Late Pleistocene calcareous nannofossils in the caribbean and their interoceanic correlation

Abstract

Pleistocene climatic fluctuations as determined by means of oxygen isotope ratios from the pelagic sedimentary record of the Caribbean can be recognized also by changes included in the calcareous nannoplankton. Of 23 species tabulated from the Pleistocene fossil record two species, Ceratolithus cristatus and Umbellosphaera tenuis, are more abundant during temperature maxima. Seven species, Coccolithus pelagicus, Disoaster perplexus, Discolithina japonica, Discosphaera tubifera, Gephyrocapsa caribbeanica, Oolithotus antillarum and Umbellosphaera irregularis, occur more abundantly during temperature minima in the Caribbean. Pseudoemiliania lacunosa, a species which becomes extinct during Pleistocene, is more abundant at times of temperature maxima during the last two temperature cycles of its existence, but prior to that appears to have been more common during temperature minima in tropical latitudes. Gephyrocapsa oceanica is the most abundant species in the Pleistocene record. It is represented by two distinct morphotypes, one more common during temperature minima and the other more common during temperature maxima. The interval examined in detail represents less than one-half million years, but contains two distinct biostratigraphic data; the Pseudoemiliania lacunosa extinction and the earliest occurrence of Emiliania huxleyi.