Late-Quaternary hydrological evolution of Fuente de Piedra playa-lake (southern Iberia) controlled by neotectonics and climate changes

Abstract. Playa-lakes developed in semi-arid regions are sensitive to water input reductions, which may be influenced not only by climate changes and human management but also by changes in the size of the watershed. We accomplished an interdisciplinary study combining structural, geomorphic, sedimentological, mineralogical and hydrological analyses to better understand the Fuente de Piedra (FdP) playa-lake evolution in southern Spain. By using previously published temperature and precipitation reconstructions, we assess the potential evapotranspiration and the runoff to estimate the maximum lake level during the FdP lifespan (>35 ka). Our results indicate that the FdP playa-lake level never exceeded 5m, although deposits at its NE margin are up to 15 m above the current lakebed at present. These lacustrine deposits are slightly tilted towards the SW. The electrical conductivity profiles of groundwater in the FdP's shore and surroundings reveal a more pronounced interface between brackish water and brine in the northern part compared to the southern part of the basin. This implies that saline water once occupied the northern playa-lake margin in an area that is hardly ever flooded at present. The presence of reworked gypsum in the sedimentary sequence of the southern margin (down to a depth of 14 m), indicates substantial erosion of prior gypsum deposits, possibly redistributed from northern deposition areas. Altogether, our data suggest a SW displacement of the playa-lake depocenter caused by an uplift of the NE and subsidence of the SW area. This shift is congruent with the combined effect of both the La Nava sinistral-normal fault and the Las Latas dextral-normal fault, respectively at the E and S margins of the FdP playa-lake.