| Reference Type | Journal (article/letter/editorial) |
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| Title | The origins of carbonatites and related rocks from the Grønnedal-Íka Nepheline Syenite complex, South Greenland: C-O-Sr isotope evidence |
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| Journal | Mineralogical Magazine | ISSN | 0026-461X |
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| Authors | Pearce, N. J. G. | Author |
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| Leng, M. J. | Author |
| Emeleus, C. H. | Author |
| Bedford, C. M. | Author |
| Year | 1997 (August) | Volume | 61 |
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| Issue | 407 |
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| Publisher | Mineralogical Society |
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| Download URL | https://rruff.info/doclib/MinMag/Volume_61/61-407-515.pdf+ |
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| DOI | doi:10.1180/minmag.1997.061.407.04Search in ResearchGate |
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| Generate Citation Formats |
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| Mindat Ref. ID | 190 | Long-form Identifier | mindat:1:5:190:6 |
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| GUID | 0 |
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| Full Reference | Pearce, N. J. G., Leng, M. J., Emeleus, C. H., Bedford, C. M. (1997) The origins of carbonatites and related rocks from the Grønnedal-Íka Nepheline Syenite complex, South Greenland: C-O-Sr isotope evidence. Mineralogical Magazine, 61 (407) 515-529 doi:10.1180/minmag.1997.061.407.04 |
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| Plain Text | Pearce, N. J. G., Leng, M. J., Emeleus, C. H., Bedford, C. M. (1997) The origins of carbonatites and related rocks from the Grønnedal-Íka Nepheline Syenite complex, South Greenland: C-O-Sr isotope evidence. Mineralogical Magazine, 61 (407) 515-529 doi:10.1180/minmag.1997.061.407.04 |
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| In | (1997, August) Mineralogical Magazine Vol. 61 (407) Mineralogical Society |
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| Abstract/Notes | AbstractThe Grønnedal-Íka ring complex (1299 ± 17 Ma) in the Gardar province, South Greenland is composed of a range of layered nepheline syenites which were intruded at a late stage by xenolithic syenite and a plug of carbonatite. The complex was subsequently intruded by a variety of basic dykes, including olivine dolerites, kersantites, vogesites, spessartites, camptonites and an alnöite, and then extensively faulted. The nepheline syenite magmas, produced by fractional crystallisation of basic magmas, show a range in δ13C (−3.86 to −7.57‰) and δ18O (8.27 to 15.12‰), distinctly different to the carbonatites which form a tight group with average δ13C = −4.31 + 0.22 ‰, (1 s.d.) and average δ18O = 7.18 ± 0.41‰ (1 s.d.). Initial 87Sr/86Sr isotope ratios (typically 0.703) suggest the syenites and carbonatites have not assimilated crustal rocks, and therefore the C and O isotope variation within each group is a result of isotopic evolution during fractional crystallisation. A suite of lamprophyre dykes (δ13C −3.86 to −7.86‰ and δ18O 9.12 to 10.81‰) form a coherent group whose stable isotope compositions overlap part of the syenite field, and again are distinctly different from the carbonatites. A single alnöite has δ13C = −3.32‰ and δ18O = 12.34‰ C and O isotope ratios are consistent with origins of syenitic and lamprophyric magmas from a similar source. Despite geochemical evidence which suggests a genetic link between nepheline syenites and carbonatites, C and O isotopic evidence shows that they are not related directly by liquid immiscibility. Comparisons are made between similar rock types from Grønnedal-Íka and from the Gardar Igaliko Dyke Swarm. The possible role of F in controlling δ13C and δ18O during crystallisation of calcite from carbonatite magmas is discussed. |
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