A revised tropical to subtropical paleogene planktonic foraminiferal zonation

Abstract

New biostratigraphic investigations on deep sea cores and outcrop sections have revealed several shortcomings in currently used tropical to subtropical Eocene planktonic foraminiferal zonal schemes in the form of: 1) modified taxonomic concepts, 2) modified/different ranges of taxa, and 3) improved calibrations with magnetostratigraphy. This new information provides us with an opportunity to make some necessary improvements to existing Eocene biostratigraphic schemes. At the same time, we provide an alphanumeric notation for Paleogene zones using the prefix ‘P’ (for Paleocene), ‘E’ (for Eocene) and ‘O’ (for Oligocene) to achieve consistency with recent short-hand notation for other Cenozoic zones (Miocene [’M’], Pliocene [PL] and Pleistocene [PT]).

Sixteen Eocene (E) zones are introduced (or nomenclaturally emended) to replace the 13 zones and subzones of Berggren and others (1995). This new zonation serves as a template for the taxonomic and phylogenetic studies in the forthcoming Atlas of Eocene Planktonic Foraminifera (Pearson and others, in press). The 10 zones and subzones of the Paleocene (Berggren and others, 1995) are retained and renamed and/or emended to reflect improved taxonomy and an updated chronologic calibration to the Global Polarity Time Scale (GPTS) (Berggren and others, 2000). The Paleocene/Eocene boundary is correlated with the lowest occurrence (LO) of Acarinina sibaiyaensis (base of Zone E1), at the top of the truncated and redefined (former) Zone P5.

The five-fold zonation of the Oligocene (Berggren and others, 1995) is modified to a six-fold zonation with the elevation of (former) Subzones P21a and P21b to zonal status. The Oligocene (O) zonal components are renamed and/or nomenclaturally emended.