick: application of biotite trace element mapping with EPMA and LA-ICP-MS |
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| 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. 507-519, https://doi.org/10.4095/296486  Open Access |
| Links | Canadian Database of Geochemical Surveys, downloadable
files
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| 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 |
| Related | This publication is related to the following
publications |
| File format | pdf |
| Province | New Brunswick |
| NTS | 21G |
| Area | Lake George |
| Lat/Long WENS | -68.0000 -66.5000 46.0000 45.0000 |
| Subjects | economic geology; tectonics; mineralogy; porphyry deposits; porphyry copper; mineral exploration; mineralization; biotite; granodiorites; hydrothermal deposits; hydrothermal alteration; tungsten;
molybdenum; gold; antimony; magmatic rocks; tectonic environments; tectonic setting; tectonic evolution; granophile deposits; mass spectrometer analysis; magmatic deposits; magmatism; Sisson deposit; Mount Pleasant deposit; Paleozoic;
Devonian |
| Illustrations | location maps; plots; photomicrographs |
| Program | Targeted Geoscience Initiative (TGI-4) Intrusion/Porphyry Ore Systems |
| Released | 2015 06 11; 2023 03 17 |
| Abstract | Two suites of felsic intrusions were emplaced during the later parts of the Appalachian orogenic cycle in New Brunswick. However, just those associated with crustal thickening processes of Acadian
orogeny, post Acadian uplift, and Neoacadian orogeny are mineralized with granophile elements to form Sn, W, Mo, Cu, Bi, Sb, and Au deposits, as well as Ta, Li, base-metals, and U mineralization. Biotite major element classification indicated that
these intrusions are mostly A- and S-type granitoids and their hybrid varieties; some I-type granitoids are also present in the area.
Magmatic biotite from forty-two of these Devonian intrusions was studied by electron microprobe (EPMA) and LA
-ICP-MS at the University of New Brunswick. Whereas major elements are typically constant from core to rim, biotite grains can show remarkable trace element zoning. LA-ICP-MS trace element maps were also produced when permitted by the size of the
biotite, frequency of the mineral inclusions, degree of alteration, and the laser spot size required to achieve sub-ppm detection limits. In this study, unaltered biotite grains with minor mineral inclusions, and diameters larger than 300 ?m, display
trace-element zoning patterns. Furthermore, smaller biotite tends to be more susceptible to intracrystalline diffusion. As a result, their elemental zoning should be further studied and cross -checked with other characteristics.
Results of this
study showed LILE zoning, including Cs, Ba, and Rb, for most of the biotite grains. As these elements are highly incompatible, any zoning can be a result of the magma evolution history recorded within the biotite crystalline structure. Any other
trace element pattern following them will also be of an igneous source. For example, biotite grains from the Pleasant Ridge granite show an increase from core to rim for Cs and Sn and a decrease for W and Sc. Copper is also high along the cleavages
where biotite is weakly altered to chlorite. These observations coupled with an increase in F/Cl content from 770 to 1300 indicate that fractional crystallisation of this granite led to Sn mineralization. Tin is positively correlated with Fe/(Fe+Mg),
but negatively correlated with FeT/ Ti; this relationship may indicate that the Sn content of biotite increases with low fo2 and low temperatures as indicated by the iron/magnesium ratio.
According to the results, the use of biotite as an
indicator of trace element changes within granitic systems was achieved; with the help of other types of data, the composition of biotite may be a useful tool to indicate a difference between barren and mineralized granophile-element rich systems.
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| 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 | 296486 |
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