Holocene hydrological changes in south-western Mediterranean as recorded by lake-level fluctuations at Lago Preola,a coastal lake in southern Sicily,Italy |
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| Authors: | Michel Magny Boris Vannière Camilla Calo Laurent Millet Aurélie Leroux Odile Peyron Gianni Zanchetta Tommaso La Mantia Willy Tinner |
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| Institution: | 1. Laboratoire de Chrono-Environnement, UMR 6249 du CNRS, UFR des Sciences et Techniques, 16 route de Gray, F-25 030 Besançon, France;2. Paleoecology, Institute of Plant Sciences and Oeschger Center for Climate Change Research, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland;3. Dipartimento di Scienze della Terra, Via S. Maria 53, 56126 Pisa, Italy;4. IGC-CNR, Via Moruzzi 1, 56100 Pisa, Italy;5. Dipartimento di Colture Arboree, Facoltà di Agraria, Viale delle Scienze 11, I-90128 Palermo, Italy;1. Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Lanzhou University, 222 South Tianshui Rd., Lanzhou, 730000 Gansu Province, China;2. Department of Geological Sciences, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912, USA;1. Institute of Mineral Resources, Chinese Academy of Geological Sciences, 100037 Beijing, China;2. Faculty of Earth Resources, China University of Geosciences, 430074 Wuhan, China;3. National Research Center of Geoanalysis, 100037 Beijing, China;4. College of Geoscience and Surveying Engineering, China University of Mining and Technology, 100083 Beijing, China;5. Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029 Beijing, China;1. Faculty of Earth Sciences, University of Iceland, Reykjavík, Iceland;2. INSTAAR and Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA;1. The Zinman Institute of Archaeology, University of Haifa, Mount Carmel, Haifa, 3498838, Israel;2. Institute of Evolution Sciences of Montpellier (ISEM), University of Montpellier, CNRS, IRD, EPHE, CIRAD, INRAP, 34900, Montpellier, France;3. Kimmel Center for Archaeological Science, Weizmann Institute of Science, Rehovot, Israel |
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| Abstract: | This paper presents a high-resolution lake-level record for the Holocene at Lago Preola (Sicily, southern Italy) based on a specific sedimentological approach, with a chronology derived from AMS radiocarbon dates. It gives evidence of three major successive palaeohydrological periods, with (1) a pronounced dryness during the early Holocene until ca 10300 cal BP, (2) a highstand from ca 10300 to 4500 cal BP, and (3) a marked lowstand from 4500 cal BP to present. Large amplitude lake-level fluctuations characterise two transition phases at ca 10300–9000 and 6400–4500 cal BP. Period 2 was interrupted between 8300 and 7000 cal BP by a dry phase that was punctuated to ca 7300 cal BP by the deposition of a tephra from neighbouring Pantelleria Island. Comparisons of the Preola record with other palaeohydrological records along north–south and west–east transects in the Mediterranean show contrasting patterns of hydrological changes: north (south) of around 40°N latitude, the records highlight a mid-Holocene period characterised by lake-level minima (maxima). Humid mid-Holocene conditions over the Mediterranean south of 40°N were probably linked to a strong weakening of the Hadley cell circulation and of monsoon winds. We suggest that the maximum of humidity in the Mediterranean during the mid-Holocene was characterised by humid winters to the north of 40°N and humid summers to the south. On a multi-centennial scale, the high-resolution palaeohydrological reconstructions in the central Mediterranean area reveal a strong climate reversal around 4500–4000 cal BP, with contrasting changes in the hydrological cycle. In addition to seasonal and inter-hemispherical changes related to orbital forcing, this major oscillation might be related to non-linear responses of the climatic system to the gradual decrease in summer insolation at northern latitudes. Another major climate oscillation around 7500–7000 cal BP may have resulted from the combined effects of (1) a strong rate of change in insolation, and (2) variations in solar activity. Finally, comparisons of the Preola lake-level record with Sicilian pollen records suggest a strong influence of moisture availability on vegetation development in Sicily. Very dry early Holocene conditions probably prevented the expansion of coastal evergreen forests, while decreasing moisture availability since the onset of the late Holocene may have exacerbated effects of intensive land-use. |
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