GEODYNAMIC EVOLUTION OF THE EUROPEAN VARISCAN FOLD BELT - PALEOMAGNETIC AND GEOLOGICAL CONSTRAINTS

The Variscan fold belt of Europe resulted from the collision of Africa , Baltica, Laurentia and the intervening microplates in early Paleozoi c times. Over the past few years, many geological, palaeobiogeographic and palaeomagnetic studies have led to significant improvements in ou r understanding of this orogenic belt. Whereas it is now fairly well e stablished that Avalonia drifted from the northern margin of Gondwana in Early Ordovician times and collided with Baltica in the late Ordovi cian/early Silurian, the nature of the Gondwana derived Armorican micr oplate is more enigmatic. Geological and new palaeomagnetic data sugge st Armorica comprises an assemblage of terranes or microblocks. Palaeo biogeographic data indicate that these terranes had similar drift hist ories, and the Rheic Ocean separating Avalonia from the Armorican Terr ane Assemblage closed in late Silurian/early Devonian times. An early to mid Devonian phase of extensional tectonics along this suture zone resulted in formation of the relatively narrow Rhenohercynian basin wh ich closed progressively between the late Devonian and early Carbonife rous. In this contribution, we review the constraints provided by pala eomagnetic data, compare these with geological and palaeobiogeographic evidence, and present a sequence of palaeogeographic reconstructions for these circum-Atlantic plates and microplates from Ordovician throu gh to Devonian times.