Eight sites on the Kerguelen Plateau were drilled during Ocean Drilling Program (ODP) Leg 183. The Kerguelen Plateau is a large igneous province in the southern Indian Ocean believed to have formed over a hotspot beginning at ~120 Ma (Shipboard Scientific Party, 2000). The major objective of this leg was the study of the igneous basement. Silicoflagellates were found to be abundant in the sediments above basement at Site 1140 and abundant in the Pliocene and Pleistocene sections at Site 1138. The purpose of this study is to provide a silicoflagellate biostratigraphy for the Kerguelen Plateau that will contribute to the biostratigraphic zonation of the Southern Ocean (Ciesielski, 1975, 1991; Perch-Nielsen, 1975; Bukry, 1975b, 1976b, 1991; Haq and Riley, 1976; Shaw and Ciesielski, 1983; McCartney and Wise, 1990; McCartney and Harwood, 1992).
Site 1138 lies ~150 km north-northwest of Site 747 (Leg 120) (see Fig. F1) at 53°33.1´S, 75°58.5´E, in a water depth of 1141.4 m. The hole penetrated 842.7 m; the lowest sample examined in this study came from 269.4 meters below seafloor (mbsf). Six sedimentary lithologic units were recognized in Hole 1138A above basement, with the uppermost three of these included in the interval studied for silicoflagellates. Sediments from the Upper Cretaceous to Pleistocene (Shipboard Scientific Party, 2000) were recovered; silicoflagellates found in this study are from the upper Oligocene to Pleistocene.
Site 1140 lies ~270 km north of the Kerguelen archipelago (Fig. F1), in a water depth of 2394 m. The location of Hole 1140A is at 46°15.6´S, 68°29.5´E, on the northernmost Kerguelen Plateau. Total penetration in Hole 1140A was 321.9 m with a sediment penetration of 234.0 m; the lowest samples studied for silicoflagellates were at 207.79 mbsf. Upper Eocene to middle Miocene sediments (Shipboard Scientific Party, 2000) were recovered, with the silicoflagellates studied being from the lower Oligocene and lower and middle Miocene and one sample from the Pleistocene.