Sea-level at the Last Glacial Maximum: evidence from northwestern Australia to constrain ice volumes for oxygen isotope stage 2

Abstract

New sea-level information from the Bonaparte Gulf in northwestern Australia is used to constrain the magnitude and rates of change of ice volumes during the Last Glacial Maximum (LGM). The region is tectonically stable and far from the former ice-covered regions. The glacio-hydro-isostatic adjustment of the coast is therefore relatively small, and the corrections for this effect are not sensitive to details of the rebound model. Microfossil analysis and AMS radiocarbon dating of 11 gravity cores taken across the shelf and Bonaparte Gulf demonstrate that: (1) the LGM sea-levels were locally at −125±4 m; (2) the LGM terminated abruptly at 19 000 cal yr BP with a rapid rise in sea-level of about 15 m over the next 500 years; and (3) the onset of the minimum sea-levels occurred before 22 000 cal yr BP. When corrected for the glacio-hydro-isostatic effects, the increase of LGM ice volumes over the present-day ice volume is 52.5×10 6 km 3. The termination of the LGM is marked by a rapid ice discharge of 5.2×10 6 km 3.