Initial Reports of the Deep Sea Drilling Project - Volume 56/57

This volume covers Legs 56 and 57 of the cruises of the Drilling Vessel Glomar Challenger. The Japan Trench area was identified three years ago as a favorable place for studying convergent margins. The IPOD Active Margins Panel focused its attention on testing the simple conceptual model of convergent margins in settings along continental and island arc margins. The Japanese IPOD committee and panel members suggested a series of sites that were designed to (1) characterize the deep ocean basin sediment, (2) explore the accretionary wedge of the lower slope, (3) date the development of the midslope terrace, (4) measure at least a minimum rate of uplift of the shelf edge structure high, (5) test the seaward extent and age of continental crust, (6) indicate the age and geologic history of the deep sea terrace, and (7) examine diagenetic and structural changes of rocks subjected to stresses associated with plate convergence. Thus the main objectives of the Japan Trench transect were to learn more about the mechanism and dynamics of plate convergence and their effects on the sedimentation complex. The Japan Trench transect constitutes one of the first studies of a convergent margin using both multichannel seismic reflection and multihole deep sea drilling data. This volume contains the results of that study by the shipboard participants of Legs 56 and 57 and by their shore-based colleagues. A principal objective of this interdisciplinary study was to determine the evolution of the Japan convergent margin and the style of tectonism at the landward slope of the Japan Trench. Legs 56 and 57 departed from and terminated in Yokohama, Japan and took place between September and December of 1977.