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Source ages of zircons in an Archaean quartzite, Rona, Inner Hebrides, Scotland

Published online by Cambridge University Press:  01 May 2009

D. R. Bowes ,
A. M Hopgood  and
R. T. Pidgeon
D. R. Bowes
Affiliation:
Department of Geology, University of Glasgow, Glasgow, G12 8QQ Scotland
A. M Hopgood
Affiliation:
Department of Geology, University of St. AndrewsSt. Andrews, KY16 9ST, Scotland
R. T. Pidgeon
Affiliation:
School of Earth Sciences, Australian National University, Canberra 2601, Australia
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Summary

The internal variations in the discordance of an inhomogenous zircon population from a bedded quartzite within a c. 2700 Ma old gneiss have been studied. Varying degrees of response to events in a common multi-episodic, post-depositional history are reflected in the uranium and lead isotopic systems of size and magnetic fractions.

A minimum 207Pb/206Pb age for non-magnetic zircons is 2840 Ma with 206Pb/238U and 207Pb/235U data for the three size fractions raising the possibility of an age of at least 3250 Ma. This is interpreted as a minimum age for crustal material that was in existence in the region before the formation of the Lewisian complex. Some of the slightly magnetic zircons also have a pre-2700 Ma radiogenic lead component.

Type
Articles
Information
Geological Magazine , Volume 113 , Issue 6 , November 1976 , pp. 545 - 552
Copyright
Copyright © Cambridge University Press 1976

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References

Allègre, C. J., Albarède, F., Grünenfelder, M. & Köppel, V. 1974. 238U/206Pb – 235U/207Pb – 232Th/208Pb zircon chronology in alpine and non-alpine environment. Contr. Mineral. Petrol. 43, 163–94.CrossRefGoogle Scholar
Bikerman, M., Bowes, D. R. & van Breemen, O. 1975. Rb-Sr whole rock isotopic studies of Lewisian metasediments and gneisses in the Loch Maree region, Rossshire. Jl geol. Soc. Lond. 131, 237–54.CrossRefGoogle Scholar
Bowes, D. R. 1976. Archaean crustal history in North-western Britain. In Windley, B. F. (Ed.): The Early History of the Earth, 469–79. Wiley, London.Google Scholar
Bowes, D. R. & Hopgood, A. M. 1975. Framework of the Precambrian crystalline complex of the Outer Hebrides, Scotland. Krystalinikum 11, 7–23.Google Scholar
Bowes, D. R., Hopgood, A. M. & Taft, M. B. 1971. Granitic injection complex of Harris, Outer Hebrides. Scott. J. Geol. 7, 289–91.CrossRefGoogle Scholar
Chowdhary, P. K. 1971. Zircon populations in Lewisian quartzite, gneiss and granite north of Loch Laxford, Sutherland. Geol. Mag. 108, 255–62.CrossRefGoogle Scholar
Gebauer, D. & Grünenfelder, M. 1974. Rb-Sr whole-rock dating of late diagenetic to anchimetamorphic, Palaeozoic sediments in southern France (Montagne Noire). Contr. Mineral. Petrol. 47, 113–30.CrossRefGoogle Scholar
Grauert, B. & Arnold, A. 1968. Deutung diskordanter zirconalter der Silvrettadecke und des Gotthardmassivs (Schweizer Alpen). Contr. Mineral. Petrol. 20, 34–56.CrossRefGoogle Scholar
Grauert, B., Hänny, R. & Soptrajanova, G. 1973. Age and origin of detrital zircons from the pre-Permian basement of the Bohemian massif and the Alps. Contr. Mineral. Petrol. 40, 105–30.CrossRefGoogle Scholar
Hart, S. R. & Davis, G. L. 1969. Zircon U-Pb and whole-rock Rb-Sr ages and early crustal development near Rainy Lake, Ontario. Bull. geol. Soc. Am. 80, 595–616.CrossRefGoogle Scholar
Holland, J. G. & Lambert, R. St, J. 1972. Chemical petrology and K-Ar ages of the Lewisian gneisses of Rona, near Skye, Scotland. Geol. Mag. 109, 339–47.CrossRefGoogle Scholar
Hopgood, A. M. & Bowes, D. R. 1972. Correlation by structural sequence in Precambrian gneisses of northwestern Britain. Rep. XXIV Int. Geol. Congr. 1, 195–200.Google Scholar
Jaffey, A., Flynn, K. F., Glendenin, L. E., Bentley, W. C. & Essling, A. M. 1971. Precision measurements of half-lives and specific activities of 235U and 238U Phys. Rev. C 4, 1889–906.Google Scholar
Jocelyn, J. & Pidgeon, R. T. 1974. Examples of twinning and parallel growth in zircons from some Precambrian granites and gneisses. Mineral. Mag. 39, 587–94.CrossRefGoogle Scholar
Köppel, V. & Grünenfelder, M. 1971. A study of inherited and newly formed zircons from paragneisses and granitized sediments of the Strona-Ceneri zone (southern Alps). Schweiz. Mineral. Petrog. Mitt. 51, 387–411.Google Scholar
Krogh, T. E. 1973. A low-contamination method for hydrothermal decomposition of zircon and extraction of U and Pb for isotopic age determinations. Geochim. cosmochim. Acta 37, 485–94.CrossRefGoogle Scholar
Lyon, T. D. B., Pidgeon, R. T., Bowes, D. R. & Hopgood, A. M. 1973. Geochronological investigation of the quartzofeldspathic rocks of the Lewisian of Rona, Inner Hebrides. Jl geol. Soc. Lond. 128, 389–404.CrossRefGoogle Scholar
Moorbath, S. 1969. Evidence for the age of deposition of the Torridonian sediments of north-west Scotland. Scott. J. Geol. 5, 154–70.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, 245–56.CrossRefGoogle Scholar
Moorbath, S., Powell, J. L. & Taylor, P. N. 1975. Isotopic evidence for the age and origin of the ‘grey gneiss’ complex of the southern Outer Hebrides, Scotland. Jl geol. Soc. Lond. 131, 213–22.CrossRefGoogle Scholar
Pidgeon, R. T. 1969. Zircon U-Pb ages from the Galway granite and the Dalradian, Connemara, Ireland. Scott. J. Geol. 5, 375–92.CrossRefGoogle Scholar
Pidgeon, R. T. & Aftalion, M. 1972. The geochronological significance of discordant U-Pb ages of oval-shaped zircons from a Lewisian gneiss from Harris, Outer Hebrides. Earth Planet. Sci. Lett. 17, 269–74.CrossRefGoogle Scholar
Pidgeon, R. T. & Bowes, D. R. 1972. Zircon U-Pb ages of granulites from the Central Region of the Lewisian, northwestern Scotland. Geol. Mag. 109,, 247–58.CrossRefGoogle Scholar
Pidgeon, R. T. & Hopgood, A. M. 1975. Geochronology of Archaean gneisses and tonalites from north of the Frederikshåbs isblink, S.W. Greenland. Geochim. cosmochim. Acta 39, 1333–46.CrossRefGoogle Scholar
Pidgeon, R. T., Köppel, V. & Grünenfelder, M. 1970. U-Pb isotopic relationships in zircon suites from a para- and orthogneiss from the Ceneri zone, southern Switzerland. Contr. Mineral. Petrol. 26, 1–11CrossRefGoogle Scholar
Stewart, A. D. 1969. Torridonian rocks of Scotland reviewed. In Kay, M. (Ed.): North Atlantic – geology and continental drift, a symposium. Mem. Am. Assoc. Petrol. Geol. 12, 595–608.Google Scholar
van Breemen, O., Aftalion, M. & Pidgeon, R. T. 1971. The age of the granitic injection complex of Harris, Outer Hebrides. Scott. J. Geol. 7, 139–52.CrossRefGoogle Scholar