Silica ‘chimneys’ related to paleo-brine discharge from the Williston Basin

Siliceous ‘solution chimneys’are described from a region unaffected by volcanism or high temperature fluid flow. The features are interpreted as low temperature dissolution/replacement structures formed in Paleozoic carbonates. The features are thought to be paleo-brine spring discharge sites similar to modern springs found within the same area which host a mid-continent marine ecosystem. Geochemical modeling shows mixing of spring waters with shallow groundwater could generate conditions of undersaturation with respect to calcite and silica oversaturation.