Differential dissolution: Modification of Late Pleistocene oxygen isotope records in the western equatorial Pacific

Abstract

Deep‐sea records of the Pacific Ocean show dramatic variations in the dissolution intensity of calcium carbonate through the late Pleistocene. Extremes are characterized by much depressed dissolution intensity during deglaciation (preservation spikes) and much enhanced dissolution intensity during ice growth (dissolution spikes). Increased dissolution intensity at dissolution spikes distorts δ18O records by preferential removal of 16O‐rich shells, resulting in heavier δ18O values at these sections. The δ18O values tend to remain unaltered at deglacial preservation spikes. Thus the fluctuations of carbonate dissolution intensity modify the late Pleistocene oxygen isotope records in such a fashion that apparent “climate optima” (as defined by the lightest δ18O values) tend to shift toward preservation spikes, while apparent “glacial maxima” (characterized by the heaviest δ18O values) shift toward dissolution spikes.