Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-10T04:51:25.731Z Has data issue: false hasContentIssue false
  • English
  • Français

The petrology and petrogenesis of the North Motzfeldt Centre, Gardar Province, South Greenland

Published online by Cambridge University Press:  05 July 2018

A. A. Finch ,
K. M. Goodenough ,
H. M. Salmon  and
T. Andersen
A. A. Finch*
Affiliation:
Crustal Dynamics Group, School of Geography and Geosciences, University of St Andrews, St Andrews, Fife KY16 9AL, UK
K. M. Goodenough
Affiliation:
Department of Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, UK
H. M. Salmon
Affiliation:
School of Earth Sciences, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, UK
T. Andersen
Affiliation:
Laboratory of Isotope Geology, Geologisk Museum, University of Oslo, Sarsgate 1, Oslo N-0562, Norway
*
*E-mail: aaf1@st-and.ac.uk
Get access Rights & Permissions [Opens in a new window]

Abstract

North Motzfeldt is an intrusive igneous centre within the Igaliku (formerly spelt Igaliko) complex, Gardar Province, South Greenland. A detailed field description of the centre is given, with preliminary geochemical and isotopic data. The North Motzfeldt centre is intruded into Ketilidian granitoid basement rocks, and current exposure retains parts of the original roof against earlier Gardar eruptives and clastic sediments of the Eriksfjord formation. The unconformity between the Ketilidian and the overlying Eriksfjord is believed to have been crucial in the siting of the centre. The centre is subdivided into two major units, NM1 and NM2. This was followed by significant peralkaline nepheline microsyenite in sheets, characterized by rare element-rich accessory minerals including rinkite-mł sandrite, pyrochlore and låvenite. A significant microsyenite body is called NM3. A preliminary Rb-Sr isochron of 1226±27 Ma indicates a far younger age for the centre than previously thought (~;1350 Ma). Cross-cutting relationships between North Motzfeldt and rocks of the adjacent Motzfeldt centre require a reappraisal of the chronology of Motzfeldt magmatism. We suggest that rocks previously believed to comprise the Motzfeldt centre represent the products of multiple phases of magmatism from Early- to Mid-Gardar times.

Keywords

GardarKetilidiannepheline syenitemagma chamberroof zones
Type
Research Article
Information
Mineralogical Magazine , Volume 65 , Issue 6 , December 2001 , pp. 759 - 774
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

†

Present address: British Geological Survey, Murchison House, West Mains Road, Edinburgh, EH9 3LA, UK

References

Allaart, J.H. (1976) Ketilidian Mobile Belt in South Greenland. Pp. 120-51 in: Geology of Greenland (Escher, A. and Watt, W.S., editors). Grł nlands Geologiske Undersł gelse, Copenhagen.Google Scholar
Andersen, T. (1997) Age and petrogenesis of the Qassiarsuk carbonatite- alkaline silicate volcanic province in the Gardar rift, South Greenland. Mineral. Mag., 61, 499–513CrossRefGoogle Scholar
Armour-Brown, A., Tukiainen, T., Wallin, B., Bradshaw, C. and Emeleus, C.H. (1983) Uranium exploration in South Greenland. Rapport Grł nlands Geologiske Undersł gelse, 115, 68–75.Google Scholar
Blaxland, A.B., van Breemen, O., Emeleus, C.H. and Anderson, J.G. (1978) Age and origin of the major syenite centres in the Gardar Province of South Greenland: Rb-Sr studies. Geol. Soc. Amer. Bull. 89, 231–44.2.0.CO;2>CrossRefGoogle Scholar
Chadwick, B., and Garde, A.A. (1996) Palaeoproterozoic oblique plate convergence in South Greenland: a reappraisal of the Ketilidian orogen. Pp. 179-96 in: Precambrian Crustal Evolution in the North Atlantic Region (Brewer, T.S., editor). Spec. Publ. 112. Geological Society, London.Google Scholar
Coulson, I.M. (1997) Post-magmatic alteration in eudialyte from the North Qôroq centre, South Greenland. Mineral. Mag., 61, 99–109.CrossRefGoogle Scholar
Emeleus, C.H. and Harry, W.T. (1970) The Igaliko nepheline syenites, South Greenland. General description. Bull. Grł nlands Geologiske Undersł gelse, 85, 116–pp. {Also Meddr. Grł nland, 186.}Google Scholar
Emeleus, C.H. and Upton, B.G.J. (1976) The Gardar Province of South Greenland. Pp. 152-81 in: Geology of Greenland (Escher, A. and Watt, W.S., editors). Grł nlands Geologiske Undersł gelse, Copenhagen.Google Scholar
Finch, A.A. (1990 a) The chemical and isotopic nature of fluids associated with alkaline magmatism, South Greenland. PhD thesis, Univ. Edinburgh, UK.Google Scholar
Finch, A.A. (1990 b) Genthelvite and willemite, zinc minerals associated with late-stage alkaline residues, Motzfeldt centre, South Greenland. Mineral. Mag., 54, 407–12.CrossRefGoogle Scholar
Finch, A.A., Parsons, I. and Mingard, S.C. (1995) Biotites as indicators of fluorine fugacities in fluids associ ated with alkaline magmatism, South Greenland. J. Petrol., 36, 1701–28.Google Scholar
Fitton, J.G., James, D., Kempton, P.D., Ormerod, D.S. and Leeman, W.P. (1988) The role of lithospheric mantle in the generation of late Cenozoic basic magmas in the Western United States. J. Petrol., Special Lithosphere Issue, 331-49.CrossRefGoogle Scholar
Garde, A.A., Chadwick, B., Grocott, J., Hamilton, M., McCaffrey, K. and Swager, C.P. (1998) An Overview of the Palaeoprote rozoic Ketilidian Orogen, South Greenland. ESCOOT – Lithoprobe Report, 68, 50––66.Google Scholar
Garde, A.A., Hamilton, M.A., Chadwick, B., Grocott, J. and McCaffrey, K.J.W. (2001) The Ketilidian orogen of South Greenland: tectonics, magmatism and forearc accretion during Palaeoproterozoic oblique convergence. Canad. J. Earth Sci. (in press).CrossRefGoogle Scholar
Goodenough, K.M. (1997) Geochemistry of Gardar intrusions in the Ivigtut area, South Greenland. PhD thesis, Univ. Edinburgh, UK.Google Scholar
Grocott, J., Garde, A.A., Chadwick, B., Cruden, A.R. and Swager, C. (1999) Emplacement of rapakivi granite and syenite by floor depression and roof uplift in the Palaeoproterozoic Ketilidian orogen, South Greenland. J. Geol. Soc., 156, 15–24.CrossRefGoogle Scholar
Jones, A.P. (1980) Petrology and structure of the Motzfeldt centre, Igal iko complex, South Greenland. PhD thesis, Univ. Durham, UK.Google Scholar
Jones, A.P. (1984) Mafic silicates from the nepheline syenites of the Motzfeldt centre, South Greenland. Mineral. Mag., 48, 1–12.CrossRefGoogle Scholar
Jones, A.P. and Peckett, A. (1990) Zr-bearing aegirines from Motzfeldt, South Greenland. Contrib. Mineral. Petrol., 75, 251–5.CrossRefGoogle Scholar
Jones, A.P. and Larsen, L.M. (1985) Geochemistry and REE minerals of nepheline syenites from the Motzfeldt centre, South Greenland. Amer. Mineral., 70, 1087–100.Google Scholar
Kunzendorf, H., Nyegaard, P. and Nielsen, B.L. (1982) Distribution of characteristic elements in the radioactive rocks of the northern part of Kvanefjeld, Ilímaussaq intrusion, South Greenland. Rapport Grł nlands Geologiske Undersł gelse, 109.Google Scholar
Larsen, L.M. and Tukiainen, T. (1985) New observations on the Easternmost extension of the Gardar suprac rustals (Eriksfjord formation), South Greenland. Rapport Grł nlands Geologiske Undersł gelse, 125, 64–6.Google Scholar
Ludwig, K.R. (2001) Isoplo t/Ex rev. 2. 49. A Geochronological Toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication No 1a.Google Scholar
McDonough, W.F. and Sun, S.-S. (1995) The composition of the Earth. Chem. Geol., 120, 223–55.CrossRefGoogle Scholar
Paslick, C.R., Halliday, A.N., Davies, G.R., Mezger, K. and Upton, B.G.J. (1993) Timing of Proterozoic magmatism in the Gardar Province, southern Greenland. Geol. Soc. Amer. Bull., 105, 272–8.2.3.CO;2>CrossRefGoogle Scholar
Pearce, N.J.G. and Leng, M.J. (1996) The origin of carbonatites and related rocks from the Igaliko Dyke Swarm, Gardar Province, South Greenland: field, geochemical and C–O–Sr–Nd isotope evidence. Lithos, 39, 21c40.CrossRefGoogle Scholar
Poulsen, V. (1964) The sandstones of the Precambrian Eriksfjord Formation in South Greenland. Rapport Grł nlands Geologiske Undersł gelse, 2, 16–pp.Google Scholar
Sł rensen, H. (1997) Agpaitic rocks – an overview. Mineral. Mag., 61, 485–98.CrossRefGoogle Scholar
Tukiainen, T. (1988) Niobium-tantalum mineralisation in the Motzfeldt centre of the Igaliko Nepheline Syenite Complex, South Greenland. Pp. 230-46 in: Mineral Deposits within the European Community (Boissonnas, J. and Omenetto, P., editors). Springer- Verlag, Berlin, Heidelberg.CrossRefGoogle Scholar
Tukiainen, T., Bradshaw, C. and Emeleus, C.H. (1984) Geological and radiometric mapping of the Motzfeldt centre of the Igaliko Complex, South Greenland. Rappo rt Grł nlands Geologiske Undersł gelse, 120, 78–83.Google Scholar
Upton, B.G.J. and Emeleus, C.H. (1987) Mid-Proterozoic alkaline magmatism in Southern Greenland: The Gardar Province. Pp. 449-71 in: Alkaline Igneous Rocks (Fitton, J.G. and Upton, B.G.J., editors). Spec. Publ. 30. Geological Society, London.Google Scholar
Upton, B.G.J. and Fitton, J.G. (1985) Gardar dykes north of the Igaliko syenite complex, Southern Greenland. Rapport Grł nlands Geologiske Undersł gelse, 127, 24–pp.Google Scholar