WOODBURNE, MICHAEL O., Department of Earth Sciences, Univ. of California, Riverside, CA

ABSTRACT: Land Mammal High-Resolution Geochronology and Intercontinental Overland Dispersals as a Basis for Regional Correlation

Detailed studies of lithostratigraphy, biostratigraphy, isotopic chronology and magnetostratigraphy combine to foster high-resolution geochronology in nonmarine sequences that contain fossil mammals. The concept of mammalian overland dispersal useful in regional correlation, possibly correlative with global falls in sea level, can be founded on theory, but ultimately isdocumented and validated by empirical data. The generally well developed and understood stratigraphic record associated with fossil mammals in North America remains one of the most useful bases for these kinds of considerations (and is associated with independent chronological data sets). Current considerations suggest that immigrations from, and emigrations to, other continental areas with respect to North America may orm the bases of 27 of the more than 40 commonly recognized Cenozoic mammal ages (and subdivisions) displayed in the stratigraphic record of that continent. Improved and updated evaluations of the correlation of these dispersal events suggests that only a small number of these can be correlated convincingly to proposed major sea level falls and, further, that prior to the Oligocene a glacial cause for sea level falls in the Cenozoic seems irrelevant. In that it is bounded by the Atlantic, Pacific, and Tethyan-Caribbean oceans, the North American record of land mammal dispersals provides a litmus test of a variety of dispersal mechanisms.

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