--> Abstract: The Global Early to Middle Eocene Hiatus(es): Calcareous Nannofossil Evidence, by M-P. Aubry; #90987 (1993).

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AUBRY, MARIE-PIERRE, Laboratoire de Geologie du Quaternaire, CNRS-Luminy, Marseille, France

ABSTRACT: The Global Early to Middle Eocene Hiatus(es): Calcareous Nannofossil Evidence

The lower to middle Eocene stratigraphic record of many regions (Turkey, Egypt, Libya, northwestern Europe, U.S. Atlantic margin and Gulf Coast area, California) is characterized by the occurrence of unconformities thought to correlate with the TA2/TA3 coastal offlap event in the curve of Haq et al. (1988). Calcareous nannofossil stratigraphy has played an important role in determining the age of these unconformities on shelves, either alone or through integration with planktonic foraminiferal stratigraphy and/or magnetostratigraphy. In this stratigraphic analysis of the lower to middle Eocene deep sea record of the Atlantic Ocean, the critical role of calcareous nannofossil stratigraphy and chronology for delineating unconformities and dating their genetic surfaces will be demonstrat d. Whereas magnetic reversals carry no inherent characteristics allowing secure identification without the help of biostratigraphy, planktonic foraminiferal stratigraphy is less applicable in the lower to middle Eocene interval than in other Cenozoic intervals, due to scarcity of the index species or their fragility with regard to dissolution. Calcareous nannofossils offer the advantage to be abundant in both epicontinental and oceanic deposits, thus allowing firm correlations from the continental shelf to the deep sea. It will be shown that during the early Cenozoic, deposition occurred essentially during the same time intervals in the deep sea and on the shelf while unconformities in these two settings also form essentially during the same time intervals.

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