High precision thorium-230 ages of corals and the timing of sea level fluctuations in the late Quaternary
Mass spectrometric techniques for the measurement of {sup 230}Th and {sup 234}U have been developed. These techniques have made it possible to reduce the analytical errors in {sup 230}Th dating of corals using very small samples (10{sup 7} to 10{sup 10} atoms). The time range over which useful data on corals can now be obtained ranges from 15 to 500,000 years. For young corals, this approach may be preferable to {sup 14}C dating. The precision with which the age of a coral can not be determined makes it possible to determine the timing of sea level fluctuations in the late Quaternary. Analyses of a number of corals that grew during the last interglacial period yield ages of 122 to 130 ky. The ages coincide with or slightly postdate the summer solar insolation high at 65{degree}N latitude, which occurred 128 ky ago. This supports the idea that changes in Pleistocene climate can be the result of orbital forcing. Coral ages may allow us to resolve the ages of individual coseismic uplift events and thereby date prehistoric earthquakes. This possibility has been examined at two localities, northwest Santo Island and north Malekula Island, Vanuatu. The {sup 230}Th growth dates of the surfaces of adjacent emerged coral heads, collected from the same elevation on northwest Santo Island, were, within analytical error, identical (A.D. 1866 {plus minus} 4 and A.D. 1864 {plus minus} 4). This indicates that the corals died at the same time and is consistent with the idea that they were killed by coseismic uplift. Similar adjacent coral heads on north Malekula Island yielded {sup 230}Th growth dates of A.D. 1729 {plus minus} 3 and A.D. 1718 {plus minus} 5. The ages are similar but analytically distinguishable. The difference may be due to erosion of the outer, younger, portion of the latter coral head.
- Research Organization:
- California Inst. of Tech., Pasadena, CA (USA)
- OSTI ID:
- 7266144
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CORALS
ISOTOPE DATING
EARTHQUAKES
AGE ESTIMATION
SEA LEVEL
GEOLOGIC HISTORY
ACCURACY
CARBON 14
COMPARATIVE EVALUATIONS
EROSION
FLUCTUATIONS
GROUND UPLIFT
MASS SPECTROSCOPY
PALEOCLIMATOLOGY
QUATERNARY PERIOD
THORIUM 230
URANIUM 234
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON ISOTOPES
CENOZOIC ERA
CNIDARIA
COELENTERATA
EVEN-EVEN NUCLEI
GEOLOGIC AGES
HEAVY ION DECAY RADIOISOTOPES
HEAVY NUCLEI
INVERTEBRATES
ISOTOPES
LEVELS
LIGHT NUCLEI
MAGNESIUM 28 DECAY RADIOISOTOPES
NEON 24 DECAY RADIOISOTOPES
NUCLEI
PALEONTOLOGY
RADIOISOTOPES
SEISMIC EVENTS
SPECTROSCOPY
THORIUM ISOTOPES
URANIUM ISOTOPES
VARIATIONS
YEARS LIVING RADIOISOTOPES
580000* - Geosciences