Initial Reports of the Deep Sea Drilling Project - Volume 94

This volume covers Leg 94 of the cruises of the Drilling Vessel Glomar Challenger. Leg 94 represents the last of four transects of sites set up by the Ocean Paleoenvironment Panel to examine climatic and oceanographic changes in the Pacific and Atlantic oceans. During Leg 94, a transect of six holes aligned roughly in a south-southwest/north-northeast direction were drilled in the North Atlantic from 37° to 53°N. The principal objective of this transect was to document the magnitude and spectral character of the surface-ocean response to high-latitude climatic change in the northern hemisphere during the Neogene. Changes in the modes of oceanic response in this highly sensitive region could then be traced from the late Quaternary record, documented from piston coring, back into times of significantly different climatic boundary conditions (no northern hemisphere ice sheets, an open Panamanian Isthmus, a closed Gibraltar Isthmus, a smaller Antarctic ice sheet). Ancillary paleoclimatic objectives included the recovery of both a faunal and an isotopic record of deepwater variations at water depths ranging from 2393 to 3871 m. Other major targets sought included ascertaining (1) the Neogene history of accelerated sediment deposition on the Feni Ridge in Rockall Trough and the Gardar Ridge on the east flank of the Mid-Atlantic Ridge; and (2) the tectonic history of the King's Trough complex north of the Azores. In addition, rotary or extended core barrel drilling at Site 608 below the upper Neogene hydraulic piston coring objectives attempted to fill gaps in the global DSDP stratigraphic array of Eocene-Oligocene sediment cores. Other significant objectives included establishing (1) a record of Neogene paleomagnetic stratigraphy including detailed polarity transitions; (2) sequences defining variations in the input of continental detritus, particularly by ice rafting; and (3) a Neogene CaCO3 dissolution history for the North Atlantic. Leg 94 began in Norfolk, Virginia in June 1983 and ended in St. John’s, Newfoundland in August 1983.