Pliocene stable isotope and carbonate stratigraphy at DSDP Holes 85-572C and 85-573A

Holes 572C and 573A provide high resolution (about 5000-yr. sampling interval) records of oxygen and carbon isotope stratigraphy (Globigerinoides sacculifera) and carbonate stratigraphy for the Pliocene of the equatorial Pacific. These data enable detailed correlation of carbonate events between sites and provide additional resolution to the previous carbonate stratigraphy. Comparison of calcium carbonate and d18O data reveal a "Pacific-type" carbonate stratigraphy throughout the Pliocene. The d18O data have two modes of variability with a boundary at 2.9 Ma. The planktonic d18O record does not have a steplike enrichment at 3.2 Ma, which is observed in benthic records elsewhere, suggesting that this event does not represent the proposed initiation of northern hemispheric glaciation. Hole 572C does record a distinct d18O enrichment event at about 2.4 Ma, which has been previously associated with the onset of major ice rafting in the North Atlantic.