The Sudetes as a Palaeozoic orogen in central Europe

Abstract

Two metasedimentary complexes are exposed in the Sudetes Mountains of Poland, Germany and the Czech Republic. Succession I comprises pelites and greywackes of Neoproterozoic–Cambrian age, deformed and metamorphosed prior to intrusion by S-type porphyritic granites at 515–480 Ma. Succession II comprises a sandstone–mudstone–chert sequence and turbidite sequence of Ordovician–early Carboniferous age accompanied by bimodal volcanogenic rocks. Both successions were intruded by late- to post-orogenic granitoid intrusions at 340–300 Ma. The sedimentary rocks of succession II show increasing maturity until mid–late Devonian times. Inversion of the basins, commencing in late Devonian–early Carboniferous times, was reflected in the emplacement of turbidites and olistostromes, concurrent with the uplift of a metamorphic core complex of succession I rocks. The original stratigraphic order of the successions was maintained, thus crustal imbrication was not significant. Instead, extensional faulting became important, followed by transpression on almost orthogonal fault zones, resulting in the presently observed juxtaposition of crustal blocks. The Palaeozoic sequences developed in mainly ensialic basins on Cadomian and older basement, parts of which became strongly reworked (2.6 to 0.54 Ga zircon inheritance ages) and incorporated into the Palaeozoic structures. The orogen developed either on the rifted margin of peri-Gondwana or on a rifted-away fragment of pre-Baltica. The Sudetic section of the Variscan Orogen is of broadly Alpine style, with significant basement involvement, but apparently without evidence for long-lived subduction of wide oceans or the accretion of numerous exotic terranes.