Abstract
Paleogene tropical Pacific: Clues to circulation, productivity, and plate motion
Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, USA
Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden
Dipartimento di Scienze della Terra, Universita G. D'Annuzio, Campus Univeritario, Chieti Scalo, Italy
Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, USA
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA
Dipartimento di Scienze della Terra, Universita G. D'Annuzio, Campus Univeritario, Chieti Scalo, Italy
Center for Geophysical Investigation for the Shallow Subsurface, Boise State University, Boise, Idaho, USA
Stratigraphic data from 63 Deep Sea Drilling Project and Ocean Drilling Program (ODP) sites that sample the lower Neogene and Paleogene sediments of the tropical Pacific have been compiled and put on the biostratigraphic and paleomagnetic timescale refined by ODP Leg 199 scientists. Sediment accumulation rates have been calculated for ten intervals ranging in age from 10 to 56 Ma and have been plotted for the midpoint of each interval at the associated paleoposition for each site used. A fixed hot spot model was used for reconstruction of the Pacific lithospheric plate. All such reconstructed intervals show the development of a tongue of high accumulation rates associated with the oceanographic divergence at the geographic equator. The development of this equatorial band is weakest between 46 and 56 Ma, the time of the peak warmth in Paleogene climate. Possible motion of the Hawaiian hot spot or true polar wander between 46 and 56 Ma appears to have had little effect on the plate rotation estimate of the position of the equator. In addition to temporal changes in the calcite compensation depth and in productivity, the biggest change in the patterns of sediment accumulation rates in the eastern tropical Pacific was the development of a relatively strong divergence between 6° and 10°N, near the region of divergence between the modern North Equatorial Current and the North Equatorial Counter Current. Changes in the equatorial circulation appear to be associated in time with the opening and closing of oceanic gateways, particularly the complex closing of the Caribbean-Pacific gateway.
Received 5 December 2003; accepted 10 June 2004; published 18 September 2004.
Citation: (2004), Paleogene tropical Pacific: Clues to circulation, productivity, and plate motion, Paleoceanography, 19, PA3013, doi:10.1029/2003PA000998.
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