Skip to content

Research at St Andrews

Zirconosilicates in the kakortokites of the Ilímaussaq complex, South Greenland: implications for fluid evolution and high-field-strength and rare-earth element mineralization in agpaitic systems

Research output: Contribution to journalArticle


A.M. Borst, H. Friis, T. Andersen, T.F.D. Nielsen, T.E. Waight, M.A. Smit

School/Research organisations


The layered agpaitic nepheline syenites (kakortokites) of the Ilímaussaq complex, South Greenland, host voluminous accumulations of eudialyte-group minerals (EGM). These complex Na-Ca-zirconosilicates contain economically attractive levels of Zr, Nb and rare-earth elements (REE), but have commonly undergone extensive autometasomatic/hydrothermal alteration to a variety of secondary mineral assemblages. Three EGM alteration assemblages are recognized, characterized by the secondary zirconosilicates catapleiite, zircon and gittinsite. Theoretical petrogenetic grid models are constructed to assess mineral stabilities in terms of component activities in the late-stage melts and fluids. Widespread alteration of EGM to catapleiite records an overall increase in water activity, and reflects interaction of EGM with late-magmatic Na-, Cl- and F-rich aqueous fluids at the final stages of kakortokite crystallization. Localized alteration of EGM and catapleiite to the rare Ca-Zr silicate gittinsite, previously unidentified at Ilímaussaq, requires an increase in CaO activity and suggests post-magmatic interaction with Ca-Sr bearing aqueous fluids. The pseudomorphic replacement of EGM in the kakortokites was not found to be associated with significant remobilization of the primary Zr, Nb and REE mineralization, regardless of the high concentrations of potential transporting ligands such as F and Cl. We infer that the immobile behaviour essentially reflects the neutral to basic character of the late-magmatic fluids, in which REE-F compounds are insoluble and remobilization of REE as Cl complexes is inhibited by precipitation of nacareniobsite-(Ce) and various Ca-REE silicates. A subsequent decrease in F– activity would furthermore restrict the mobility of Zr as hydroxyl-fluoride complexes, and promote precipitation of the secondary zirconosilicates within the confines of the replaced EGM domains.


Original languageEnglish
Pages (from-to)5-30
Number of pages26
JournalMineralogical Magazine
Issue number1
Publication statusPublished - Feb 2016

    Research areas

  • Ilimaussaq, Late-magmatic alteration, Eudialyte, Catapleiite, Gittinsite, HFSE and REE mineralization, Nepheline syenites, Chemographic analysis, Agpaitic systems

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. Dating agpaitic rocks: a multi-system (U/Pb, Sm/Nd, Rb/Sr and 40Ar/39Ar) isotopic study of layered nepheline syenites from the Ilímaussaq complex, Greenland

    Borst, A. M., Waight, T., Finch, A. A., Storey, M. & Le Roux, P., Jan 2019, In : Lithos. 324-325, p. 74-88 15 p.

    Research output: Contribution to journalArticle

  2. Bulk and mush melt evolution in agpaitic intrusions: insights from compositional zoning in eudialyte, Ilimaussaq complex, South Greenland

    Borst, A. M., Friis, H., Nielsen, T. F. D. & Waight, T. E., 14 Apr 2018, In : Journal of Petrology. 59, 4, p. 589-611 23 p.

    Research output: Contribution to journalArticle

  3. Probing the structural state of Y and Nd in eudialyte using X-ray absorption spectroscopy

    Borst, A. M., Gamaletsos, P., Finch, A. A., Horsburgh, N. J., Friis, H., Kasama, T., Goettlicher, J., Steiniger, R. & Gerakis, K., 10 Jan 2018, (Unpublished).

    Research output: Contribution to conferencePoster

  4. Optimising the REE-Zr-Nb potential of eudialyte and its alteration products in the Ilímaussaq complex, South Greenland

    Borst, A. M., Mortensen, H. F. & Finch, A. A., 19 Dec 2016, p. 18. 1 p.

    Research output: Contribution to conferenceAbstract

Related by journal

  1. Megacrysts and salic xenoliths in Scottish alkali basalts: derivatives of deep crustal intrusions and small-melt fractions from the upper mantle

    Upton, B. G. J., Finch, A. A. & Slaby, E., Dec 2009, In : Mineralogical Magazine. 73, 6, p. 943-956 14 p.

    Research output: Contribution to journalArticle

  2. Synthetic amphiboles and triple-chain silicates in the system Na2O-MgO-SiO2-H2O: phase characterization, compositional relations and excess H

    Maresch, W. V., Welch, M. D., Gottschalk, M., Ruthmann, W., Czank, M., Ashbrook, S. E. & Ashbrook, S. E. M., Dec 2009, In : Mineralogical Magazine. 73, 6, p. 957-996 40 p.

    Research output: Contribution to journalArticle

  3. U-Pb geochronology of felsic volcanic rocks hosted in the Gafo Formation, South Portuguese Zone: relationship with Iberian Pyrite Belt magmatism

    Rosa, DRN., Finch, A. A., Andersen, T. & Inverno, MC., Oct 2008, In : Mineralogical Magazine. 72, 5, p. 1103-1118

    Research output: Contribution to journalArticle

  4. Coordination of Sr and Mg in calcite and aragonite

    Finch, A. A. & Allison, N., Oct 2007, In : Mineralogical Magazine. 71, p. 539-552 14 p.

    Research output: Contribution to journalArticle

ID: 245703514