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A large fraction of the Iberian Peninsula climate is controlled by the North Atlantic Oscillation (NAO) circulation pattern. However, besides the NAO mode, the East Atlantic (EA) and Scandinavian (SCAND) patterns also play significant roles. The conjunction of these atmospheric circulation patterns (ACPs) exerts a strong effect on air temperatures, precipitation and wind patterns over the south-western Europe during the boreal winter, but the effects of these ACPs are not restricted to the winter. Summer conditions do not follow a simple pattern and, particularly in Mediterranean regions, other ACPs besides the NAO may better explain the climate variability. It is well-known that lake dynamics on the Iberian Peninsula is greatly controlled by climatic parameters, but the relationships between these various ACPs and lake dynamics have not yet been investigated in detail. We have analyzed seasonal averaged instrumental meteorological and limnological long term datasets from two lakes in northern and central Iberian Peninsula (Lakes Sanabria and Las Madres) to unveil the seasonal influence of the NAO, EA and SCAND circulation patterns over these freshwater systems. The limnological variability within Lakes Sanabria and Las Madres is primarily controlled by fluctuations in precipitation, wind and to lesser extent, by temperature. The primary ACPs associated with the winter limnological processes on Lake Sanabria are the NAO and the SCAND modes, whereas only the EA mode appears to weakly influence during the summer. In contrast, the ACPs influence on Lake Las Madres is less evident. The results obtained from both lakes indicate that the impact of the ACPs over the lake dynamics can be higher than that owing to single local meteorological variables. However, certain local features, such as the altitude, orientation, relief, lake morphology and anthropic influence, are crucial to properly record the signals of these ACPs.

We present a source-to-sink environmental magnetic study of a sediment core from Lake Sanabria (north-west Iberian Peninsula) and rocks of its catchment. The results indicate the occurrence of magnetite, and probably also pyrrhotite, in sediments accumulated between ca. 26 and 13 cal ka BP in a proglacial lake environment. These minerals also appear to dominate the magnetic assemblage of Palaeozoic rocks from the lake catchment. This indicates that sedimentation was then driven by the erosion of glacial flour, which suffered minimal chemical transformation due to a rapid and short routing to the lake. A sharp change in magnetic properties observed in the lake sediments between 13 and 12.6 cal ka BP reflects the rapid retreat of glaciers from the lake catchment. Sediments from the upper half of the studied sequence, accumulated after 12.6 cal ka BP in a lacustrine environment with strong fluvial influence, contain magnetite and smaller amounts of maghemite and greigite. We suggest that greigite grew authigenically under anoxic conditions caused by enhanced accumulation of organic matter into the lake. The occurrence of maghemite in these sediments suggests pedogenic activity in the then deglaciated lake catchment before the erosion and transportation of detrital material into the lake. © 2015 John Wiley & Sons, Ltd., The research was funded by the Spanish Ministry of Science and Competitiveness (CONSOLIDER − GRACCIE Project), the Fundación Patrimonio Natural de Castilla y León, and a Marie Curie Intra European Fellowship IEF-2012 (M.G.-P.). We are grateful to the Paleomagnetic Laboratory CCiTUB-ICTJA CSIC and the Magnetic Fabric Laboratory at the University of Zaragoza for their support and technical assistance with rock magnetic experiments, and to Qingsong Liu for his assistance with interpretation of thermomagnetic runs.

4 páginas, [EN] Lake Sanabria (42º07’30’’N, 06º43’00’’W; 1000 m a.s.l.) in Zamora province, northwest Spain is the largest glacial lake in the Iberian Peninsula. Five Kullenberg long cores and 10 short gravity cores were studied using magnetic susceptibility, sedimentological analyses and Total Carbon content. The chronological model is based in 13 14C AMS. The basal age of the longest core (ca. 26000 cal. yr. BP) indicates that the maximum extension of the Tera Valley glacier occurred prior to the global Last Glacial Maximum. During a long proglacial lake phase (unit 7, > 26 – 14,3 ka BP) light grey banded, coarse sands and silts with low organic matter content deposited. Glaciolacustrine sediments (unit 6, 14,3 – 13,1 ka BP), with organic matter-rich silts, represent the onset of the last deglaciation. An increase of clastic input (sandy silts) occurred between (13,1- 12,2 ka BP, unit 5) and likely corresponds to a cold pulse within the deglaciation period. Finally, units 4 to 1 (Holocene) are made of organic –rich silts with intervals of sandy layers., [ES] El Lago de Sanabria (42º07’30”N, 06º43’00”O; 1000 m s.n.m.) en la provincia de Zamora, es el mayor lago de origen glacial de la Península Ibérica. En este trabajo se describen los resultados del análisis sedimentológico, de susceptibilidad magnética y composicional (Carbono orgánico total) de cinco sondeos largos tipo Kullenberg y 10 sondeos cortos de gravedad. El modelo cronológico se basa en 13 dataciones de 14C AMS. La edad basal del sondeo más largo es de 26000 cal. años BP lo que indica que la extensión máxima del glaciar del valle del Tera ocurrió antes del Último Máximo Glacial a escala global. Durante una fase de lago proglacial (unidad 7, > 26 – 14,3 ka BP) se depositaron facies clásticas de arenas gruesas y limos grises. Facies de limos con mayor contenido orgánico depositados en un ambiente glaciolacustre (Unidad 6, 14,3 – 13,1 ka BP), representan el comienzo de la última deglaciación. Un aumento en el aporte clástico y la sedimentación de facies de limos arenosos (Unidad 5, 13,1 – 12,2 ka BP) se corresponde probablemente con una fase fría durante la deglaciación. Finalmente, la sedimentación durante el Holoceno (unidades 4 a 1) está dominada por limos orgánicos con intercalaciones finas de arenas., Este estudio se ha realizado con financiación de los proyectos CALIBRE (CGL2006- 13327-C04/CLI), GRACCIE – CONSOLIDER (CSD2007-00067) y de la Fundación Patrimonio Natural de Castilla y León. Margarita Jambrina tiene una beca de Formación de Personal de Investigación de la Universidad de Salamanca.