PP52B-08:
A Synthesis View of Ocean Productivity during the Plio-Pleistocene Transition
Friday, 19 December 2014: 12:05 PM
Kira T Lawrence1, Daniel Mikhail Sigman2, Timothy Herbert3, Catherine A Riihimaki2, Clara T Bolton4, Alfredo Martinez-Garcia5, Antoni Rosell Mele6 and Gerald Hermann Haug5, (1)Lafayette College, Easton, PA, United States, (2)Princeton University, Princeton, NJ, United States, (3)Brown Univ, Providence, RI, United States, (4)University of Oviedo, Oviedo, Spain, (5)ETH Swiss Federal Institute of Technology Zurich, Zurich, Switzerland, (6)Autonomous University of Barcelona, Cerdanyola del Val, Spain
Abstract:
In concert with the intensification of Northern Hemisphere glaciation, marine biological export productivity declined in high latitude regions in the North Pacific and Southern Ocean 2.7 million years ago. Our data from the North Atlantic show a similar but time-transgressive pattern of high-latitude productivity decline from 3.3 to 2.5 Ma. We argue that, taken together, these data are most readily explained by an equatorward migration of the westerly winds in both hemispheres and associated equatorward shift of the zones of Ekman divergence, which would have decreased productivity in polar waters. At 2.7 Ma, tropical and temperate Atlantic sites productivity increases abruptly and persists with orbital pacing thereafter, consistent with a shoaling and meridional contraction of the nutrient-depleted, low latitude, surface ocean, warm pool. This timing coincides with major Southern Ocean changes suggesting a strong influence of Southern Ocean on the fertility of the low latitude ocean.
