Holocene sediments of Wistari Reef: towards a global quantification of coral reef related neritic sedimentation in the Holocene

Wistari Reef, within the southern Great Barrier Reef, is a shallow coral reef platform featuring a very clearly defined leeward accretionary wedge of carbonate sediments. The total global area of shallowly submerged coral reef has been quantified as 255 000 km2. The question then becomes: ‘What additional area of sediment of significant thickness is associated with the measured shallow reef areas?’ At Wistari Reef, the leeward sedimentary wedge has an area and a thickness that are roughly equal to the Holocene sediments that have accumulated on the platform. Several important observations can be made from these data. Firstly, the area of significant neritic carbonate sedimentation (>1 m/ka) associated with coral reefs is near 500 000 km2. Secondly, the production rate of neritic carbonates at Wistari Reef is almost 50% less than the accumulation rate needed to obtain the volume of Holocene reef sediments observed. This implies that both production and accumulation neritic carbonate must have been more than a factor of two higher in the early to mid Holocene.