A high-resolution Sr/Ca and [delta][sup 18]O coral record from the Great Barrier Reef, Australia, and the 1982-1983 El Nino
- Australian National Univ., Canberra (Australia)
- Australian Institute of Marine Science, Queensland (Australia)
A high-resolution (near weekly) Sr/Ca and oxygen isotopic record is presented for a coral from the Pandora Reef in the Great Barrier Reef (GBR) of Australia during the period of 1978 to 1984. The records are well correlated except for periods of high rainfall when river runoff has significantly modified the [delta][sup 18]O value of seawater. Using the Sr/Ca temperature calibration of De Villiers et al., the Sr/Ca records exhibit seasonally controlled cyclical SST (sea surface temperature) variations of from [approximately] 21 to [approximately] 28[degrees]C. During the very strong El Nino of 1982-1983, the Sr/CA systematics indicate a sharp drop in the winter SST to [approximately] 18.5[degrees]C. This represents a temperature anomaly of -3[degrees]C which is approximately twice that given by the [delta][sup 18]O variations, suggesting an [approximately] x2 amplification of the anomaly by the Sr/Ca system, possibly due to the increasing dominance of inorganically controlled aragonite-seawater fractionation. The oxygen isotope systematics show the combined effects of both temperature and changing seawater [delta][sup 18]O values, the latter reflecting the influx of [sup 18]O-depleted runoff during periods of high rainfall. Due to the extremely low ([approximately] 10[sup [minus]3]) Sr and Ca contents of river runoff relative to seawater, it is possible to use the Sr/Ca thermometer to calculate temperatures independent of major floods and hence deconvolve the combined effects in the oxygen isotopic record of variable temperature and the [delta][sup 18]O value of seawater. Using this approach it is possible to quantitatively reproduce the volume of runoff from the Burdekin River during the periods of major flooding that occurred in early 1979 and 1981. The results of this study demonstrate that the combined use of high-resolution Sr/Ca and [delta][sup 18]O systematics in scleractinian corals is a powerful tool for providing quantitative constraints on past climate.
- OSTI ID:
- 6653187
- Journal Information:
- Geochimica et Cosmochimica Acta; (United States), Vol. 58:12; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CORALS
ISOTOPE RATIO
EARTH PLANET
PALEOCLIMATOLOGY
SEAS
TEMPERATURE MEASUREMENT
CALCIUM
OXYGEN 18
STRONTIUM
ALKALINE EARTH METALS
ANIMALS
CNIDARIA
COELENTERATA
ELEMENTS
EVEN-EVEN NUCLEI
INVERTEBRATES
ISOTOPES
LIGHT NUCLEI
METALS
NUCLEI
OXYGEN ISOTOPES
PALEONTOLOGY
PLANETS
STABLE ISOTOPES
SURFACE WATERS
540310* - Environment
Aquatic- Basic Studies- (1990-)