| Title | The geochemistry of thallium and its isotopes in rare-element pegmatites |
| Download | Download (whole publication) |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Jacques, I J; Anderson, A J; Nielsen, S G |
| Source | Targeted Geoscience Initiative 5: grant program final reports (2018-2020); by Targeted Geoscience Initiative Coordination Office; Geological Survey of Canada, Open File 8755, 2021 p. 59-84, https://doi.org/10.4095/328983  Open Access |
| Year | 2021 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This publication is contained in Targeted Geoscience
Initiative 5: grant program final reports (2018-2020) |
| File format | pdf; xlsx (Microsoft® Excel®) |
| Subjects | economic geology; geochemistry; Science and Technology; Nature and Environment; mineral exploration; mineral deposits; ore mineral genesis; mineralization; isotopic studies; thallium geochemistry; trace
element geochemistry; feldspar; mica; muscovite; bedrock geology; lithology; igneous rocks; intrusive rocks; pegmatites; alteration; Tanco Pegmatite; Kamativi Pegmatite District |
| Illustrations | cross-sections; location maps; photomicrographs; tables; plots; digital images |
| Program | Targeted Geoscience Initiative (TGI-5) Knowledge Management Coordination |
| Released | 2021 10 27 |
| Abstract | The Tl isotopic and trace element composition of K-feldspar, mica, pollucite and pyrite from 13 niobium-yttrium-fluorine (NYF)-type and 14 lithium-cesium-tantalum (LCT)-type rare-element pegmatites was
investigated. In general, the epsilon-205Tl values for K-feldspar in NYF- and LCT-type pegmatites increases with increasing magmatic fractionation. Both NYF and LCT pegmatites display a wide range in epsilon-205Tl (-4.25 to 9.41), which complicates
attempts to characterize source reservoirs. We suggest 205Tl-enrichment during pegmatite crystallization occurs as Tl partitions between the residual melt and a coexisting aqueous fluid or flux-rich silicate liquid. Preferential association of 205Tl
with Cl in the immiscible aqueous fluid may influence the isotopic character of the growing pegmatite minerals. Subsolidus alteration of K-feldspar by aqueous fluids, as indicated by the redistribution of Cs in K-feldspar, resulted in epsilon-205Tl
values below the crustal average (-2.0 epsilon-205Tl). Such low epsilon-205Tl values in K-feldspar is attributed to preferential removal and transport of 205Tl by Cl-bearing fluids during dissolution and reprecipitation. The combination of thallium
isotope and trace element data may be used to examine late-stage processes related to rare-element mineralization in some pegmatites. High epsilon-205Tl and Ga in late-stage muscovite appears to be a favorable indicator of rare-element enrichment LCT
pegmatites and may be a useful exploration vector. |
| Summary | (Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI) is a collaborative federal geoscience program that provides industry with the next generation of geoscience
knowledge and innovative techniques, which will result in more effective targeting of buried mineral deposits. This compendium is the result of the TGI Grant Recipients 2018-2020. |
| GEOSCAN ID | 328983 |
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