(Table 1) Diatom species composition and distribution at ODP Site 116-717C

Autochthonous marine pelagic and allochthonous coastal and freshwater diatoms were encountered in five samples from the Ocean Drilling Program (ODP) Leg 116 Holes 717A, 717B, and 717C. Allochthonous diatoms were transported to the equatorial Indian Ocean from inland locations and coastal waters, respectively. The pelagic diatom assemblage consists mainly of warm and/or tropical diatoms known from the Neogene to Holocene. A stratigraphic marker, Rhizosolenia praebergonii var. robusta, which indicates Pliocene-Pleistocene (2.4-1.55 Ma) age of the sediments, was present in the samples from Core 116-717C-27X. Species composition of the whole assemblage is most similar to the tropical Indian Ocean Diatom Zone 6 of Schrader and supports an estimated age of 1.8-2.1 Ma for the sediments.