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Radiocarbon in corals from the Cocos (Keeling) Islands and implications for Indian Ocean circulation
Author(s) -
Hua Quan,
Woodroffe Colin D.,
Smithers Scott G.,
Barbetti Mike,
Fink David
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl023882
Subject(s) - oceanography , thermohaline circulation , upwelling , porites , indian ocean , geology , coral , radiocarbon dating , ocean current , ocean gyre , anomaly (physics) , climatology , paleontology , subtropics , biology , fishery , physics , condensed matter physics
Annual bands of a Porites coral from the Cocos (Keeling) Islands, eastern Indian Ocean, were analysed by radiocarbon for 1955–1985 AD. A rapid oceanic response of the site to bomb 14 C is found, with a maximum Δ 14 C value of 132‰ in 1975. This value is considerably higher than those for the northwestern Indian Ocean, suggesting that surface waters reaching Cocos are not derived from the Arabian Sea. Instead, Δ 14 C values for Cocos and those for Watamu (Kenya) agree well over most of the study interval, suggesting that the South Equatorial Current carries 14 C‐elevated water rather than 14 C‐depleted water westward across the Indian Ocean. This implies that oceanic upwelling in the northwestern Indian Ocean is spatially confined with little contribution to the upper limb of the global thermohaline circulation.