 |
| Titel |
High resolution climate records from modern and last interglacial period derived from giant clam shells (Tridacnidae) from Sulawesi, Indonesia. |
| VerfasserIn |
Camilo Arias Ruiz, Mary Elliot, Antoine Bezos, Kevin Padoja, Laurent Husson, Elisabeth Michel, Carole La |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152312
|
| Publikation (Nr.) |
 EGU/EGU2017-17134.pdf |
|
|
|
|
|
| Zusammenfassung |
| We studied Tridacnidae giant clams as environmental archives to reconstruct climate evolution in a region characterized by major ocean-atmosphere exchange on seasonal and inter-annual timescales: the Sulawesi archipelago.
Using environmental proxies (18O and trace elements) we present reconstructions of inter-annual climate change derived from modern and past interglacial period (MIS 5). For fossil archive, U-Th ages were obtained from fossil coral samples from the same paleo-reef of Tridacna samples, because these bivalves exhibit an open system behavior in U-Th series. Comparison of a 18O profile derived from a 6 year old modern T. squamosa (2006-2012) and a predicted 18O profile derived from local temperature and salinity records confirms the isotopic equilibrium in shell deposition. The strong sea surface temperature (SST) anomaly of 2010 related to a strong La Niña was also recorded in the shell 18O signal. The modern 18O record presents a mean seasonal range of 0.5 ± 0.1 ‰. Additional trace element analyses show that Mg/Ca and Sr/Ca are also temperature dependent in this species and appear less affected by changes in salinity/rainfall. Finally, Ba/Ca ratio appears to reflect both primary production related to coastal up-welling during the dry season, and continental run-off during the wet season. Trace element profiles also exhibit strong anomalies reflecting changes in local hydrography related to the 2010 La Niña.
The ages of the Tridacna fossils derived from U-Th dating are around last interglacial MIS-5 period. 18O records derived from a fossil Tridacna gigas specimen provide a time-window of 14 years. The record shows a reduced mean seasonal range of 18O of around 0.4±0.2 ‰. Absence of Ba/Ca peaks during the wet season suggest a weakened monsoon rainfall activity, but the presence during the dry season suggests a persistent seasonal up-welling at this time. Our study illustrates the usefulness of Tridacnidae fossils in reconstructing past environmental processes with seasonal resolutions.
Keywords: Tridacnidae, 18O, monsoon rainfall, SST, Interglacial periods. |
|
|
|
|
|
|