Seasonally resolved paleoclimate records derived from fossil giant clam shells (Tridacna spp.), application to paleoENSO studies during the past 200ka.
Professor Mary Elliot
Fossil shells of marine bivalves such as giant Tridacna provide information on past environments with seasonal resolutions.
Similarly to corals, changes in mean seasonal cycles and inter-annual variability can be reconstructed by sequentially analyzing the annual layers of calcium carbonate. Inter-comparison studies conducted on modern material show that seasonally resolved records derived from marine bivalves (Tridacna gigas) and corals (Porites) provide similar information.
In this talk I will provide a summary of recent research derived from geochemical analyses of shells of modern and fossil Tridacna collected in several localities around the Western Pacific Warm Pool. Stable isotope (del-18O) and trace element profiles (Mg/Ca, Ba/Ca) are measured on modern samples and compared to local hydrology : sea surface temperature, rainfall and productivity. Information derived from the fossil samples which range from the Holocene to the past interglacial periods (MIS5 and MIS7) provide unique insight into past seasonality and interannual climate change.