Calcareous nannofossil biostratigraphy and revised zonation of the Pleistocene

Abstract

Deep Sea Drilling Project sites 154A, 206, and 289 yielded reasonably complete Pleistocene sections of deep-sea sediments in which a good to excellent succession of calcareous nannofossils is present. A detailed study of the nannofossils from the above three sections and an evaluation of data from several piston cores have resulted in a revised zonation of the Pleistocene in which seven zones are recognized. A reasonably rigorous chronology is established for this zonal succession by correlating all possible biostratigraphic datum levels with magnetic stratigraphy in the Pacific and with paleoclimatic fluctuations in the Pacific and the Caribbean. The ages for intermediate levels are interpolated. From youngest to oldest the proposed zones for the Pleistocene and the absolute ages for their limits are as follows: Emiliania huxleyi Acme Zone 0.07 m.y. Small Gephyrocapsa Zone 1.22 to 0.92 m.y. Emiliania huxleyi Zone 0.27 to 0.07 m.y. Helicopontosphaera sellii Zone 1.51 to 1.22 m.y. Geophyrocapsa oceanica Zone 0.44 to 0.27 m.y. Cyclococcolithina macintyrei Zone 1.65 to 1.51 m.y. Pseudoemiliania lacunosa Zone 0.92 to 0.44 m.y. All of the above zones except one span time periods of 0.3 m.y. or less. The mid-Pleistocene Pseudoemiliania lacunosa Zone extends over a time interval of nearly 0.5 m.y. For the most part the marker species are cosmopolitan forms which have considerable latitudinal range, and are useful in hemipelagic as well as in oceanic Pleistocene strata.