THE SCANDINAVIAN CALEDONIDES AND THEIR RELATIONSHIPSTO THE VARISCAN BELT

P.F REY*, J. P. BURG** & M. CASEY**

*Dept. of Earth Sciences, Monash University, Clayton, VIC 3168, Australia

**ETHZ-Zentrum, Sonneggstrasse 5, CH-8092 Zurich, Switzerland

In: OROGEN THROUGH TIME. J.P Burg and M. Ford (eds). SPECIAL PUBLICATIONOF THE GEOLOGICAL SOCIETY OF LONDON (1996).

ABSTRACT

The main events that mark the contraction and extension histories of theScandinavian Caledonides and the European Variscides are summarized. Itis shown that continental subduction may have developed similarly largeand asymmetric thrust systems in both orogens. However, whereas continent-continentcollision developed in the Variscides, extension began in the ScandinavianCaledonides marking the end of continental subduction. This led extensionaltectonics to affect two continental crusts with contrasting rheology andtherefore led to contrasting extensional modes. We argue that plate divergence,responsible for extension in the Scandinavian Caledonides, was triggeredby the Variscan collision between Laurasia and Gondwana. In contrast, horizontalbuoyancy forces acting on a thermally softened thickened crust are morelikely to have been responsible for extension in the Variscan belt.

ACKNOWLEDGMENTS

This work has been supported by the INSU-CNRS (ATP-ECORS 891705) for thefield study in the Variscan belt and by the NSF grant EAR-9003956 for thefield study in the Caledonian belt. An early version of this work profitedfrom helpful comments provided by H. Austrheim, A. Chauvet, S. Costa, B.John, D. Fountain and M. SÚranne. The final version has been improvedby the reviews of A.G. Milnes, N.J. Soper, and an anonymous reviewer, allof them are gratefully thanked.

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