Progressive Intensification of Pacific Deep Water Circulation Since the Early Pliocene

An important stage in global ocean overturning circulation is the upwelling of the Antarctic Bottom Water into the Pacific Deep Water (PDW). The long-term evolution of PDW circulation, however, is scarcely addressed. We use seismic reflection data and cores from the International Ocean Discovery Program (and its predecessors) in contourites to reconstruct regional deep ocean circulation patterns. Here, we demonstrate that PDW circulation was progressively enhanced at about 4.35, 3.84, 2.16, and 0.97 Ma since the early Pliocene. Coeval growth of volcanic arcs and tectonic uplifts gradually isolated marginal seas from the PDW and, in conjunction with climate cooling, effectively increasing deep-water flux within a shrinking Pacific basin. Regional stratigraphic discontinuities in contourites indicate thresholds in the intensification of ocean circulation.