THE SCANDINAVIAN CALEDONIDES AND THEIR RELATIONSHIPS TO 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 PUBLICATION OF THE GEOLOGICAL SOCIETY OF LONDON (1996).

ABSTRACT

The main events that mark the contraction and extension histories of the Scandinavian Caledonides and the European Variscides are summarized. It is shown that continental subduction may have developed similarly large and asymmetric thrust systems in both orogens. However, whereas continent-continent collision developed in the Variscides, extension began in the Scandinavian Caledonides marking the end of continental subduction. This led extensional tectonics to affect two continental crusts with contrasting rheology and therefore led to contrasting extensional modes. We argue that plate divergence, responsible for extension in the Scandinavian Caledonides, was triggered by the Variscan collision between Laurasia and Gondwana. In contrast, horizontal buoyancy forces acting on a thermally softened thickened crust are more likely to have been responsible for extension in the Variscan belt.

ACKNOWLEDGMENTS

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

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