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The geochemistry of...
The geochemistry of Tl and its isotopes during magmatic and hydrothermal processes: The peralkaline Ilimaussaq complex, southwest Greenland
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Hettmann, K. (författare)
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Marks, M. A. W. (författare)
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Kreissig, K. (författare)
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- Zack, Thomas, 1968 (författare)
- Gothenburg University,Göteborgs universitet,Institutionen för geovetenskaper,Department of Earth Sciences
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Wenzel, T. (författare)
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Rehkämper, M. (författare)
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Jacob, D. E. (författare)
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Markl, G. (författare)
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(creator_code:org_t)
- Elsevier BV, 2014
- 2014
- Engelska.
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Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541. ; 366, s. 1-13
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https://gup.ub.gu.se...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- We use thallium (Tl) concentrations, K/Rb, K/Tl and Rb/Tl ratios and Tl isotopes in minerals from the alkaline to peralkaline Ilimaussaq complex (South Greenland) to trace magmatic differentiation, crustal assimilation, magmatic degassing, ore precipitation and hydrothermal metasomatism. Closed-system magmatic differentiation is marked by a coherent decrease of K/Tl- and K/Rb-ratios, whereas crustal assimilation results in a strong Tl-enrichment, causing low K/Tl-ratios compared to K/Rb-ratios. Thallium isotopes show only slight changes during orthomagmatic differentiation and the assimilation of crustal material cannot be traced, since the isotopic composition of the average crust is within the range of the mantle and mantle-derived rocks. Magmatic degassing, however, increases Rb/Tl-ratios and changes the isotopic composition of Tl. The released fluids are enriched in Tl, characterized by high 205Tl/203Tl ratios and can precipitate Tl-rich sulfide and silicate minerals as indicated by some late-magmatic hydrothermal veins, which contain a conspicuous assemblage of Tl-Fe-Cu-sulfides (thalcusite, djerfisherite, chalcothallite). The oxidative alteration of these assemblages at high pH results in small-scale redistribution of Tl. Thallium released by this process is entrained into late-stage Tl-enriched astrophyllite. © 2013 Elsevier B.V.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)
Nyckelord
- LILE
- Magmatic processes
- Peralkaline
- Thallium isotopes
- Astrophyllite
- Crustal materials
- Djerfisherite
- Hydrothermal process
- Isotopic composition
- Magmatic process
- Alkalinity
- Degassing
- Ores
- Silicate minerals
- Thallium
- Isotopes
- geochemistry
- magma assimilation
- magmatic differentiation
- magmatism
- peralkaline rock
- Arctic
- Greenland
- Ilimaussaq Complex
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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