Skip to content

Research at St Andrews

Independent ages of magmatic and hydrothermal activity in alkaline igneous rocks: The Motzfeldt Centre, Gardar Province, South Greenland

Research output: Contribution to journalArticle

Author(s)

J. A. McCreath, A. A. Finch, S. L. Simonsen, C. H. Donaldson, A. Armour-Brown

School/Research organisations

Abstract

The Motzfeldt Centre is one of four major alkaline centres belonging to the Igaliko complex, part of the Mid-Proterozoic Gardar province of South Greenland. Motzfeldt comprises syenites and nepheline syenites displaying complex magmatic and subsolidus histories. Ta, Nb and REE-rich zones are associated with a pervasive hydrothermal alteration process in the North and East of the complex, part of a subdivision of the Centre called the Motzfeldt So Formation (MSF). The zircons from the MSF show textures that are both magmatic and altered, whereas the textures of pyrochlore have a predominantly subsolidus chemistry. We compare and contrast the radiogenic isotope geochemistry of the zircon and pyrochlore to obtain independent age estimates of the magmatic and hydrothermal episodes. Selected analyses of magmatic zircons are concordant with an age of 1,273 +/- A 6 Ma. Altered zircons are normally discordant with one intercept at 1,261 +/- A 28 Ma and the other at 349 +/- A 49 Ma. This younger age would appear on face value to date the hydrothermal event at Motzfeldt to similar to 900 Ma after the magmatism. However, the Pb-Pb isotope systematics from altered pyrochlore define an isochron age of 1,267 +/- A 6 Ma for isotopic closure of the pyrochlore following alteration during the subsolidus. There is no known magmatic event in Southern Greenland at similar to 350 Ma and discordant points have high common lead. We therefore infer that the younger intercept age is spurious. The overlap between the magmatic U-Pb zircon and the Pb-Pb pyrochlore age suggests that alteration of the Motzfeldt centre occurred shortly after magmatism.

Close

Details

Original languageEnglish
Pages (from-to)967-982
Number of pages16
JournalContributions to Mineralogy and Petrology
Volume163
Issue number6
DOIs
Publication statusPublished - Jun 2012

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

View graph of relations

Related by author

  1. Hydrothermal alteration of eudialyte-hosted critical metal deposits: fluid source and implications for deposit grade

    van de Ven, M. A. J., Borst, A. M., Davies, G. R., Hunt, E. J. & Finch, A. A., 10 Jul 2019, In : Minerals. 9, 7, 23 p., 422.

    Research output: Contribution to journalArticle

  2. Optical determination of the width of the band-tail states, and the excited state and ground state energies of the principal dosimetric trap in feldspar

    Riedesel, S., King, G. E., Prasad, A. K., Kumar, R., Finch, A. A. & Jain, M., Jun 2019, In : Radiation Measurements. 125, p. 40-51

    Research output: Contribution to journalArticle

  3. From Mantle to Motzfeldt: a genetic model for syenite-hosted Ta,Nb-mineralisation

    Finch, A. A., McCreath, J. A., Reekie, C. D. J., Hutchison, W., Ismaila, A., Armour-Brown, A., Andersen, T. & Simonsen, S. L., Apr 2019, In : Ore Geology Reviews. 107, p. 402-416 15 p.

    Research output: Contribution to journalArticle

  4. A high sensitivity system for luminescence measurement of materials

    Finch, A. A., Wang, Y., Townsend, P. D. & Ingle, M., 5 Feb 2019, In : Luminescence. Early View

    Research output: Contribution to journalArticle

  5. 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

Related by journal

  1. Evidence for distinct stages of magma history recorded by the compositions of accessory apatite and zircon

    Miles, A. J., Graham, C. M., Hawkesworth, C. J., Gillespie, M. R., Hinton, R. W. & EIMF, Jul 2013, In : Contributions to Mineralogy and Petrology. 166, 1, p. 1-19 19 p.

    Research output: Contribution to journalArticle

  2. Textural and chemical variation in plagioclase phenocrysts from the 1980 eruptions of Mount St. Helens, USA

    Berlo, K., Blundy, J., Turner, S. & Hawkesworth, C., Sep 2007, In : Contributions to Mineralogy and Petrology. 154, 3, p. 291-308 18 p.

    Research output: Contribution to journalArticle

  3. Pre-eruptive magma mixing in ash-flow deposits of the Tertiary Rum igneous centre, Scotland

    Troll, VR., Donaldson, C. H. & Emeleus, CH., Aug 2004, In : Contributions to Mineralogy and Petrology. 147, 6, p. 722-739 18 p.

    Research output: Contribution to journalArticle

ID: 38881894