The origin of rhythmic sulphide bands from the Permian sandstones (Weissliegendes) in the footwall of the Fore-Sudetic “Kupferschiefer” (Poland) |
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| Authors: | Z Sawlowicz K H Wedepohl |
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| Institution: | 1. Geochemisches Institut, Goldschmidtstra?e 1, W-3400, G?ttingen, FRG
2. Institute of Geological Sciences, Jagellonian University, ul. Oleandry 2A, 30-063, Krakow, Poland
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| Abstract: | Rhythmic copper sulphide bands occur in the Weissliegendes sandstones, in the footwall of the Kupferschiefer in the mining
district of SW Poland. The δ
34S values of sulphides vary from −39 to — 44‰ (6–7‰ lighter than Kupferschiefer sulphides). The copper sulphides are represented
mainly by digenite and chalcocite. According to microprobe results their Pb, Ni, Zn and Ag contents are similar to those in
the Kupferschiefer. The bands are assumed to be formed by diffusion of bacterially produced hydrogen sulphide from the Kupferschiefer
into the porous volume of the white sandstones containing dissolved copper. The sulphides were precipitated in almost equidistant
bands, from top to bottom, probably according to the Ostwald-Prager supersaturation theory. The increase of isotopically heavier
sulphur towards the lower levels in the sandstone might be explained by closing of the bacterial sulphate reduction system.
Contribution to the IGCP Project No. 254 |
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