2022 年 128 巻 1 号 p. 75-80
Two dead specimens of the precious coral Pleurocorallium elatius were obtained from the sea-bottom surface in submarine depressions at ~350 m water depth off Zanpa Cape, Okinawajima Island. Three samples were dated by 14C analysis, and yielded ages of 32,824-31,709 and 33,685-32,911 cal BP for one specimen and 20,480-20,060 cal BP for the other. These ages suggest that there was almost no deposition of sediment for an extended period in the depressions, which are interpreted as obstacle scours on the basis of their acoustic features. The obtained ages are the oldest known for dead precious corals, suggesting that favorable chemical conditions in the sea water facilitated long-term preservation of dead coral.
