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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. INTRODUCTION During December 1982 and January 1983, Deep Sea Drilling Project Leg 90 recovered more than 3700 m of sediment cores from eight sites in a traverse by the Glomar Challenger from the tropics to the sub-Antarctic (Fig. 1, Table 1). Leg 90 sites were located in all the major surface-water masses between the tropics and the sub-Antarctic in order to compare and be able to correlate Cenozoic faunas across a wide range of latitudes from the equator to latitude 45°S. The cores were recovered from uncomplicated calcareous oozes and chalks of late Eocene-Pleistocene age, in relatively shallow waTable 1. Locations and water depths of Leg 90 sites. Site 587 588 589 590 591 592 593 594 Latitude (S) 21°11.87' 26°06.70' 30°42.72' 31°1O.O2' 31°35.O6' 36°28.40' 40°30.47' 45°31.41' Longitude (E) 161°19.99' 161°13.60' 163°38.39' 163°21.51' 164° 26.92' 165°26.53' 167°40.47' 174°56.88' Water depth (m) 1101 1533 1391 1299 2131 1098 1068 1204 Kennett, J. P., von der Borch, C. C , et al., Init. Repts. DSDP, 90: Washington (U.S. Govt. Printing Office). 2 Addresses: (Jenkins) Department of Earth Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA, Buckinghamshire, United Kingdom; (Srinivasan) Banaras Hindu University, Varanasi, 221005, India. ten Core recovery was 85% and the quality of the cored sequences was good; the cores were obtained by using the hydraulic piston corer (HPC) and extended core barrel (XCB). PROCEDURES On board ship core-catcher sediment samples were washed, dried, and sieved to fine, medium, and coarse fractions; the planktonic foraminifers were then examined. Subsequently, in order to determine the position of zonal boundaries, intermediate samples in the cores were examined. The species identified from Sites 586 to 594 were recorded in stratigraphic tables. Previous relevant work on the southwest Pacific includes that of Jenkins (1971, 1975), Kennett (1973), Srinivasan and Kennett (1981a, b), and Kennett and Srinivasan (1983). ZONAL SCHEMES Zonal schemes are empirical and their identification is dependent on the paleogeographic limitations of zonal markers in the Cenozoic. Consequently, five main zonal schemes were employed. The tropical zonal scheme was used for Hole 586B (N22-N17a), drilled by leg 89; the warm subtropical zonal scheme was used at Sites 587, 588, 589, and 590; the cool subtropical scheme at Sites 591 and 592; the temperate scheme at Site 593 and the subantarctic scheme at Site 594. Figure 2 shows four zonal schemes and the intersite datums used for correlation from the warm subtropical to subantarctic sites; the zonal markers and zonal schemes for the tropical to subantarctic sites are shown in Tables 2-6. The latitudinal distribution of zonal markers and major boundary markers is shown later in Figure 3 and Table 7, the biostratigraphic details of Jenkinsina samwelli and Chiloguembelina cubensis at sites around Antarctica in Figure 4, and some unconformities in the Tasman Sea in Figure 5.

Cenozoic Planktonic Foraminifers from the Equator to the Subantarctic of the Southwest Pacific