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This paper details the occurrence of planktonic foraminifera from Sites 319, 320, and 321, recovered from Leg 34 of the DSDP—the Nazca Plate leg. In addition, the report includes discussion of the planktonic foraminifera from two piston cores (DWBP 134 and AMPH 30P) also from the Nazca Plate, both close to the East Pacific Rise and at a latitude close to that (9°13°S) drilled on the Nazca Plate during the operation of Leg 34. Foraminifera and sediments from the piston cores are Quaternary. Sediments containing foraminifera are at Site 319, early Miocene (N8) to late Miocene or Pliocene (NI8/19); at Site 320, Oligocene (N2), early Miocene (N4-N8) and Quaternary, and at Site 321 late Eocene (P16) to Oligocene (N2/3). At each DSDP site, records are made of residue percentage, small planktonic percentage (both defined herein), planktonic percentage, planktonic diversity and age. The following species are described as new: Globorotalia (Turborotalia) akersi, G (T.) bauerensis and Clavigerinella nazcaensis. INTRODUCTION Three sites (319, 320, 321) on the Nazca plate were drilled by D/V Glomar Challenger on Leg 34 of the Deep Sea Drilling Project. The positions of the sites are shown in Figure 1 which includes the locality of Site 157 of Leg 16—which also falls on the Nazca plate—and the localities of two piston cores also studied. Table 1 is a summary of the basic information for each hole. This chapter discusses primarily the planktonic foraminifera from the three Leg 34 sites and also includes occasional data from Site 157 and two piston cores. Remarks are restricted mainly to discussion of the planktonic foraminiferal faunas of all sites listed. Biostratigraphic relationships are discussed further in Quilty et al. (this volume). PREVIOUS STUDIES Very little is known of the distribution of planktonic foraminifera in the Cenozoic of the Nazca plate. Apart from the three sites reported on here, only Site 157 from DSDP Leg 16 (Kaneps, 1973) has penetrated anything other than Pleistocene on this plate. That hole penetrated 437 meters of late Miocene to Recent section before entering basalt basement. Blow (1969) produced his comprehensive middle Eocene to Recent zonation of planktonic foraminiferal faunas and this has won almost universal acceptance, and any studies carried out here will be referred directly to Blow's scheme wherever possible. There have been several papers in the last few years critical of the use of Blow's (1969) "letter-number" scheme for Cenozoic planktonic foraminiferal zonation (e.g., Jenkins and Orr, 1972). The criticisms are of two kinds. One is that the zonation is not universally applicable or the ultimate zonation. This is a valid criticism, but is true of any zonation, no matter what the terminology. Another criticism is that the zonation is not allowed by codes of stratigraphic nomenclature. Blow's scheme is an extremely valuable shorthand method of communicating effectively even with nonstratigraphers. This is perhaps a criticism of codes of nomenclature more than of Blow's scheme. It is perhaps a classic example of the possible stultifying effect that rigid adherence to a defined code can have. An excellent zonation for use in the area was developed by Jenkins and Orr (1972) on faunas collected by DSDP Leg 9 a little west of the area studied by Leg 34. This work has proved invaluable in the present study. However, Blow's zonation can be applied directly here and has been used in preference. The other very important work of immediate use is that by Brönnimann and Resig (1969) which did a great deal to document the systematics of faunas which have been encountered in Leg 34 samples. The systematics outlined by Parker (1962) are very relevant to the piston core samples and those from the shallower cores at Site 320. As well as these few papers, there is a very large number of papers which cannot be overlooked in any study of this type. Many will be referred to elsewhere in this paper. SAMPLES Two types of samples are used in analyzing DSDP sediment—core catcher and section samples. Corecatcher samples come from the short tube leading into the base of the core barrel. Core-catcher samples contain the oldest material from each core and are probably the least disturbed. Section samples are taken later than core-catcher samples and consist of a 20-cc sample (not all of which has been used in any instance in preparing this paper),

Planktonic Foraminifera DSDP Leg 34Nazca Plate

Planktonic Foraminifera DSDP Leg 34Nazca Plate