Initial Reports of the Deep Sea Drilling Project - Volume 55

This volume covers Leg 55 of the cruises of the Drilling Vessel Glomar Challenger. Leg 55 was conceived as part of the decade-long experiment to test the kinematic hot-spot hypothesis and several of its more important corollaries for the origin of the Hawaiian-Emperor chain. Also of particular importance was the question of whether the Hawaiian hotspot has remained fixed in the mantle. In addition to obtaining data relevant to the hot-spot experiment, we hoped that the drilling would permit us to establish the Cenozoic biostratigraphic zonation for sediments atop the seamounts and better understand the Neogene environment of the central north Pacific. The specific primary objectives of Leg 55, discussed more fully in what follows, were to determine (1) whether the known increase in the age of the volcanoes on the Hawaiian chain with distance from Kilauea continues northward along the Emperor Seamounts; (2) whether the lavas of the Emperor volcanoes are of the same chemical composition and were erupted in the same sequence as those of Hawaiian volcanoes; (3) the latitude of formation of Suiko Seamount as a test of hot-spot fixity; and (4) whether the Emperor Seamounts were once islands and, if so, to determine their post-volcanic and subsidence history. The Glomar Challenger departed Honolulu, Hawaii on 23 July 1977, drilled 11 holes at 4 sites in the Emperor Seamount chain, including a multiple re-entry hole on Suiko Seamount, and arrived at Yokohama, Japan on 6 September 1977.