Temperate and semi-arid tufas in the Pleistocene to Recent fluvial barrage system in the Mediterranean area:: The Ruidera Lakes Natural Park (Central spain)

The Ruidera Lakes Natural Park, in Central Spain, contains a well-exposed Pleistocene to Recent freshwater carbonate (tufa) succession dominated by fluvial barrages and lacustrine deposits. The majority of exposed tufas are Holocene to Recent in age. Today, carbonate accumulation is currently manifested as active phytoherm barrage constructions, marginal lacustrine stromatolitic terraces, lacustrine lime muds (all produced mainly by precipitation) and sand-size detrital tufa. The depositional history of the Ruidera Park sites has been interpreted from natural outcrops, rotary drill and percussion auger cores. These reveal a long Quaternary record of microbially dominated barrage framework developments and associated lacustrine carbonates. These alternate with frost weathering deposits and detrital tufa episodes, especially during cooler conditions. U-series dating of several earlier tufa deposits within the park indicates four distinct episodes of tufa development at 190-250 ka B.P., 90-130 ka B.P., 30-40 ka B.P. and 16 ka B.P.-Present. The three oldest episodes appear to be related to cyclic tufa-building events associated with warm periods of Oxygen Isotope Stages (OIS): 7, 5 and 3. Growth under present conditions is slow and several barrages have been damaged by human activity and drought events. (c) 2005 Elsevier B.V. All rights reserved.