University of Southern California, United States

Based on calcareous microfossil stratigraphy and chemostratigraphy (d (super 13) C isotopes) at three oceanic sites (DSDP Sites 548, 550 and ODP Site 690) we have established an upper Paleocene-lower Eocene composite reference section for integrated chemobiostratigraphy and propose a six-fold biostratigraphic and a seven-fold chemostratigraphic subdivision of this interval. Tied to the GPTS, the integrated biochemostratigraphic framework provides a very high chronologic resolution (approx. 20,000 yrs) for Chron C24r. Integrated magneto-chemo-biostratigraphic correlations at several DSDP/ODP sites in the Atlantic, Pacific and Indian Oceans reveal the widespread occurrence of unconformities near the Paleocene/Eocene boundary. Our chemo-biostratigraphic framework allows precise estimate of the duration of their associated hiatus and of the ages of the unconformable surfaces. We present maps comparing the temporal (late Paleocene-early Eocene) significance of several upper Paleocene-lower Eocene stratigraphic sections in the Atlantic, Pacific and Tethyan realms. We compare this record to the recently revised sequence stratigraphic framework of Vail et al., and discuss its paleoceanographic versus tectonic significance. Regardless of the mechanism(s) involved in the formation of the late Paleocene-early Eocene hiatuses, this study emphasizes (1) the strength of integrated chemobiostratigraphic correlations for the Paleogene, and (2) the fact that fine tuning of the chronostratigraphic record necessitates rigorous analysis of sections and may require the establishment of composite reference sections.