Foraminifera abundances and biostratigraphy of Cenozoic sediments from the Ontong Java Plateau

Biserial planktonic foraminifers are rare or absent in the latest Oligocene and early Miocene, an interval characterized by warm bottom water and low temperature gradients.

These conditions supported a surface assemblage rather than the biserial planktonic foraminifers, whose Neogene species inhabited the oxygen minimum at intermediate depths in the upper water column. Biserial planktonic foraminifers tend to be of high frequency during high sea stands and low frequency during low sea level, presumably in response to the strengthening or weakening of the oxygen minimum. Species extinction and evolution events occur during low sea stands in the Neogene and sometimes correspond to strong reflection horizons of the plateau's seismic stratigraphy.