Ocean Drilling Program: Results From Seventh Year of Drilling Operations
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AbstractThe Ocean Drilling Program (ODP) has completed 40 internationally staffed expeditions and seven years of scientific ocean drilling in search of answers relating to the tectonic evolution of passive and active continental margins, origin and evolution of oceanic crust, origin and evolution of marine sedimentary sequences, and paleoceanography. To address these problems, OOP has made numerous advances in technology for retrieval of continuous undisturbed cores under hostile environmental conditions. ODP curates over 160 km of cored material and associated scientific data bases and publishes results of the scientific expeditions in a continuous series of Proceedings volumes.During its seventh year, ODP has completed pioneering scientific and technical exploration in the Pacific Ocean. Leg 135 studied the geologic history of the Lau Basin and adjoining TofuaiTonga Arc. The results here yield important information on the geologic processes that form new oceanic crust at convergent plate margins. Leg 136 drilled and cased a reentry hole off Hawaii to provide a site for the future employment of a broad-band ocean seismometer. This is the first site of an envisioned global network of 15-20 permanent seismic observations in the deep ocean. Leg 137 cleaned and conditioned and slightly deepened Hole 504B, off the Galapagos, for future coring and downhole measurements. This hole is the deepest hole we have into the basaltic ocean crust. Leg 138 broke the Leg 133 core recovery record by retrieving 5537 m of material on two north-south transects in order to define the paleoceanographic evolution of the eastern Pacific during the last 12 million years. Leg 139 recovered core in the Middle Valley of the northern Juan de Fuca Ridge with the major objective of elucidating processes and products of hydrothermal circulation in a sedimented spreading center. Future cruises include, amongst others, Leg 141 in the Chile Triple Junction region which will focus on the effects of ridge-crest subduction; Leg 142, the third ODP engineering leg in order to test the diamond coring system, Phase liB, on the East Pacific Rise; Legs 143 and 144, Northwest Pacific Atolls and Guyots, to address problems relating to changes in sea level; Leg 145 to address broad themes of surface and deep water evolution through the Neogene in the North Pacific; leg 146 to drill on convergent margin accretionary prisms off Vancouver and Oregon; Leg 147 to drill in Hess Deep to understand igneous, tectonic and metamorphic evolution of fast spreading oceanic crust and to understand the processes of rifting in young oceanic crust. After Leg 147, in January 1993, the JOIDES Resolution will commence an Atlantic ocean drilling campaign.This paper focuses on ODP's scientific and technical achievements during its seventh year of field operations and discusses areas of future study.IntroductionThe Ocean Drilling Program (ODP), an international basic research program of scientific ocean drilling, is the successor program to the Deep Sea Drilling Project (DSDP) with Texas A&M University as the science operator. ODP is funded by the U.S. National Science Foundation with major contributions from 19 non-U.S. countries.
