Neogene diatoms at DSDP Leg 55 Holes

Eleven holes were drilled at 4 sites; a multiple re-entry hole was drilled on Suiko Seamount. As originally planned, Leg 55 had two objectives: (1) drilling at least two sites on the Emperor Seamount chain, and (2) drilling a third site in Mesozoic Pacific crust in anomaly M-l on the oceanic side of the Kuril trench.

The proposed site in Mesozoic crust, however, was abandoned for logistical reasons. Because the principal objective of Leg 55 was to test the "hot-spot" hypothesis of the origin of the Hawaiian and Emperor chains, the recovery of sedimentary sequences for diatoms was not of primary importance. Drilling on Suiko Seamount (Site 433), however, yielded pelagic sediments which consist mostly of skeletons of diatoms, radiolarians, and foraminifers, without the terrigenous material such as sand, silt, and volcanic ash.