Initial Reports of the Deep Sea Drilling Project - Volume 31

This volume covers Leg 31 of the cruises of the Drilling Vessel Glomar Challenger. Leg 31 of the Deep Sea Drilling Project started on 13 June 1973 at Apra, Guam, and ended 52.3 days later at Hakodate, Japan, on 4 August 1973. Glomar Challenger traveled 4111 nautical miles and drilled a total of 17 holes at 13 sites in the Philippine Sea and the Sea of Japan. The prime focus of the 31st voyage of Glomar Challenger was to probe the history of the West Philippine Basin and the Sea of Japan. The major purpose of Leg 31 was the scrutiny of tectonic, sedimentologic, volcanic, paleontologic, and paleo-oceanographic processes operative in arc-marginal basin complexes along with a deciphering of basin history. The following major goals were outlined on the basis of precruise analyses of the area: 1) Testing of the various proposed origins of the West Philippine Basin and the basins of the Sea of Japan. 2) Dating the major geologic events in and surrounding the Philippine Sea to better understand the formation of arc complexes as developed in the western Pacific. 3) Documentation of Cenozoic planktonic biostratigraphy in areas influenced by tropical, transitional, and subarctic water masses in some marginal seas of the western Pacific and their correlation with key reference sections exposed in the Japanese Islands, Taiwan, and the Philippine Islands. 4) Analysis of variations in late Paleogene and Neogene planktonic biofacies in terms of major paleo-oceanographic and paleoclimatological events. 5) Scrutiny of sedimentary processes within marginal basins with focus on turbidite deposition and sediment provenance. 6) Investigating volcanogenic processes and post-depositional sediment alteration which might be operative in marginal basins.