Tungsten Mineralization in the Eastern Alps (Austria): Implications of Scheelite Trace Element Composition for Exploration Potential Evaluation

Greenfield exploration during the 1970s to 1980s has revealed tungsten enrichment in various geologic units of the Eastern Alps. This study aims to develop assessment criteria (fingerprints) for the evaluation of regional tungsten potentials in the Eastern Alps based on mineralogical and chemical criteria from 17 of these tungsten discoveries, including the world-class Felbertal tungsten deposit. Scheelite (CaWO4) is the most common tungsten mineral in the Eastern Alps and was investigated by combined cathodoluminescence imaging, electron probe microanalysis (EPMA), and in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). This approach allows the identification of three mineralization styles in the Eastern Alps: (1) intrusion-related, (2) polymetallic (As, Sb, Au), and (3) carbonate-hosted stratabound scheelite mineralization. Our results show that the trace elements Na, Sr, Nb, Mo, and total rare earth elements (ΣREE) + Y are suitable for distinguishing scheelite from different ore-forming environments. The proposed (log[Sr/Mo] vs. log[Na/Nb]) diagram facilitates the discrimination of these mineralization styles irrespective of the metamorphic overprint and reflects chemical signatures of specific ore-forming processes. The diagram provides a clear distinction of intrusion-related magmatic-hydrothermal deposits from other styles of tungsten mineralization with less promising economic potential as well as orogenic gold deposits of metamorphogenic origin. Felbertal is clearly assigned to the intrusion-related magmatic-hydrothermal deposits and differs significantly from all the other examined scheelite occurrences in the Eastern Alps. The comparison with global scheelite data sets shows that these findings have the potential to be implemented across worldwide exploration projects.