Plate tectonic processes that governed the mineralization of the Eastern Alps

The notably limited post-Hercynian mineralization of the Eastern Alps is shown to be a direct function of the particular plate tectonic history of the region. The Alpine orogeny can be viewed as consisting of two separate, although overlapping events. Formation and then destruction of a "Penninic Ocean" of Jurassic age left a root of subduced oceanic crust in the Asthenosphere. Cyprus style copper deposits and submarine exhalative tungsten and base metal ore-bodies are the main mineralization episodes that can be related to this Penninic event. In the second stage of the Alpine orogeny the northward subducing Tethyan ocean floor collided with the Penninic remnant causing steepening and deflection of the Benioff-zone. The Alps were thus insulated by the Penninic root from many of the thermal events typical of normal subduction induced orogenies. Minor transport of earlier disseminated mineralization into faults formed in the Alpine tectonism is the dominant manifestation of the limited Alpine thermal event. However, although the geometry of the Alpine orogeny favoured only minor metallization it is also noted that earlier orogenies of the Alpine region are metal poor compared to many orogenic regions. It is suggested therefore that inheritance of the metallogenetic character of the preceeding basement may also play a role in the metalliferous nature of later orogenic episodes.