Formación de yeso autigénico en la llanura de inundación del río Tinto (Huelva). Implicaciones paleoambientales

Abstract

This paper describes the occurrence of auth¡genic gypsum on the flood plain of the Río Tinto, a river highly polluted by acid mine-drainage. Gypsum appears typically as isolated tabular crystals of selenite scattered within the muddy sediment, and associated with day minerals, quartz, feldspars and halite. Both field and experimental data strongly suggest that the gypsum precipitated authigenically on the mudflat as a result of the reaction of acidic sulphate waters with detrital and biogenic calcite locally supplied by unpolluted tributaries. Consequently, in this case the presence of authigenic gypsum could be used as a paleoenvironmental indicator of the stream contamination