Middle Pleistocene magnetostratigraphy and susceptibility stratigraphy: data from a carbonate aeolian system,Mallorca, Western Mediterranean |
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| Institution: | 1. University of Groningen, Groningen Institute of Archaeology, P.O. Box 716, 9700 AS Groningen, The Netherlands;2. Netherlands Cultural Heritage Agency (RCE), P.O. Box 1600, 3800 BP Amersfoort, The Netherlands;1. AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Department of General Geology and Geotourism, al. A. Mickiewicza 30, 30-059 Kraków, Poland;2. Jagiellonian University, Institute of Geological Sciences, Oleandry 2a, 30-063 Kraków, Poland;1. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;2. Laboratoire Géosciences Paris Sud (GEOPS), UMR 8148 CNRS-Université Paris-Sud, Orsay 91405, France;1. Department of Computer Science, University of North Carolina at Chapel Hill, USA 201 S. Columbia St., Chapel Hill, NC 27599, USA;2. Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, USA 125 Mason Farm Road, Chapel Hill, NC 27599, USA;3. Imaging Genetics Center, University of Southern California, USA 2001 N. Soto Street, SSB1-102, Los Angeles, CA 90032, USA;4. Department of Radiology, University of Pennsylvania, USA 3400 Civic Center Boulevard Atrium, Ground Floor, Philadelphia, PA 19104, USA;5. Department of Computer Science, University of Salzburg, Austria Jakob Haringer Strasse 2, 5020 Salzburg, Austria |
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| Abstract: | This study shows that successions of Pleistocene carbonate aeolian deposits can be placed successfully in a geochronologic framework using magnetostratigraphic and susceptibility stratigraphic analysis supplemented by luminescence dating, studies of wave-cut platforms, and biostratigraphic evidence. The investigated aeolian system covers a significant part of southernmost Mallorca and is exposed in impressive coastal cliff sections.At the study site at Els Bancals the aeolian system has a maximum thickness of 16 m and is composed of alternating dark red colluvial deposits and greyish red aeolian dune and sand-sheet deposits forming seven cyclostratigraphic units. Each cyclostratigraphic unit represents landscape stabilisation, colluviation, and soil formation followed by dunefield development, when marine carbonate sand was transported far inland by westerly or north-westerly winds. The aeolian system is located on top of a wave-cut marine platform 12–14 m a.s.l. This platform probably formed during a sea-level highstand in Marine Isotope Stage (MIS) 11 (427–364 ka), and renewed marine activity probably later in MIS 11 is indicated by the formation of beach deposits.Two sections at Els Bancals were sampled for a paleomagnetic study; additional samples were taken to detect variations in magnetic susceptibility (MS). The characteristic remanent magnetisation has been recovered for the most part of the succession in spite of diagenetic overprinting. There is evidence for two probably three reversal polarity excursions, possible connected to the Levantine, CR1 and CR0/Biwa III episodes. If this correlation is correct, the sampled succession represents a time interval in the Middle Pleistocene between ca 410 and ca 260 ka. This age estimate is supported by the MS study and by luminescence dates of 333±70 ka (aeolianite from lower part of the succession) and 275±23 ka (aeolianite from the top of the succession).The nature of the succession suggests deposition during alternating warm and moist (colluvial deposition; soil formation) and cold, dry and windy conditions (dunefield formation). The susceptibility signal can be correlated with the insolation signal at 65°N suggesting that environmental variation on Mallorca was linked to orbitally forced climate change, and it seems that aeolian activity and dunefield formation were linked to glacial or stadial periods. |
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