Benthic foraminifers from DSDP Site 516 (upper Maestrichtian-Quarternary, South Atlantic)

A study is presented of the benthic foraminifers (size fraction > 63 microns) recovered from 75 upper Maestrichtian through Quaternary sediment samples at DSDP Site 516. This site is located in the South Atlantic on the Rio Grande Rise, at a water depth of 1313 m. It represents one of the most complete successions of Tertiary and late Cretaceous marine deposits and contains only two minor gaps in the upper Miocene. A total of 382 taxa were identified. The unilocular calcareous foraminifers were not studied. Six biostratigraphical zones were established. The most important faunal turnover recorded occurred between the lower and the middle Eocene, and minor faunal breaks took place in the upper Oligocene and in the upper Maestrichtian. In general terms, the faunal breaks observed are approximately coincident with minima in the species diversity curve. The most long-ranging species found are "Seabrookie rugosa" and "Heronallenia toddae" covering from the upper Maestrichtian to the Quaternary. "Pleurostomella obtusa" was found from the upper Maestrichtian to the Pliocene. Comparison with the results of Dailey and Tjalsma, who studied the benthic foraminifers of the same sections of Site 516, showed some disagreements which are explained not only by the different interpretation of several taxa, but probably mainly by the fact that we studied different samples, and that the authors cited used a larger size fraction (> 150 microns, rather than > 63 microns).