MAGNITUDE OF THE CACO3 DISSOLUTION EVENTS MARKING THE ONSET OF TIMES OF GLACIATION

The availability of CaCO3 and He-3 content results for core TT 13-72 f rom 4,3 km depth in the equatorial Pacific [Marcantonio et al., 1996] allows the magnitude of the excess (i,e,, over ambient) CaCO3 dissolut ion at the onset of marine glacial stages 10, 8, and 6 to be estimated . These three events are remarkably similar; during each ax integrated loss of about 28 g CaCO3 per cm(2) occurred. While the magnitude of t his loss is consistent with that expected from the interglacial to gla cial pH shifts reconstructed based on boron isotope measurements on be nthic foraminifera [Sanyal et al, 1995], measurements at a number of o ther locations and water depths will be required before this approach can be used to evaluate the global toll of these dissolution events.