HR: 0800h
AN: PP31B-1525    [Abstracts]
TI: High Resolution Coral Record of Indo-Pacific Warm Pool Climate During the Penultimate Deglaciation, Sumba, Indonesia
AU: * Qu, D
EM: Dingchuang.Qu@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Gagan, M K
PP31B-1525 AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Dunbar, G B
PP31B-1525 AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Hantoro, W S
PP31B-1525 AF: Research and Development Center for Geotechnology, Indonesian Institute of Sciences, Bandung, 40135 Indonesia
AU: Suwargadi, B W
PP31B-1525 AF: Research and Development Center for Geotechnology, Indonesian Institute of Sciences, Bandung, 40135 Indonesia
AU: Mortimer, G E
PP31B-1525 AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: McCulloch, M T
PP31B-1525 AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AB: Ocean-atmosphere interactions in the tropical Indo-Pacific Warm Pool are fundamental drivers of the global meridional Hadley and zonal Walker circulations. Recent research indicates that changes in sea surface temperatures and atmospheric convection in this region play important roles in modulating global climate on interannual, decadal, millennial, and even glacial-interglacial time-scales. Knowing the natural bounds of past ocean-atmosphere variability in the Warm Pool region will enhance our ability to predict the climate in the future. Massive, long-lived corals are one of the only paleoclimate archives capable of providing high resolution records (weekly to monthly) for periods when climate boundary conditions were different from those of the present day. Here we report a 35-year-long high resolution ¹⁸O/¹⁶O record for a sea-level highstand during the penultimate deglaciation reconstructed from a massive Porites coral from the Mondu raised reefs, located southwest of Cape Laundi on the island of Sumba, eastern Indonesia. Topographic surveys and stratigraphic analysis of the Mondu raised reefs indicate that the highstand reef developed between MIS 6e and 5e, when the sea level was about 15 meters lower than it is today. U/Th dating shows that the well preserved massive Porites coral we analyzed grew 136 ± 1.5 thousand years ago. Based on this age, and previous studies, it is likely that the coral grew during a highstand period of the penultimate deglaciation when the sea level peaked at this height for only a short period of time before it dropped 60 to 80 meters at about 130 thousand years ago and finally rose again up to a few meters higher than its present level at the Last Interglacial Maximum. The average ¹⁸O/¹⁶O for the fossil coral is -4.4‰, which is 0.6‰ higher than the average value for mid-late Holocene corals on the Mondu reefs. Taking into account the ice volume effect, and assuming constant surface salinity, the shift in ¹⁸O indicates that the SST during this period of the penultimate deglaciation at 130 ± 1.5 ka was 2°C cooler than that in mid-late Holocene and today. The high resolution coral ¹⁸O/¹⁶O record shows excellent preservation of annual cycles and, in some years, a double peak indicating the seasonal development of the wet/warm summer monsoon. The double peak reflects the cross-equatorial movement of the Inter-Tropical Convergence Zone, presumably during years when monsoon rainfall is strong. The record also shows that the frequency of cooler/drier years, indicative of El Nino events, was lower than today.
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
DE: 4870 Stable isotopes (0454, 1041)
DE: 4916 Corals (4220)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005