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Comparison of two Late Quaternary interglacials using stable isotopes: the record from Lake Pamvotis, Ioannina, NW Greece
by
Michael R. Frogley
Centre for Environmental Research, University of Sussex, Brighton, BN1 9QJ, UK
Coauthors: Tim H.E. Heaton (NERC Isotope Geosciences Laboratory, Keyworth), P.C. Tzedakis (Department of Geography, University of Leeds), Ian T. Lawson (Department of Geography, University of Cambridge)
Marine and ice core records that span several climatic cycles have been making increasingly important contributions to our understanding of the character of interglacial climatic variability. Despite this, however, there remains a need to establish the nature of interglacial environmental conditions on land and to chart the response of terrestrial ecosystems to any changes. One potential method of achieving this is to analyse stable isotopic records from temporally extensive Quaternary lacustrine sequences.
An example of such a sequence is core I-284, a 319 m record of continuous sedimentation from Lake Pamvotis, located in the Ioannina Basin of NW Greece. A combination of palaeomagnetic, radiocarbon, pollen biostratigraphical and uranium-series dating techniques have provided a chronology for the core that extends back approximately 430 ka. The lake is effectively closed from a hydrological viewpoint, since it has no outflow or major basin drainage, making it an ideal candidate for isotopic studies.
An interdisciplinary research group has been analysing the sequence with particular respect to the multiple interglacials represented in I-284. Here we present high resolution isotopic results from two intervals of the core that span both time-streams of PEP III, namely: (1) the Last Glacial – Holocene; and (2) the Eemian (or Last Interglacial), being the terrestrial equivalent of Marine Isotope Stage (MIS) 5e.
The major control on the isotopic signal of the modern lake waters is known to be the precipitation/evaporation (P/E) regime acting on the catchment: it appears that this is also true for other interglacial periods in the lake's history. In this study, fossil isotopic data were derived from primary carbonates extracted from the I-284 sediments (either endogenic precipitates or ostracod shells) and compared with other proxy climatic data (in particular, the pollen record). Millennial-scale variability is apparent across the Eemian interval and suggests that the frequency and amplitude of changes during the transitional late glacial and late interglacial phases were markedly higher than during the full interglacial. This suggests that during intervals of minimum ice volume there may be a decoupling between the North Atlantic system and the downstream continental climates of the Eastern Mediterranean. Whilst variability over the Late Glacial – Holocene interval is not as marked, the data nevertheless reveal a climatic history that is in accordance with other established Balkan records. In addition, this interval also exhibits a marked cool and arid period that may correspond with the Younger Dryas stadial known from north-west Europe and elsewhere.
Date received: April 27, 2001
Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cahi-40.