Hydrocarbon-bearing fluid inclusions in the Drau Range (Eastern Alps, Austria): implications for the genesis of Bleiberg-type Pb-Zn deposits

摘要

Hydrocarbons in ore minerals of Bleiberg-type Pb-Zn deposits and in authigenic quartz of the Drau Range (EasternAlps) have been analysed by bulk-sample gas chromatography andfluorescence microscopy. Microthermometric data and themolecular composition of the hydrocarbons indicate a hot (120℃to 130℃) pulse of migrating condensate-like hydrocarbons withinLate Triassic sediments during Middle Cretaceous to EarlyTertiary times. The molecular composition of hydrocarbonsenclosed in authigenic quartz corresponds to the composition ofhydrocarbons trapped in Bleiberg-type ore minerals, therefore acommon fluid source is assumed. The hydrocarbons possiblyplayed an important role as reducing agents in the late stage ofsulfide precipitation.