Distribution of Paleocene-Eocene Benthic Foraminifera in Atlantic: ABSTRACT

Abstract

A study of Paleocene-Eocene deep sea benthic foraminifera from DSDP sites in the Atlantic, Caribbean, and the Gulf of Mexico, reveals two major faunas: (1) a Paleocene fauna dominated by Cretaceous relict species, and (2) an Eocene fauna characterized by many new faunal elements. An abrupt faunal turnover, resulting in the extinction of almost all Cretaceous species, occurs during the latest Paleocene (Zone P6a). Using the backtracking method of Berger, the relative plate motions of Phillips and Forsyth, and the paleomagnetic data of McElhinny, the paleobathymetric and paleolatitudinal distribution of benthic forams was studied. A principal component analysis identifies three distinct Paleocene and four Eocene assemblages. A Gavelinella beccariiformis assemblage, with a wide bathymetric range during the early Paleocene, becomes restricted to shallower water during the late Paleocene before becoming extinct in Zone P6a. A deep water Nuttallides assemblage, consisting of long-range taxa, follows this trend, occurring at intermediate depths during the latest Paleocene. A third assemblage, with predominantly Nuttallides crassaformis and various buliminids, is restricted to the low-middle latitudes. In the Eocene the Nuttallides (mainly N. truempyi) becomes restricted to deep water prior to its extinction in the late Eocene, when it is replaced by a previously shallow assemblage characterized by Cibicidoides ungerianus (2). A second trend discriminates between a shallow assemblage (3) with Lenticulina, Osangularia mexicana, and various buliminids, which is m st prominent during the middle Eocene, and a deep assemblage (4) with Globocassidulina subglobosa, Gyroidinoides, C. ungerianus, Stilostomella aculeata, and Oridorsalis umbonatus, which is most prominent during the middle and late Eocene. End_of_Article - Last_Page 1002------------