HR: 1330h
AN: PP52A-0954    [PDF]
TI: 280-year Long Sr/Ca and $\delta$$^{18}$O Records From Flinders Reef, Western Coral Sea
AU: * Calvo, E
EM: Eva.Calvo@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Marshall, J F
EM: John.Marshall@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Pelejero, C
EM: Carles.Pelejero@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: McCulloch, M T
EM: Malcolm.McCulloch@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Lough, J
AF: Australian Institute of Marine Science, PMB3, Townsville MC, Qld 4810 Australia
AU: Gagan, M K
EM: Michael.Gagan@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AB: The combination of parallel Sr/Ca and $\delta$$^{18}$O records in corals allows reconstruction of past changes in sea surface temperature (SST) and seawater $\delta$$^{18}$O composition (McCulloch et al., 1994). The latter provides climatic information related to changes in the hydrologic cycle and can be interpreted as a salinity proxy. Since the $\delta$$^{18}$O signal is affected by both SST and seawater isotopic composition, a salinity record can be obtained by removing the temperature signal using a parallel Sr/Ca record, a proxy for SST, obtained from the same coral. Low resolution (5-year intervals) Sr/Ca and $\delta$$^{18}$O analyses, going back to 1710 AD, have been performed on a {\it Porites} coral core collected from Flinders Reef, an offshore reef on the Queensland Plateau ($17\deg$S, $149\deg$E), 250 km from the north-east coast of Australia. For the last 280 years, the preliminary Sr/Ca-SST record shows an increasing long-term trend towards the warm temperatures recorded during 1990, when the coral was collected. An increasing trend towards more negative $\delta$$^{18}$O values (warmer and/or less saline conditions) is also observed in the isotopic record, which also reflects the 20th century warming. Despite this general common trend, interdecadal variability differences between both records suggest that temperature alone cannot explain the $\delta$$^{18}$O changes observed in this site of the Coral Sea. A freshening of surface waters after 1870 has recently been reported from coral cores collected from the inshore region in the Great Barrier Reef and interpreted as indicating a weakening in trade winds and ocean circulation (Hendy, 2002). In the Flinders coral, however, an apparent freshening occurs in the early 1800s, followed by a subsequent transition to more saline conditions during the first half of the 20th century. Our data will be compared to that from the GBR and elsewhere in the SW Pacific (Quinn, 1998).\\ Hendy, E. J. et al. Science 295, 1511-1514 (2002) McCulloch, M.T. et al. Geochimica at Cosmochimica Acta, 58, 2747-2754 (1994) Quinn, T.M. et al. Paleoceanography 13, 412-426 (1998)
DE: 1050 Marine geochemistry (4835, 4850)
DE: 3344 Paleoclimatology
DE: 4870 Stable isotopes
DE: 4875 Trace elements
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting