Formation of fossil hydrothermal chimneys and mounds from Silvermines, Ireland

Abstract

Sulphur isotope analyses reveal that the fossil hydrothermal pyrite mound and tubes at Silvermines were produced by the reaction of hydrothermal Fe(II) with bacteriogenically-reduced sulphur species (δ34S range:−18.4 to −42.5%). This took place in a brine pool dominated by hyper saline Carboniferous seawater. This is in contrast to their modern, but considerably larger, morphological counterparts forming by direct precipitation of hydrothermal sulphides on the East Pacific Rise at 21°N