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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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