The Haidbach deposit in the Central Tauern Window, Eastern Alps, Austria: a metamorphosed orthomagmatic Ni-Cu-Co-PGE mineralization in the Polymetallic Ore District Venediger Nappe System – Hollersbach Complex

Abstract Cu-Ni-Co-PGE mineralization occurs at Haidbachgraben in the Early Palaeozoic, Subpenninic Hollersbach Complex of Central Tauern Window, Austria. Massive sulfide ore formed from melt segregated silicate during intrusion pyroxenite into magmatic rocks an MORB-type environment. Relics minerals include chromian spinel and polyphase droplets composed pyrrhotite, chalcopyrite pentlandite preserved recrystallized pyrite. Both host were multiply deformed metamorphosed, leading to hornblendite carrying ore, enveloped by chlorite-epidote schist. Conditions – likely Variscan amphibolite facies metamorphism are documented relict pargasitic cores hornblende actinolite-tremolite, ternary sulfarsenide compositions Co-Ni-Fe solid solution series that most common accessory found ore. Pyrrhotite, pentlandite, pyrite major minerals. Chalcopyrite is Cd-rich retains a high-temperature signature. High Co/Sb moderate Se/As ratios also point environment mineralization. The mineral assemblage small grain size (mostly <10 µm) comprises native Au-Ag alloy petzite as minerals, sperrylite, variety Pd tellurides bismuthotellurides with elevated Sb, irarsite, Re sulfides such tarkianite Pb-Re sulfide. In addition, minor molybdenite, bournonite, scheelite selenides have been identified. Two precious metal assemblages present individual samples: (1) hessite associated tellurides, often accompanied sphalerite chalcopyrite; (2) forming euhedral inclusions Sperrylite alloys throughout detected matrix. Most metal-bearing phases must recrystallization base after magmatic, probably later metamorphic events terminating Neoalpine crystallization.