The multi-proxy analysis of sediment cores recovered in karstic Lake Estanya (42°02′ N, 0°32′ E; 670 m a. s. l., NE Spain), located in the transitional area between the humid Pyrenees and the semi-arid Central Ebro Basin, provides the first high-resolution, continuous sedimentary record in the region, extending back the last 21 000 years. The integration of sedimentary facies, elemental and isotopical geochemistry and biogenic silica, together with a robust age model based on 17 AMS radiocarbon dates, enables precise reconstruction of the main hydrological and environmental changes in the region during the last deglaciation. Arid conditions, represented by shallow lake levels, predominantly saline waters and reduced organic productivity occurred throughout the last glacial maximum (21-18 cal kyrs BP) and the lateglacial, reaching their maximum intensity during the period 18-14.5 cal kyrs BP (including Heinrich event 1) and the Younger Dryas (12.9-11.6 cal kyrs BP). Less saline conditions characterized the 14.5-12.6 cal kyrs BP period, suggesting higher effective moisture during the Bölling/Allerød. The onset of more humid conditions started at 9.4 cal kyrs, indicating a delayed hydrological response to the onset of the Holocene which is also documented in several sites of the Mediterranean Basin. Higher, although fluctuating, Holocene lake levels were punctuated by a mid Holocene arid period between 4.8 and 4.0 cal kyrs BP. A major lake-level rise occurred at 1.2 cal kyrs BP, conducive to the establishment of conditions similar to the present and interrupted by a last major water level drop, occurring around 800 cal yrs BP, which coincides with the Medieval Climate Anomaly. The main hydrological stages in Lake Estanya are in phase with most Western Mediterranean and North Atlantic continental and marine records, but our results also show similarities with other Iberian and northern African reconstructions, emphasizing peculiarities of palaeohydrological evolution of the Iberian Peninsula during the last deglaciation.
Bibliographical noteFunding Information:
This research has been funded through the projects LIMNOCLIBER (REN2003-09130-C02-02), IBERLIMNO (CGL2005-20236-E/CLI), LIMNOCAL (CGL2006-13327-C04-01), PALEODIVERSITAS (CGL2006-02956/BOS), GRACCIE (CSD2007-00067); provided by the Spanish Inter-Ministry Commission of Science and Technology (CICYT); and PIRINEOSABRUPT (PM073/2007), provided by the Diputación General de Aragón. Additional funding for XRD analyses (Univ. of Cádiz) and geochemical analyses (EEZ-CSIC and MARUM Centre) was provided by the Aragonese Regional Government – CAJA INMACULADA by means of 2 travel grants.
M. Morellón and J.P. Corella are supported by PhD contracts with the CONAI + D (Aragonese Scientific Council for Research and Development) and A. Moreno and M. Rico hold post-doctoral contracts funded by the ESF (‘Marie Curie programme’) and the Spanish Ministry of Science and Innovation (‘Juan de la Cierva programme’), respectively. We are indebted to Anders Noren, Doug Schnurrenberger and Mark Shapley (LRC-Univ. of Minnesota) for the 2004 coring campaign and Santiago Giralt and Armand Hernández (IJA-CSIC), as well as Alberto Sáez and J.J. Pueyo-Mur (Univ. of Barcelona) for coring assistance in 2006. We thank Andrés Ospino for his help in diatom sample treatment and slide mounting and Marco Klann (MARUM Centre, Univ. of Bremen) for biogenic silica analyses. We are also grateful to EEZ-CSIC, EEAD-CSIC and IPE-CSIC laboratory staff for their collaboration in this research. We thank Santiago Giralt and anonymous reviewer for their helpful comments and their criticism, which led to a considerable improvement in the manuscript.
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