Mineralogy and Petrology (1999) 65:141-159 Mineralogy and Petrology © Springer-Verlag 1999 Printed in Austria Hydrocarbon-bearing fluid inclusions in the Dra.u Range (Eastern Alps, Austria): implications for the genesis of Bleiberg-type Pb-Zn deposits G. Rantitsch 1, J. Jochum 2, R. F. Sachsenhofer 1, B. Russegger 1, E. Schroll 3, and B. Horsfield 4 1Institut ftir Geowissenschaften, Montanuniversit/it, Leoben, Austria 2Institut ftir Mineralogie und Lagerst~ttenlehre, RWTH Aachen, Federal Republic of Germany 3 Institut ftir Mineralogie und Kristallographie, Universit/it Wien, Austria 4 Institut ftir Erd61 und organische Geochemie (IGC-4), Forschungszentrum Jtilich, Federal Republic of Germany With 6 Figures Received February 10, 1998; revised version accepted December 7, 1998 Summary Hydrocarbons in ore minerals of Bleiberg-type Pb-Zn deposits and in authigenic quartz of the Drau Range (Eastern Alps) have been analysed by bulk-sample gas chromatography and fluorescence microscopy. Microthermometric data and the molecular composition of the hydrocarbons indicate a hot (120 ° to 130 °C) pulse of migrating condensate-like hydrocarbons within Late Triassic sediments during Middle Cretaceous to Early Tertiary times. The molecular composition of hydrocarbons enclosed in authigenic quartz corresponds to the composition of hydrocarbons trapped in Bleiberg-type ore minerals, therefore a common fluid source is assumed. The hydrocarbons possibly played an important role as reducing agents in the late stage of sulfide precipitation. Zusammenfassung Kohlenwasserstoffhiiltige Fliissigkeitseinschliisse im Drauzug (Ostalpen, Osterreich) und ihre Bedeutung fiir die Genese der Pb-Zn-Lagerstiitten vom Bleiberg-Typ Die organo-chemische Zusammensetzung yon Kohlenwasserstoffen, die in Erzmine- ralen vom Typus Bleiberg und in authigenen Quarzen des Drauzuges (Ostalpen)