Sea-level during the early deglaciation period in the Great Barrier Reef, Australia

Ooids samples recovered from the Capricorn Channel in the southern Great Barrier Reef (GBR) were analyzed to study paleo sea-level during the late glacial period. Their ages and depth distribution were compared with numerical predictions obtained using a detailed glacio-hydro isostatic model to examine the reliability of the ice model. A step-wise dissolution technique was used to remove secondary carbon contamination and determine the exact timing of formation. The dating results indicate that ooid formation took place around 16,800 cal. yr BP, immediately prior to a period of accelerated melting of the global ice sheets, the Meltwater pulse 1a event. Sea-level predictions obtained using rheological parameters optimized for the Australian coast are consistent with the radiocarbon-derived ooid depth-age data, which suggest that at 16.8 cal. ka sea-level in the southern GBR was 100 m below its present height.