Upper Oligocene to Quaternary diatom biostratigraphy of ODP Hole 121-758A in the equatorial Indian Ocean

Diatoms occur at Site 768 in the equatorial Indian Ocean in three intervals: (1) Quaternary to upper Pliocene, (2) lower Miocene to upper Oligocene, and (3) upper Campanian. The diatom assemblages are documented for each of these intervals. Similarities between the diatom flora in the equatorial Pacific and at Site 758 allow diatom zonations established in the equatorial Pacific to be used at Site 758, and the presence of a hiatus of about 3-m.y. duration at the Miocene/Oligocene boundary is demonstrated. Upper Pliocene to Quaternary diatom datums levels calibrated to magnetostratigraphy are compared between Site 758, the equatorial Pacific Ocean, and the North Atlantic Ocean. Diachroneity is shown for some of the events. One new taxa, Craspedodiscus elegans var. asymmetricus, n. var., is described, and one new combination, Rossiella magna (Lohman) n. comb., is proposed.