Deep-Water Drilling: Atlantic Basin: ABSTRACT

Abstract

The Atlantic deep-water drilling campaign of Glomar Challenger has been an outstanding success. The extensive seismic reflector Horizon A has been sampled. It consists of a sequence of hard radiolarian cherts of late Mesozoic to early Cenozoic age; the presence of these beds supports the suggestion that an opening connected the Pacific with the Caribbean when extensive Eocene chert beds were formed in the Caribbean. Turbidites form an important part of the Atlantic basin deposits and lead to uncertainty in determining accumulation rates to unsampled sections. Where igneous rocks have been reached beneath sediments on the Mid-Atlantic Ridge, the ages of the oldest sediments are in general agreement with those predicted on the basis of correlation with magnetic anomaly patt rns and the hypothesis of sea-floor spreading. The Tithonian sediments from a site east of the Bahamas are underlain by a considerable unsampled sedimentary section, suggesting that deep-water, open-ocean conditions have existed here since at least Early Jurassic time. End_of_Article - Last_Page 717------------