La sucesión lacustre pliocena de Villarroya (La Rioja). Principales características paleoambientales basadas en ostrácodos y moluscos

Abstract

Two main episodes have been distinguished in the Pliocene lacustrine sequence of Villarroya (La Rioja, Spain) on the basis of the ostracode and mollusc faunal assemblages. The early episode, which corresponds to a relatively deep lacustrine environment, is recorded in two sequences. Most of the lower sequence may represent oligohaline, bicarbonated waters, with noticeable salinity variations, taking into account the presence of Parathetyan-like ostracodes. The second lacustrine sequence and upper part of the lower sequence correspond to oligohaline to mesohaline waters, recording a chloride character in its upper part. The late episode corresponds to a shallow, palustrine-like setting with temporary ponds feed by sources, and relatively cold, non-carbonated water, as revealed by the ecological features of terrestrial and aquatic gastropods and ostracodes