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Evidence for an incipient early Caledonian (Cambrian) orogenic phase in southwestern Norway

Published online by Cambridge University Press:  01 May 2009

H. Furnes ,
H. Austrheim ,
K. G. Amaliksen  and
J. Nordas
H. Furnes
Affiliation:
Geologisk Institutt, Avd A Allegt 41, 5014 Bergen, Norway
H. Austrheim
Affiliation:
Mineralogisk-geologisk museum, Sarsgt 1, Oslo 5, Norway
K. G. Amaliksen
Affiliation:
Geologisk Institutt, Avd A Allegt 41, 5014 Bergen, Norway
J. Nordas
Affiliation:
Geologisk Institutt, Avd A Allegt 41, 5014 Bergen, Norway
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Abstract

Summary. Quartz-keratophyres from an ensimatic island arc on Bømlo, southwest Norwegian Caledonides, resting on the Lykling ophiolite, have yielded a Rb/Sr whole rock age of 535 ± 46 Ma. This Cambrian age, which is a minimum age of formation for the ophiolite, indicates an early phase of subduction, corresponding with the orogenic activity known from northern Norway, i.e. the Finnmarkian. Before Middle Ordovician time, the ophiolite and ensimatic arc had been obducted onto continental crust and deformed, as they are unconformably overlain by a volcanic complex of subaerial rhyolites and andesites which have yielded Rb/Sr whole rock ages of 464 ± 16 and 468 ± 23 Ma respectively.

Type
Articles
Information
Geological Magazine , Volume 120 , Issue 6 , December 1983 , pp. 607 - 612
Copyright
Copyright © Cambridge University Press 1983

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References

REFERENCES

Blake, D. H. 1962. A new Lower Ordovician graptolite fauna from the Trondheim region. Norsk. geol. Tidsskr. 42, 223–38.Google Scholar
Bluck, B. J., Halliday, A. N., Aftalion, M. & Macintyre, R. M. 1980. Age and origin of Ballantrae ophiolite and its significance to the Caledonian orogeny and Ordovician time scale. Geology 8, 492–5.2.0.CO;2>CrossRefGoogle Scholar
Furnes, H. & Lippard, S. J. 1979. On the significance of Caledonian paheohoe, aa, and pillow lava from Bømlo, S.W. Norway. Norsk geol. Tidsskr. 59, 107–14.Google Scholar
Furnes, H., Fridleifsson, I. B. & Atkins, F. B. 1980. Subglacial volcanics - on the formation of acid hyaloclastites. J. volcanol. geotherm. Res. 8, 95–110.CrossRefGoogle Scholar
Furnes, H., Roberts, D., Sturt, B. A., Thon, A. & Gale, G. H. 1980. Ophiolite fragments in the Scandinavian Caledonides. Proc. Int. Ophiolite Symp., Cyprus 1979, 582–600.Google Scholar
Furnes, H., Ryan, P. D., Grenne, T., Roberts, D., Sturt, B. A. & Prestvik, T. 1983. Geological and geochemical classification of ophiolite fragments in the Scandinavian Caledonides. In The Caledonide Orogen - Scandinavia and Related Areas (ed. Gee, D. G. and Sturt, B. A.). New York: John Wiley. (In the Press.)Google Scholar
Maaløe, S. & Petersen, T. S. 1981. Petrogenesis of oceanicandesite. J. Geophys. Res. 86 (B11), 10273–86.CrossRefGoogle Scholar
Nordas, J., Amaliksen, K. G., Brekke, H., Suthren, R., Furnes, H., Sturt, B. A. & Robins, B. 1983. Lithostratigraphy and petrochemistry of Caledonian rocks on Bømlo, S.W. Norway. In The Caledonide Orogen-Scandinavia and Related areas (ed. Gee, D. G. and Sturt, B. A.). New York: John Wiley. (In the Press.)Google Scholar
Pankhurst, R. J. & O'Nions, R. K. 1973. Determination of Rb/Sr and 87Sr/86Sr ratios of some standard rocks and evaluation of X-ray fluorescence spectrometry in Rb-Sr geochemistry. Chem. Geol. 12, 127–36.CrossRefGoogle Scholar
Roberts, D. & Sturt, B. A. 1980. Caledonian deformation in Norway. J. geol. Soc. Lond. 137, 241–50.CrossRefGoogle Scholar
Roberts, D., Grenne, T. & Ryan, P. D. 1983. Ordovician marginal basin development in the central Norwegian Caledonides. J. Geol. Soc. Lond. (In the Press).Google Scholar
Ryan, P. D., Williams, D. M. & Skevington, D. 1980. A revised interpretation of the Ordovician stratigraphy of Sør Trøndelag, and its implications for the evolution of the Scandinavian Caledonides. In Proc. ‘The Caledonides in the USA’ (ed. Wones, D. R.). Department of Geological Sciences, Virginia Polytechnic Inst. and State Univ., Mem. no. 2, 99–106.Google Scholar
Skevington, D. 1963. On the age of the Bogo shale. Norsk geol. Tidsskr. 43, 257–60.Google Scholar
Sturt, B. A. & Thon, A. 1978. A major early Caledonian igneous complex and a profound unconformity in the Lower Palaeozoic sequence of Karmøy, southwest Norway. Norsk. geol. Tidsskr. 58, 221–8.Google Scholar
Sturt, B. A., Pringle, I. R. & Ramsay, D. M. 1978. The Finnmarkian phase of the Caledonian orogeny. J. geol. Soc. Lond. 135, 597–610.CrossRefGoogle Scholar
Sturt, B. A., Roberts, D. & Furnes, H. 1983. A conspectus of Scandinavian Caledonian ophiolites. J. geol. Soc. Lond. (In the Press.)Google Scholar
York, D. 1969. Least square fitting of a straight line with correlated errors. Earth Planet. Sci. Lett. 5, 320–4.CrossRefGoogle Scholar