A gravity core (GC11) was collected from a depth of 502 mbsl within the Capricorn Channel, southern Great Barrier Reef (GBR). The percentage of calcium carbonate in samples collected from different depths were analysed, along with other parameters, to determine changes in carbonate mineralogy and terrestrial influx. The results indicate that CaCO3% increases rapidly at the terminations, with highs during the interglacials and as low as 50% during some of the glacials. The CaCO3% highs of around 85% coincide with very low sedimentation rates of <1 cm/kyr and are probably dominated by pelagic productivity.