Planktonic foraminifera from DSDP Leg 90 holes and DSDP Site 89-586

Planktonic foraminifers from DSDP Site 586 on Leg 89 and Sites 587-594 on Leg 90, cored by the Glomar Challenger from the equator to subantarctic waters of the southwest Pacific, are recorded. Five zonal schemes were used because of latitudinal changes in faunal assemblages and these are discussed; inter site correlation was established by selected datum species. Major epoch boundaries were normally marked by the following species: Pliocene/Pleistocene, the appearance of Globorotalia truncatulinoides; Miocene/Pliocene, appearance of G. tumida in the north and the extinction of G. conomiozea in the south; Oligocene/Miocene, the appearance of Globoquadrina dehiscens at 586, 588, and 593; Eocene/Oligocene, at the extinction of Globigerinatheka index. The appearances and extinctions of most datum species were regarded as isochronous but a few were demonstrably diachronous at their paleogeographic limits, such as the appearances of G. truncatulinoides at Site 594 and G. inflata at 587. The presence of Jenkinsina samwelli in the late Oligocene at Site 593 is further support for the hypothesis that the Circum-Antarctic Current began about 30 Ma ago. At the same time, a major unconformity was formed and is widespread in the Tasman Sea area; sedimentation did not resume at Site 592 until the early Miocene. Selected taxonomic problems are discussed and 39 species illustrated