Hostname: page-component-77c89778f8-5wvtr Total loading time: 0 Render date: 2024-07-18T20:35:47.488Z Has data issue: false hasContentIssue false
  • English
  • Français

Mafic silicates from the nepheline syenites of the Motzfeldt centre, South Greenland

Published online by Cambridge University Press:  05 July 2018

A. P. Jones
A. P. Jones*
Affiliation:
The University of Chicago, Department of Geophysical Sciences, 5734 South Ellis Avenue, Chicago, Illinois, USA 60637
Get access Rights & Permissions [Opens in a new window]

Abstract

At least five successive intrusions of nepheline-bearing magmas fractionated in situ and developed repeatedly overlapping, yet distinct chemical trends in the mafic silicates. Representative electron probe analyses are given for olivine, clinopyroxene, amphibole, biotite, and aenigmatite and their variations discussed. Increasing Na with fractionation produced aegirine-rich clinopyroxene and caused Na/K in amphibole to increase from 2.4 to 7.0. Siz/Alz increased in both amphibole and in the less abundant mica. Mn-enrichment is common to all of the mafic silicates, including the olivines and it is suggested that the parent magmas were initially Mn-rich.

Mineralogically the Motzfeldt centre is evolved and similar to the other centres in the Igaliko complex. However, the Motzfeldt centre contains the most fractionated rocks (lujavrites) and is in this respect similar to the peralkaline Ilimaussaq intrusion. The compositional ranges and trends of the mafic silicates in Motzfeldt thus provide links between the uncommon peralkaline plutons and the more abundant and typical nepheline syenites.

Type
Research Article
Information
Mineralogical Magazine , Volume 48 , Issue 346 , March 1984 , pp. 1 - 12
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1984

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: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA

References

Anderson, J. G. (1974) The geology of Alangorssuaq, Northern Nunarssuit complex, S. Greenland. Ph.D. thesis, Univ. of Aberdeen (unpubl.).Google Scholar
Blaxland, A. B., van Breeman, O., Emeleus, C. H., and Anderson, J. G. (1978) Bull. Geol. Soc. Am. 89, 231–44.2.0.CO;2>CrossRefGoogle Scholar
Brown, G. E. (1980) In Reviews in Mineralogy 5; Orthosilicates (Ribbe, P. H., ed.), Mineral. Soc. Am., Washington.Google Scholar
Brown, G. M., and Vincent, E. A. (1963) J. Petrol. 4, 175–97.CrossRefGoogle Scholar
Cawthorn, R. G. (1976) Geochim. Cosmochim. Acta 40, 1319–28.CrossRefGoogle Scholar
Chambers, A. D. (1976) The petrology and geochemistry of the North Qoroq Centre, Igaliko Complex, South Greenland. Ph.D. thesis, Univ. of Durham (unpubl.).Google Scholar
Dawson, J. B., Hervig, R. L., and Smith, J. V. (1981) Fortschr. Mineral. 59, 303–24.Google Scholar
Deer, W. A., and Wager, L. R. (1939) Am. Mineral. 24, 18–25.Google Scholar
Howie, R. A., and Zussman, J. (1978) Rock-Forming Minerals. Vol. 2A: Single Chain Silicates. Longmans, London.Google Scholar
Downes, M. J. (1974) Contrib. Mineral. Petrol. 47, 187–96.CrossRefGoogle Scholar
Emeleus, C. H., and Harry, W. T. (1970) Meddels. Gronland, 186, No. 3; also Bull. Gmnlands Geol. Unders. No. 85.Google Scholar
Emeleus, C. H. and Upton, B. G. J. (1976) In Geology of Greenland (Escher, A. and Watt, W. S., eds.). Geol. Survey Greenland, Copenhagen, 152–81.Google Scholar
Ferguson, J. (1970) Can. Mineral. 10, 335–49.Google Scholar
Finger, L. W. (1972) Carnegie Inst. Wash. Yearb. 71, 600–3.Google Scholar
Gerasimovsky, V. J., and Kusnetsova, S. Ya. (1967) Geochem. Int. 4, 236–46.Google Scholar
Gomes, C., de B., Moro, S. L., and Dutra, C. V. (1970) Am. Mineral. 55, 224–30.Google Scholar
Helz, R. T. (1973) J. Petrol. 14, 249–302.CrossRefGoogle Scholar
Hodges, F. N., and Barker, D. S. (1973) Carnegie Inst. Wash. Yearb. 72, 578–81.Google Scholar
Hollister, L. S., and Gancarz, A. J. (1971) Am. Mineral. 56, 959–79.Google Scholar
Jones, A. P. (1980) The petrology and structure of the Motzfeldt Centre, Igaliko, South Greenland. Ph.D. thesis, Univ. of Durham (unpubl.).Google Scholar
Jones, A. P. and Peckett, A. (1980) Contrib. Mineral. Petrol. 75, 251–5.CrossRefGoogle Scholar
Larsen, L. M. (1976) J. Petrol. 17, 258–90.CrossRefGoogle Scholar
Larsen, L. M. (1977) Lithos. 10, 257–70.CrossRefGoogle Scholar
Leake, B. E. (1978) Mineral. Mag. 42, 533–63.CrossRefGoogle Scholar
Moore, P. B. (1972) Am. Mineral. 57, 1333–44.Google Scholar
Mossman, D. J., and Pawson, D. J. (1976) Can. Mineral. 14, 479–86.Google Scholar
Nash, W. P., and Wilkinson, J. F. G. (1970) Contrib. Mineral. Petrol. 25, 241–69.CrossRefGoogle Scholar
Nicholls, J., and Carmichael, I. S. E. (1969) Ibid. 268, 94.Google Scholar
Parsons, I. (1979) J. Petrol. 20, 653–94.CrossRefGoogle Scholar
Phillips, R. (1966) Mineral. Mag. 33, 1097–109.Google Scholar
Pitcher, W. S., and Bussell, M. A. (1977) J. Geol. Soc. Lond. 133, 249–56.CrossRefGoogle Scholar
Poldervaart, A., and Hess, H. H. (1951) J. Geol. 59, 472–89.CrossRefGoogle Scholar
Powell, M. (1976) Theoretical, geochemical and petrological study of the Igdlerfigssalik nepheline syenite intrusion, Greenland. Ph.D. thesis, Univ. of Leeds (unpubl.).Google Scholar
Powell, M. (1978) Lithos. 11, 99–120.CrossRefGoogle Scholar
Stephenson, D. (1972) Ibid. 187, 201.Google Scholar
Stephenson, D. (1973) The petrology and mineralogy of the South Qoroq Centre, Igaliko Complex, South Greenland. Ph.D. thesis, Univ. of Durham (unpubl.).Google Scholar
Stephenson, D. (1974) Lithos. 7, 35–41.CrossRefGoogle Scholar
Stephenson, D. (1976) Bull. Grenlands Geol. Unders. No. 118.Google Scholar
Stephenson, D. and Upton, B. G. J. (1982) Mineral. Mag. 46, 283–300.CrossRefGoogle Scholar
Sweatman, T. R., and Long, J. V. P. (1969) J. Petrol. 10, 332–79.CrossRefGoogle Scholar
Tyler, R. C., and King, B. C. (1967) Mineral. Mag. 36, 5–22.Google Scholar
Upton, B. G. J. (1974) In The Alkaline Rocks (Sørenson, H., ed.). J. Wiley and Sons, London. 221–38.Google Scholar
Watson, E. B. (1979) Contrib. Mineral. Petrol. 70, 407–19.CrossRefGoogle Scholar