[M-IS19] Paleoclimatology and paleoceanography

[MIS19-09] A 70 years changes of the Java Sea surface condition based on geochemical analyses of a coral core

*Ai Genda¹, Atsushi Suzuki², Toyoho Ishimura³, Minoru Ikehara⁴, Mayuri Inoue¹ (1.Graduate School of National Science and Technology, Okayama University, 2.Geological Survey of Japan Natinal Institute of Advanced Industrial Science and Technology, 3.National Institute of Technology, Ibaraki College, 4.Center for Advanced Marine Core Research, Kochi University)

At Indonesian Archipelago, observed and instrumental records have not been well recorded because of complex terrain. In this study, we have reconstructed sea surface condition of the Java Sea for past 70 years based on δ¹³C, Sr/Ca and U/Ca ratios in the coral skeleton.
A coral core (Porites sp.) was collected from the the Seribu Islands located at the Java Sea, Indonesia. Measurements of Sr/Ca, U/Ca ratios and δ¹³C were performed by inductively coupled plasma (ICP)-optical emission spectrometer, ICP-mass spectrometer and stable isotope ratio mass spectrometer with about 2-month time resolution.
Although it has been reported that both coral Sr/Ca and U/Ca ratios can be used as paleothermometer [Beck et al., 1992; Min et al., 1995], coral U/Ca ratios also depends on seawater pH [Inoue et al., 2011] and carbonate ion concentration ([CO₃^2-]) [Anagnostou et al., 2011]. Furthermore, since coral δ¹³C reflects DIC of ambient seawater, we will discuss about marine environments such as water temperature and seawater pH at the Java Sea for 70 years.