PP33C-1253:
Evidence for Stable Sea-level during Marine Isotope Stage 5e of the Last Interglacial from the Western Mediterranean
Wednesday, 17 December 2014
Victor J Polyak, University of New Mexico Main Campus, Albuquerque, NM, United States, Bogdan P Onac, University of South Florida Tampa, School of Geosciences, Tampa, FL, United States, Yemane Asmerom, University of New Mexico Main Campus, Earth and Planetary sciences, Albuquerque, NM, United States, Joan J Fornos, Universitat de les Illes Balears, Department de Ciencies de la Terra, Palma de Mallorca, Spain, Jeffrey A Dorale, University of Iowa, Earth and Environmental Sciences, Iowa City, IA, United States and Paola Tuccimei, Roma Tre University, Dipartimento di Scienze Geologiiche, Roma, Italy
Abstract:
Marine isotope stage (MIS) 5e of the last interglacial (LIG) is of great interest because it serves as an analog for the Holocene. Changes in sea-level are, in part, indicative of the global-scale changes in climate. Unlike the stable Holocene, significant drops and/or rises, up to nine meters, have been reported during MIS-5e, suggesting that MIS-5e climate may not have been as stable as the Holocene. Phreatic overgrowths on speleothems (POS) from coastal caves of Mallorca Island (Spain) are deposited less than 40 cm below the brackish water/air interface (water table) at elevations equivalent to sea-level. Thus, stable sea-level stands result in POS that have grown large enough to be used as accurate sea-level markers. Like reefs, the POS are also discontinuous in their coverage of sea-level through time, but the method potentially locates both the position and the age of a particular past sea-level stand with very high accuracy and precision. Uranium-series dating of 18 POS samples from ten Mallorcan caves indicates that for 11,000 years (between 127.4 +/- 0.5 and 116.3 +/- 1.3 ka) the sea-level was remarkably stable at 2.25 +/- 0.75 m above the present sea-level. Given there were any deviations from this Mallorcan MIS-5e sea-level, they were likely too rapid to form POS. Also indicated by our record is a fast 5 mm/year decline in sea-level from MIS-5e to -5d, and from MIS-5b to -5a sea-level rose at 18 mm/year, peaked for 1000 years, then fell rapidly at 5-10 mm/year at the onset of MIS 4. In all, these changes roughly follow Northern Hemisphere summer insolation. Further uranium-series dating of highstands preceding MIS-5 are ongoing to document the tectonic stability of the Mallorcan sea-level site.
