Casting new light on tungsten deposits in the Eastern Alps

Based on economic importance and potential supply risk tungsten is considered as a critical raw material by the EU as about 80 % of the global tungsten supply comes from China. Within the EU the Felbertal scheelite deposit in Austria is one of the few producing tungsten mines. Vein-stockwork scheelite mineralization in this area was formed at ~340 Ma during the Variscan Orogeny, with subsequent metamorphic overprint and remobilization. Thus, several generations of scheelite can be distinguished. REE analyses (LA-ICP-MS) of these scheelite generations demonstrate that primary magmatic-hydrothermal (Scheelite 1 and 2) and metamorphic scheelite (Scheelite 3) have different chemical signatures. Extensive greenfield exploration during the 1980s led to the discovery of many other scheelite occurrences in the Eastern Alps. Since then, tungsten mineralization is known from different parts of the Austroalpine Unit and the Penninic/Subpenninic Nappe System. Mineralization style includes strata-bound mineralization, for example in metabasites (Felbertal), metacarbonates partly with magnesite (Tux-Lanersbach, Mallnock) and calc-silicate rocks (Messelingscharte, Lienzer Schlossberg), orogenic Au-W veins (Schellgaden) and scheelite-bearing metamorphic veins (Mühlbach/Neukirchen). The “W Alps” project (W stands for the chemical symbol of tungsten) aims to develop assessment criteria for the evaluation of regional tungsten potentials in Austria. In order to understand the context in the current geological-tectonic concept for the Eastern Alps the project includes field-based studies of tungsten-bearing geological units. The data will be integrated in a metallogenetic model of Alpine tungsten mineralization. We will define the scheelite trace element characteristics from different deposit types and develop an exploration tool that can be applied to samples lacking geological context (i.e. stream sediments). In conjunction, we aim to provide a consistent set of geological and geochemical data allowing us to define areas of high prospectivity for W mineralization in the Eastern Alps.