Initial Reports of the Deep Sea Drilling Project - Volume 89

This volume covers Leg 89 of the cruises of the Drilling Vessel Glomar Challenger. Because drilling during the DSDP-IPOD program had not yet succeeded in sampling Jurassic sediments from the Mesozoic superocean, remnants of which remain in the western Pacific, Leg 89 was designed to recover sediments of probably Bathonian-Callovian age (150-160 m.y. old). Recovery of such sediments would enable us to compare Mesozoic superocean strata and paleoenvironmental conditions with Atlantic sediments, paleoenvironments of similar age, and coeval strata deposited along Tethyan continental margins—now exposed in Tertiary fold belts. The specific paleoenvironmental questions to be addressed on Leg 89 include the following: 1. How did the early evolution and radiation of the oceanic plankton (coccoliths, radiolarians, benthic and planktonic foraminifers) influence the composition of pelagic sediments, and how do these fauna and flora reflect Mesozoic ocean chemistry? 2. Did the opening of the North Atlantic Ocean affect the circulation and chemistry of the world ocean in a manner similar to that which has been proposed for the opening of the South Atlantic? 3. Are "pelagic" sediments exposed in Tertiary fold belts (ribbon radiolarites, ammonitico rosso, etc.) characteristic of open ocean environments? 4. Can we establish an early Mesozoic pelagic bio- and magneto-chronology? 5. Were the mid-Cretaceous sedimentary environments in the deep Pacific better oxygenated than those in the Atlantic and Indian oceans? The basic objective of Leg 89 was the recovery of a truly oceanic sediment record, which is only preserved in the western Pacific. Leg 89 began in Yokohama, Japan in October 1982 and ended in Noumea, New Caledonia in November 1982.