U-series dates of Great Barrier Reef corals suggest at least +0.7 m sea level ~7000 years ago

Abstract

Strong evidence from field observation and high-precision TIMS U-series dating of exposed in situ massive corals and exposed microatolls on Magnetic Island, Great Barrier Reef, indicates that the relative sea level was at least 0.7 m higher than present ~7000 calendar years (cal yr) ago, and culminated to at least ~1.6 m higher than present ~5800 cal yr ago. The present sea level was probably first reached around 7300—7100 cal yr ago. Together with the youngest age (2236 ± 27 cal yr) of an exposed microatoll colony, the data suggest past sea-level highstands occurred between 7200 and 2200 cal yr ago, lasting for 5000 years. This study represents the first attempt to date sea-level indicators from the Great Barrier Reef by the high-precision U-series method. The results are broadly consistent with a sea-level reconstruction based on a compilation and re-examination of 115 calibrated 14C dates from eastern Australia by Lewis et al. (2008).