Ocean Drilling Program: Results From Ninth Year Of Drilling Operations

Abstract

ABSTRACT The Ocean Drilling Program (ODP) has completed 52 internationally staffed expeditions and nine 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, ODP has made numerous advances in technology for retrieval of continuous undisturbed cores under hostile environmental conditions. ODP curates over 187 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 ninth year, ODP completed its pioneering exploration in the Pacific Ocean and commenced a campaign of Atlantic Ocean coring. Leg 147 sampled Hess Deep in order to understand igneous, tectonic and metamorphic evolution of fast spreading oceanic crust and to understand the processes of rifting in young ocean crust. Leg 148, near the Galapagos, deepened Hole 504B, the deepest hole we have beneath the deep sea floor to 2111 mbsf in an attempt to penetrate oceanic Layer 3. Leg 149, entered the Atlantic Ocean and cored the rifted margin of the Iberian Abyssal Plain in order to study its subsidence history and the age and nature of the ocean-continent transition. Leg 150 retrieved 4034 m of core on a transect of sites off New Jersey aimed at studying late Oligocene through Miocene sea level changes. Leg 151 in the Norwegian-Greenland Sea made use of an ice-support vessel in the Fram Strait region of the Arctic Ocean to investigate high northern latitude ocean's role in global climate and ocean systems. Leg 152 investigated deformation of the lithosphere and mechanisms of magma emplacement on the East Greenland Margin. Leg 153 is scheduled to drill the lower crust and upper mantle in the MARK area of the mid-Atlantic Ridge; Leg 153, on the Ceara Rise in the western equatorial Atlantic will piston core a depth transect and answer important questions of paleoceanographic significance; Leg 155 on the Amazon Fan will sample several acoustic units to determine their lithologies, facies and ages; and Leg 156 is scheduled to drill a number of holes penetrating the deéollement zone and spanning the deformation fronton the Northern Barbados Ridge. Legs 157 to 165 will continue our Atlantic Ocean exploration by drilling near Volcanic Island Apron of the Canary Islands (Leg 157), TAG Hydrothermal province of Mid-Atlantic Ridge (Leg 158), Equatorial Atlantic Transform (Leg 160), Mediterranean (Leg 161, 162), Atlantic Arctic Gateways (Leg 163), Gas Hydrates on Blake-Outer Ridge (Leg 164) and Vema Fracture Zone (Leg 165). One expedition will visit the SW Indian Ridge in the Indian Ocean (Leg 159). This paper focuses on ODP'S scientific and technical achievements during its ninth year of field operations and discusses areas of future study.