The record of Periadriatic volcanism in the Eastern Alpine Molasse zone and its palaeogeographic implications

Precise provenance analysis of andesite and dacite pebbles from conglomerat es in the Eastern Alpine Molasse zone, using geochemical and geochronologic al methods, provides evidence for a synorogenic volcanic chain in the Easte rn Alps which is completely eroded today. This volcanism was related to Per iadriatic magmatism along the Periadriatic lineament and took place in the Palaeogene, roughly between 40 and 30 Ma. The occurrence of remnants of the se volcanic rocks together with other marker lithologies in the Eastern Alp ine Molasse, implies an early to middle Miocene drainage system which was, in some respects, similar to the present Inn river system, but had a consid erably larger catchment area, reaching farther south. The Palaeo-Inn draine d the central and eastern sections of the Periadriatic magmatic belt to the northern foreland basin.