Sea level and coral atolls: Late holocene emergence in the Indian Ocean
- Univ. of Wollongong, New South Wales (Australia)
- Australian Defence Force Academy, Canberra (Australia)
- Australian National Univ., Canberra (Australia)
The Cocos (keeling) Islands in the eastern Indian Ocean were visited by Charles Darwin, who described geomorphological evidence that he considered supported his subsidence theory of coral-reef development. However, several other accounts of the reef islands have questioned Darwin's interpretation, and have suggested that a conglomerate platform that underlies most of the reef islands may indicate recent emergence of the atoll. Radiocarbon ages on corals from this conglomerate platform, reported here, indicate that it formed in the late Holocene. Fossil in situ microatolls above present upper coral growth limits, the elevation of associated beachrock, and the morphological similarity of the conglomerate platform to the present reef-flat deposits indicate a late Holocene sea level above the present relative to the atoll. The atoll has undergone at least 0.5 m of emergence since about 3000 yr B.P. This represents the first radiometrically dated evidence of Holocene emergence from islands in the eastern or central Indian Ocean.
- OSTI ID:
- 6140713
- Journal Information:
- Geology; (USA), Vol. 18:1; ISSN 0091-7613
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CORALS
AGE ESTIMATION
INDIAN OCEAN
ISLANDS
ORIGIN
CARBON 14
CONGLOMERATES
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOMORPHOLOGY
ISOTOPE DATING
QUATERNARY PERIOD
REEFS
SEA LEVEL
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON ISOTOPES
CENOZOIC ERA
CNIDARIA
COELENTERATA
EVEN-EVEN NUCLEI
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
INVERTEBRATES
ISOTOPES
LEVELS
LIGHT NUCLEI
NUCLEI
RADIOISOTOPES
ROCKS
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
YEARS LIVING RADIOISOTOPES
580000* - Geosciences