Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-26T03:54:35.635Z Has data issue: false hasContentIssue false
  • English
  • Français

Primitive olivine melanephelinite dykes from the Orkney Islands, Scotland

Published online by Cambridge University Press:  01 May 2009

B. G. J. Upton ,
R. H. Mitchell ,
A. Longs  and
P. Aspen
B. G. J. Upton
Affiliation:
Department of Geology and Geophysics, University of Edinburgh, Edinburgh EH9 3JW, U.K.
R. H. Mitchell
Affiliation:
Department of Geology, Lakehead University, Thunder Bay, Ontario P7B 5E1, Canada
A. Longs
Affiliation:
Department of Geology, University of London, Royal Holloway and Bedford New College, Egham TW2O OEX, U.K.
P. Aspen
Affiliation:
Department of Geology and Geophysics, University of Edinburgh, Edinburgh EH9 3JW, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

Two suites of Permian dykes in the Orkney Islands consist of a predominantly ENE trending camptonite suite and a mainly N-to NE-trending suite formerly referred to as monchiquitic. Some of the silica-poor and more magnesium dykes in the latter suite can be more precisely defined as olivine melanephelinites. Within the parochial context of the British Isles, such compositions appear to be unique. The magmas are deduced to have been primitive, small-scale (? < 0.2%) partial melt products of the asthenospheric mantle that have experienced relatively little modification in transit through the lithosphere.

Type
Articles
Information
Geological Magazine , Volume 129 , Issue 3 , May 1992 , pp. 319 - 324
Copyright
Copyright © Cambridge University Press 1992

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.)

References

Baxter, A. N. 1986. Petrochemistry of the late Palaeozoic alkali lamprophyre dykes from N. Scotland. Transactions of the Royal Society of Edinburgh, Earth Sciences 77, 267–77.CrossRefGoogle Scholar
Baxter, A. N. & Mitchell, J. G. 1984. Camptonitemonchiquite dyke swarms of Northern Scotland: age relationships and their implications. Scottish Journal of Geology 20, 297–308.CrossRefGoogle Scholar
Brown, J. F. 1975. Potassium–argon evidence of a Permian age for the camptonite dykes: Orkney. Scottish Journal of Geology 11, 259–62.CrossRefGoogle Scholar
Fitton, J. G. & Dunlop, H. M. 1985. The Cameroon line, West Africa, and its bearing on the origin of oceanic and continental alkali basalt. Earth and Planetary Science Letters 72, 23–38.CrossRefGoogle Scholar
Fitton, J. G. & James, D. 1986. Basic volcanism associated with intraplate linear features. Philosophical Transactions of the Royal Society, London A 317, 252–66.Google Scholar
Firron, J. G., James, D., Kempton, P. D., Ormerod, D. S. & Leeman, W. S. 1988. The role of lithospheric mantle in the generation of late Cenozoic basic magmas in the western United States. Journal of Petrology, Special Lithosphere Issue, 331–49.Google Scholar
Flett, J. D. 1900. The trap dykes of the Orkneys. Transactions of the Royal Society of Edinburgh 39, pt. 4, 865–908.CrossRefGoogle Scholar
Fletf, J. S. 1935. Petrography. In The Geology of the Orkneys, pp. 173–88. Memoir of the Geological Survey of Great Britain.Google Scholar
Govindaraju, K. 1989. 1989 compilation of working values and sample description for 272 geostandards. Geostandards Newsletter 13, 1–113.CrossRefGoogle Scholar
Halliday, A. N., McAlpine, A. & Mitchell, J. G. 1977. The age of the Hoy lavas, Orkney. Scottish Journal of Geology 13, 43–52.CrossRefGoogle Scholar
le Bas, M. J. 1989. Nephelinitic and basanitic rocks. Journal of Petrology 30, 1299–312.CrossRefGoogle Scholar
Norrish, K. & Hutton, J. T. 1969. An accurate spectrographic method for the analysis of a wide range of geological samples. Geochimica et Cosmochimica Acta 33, 431–53.CrossRefGoogle Scholar
Rock, N. M. S. 1983. The Permo–Carboniferous campto nite–monchiquite dyke-suite of the Scottish Highlands and Islands: distribution, field and petrological aspects. Report 82/14, Institute of Geological Sciences.Google Scholar
Rock, N. M. S. 1987. The nature and origin of lamprophyres: an overview. In Alkaline Igneous Rocks (ed Fitton, J. G. and Upton, B. G. J.), pp. 191–226. Geological Society of London, Special Publication no. 30, Oxford: Blackwell.Google Scholar
Smedley, P. L. 1988. The geochemistry of Dinantian volcanism in south Kintyre and the evidence for provincialism in the Southern Scottish mantle. Contributions to Mineralogy and Petrology 99, 374–84.CrossRefGoogle Scholar
Sweatman, T. R. & Long, J. V. P. 1969. Quantitative electron microanalysis of rock-forming minerals. Journal of Petrology 10, 332–79.CrossRefGoogle Scholar
Thirlwall, M. F. 1991. Long-term reproducibility of multi-collector Sr and Nd isotope ratio analysis. Chemical Geology (Isotope Geoscience Section) 94, 85–104.CrossRefGoogle Scholar