HR: 0800h
AN: PP31A-0177    [Abstracts]
TI: Seasonality Records From Stable Isotopes and Trace Elements in Mussel and Limpet Shells From Archaeological Sites on Gibraltar
AU: Fa, D
EM: darrenfa@gibraltar.gi
AF: The Gibraltar Museum, 18-20 Bomb House Lane, Gibraltar, PO Box 939, Gibraltar
AU: * Ferguson, J E
EM: julie.ferguson@earth.ox.ac.uk
AF: Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom
AU: Atkinson, T C
EM: t.atkinson@ucl.ac.uk
AF: Hydrogeology Research Group, Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, United Kingdom
AU: Barton, R N
EM: nick.barton@archaeology.oxford.ac.uk
AF: Institute of Archaeology, University of Oxford, Beaumont Street, Oxford, OX1 2PG, United Kingdom
AU: Ditchfield, P
EM: peter.ditchfield@rlaha.ox.ac.uk
AF: Research Laboratory for Archaeology and the History of Art, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford, OX1 3QY, United Kingdom
AU: Finlayson, G
EM: gfjmh@gibraltar.gi
AF: The Gibraltar Museum, 18-20 Bomb House Lane, Gibraltar, PO Box 939, Gibraltar
AU: Finlayson, J C
EM: jcfinlay@gibraltar.gi
AF: The Gibraltar Museum, 18-20 Bomb House Lane, Gibraltar, PO Box 939, Gibraltar
AU: Henderson, G M
EM: gideon.henderson@earth.ox.ac.uk
AF: Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom
AB: Seasonal resolution climate records from mid and high latitudes would allow investigation of the role of seasonality in controlling mean climate on diverse timescales, and of the evolution of climate systems such as the North Atlantic Oscillation (NAO). But achieving such seasonal resolution is difficult for regions outside the growth range of surface corals. Marine mollusc shells provide a possible archive and contain growth increments varying in scale from tidal to annual. However, finding and dating sequences of marine mollusc shells spanning long periods of time is difficult due to sea-level change and the destructional nature of most coastal environments. In this study, we have made use of the habit of hominins on Gibraltar to collect molluscs for food over at least the last 120 kyr. In archaeological excavations of two caves (Gorham's and Vanguard Caves), mollusc shells were found, in habitation levels and in sediment blown into the caves. Existing ¹⁴C, OSL, and U-series chronologies provide a chronological framework for this suite of samples. The species found are predominantly Mytilus (mussels) or Patella (limpets). Gibraltar is an interesting location for paleoclimate reconstruction due to its proximity to the boundary of modern day climate belts but also due to its anthropological and archaeological importance. To gain a quantitative understanding of the local controls on stable isotopes and trace elements within Gibraltarian shells, we have initiated a water-sampling programme; emplaced a temperature and salinity logger near the sampling site; and marked live Patella and Mytilus with fluorescent dye to firmly establish growth rates and controls on chemical composition. We have also conducted stable-isotope and trace-element analysis of modern and fossil Patella and Mytilus shells by micromilling. Recent Patella and Mytilus shells show that the oxygen isotope composition of modern shells allow the accurate reconstruction of the full seasonal range in sea-surface temperature. Analysis of three fossil Mytilus samples contained within a Neanderthal occupation level from approximately 115 kyr show clear annual cycles in δ ¹⁸O but with different absolute values. Patella samples have also been analysed from the last glacial and from 800-300B.C. Results allow an assessment of past changes in seasonality and of the utility of this archeological shell material as an archive for past change.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting