A gravity core (GC12) was collected from a depth of 990.5 mbsl within the Capricorn Channel, southern Great Barrier Reef (GBR). The percentage of CaCO3 in samples collected from different depths were analysed, along with other parameters, to determine changes in carbonate mineralogy and terrestrial influx. Levels of CaCO3% exhibit an higher percentage of >60% during the middle of Marine Isotope Stage (MIS) 3, levels similar to those seen in MIS 1. Throughout MIS 2 and during the glacial termination the CaCO3% remains relatively constant at ~60%. CaCO3 drops to 50% prior to a possible Antarctic cold reversal (between 14 ka BP and 12 ka BP) at 80cm in the core, before recovering to the 65-70% in the Holocene again.