Eocene calcareous nannofossils, Deep Sea Drilling Project Site 605, upper continental rise off New Jersey, USA.

Abstract

Deep Sea Drilling Project Site 605 recovered a nearly continuous and thick (366 m) lower to middle Eocene carbonate sequence. The diversity of nannofossils is quite high and coccoliths are generally abundant to very abundant. Preservation is moderate in the upper part of the sequence and poor in the lower part, corresponding to a marked decrease in the biogenic silica content. Unrestricted open marine conditions are indicated by the high pelagic content of the section. The proximity to the continent is suggested by the early representatives of Tribrachiatus in CP9a and the occurrence of braarudosphaerids where preservation is moderate. Strict application of the low latitude zonation of Bukry is hindered somewhat in two instances by 1) the apparent absence of the zonal marker Coccolithus crassus in this section, and 2) the unanticipated overlap of the subzonal markers Chiasmolithus gigas and Reticulofenestra umbilica over 53.1 m of section. -Authors