On eustatic sea level history: Last Glacial Maximum to Holocene

This paper addresses the question of the magnitude and time dependence of the globally averaged (eustatic) rise of sea level that occurred subsequent to the time of Last Glacial Maximum (LGM) at approximately 21,000 calendar years before present. Through the analysis of relative sea level (RSL) histories predicted by a realistic mass conserving and gravitationally self-consistent theory of postglacial sea level change, it is demonstrated that there are preferred oceanic locations at which this eustatic function is well approximated by local sea level history. One such location is the Island of Barbados in the Caribbean Sea, a site from which a coral based record exists that extends from mid-Holocene to LGM. Because of the sea level ambiguity that is inherent to coral based records, however, it is important that the global ice-equivalent eustatic sea level curve inferred on the basis of the Barbados data be tested against observations at other locations from which similarly extensive records are also available but which are derived on the basis of sea level indicators which are not subject to the ambiguities inherent to corals. It is shown that, when the eustatic function employed in the global theoretical model is tuned so as to enable the model to fit the Barbados observations, where the maximum relative sea level (RSL) depression is assumed to be near 120 m, then the theory misfits the record from the Sunda Shelf in the Indonesian Archipelago as well as the record from J. Bonaparte Gulf in northern Australia. Both of these recently published records appear to constrain the LGM low stand of RSL to a value above 120 m. The implications of these results for interpretation of the long coral derived records from the Huon Peninsula of Papua, New Guinea and the island of Tahiti are also discussed.