Initial Reports of the Deep Sea Drilling Project - Volume 65

This volume covers Leg 65 of the cruises of the Drilling Vessel Glomar Challenger. Deep Sea Drilling Project (DSDP) Legs 64 and 65 were planned as a coordinated drilling investigation of the Gulf of California. Leg 65 was designed to study the processes of crustal accretion along the relatively fast spreading East Pacific Rise for comparison with the slow-spreading Mid-Atlantic Ridge. On Leg 65 it was planned to drill a transect across the East Pacific Rise just south of the Tamayo Fracture Zone and to penetrate deep into the crust at one site near the ridge crest. The purpose was to sample crustal sections formed at a relatively fast spreading ridge to investigate the processes of crustal accretion in this environment. The final sites selected for Leg 65 were designed not only to test models for crustal accretion at the rift axis but to make possible several downhole experiments. During Leg 65, three principal sites (482, 483, and 485) were drilled on the flanks of the ridge at 23 °N, together with a less successful site (484) in the Tamayo Fracture Zone. These sites, together with one site (474) drilled in older crust on Leg 64, represent an axial transect along an approximate spreading flow line. The Glomar Challenger departed San Pedro, California in January 1979, and returned to Mazatlán, Mexico in March 1979.