Abstract

Baryte vein deposits confined to the unconformity between Palaeozoic or Precambrian basement and the Permian–Triassic cover are of widespread occurrence in Central Europe. Age dating carried out on pitchblende predating and postdating baryte, indicates that baryte mineralization took place between Lower Permian and Lower Jurassic times (290 to 200 Ma). 87Sr/86Sr ratios exclude any derivation of ore-bearing fluids from a mantle source and point to a crustal origin. Sulphur was derived from sulphate and sulphide contained in the host rocks folded during the Variscan orogeny (Sudetian phase) and from the Permian and Mesozoic sedimentary cover. Strontium isotopes bear witness to a mixture of granite-derived strontium and strontium from the enclosing wall rocks. The unconformity is considered to be a first-order geohydraulic surface which favoured fluid migration via convective cells. The thermal convection may be related to Variscan granites which might have provided additional heat by the decay of U, Th and K.

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