--> Abstract: Accelerated Dispersion of New Pelagic Taxa Associated with Cooler Climates and More Vigorous Oceanic Circulation, by W. Wei, S. W. Wise, and A. Peleo-Alampay; #90987 (1993).

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WEI, WUCHANG, Scripps Institution of Oceanography, University of California, San Diego, CA; SHERWOOD W. WISE, Department of Geology, Florida State University, Tallahassee, FL; ALYSSA PELEO-ALAMPAY, Scripps Institution of Oceanography, University of California, San Diego, CA

ABSTRACT: Accelerated Dispersion of New Pelagic Taxa Associated with Cooler Climates and More Vigorous Oceanic Circulation

Global calibration of calcareous nannofossil species events with oxygen isotope stratigraphy in the late Neogene and with magnetostratigraphy in the Paleogene using core material from Deep Sea Drilling Project/Ocean Drilling Program sites shows important differences in the synchroniety of events between these two time periods. Upper Neogene calcareous nannofossil events are either synchronous within individual oxygen isotope stages (<0.05 m.y.) or diachronous by no more than 0.2 m.y. In contrast, few Paleogene nannofossil events are synchronous within 0.5 m.y. and many are diachronous by 1 or 2 m.y. at different latitudes. We suspect that this may be true for other fossil groups, although calibrations this detailed have not been done for other fossil groups. Generally poorer preser ation of fossils and poorer stratigraphic correlation for the older sediments can account in part for the difference between the Paleogene and upper Neogene results, however, a significant difference still exists after these factors are taken into account. We propose that cooler climate and more vigorous ocean circulation in the late Neogene accelerates the dispersion of new taxa and their associated gene pools, thereby resulting in more synchronous occurrences of species at different latitudes. Cooler and larger fluctuations of climate in the late Neogene also accelerated the retreat of species and led to more synchronous disappearances of species at different latitudes.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.