Lateglacial and Holocene palaeohydrology in the western Mediterranean region: The Lake Estanya record (NE Spain)

Abstract

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 late glacial, 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.

Vegetation and fire history since the last glacial maximum in an inland area of the western Mediterranean Basin (Northern Iberian Plateau, NW Spain)

“…This vegetation shift is typical of the stadial GS-1 (12,850-11,650 cal yr BP, Younger Dryas) in northwestern Iberian sites that have a certain oceanic influence (Allen et al, 1996;Penalba et al, 1997;Munoz Sobrino et al, 2007), but the dryness was probably exacerbated in Ayoo due to its lower altitude and more inland location. This inferred climatic change towards colder temperatures and aridity during the Younger Dryas is quite apparent in other climatic reconstructions from northern Iberia (Morellon et al, 2009;Moreno et al, 2010Moreno et al, , 2011Munoz Sobrino et al, 2013).…”

“…4300, 3900, 3500 and 2800 cal yr BP, which are also detected in the charcoal concentration curve). Arid climatic conditions reconstructed for this period from Lake Zonar (4.0-2.9 cal ka BP; Martin-Puertas et al, 2008), Lake Siles (lake desiccation phases centered at 4.1 and 2.9 cal ka BP; Carrion, 2002), Lake Estanya (4.8-4.0 cal ka BP; Morellon et al, 2009) or the Ronanzas peat bog (4.5-3.0 cal ka BP; Ortiz et al, 2010) would have favored fire spread after human ignitions and consequently forest clearance. This forest clearance process would have increased plant diversity through increasing the variety of niches available and promoting disturbance-tolerant taxa.…”

Hydrological change in Southern Europe responding to increasing North Atlantic overturning during Greenland Stadial 1

“…These marine sequences reveal rapid shifts between weak and strong modes of deep convection during the last deglaciation with potential consequences for European environments that need to be further assessed. The Northern Iberian Peninsula (IP), located within the polar front during the time of the coldest temperatures in GS-1 (10), is a very sensitive location to determine the exact sequence of temperature and hydrological changes in Southern Europe during this stadial, not yet well resolved due to the lack of high-resolution records (11)(12)(13). Here, we present the first stalagmite record, to our knowledge, that covers the entire GS-1 period in Southern Europe, providing an excellent and independent chronological framework and a high-resolution climate reconstruction of this event, allowing understanding of the climate mechanisms that caused the mid-GS-1 transition.…”

Cave monitoring and the potential for palaeoclimate reconstruction from Cueva de Asiul, Cantabria (N. Spain)

“…This region is therefore ideally placed to record variations in competing air masses and is of critical significance for understanding the role of the North Atlantic in controlling Europe's climate (Baldini et al, 2015). Current palaeoclimate records from this International Journal of Speleology 45 (1) 1-9 Tampa, FL (USA) January 2016 region are principally derived from lake (GonzalezSamperiz et al, 2008;Morellón et al, 2009;Roberts et al, 2012) or ocean sediments (Martínez-García et al, 2014, 2015Mojtahid et al, 2013), cave speleothems (Dominguez-Villar et al, 2009;Moreno et al, 2010;Stoll et al, 2013;Martinez-Pillado et al, 2014;Baldini et al, 2015) and from archaeological evidence (LopezMerino et al, 2010). However, few of these records replicate at high resolution over long periods of time.…”