HR: 1020h
AN: PP52A-0656    [Abstracts]
TI: New Climate Reconstruction Method Well Suited To The Last Centuries: The Coral Exemple
AU: * Juillet-Leclerc, A
EM: Anne.Juillet-Leclerc@lsce.cnrs-gif.fr
AF: Anne Juillet-Leclerc, LSCE Avenue de la Terrasse, Gif sur Yvette, 91189 France
AB: Reconstructions of environmental parameters conducted to elucidate the climatic changes of the last centuries obey to specific constraints leading to specific methodology. These investigations essentially require high resolution (from seasonal to interannual resolution), quantitative and well dated records. It supposes the improvement and the development of several proxies, based on non-empirical transfer functions and examined with new statistical approaches. The tool that I developed derived from coral skeleton responds to these conditions. First, coral aragonite offers natural features: growth bands visible on X-ray pictures allow an easy and rapid chronology, the mean annual growth of Porites (species commonly used for paleoclimatic purpose) of more than 1 cm per year insures at least a monthly sampling, the geochemical tracers of aragonite are used for a long time. By combining biological, bio-crystallization and geochemical understanding, I can demonstrate that in opposite with the interpretation commonly used, the coral skeleton deposit is essentially governed by kinetic processes. In addition, following time and space scales, coral presents successive growth units driving to different significance for monthly and annual proxies. On the other hand, this understanding highlights the limits of the tool: for example, the highest resolution is limited to monthly sample. Up to now, the interpretation is restricted to interannual signals. Future experiments conducted on cultured corals are planned to provide evidences to identify the factors forcing the seasonal variability. Since the aragonite deposition is more complex than it was earlier supposed, the proxy signals are not linear versus time. The neural network approach, well suited to non-linear records, applied on several stable isotopes and trace elements provided realistic SST and SSS reconstructions in Fiji Island during the last century. This cross-disciplinary investigation may be achieved only through multi collaborations.
DE: 0419 Biomineralization
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005