Initial Reports of the Deep Sea Drilling Project - Volume 43

This volume covers Leg 43 of the cruises of the Drilling Vessel Glomar Challenger. Leg 43 began on 13 June 1975 at Istanbul, Turkey, and terminated 12 August 1975 in Norfolk, Virginia. We drilled six holes at six sites (382-387) on Leg 43. Leg 43 was planned to examine a wide variety of geological problems at numerous sites in the deep western North Atlantic basin. A variety of objectives were to be addressed on Leg 43, the principal emphasis being concentrated on, but not limited to, the following: 1) To core continuously through the major acoustic horizons ("A", A*, and ß) at several locations in the basin to establish the lithostratigraphic and chronostratigraphic correlations of the reflectors, and to determine if variations in these correlations could be related to lateral changes in acoustic character of the reflectors. 2) To investigate the sedimentary development of the North American basin with particular emphasis on (a) the age and nature of presumed calcareous sediments below the most seaward occurrence of Horizon ß on the western Bermuda Rise, (b) the seaward limit of Lower Cretaceous black clays in the western North Atlantic, the cause of the black-clay deposition, and the depth limits within which the clays were deposited, (c) the age, distribution and origin of the multicolored clays overlying the black clays, (d) the sources and distribution of the markedly siliceous Paleogene sediments on the Bermuda Rise, and (e) the role of surface/abyssal currents and surface productivity patterns in the Mesozoic and Cenozoic development of the sedimentary record. 3) To recover sediments containing late Mesozoic and Cenozoic fossils for biostratigraphic, paleobiogeographic, and paleoceanographic studies. 4) To recover samples of basaltic basement from the smooth crest of the basement ridge associated with the high-amplitude "J" magnetic anomaly north of the New England seamounts and determine whether the anomaly is accompanied by unusual basement composition and magnetic properties. 5) To examine the age and nature of volcanism on Bermuda and along the New England seamount chain, in order to test ideas on volcani* origin such as the "hot-spot" hypothesis, and to examine volcaniclastic lithofacies and assess the role of volcanic sources for certain North Atlantic sediments. 6) To determine the age of basement in the central part and at the young end ("J-anomaly") of the Keathley (M-series) magnetic anomalies, and in the older part of the Cretaceous "magnetic quiet zone," in order to better calibrate the M-series (Keathley) reversal chronology and the sea-floor-spreading history of the North Atlantic.