Sr/Ca analysis of a fossil Porites coral from Kenya-s coastal area on seasonal temperature variations during the mid-Holocene
A. Blume1, M. Leupold1, M. Pfeiffer2, L. Reuning2, D. Garbe-Schönberg2, S.Y. Cahyarini 3
1EMR-Group, Geological Institute, RWTH Aachen University, Wuellnerstr. 2, 52056 Aachen, Germany
2Institute of Geosciences, Kiel University, Ludewig-Meyn-Str. 10, 24118 Kiel, Germany
3Indonesian Institute of Sciences (LIPI)-R.C for Geotechnology
Abstract
The Sea Surface Temperature (SST) of the western Indian Ocean shows a bimodal distribution caused by insolation changes and the migration of the Inter-Tropical Convergence Zone. Moreover, on inter-annual timescales, the western Indian Ocean is influenced by two monsoon periods and two seasonally-occurring events, the Indian Ocean Dipole (IOD) and the El Niño Southern Oscillation (ENSO). An understanding of paleoclimate is essential to better understand these ocean-atmosphere interactions and be able to predict future climate variability. Chemical analyses of corals allow us to reconstruct SST changes in high resolution (monthly-seasonal) and therefore help us to link them to seasonal insolation pattern variations caused by orbital forcing. Here, we use a Sr/Ca record of a fossil Porites coral, which is dated to the mid-Holocene (6k) and covers 16 years. Sr/Ca-ratios were measured using ICP-OES with simultaneous data acquisition. The results show variations in the bimodality and average maximum temperatures of each year. A sudden increase in SST by 1.66° C lasted for about 5 years and suggests a possible positive IOD/ENSO-event.
Keywords: Sr/Ca, coral, SST
Topic: Coastal and Ocean Dynamics