Lacustrine and tufa deposits from Laguna de Taravilla (Iberian Range, Guadalajara province, Spain, 40°39′ N, 1°59′ W, 1100 m a.s.l.) have been analyzed using sedimentological, mineralogical, geochemical and palynological techniques. A preliminary chronological framework is presented, based on U/Th, 14C AMS, 210Pb and 137Cs analyses. The lacustrine-tufa system developed in a hanging tributary valley of the Upper Tajo River and is composed of a large perched springline tufa build-up, and a barrage tufa dam that impounds Laguna de Taravilla. The Taravilla tufa stable-isotope compositions are similar to other examples in central and southern Spain and they plot in the same field as other lowland European stream tufas. These values are coherent with the range of isotopic compositions measured in the Taravilla spring and lake water. Several sediment cores retrieved from the Laguna de Taravilla have been dated with 14C AMS and analyzed using a multiproxy approach including magnetic properties, sedimentology, geochemistry, stable isotopes, palynology and ostracode assemblages. Sedimentary facies analyses show the dominance of clastic depositional processes in the lacustrine depositional system and suggest the potential of the sequences as palaeoflood records. Sands and coarse silts reflect periods of increased alluvial activity of the inlet. The dominance of clastic depositional processes and the input of detrital carbonate hinder the use of lake mud stable-isotope compositions as environmental indicators. Phases of increased tufa growth occurred during the Late Pleistocene (Last Glacial to Interglacial transition from oxygen isotopic stage 6 to 5) and during the Late Glacial and Early Holocene. Although the Taravilla chronology does not allow a detailed analysis of flood frequency, the reconstructed evolution is coherent with the palaeoflood history of the Tajo River for the last 2000 years, particularly with an increase during the last 500 years. The increase in flood frequency coincides with other evidence of wetter and colder climate and environmental change in Central Spain and in Europe during the Little Ice Age.
Bibliographical noteFunding Information:
Financial support for research at Laguna de Taravilla was provided by the Spanish Inter-Ministry Commission of Science and Technology (CICYT), through the projects IBERARID (REN 2000-1136) “Arid periods in the Mediterranean areas of the Iberian Peninsula since the last glacial maximum: chronology, characterization and palaeoclimate implications”, LIMNOCLIBER (REN2003-09130-C02-02) “Climate and hydrological variability in the Iberian Peninsula since the Last Glacial Maximum: high-resolution analyses of lacustrine cores and its implications for the climate change” and IBERLIMNO (CGL2004-20236-E), “High resolution lacustrine records of climate variability in Spain”. P. González-Sampériz and A. Moreno have benefited from a CSIC-ESF research contract (I3P postdoctoral program). We thank the Director and the staff of the “Parque Natural del Alto Tajo” for their help during fieldwork and also for access to unpublished data. Daniel Ariztegui (Geneva University, Switzerland) and Michael Schnellmann (ETH Zürich, Switzerland) performed the seismic survey on the lake. Dirk Verschuren (Universiteit Gent, Belgium) helped to retrieve and sample the 2001–2002 cores. We are most grateful to Doug Schnurrenberger, Anders Noren and Mark Shapley (LRC, University of Minnesota, USA) for the 2004 coring expedition. We also are thankful to Mark Shapley for his comments and suggestions to an early version of the manuscript. M. Pedley and J. Andrews are acknowledged for their criticism and suggestions that improved the manuscript.
- stable isotope