Inverted metamorphic zonation and large-scale thrusting in the Varsican belt: An example

SUMMARY: Half of the northern part of the French Massif Central h s been shown to be allochthonous. In the allochthonous rocks, preserved high-pressure granulites represent an early tectonometamorphic event which took place before thrusting. During the southward-directed overthrusting of this high-grade metamorphic slab a plurifacial inverted metamorphism was developed in the underlying sediments. Adjacent areas how different types of metamorphism in the autochthonous and parautochthonous pelites. The climax of the metamorphism is shown to have been reached bythe end of the thrusting episode. This was followed by the retrogression of the high-grade rocks and the stablish-ment of a low-pressure metamorphism in both the thrust unit and the autochthonous-parautochthonous terranes beneath. We describe this example of inverted metamorphic zonation associated with the large-scale thrusting of an already metamorphosed series. Two principal domains with different litho-stratigraphic, tectonic, metamorphic and mag-~ matic characteristics have been distinguished in the eastern French Massif Central (Burg &amp