Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-24T01:48:19.905Z Has data issue: false hasContentIssue false
  • English
  • Français

Isotopic age data from Scourian intrusive rocks on the Isle of Barra, Outer Hebrides, north-west Scotland

Published online by Cambridge University Press:  01 May 2009

P. W. Francis ,
S. Moorbath  and
H. J. Welke
P. W. Francis
Affiliation:
Department of Geology, Imperial College, London
S. Moorbath
Affiliation:
Department of Geology, Oxford University
H. J. Welke
Affiliation:
Department of Geology, Oxford University
Get access Rights & Permissions [Opens in a new window]

Summary

Rubidium–strontium and potassium–argon measurements on Lewisian intrusive rocks, considered to be late Scourian in age on general geological grounds, have indeed yielded dates in the range 2450–2600 m.y. This demonstrates that rocks of Scourian age that have escaped substantial Laxfordian reworking are preserved in the Eastern Gneisses of Barra. The relevant geological consequences and correlations are briefly discussed. A cross-cutting late pegmatite yields a typical Laxfordian date of 1679 m.y.

Type
Articles
Information
Geological Magazine , Volume 108 , Issue 1 , January 1971 , pp. 13 - 21
Copyright
Copyright © Cambridge University Press 1971

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

Coward, M. P., Francis, P. W., Graham, R. H. & Watson, J. V. In press. Large scale Laxfordian structures in the Outer Hebrides in relation to those of the Scottish Mainland. Tectonophysics.Google Scholar
Dearnley, R. 1962. An outline of the Lewisian complex of the Outer Hebrides in relation to that of the Scottish mainland. Q. Jl geol. Soc. Lond. 118, 143–66.CrossRefGoogle Scholar
Dearnley, R. & Dunning, F. W. 1968. Metamorphosed and deformed pegmatites and basic dykes in the Lewisian complex of the Outer Hebrides and their geological significance. Q. Jl geol. Soc. Lond. 123, 353–78.CrossRefGoogle Scholar
Evans, C. R. 1965. Geochronology of the Lewisian basement near Lochinver, Sutherland. Nature, Lond. 207, 54–6.CrossRefGoogle Scholar
Evans, C. R. & Tarney, J. 1964. Isotopic ages of Assynt dykes. Nature, Lond. 204, 638–41.CrossRefGoogle Scholar
Giletti, B. J., Moorbath, S. & Lambert, R. St J. 1961. A geochronological study of the metamorphic complexes of the Scottish Highlands. Q. Jl geol. Soc. Lond. 117, 233–72.CrossRefGoogle Scholar
Hopgood, A. M. 1965. Theoretical consideration of the mechanics of tectonic re-orientation of dykes, with particular reference to the Lewisian dykes of the Isle of Barra. Tectonophysics. 3, 17–28.CrossRefGoogle Scholar
Jehu, T. J. & Craig, R. M. 1923. Geology of the Outer Hebrides, Part I: the Barra Isles. Trans. R. Soc. Edin. 53, 419–41CrossRefGoogle Scholar
Jehu, T. J. & Craig, R. M. 1925. Geology of the Outer Hebrides, Part II: South Uist and Eriskay. Trans. R. Soc. Edin. 53, 615–41.CrossRefGoogle Scholar
Moorbath, S., Welke, H. & Gale, N. H. 1969. The significance of lead isotope studies in ancient, high-grade metamorphic basement complexes, as exemplified by the Lewisian rocks of northwest Scotland. Earth Planet. Sci. Lett. 6, 245–56CrossRefGoogle Scholar
Sutton, J. & Watson, J. 1951. The pre-Torridonian metamorphic history of the Loch Torridon and Scourie areas in the North-West Highlands, and its bearing on the chronological classification of the Lewisian. Q. Jl geol. Soc. Lond. 106, 241–307.CrossRefGoogle Scholar
York, D. 1966. Least-squares fitting of a straight line. Can. J. Phys. 44, 1079–86.CrossRefGoogle Scholar