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This paper presents the planktonic foraminifer biostratigraphy of the sites drilled during Ocean Drilling Program Leg 124 in the Celebes and Sulu Seas. It discusses preservation of foraminifers in pelagic sediments and in calcareous turbidites. In the Celebes Sea, pelagic carbonates are only found in the Eocene and Oligocene at Site 770. The faunas are poorly preserved due to severe dissolution and offer little biostratigraphic detail. In the Sulu Sea, pelagic carbonates are found in the upper Pliocene and Pleistocene at Sites 768 and 769 and throughout the recovered sequence at the shallower Site 771. The foraminifer faunas from these sediments allow for recognition of most standard zones. Variations in preservation of pelagic foraminifer faunas with time are due to changes in the depth of the lysocline. Shifts to improved preservation at Sites 768 and 769 are synchronous in the upper Pliocene/Pleistocene and may be related to global sea-level cycles. Planktonic foraminifers are also abundant in calcareous turbidites, which were deposited in both basins from the late Miocene onward. However, the turbidites are fine-grained, and biostratigraphic marker species are absent as a result of size-sorting during transport. In the Celebes Sea, shelf-derived material was a major component of early-late Miocene and middle Pliocene to early Pleistocene turbidites. Changes in the composition of the turbidites may correspond to global sea-level changes. In the Sulu Sea, a shift from shelf-derived material in Pliocene calcareous turbidites to a pelagic source in the Pleistocene may be related to subsidence of the Cagayan Ridge. INTRODUCTION During Leg 124, ODP drilled in the Celebes and Sulu Seas. The main objectives of this leg were to determine age and nature of the basement of these two marginal basins, and to trace their paleoceanographic history. To this purpose, five sites were drilled, two in the Celebes Sea and three in the Sulu Sea (Fig. 1). Deposition of carbonate-rich pelagic sediments occurred during certain times at all sites except at Site 767 in the Celebes Sea. But, as most of the sites were drilled in deep water, extensive parts of the recovered sequences were deposited below the calcite compensation depth (CCD). These two basins are close to land in an area of Neogene tectonic activity, which caused the influx of turbidites. Calcareous fossils are preserved in carbonate-containing turbidites. The distribution of the different types of foraminifer faunas, i.e., pelagic calcareous, displaced calcareous, and noncalcareous faunas deposited below the CCD, is shown in Figure 2. This paper documents the planktonic foraminifer biostratigraphy of pelagic carbonates and describes variations in the faunal composition of calcareous turbidites, to trace the source from which the material was derived. MATERIAL AND METHODS Within pelagic carbonates, two or three samples were taken in each core at regular intervals. Calcareous turbidites in those parts of the sequence that do not contain autochthonous carbonate were sampled wherever they occurred, to a maximum of three samples per core. 1 Silver, E. A., Rangin, C , von Breymann, M. T., et al., 1991. Proc. ODP, Sci Results, 124: College Station, TX (Ocean Drilling Program). 2 Instituut voor Aardwetenschappen, Vrije Universiteit, de Boelelaan 1085, 1081 HV Amsterdam, the Netherlands. All samples were washed over a 63-μm sieve. For biostratigraphic purposes, samples were subsequently drysieved over a 125-μm sieve, and scanned for the presence of biostratigraphic markers. In addition, the number of planktonic and benthic foraminifers and fragments of planktonic tests were counted in a representative split of the sieve fraction >125 μm. The percentage of fragments and of benthic foraminifers is used as a measure of the extent of dissolution. Foraminifers are abundant in calcareous turbidites, but most faunas contain few or no specimens in a sieve fraction >125 μm. Therefore, estimates of the faunal composition in calcareous turbidites were made in the >63-μm sieve fraction. Large washed residues were split to obtain a representative sub sample. The abundance of faunal components was estimated qualitatively, using the following criteria: VR = very rare, at most a few specimens per sample or split; R = rare, at most 1% or 2% of the sample; C = common (approx. 2%-20%); A = abundant (approx. 20%-80%); D = dominant, forming the bulk of the sample (>80%). The zonation used here follows that of Blow (1969, 1979) with ranges of species after Bolli and Saunders (1985) with additions from Stainforth et al. (1975) for the Neogene and from Toumarkine and Luterbacher (1985) for the Paleogene. In addition, changes in the predominant coiling direction of Neogloboquadrina acostaensis Blow and Pulleniatina spp. are assigned ages as given by Van Gorsel and Troelstra (1981). As the zonal marker Globorotalia truncatulinoides (d'Orbigny) is rare, occurring only in the upper Pleistocene, the lower boundary of Zone N22 is tentatively set at the change in coiling direction of Globorotalia menardii (Parker, Jones, and Brady) from predominantly dextral to sinistral.

Distribution and Preservation of Cenozoic Planktonic Foraminifers from the Celebes and Sulu Seas, Leg 124