The objectives of Leg 171B were to drill sites (170600 m penetration) in a transect from the margin of the Blake Plateau to the edge of the Blake Escarpment. Our main interest was to interpret the vertical structure of the Paleogene oceans and test the Warm Saline Deep Water hypothesis near the proposed source areas. A related objective was to provide critically needed low-latitude sediments for interpreting tropical sea-surface temperature (SST) by using well-preserved calcareous microfossils. We also hoped to develop a cyclostratigraphy tuned to orbital cycles that could be used to establish an extremely accurate chronology for biozones and magnetochrons in the Cretaceous and Paleogene. The Leg 171B Blake Nose depth transect drilled one of the best locations to recover distinct horizons such as the Paleocene/Eocene and Cretaceous/Paleogene boundaries to document critical paleoceanographic and biological evolutionary events surrounding the boundaries and water depth-related variations in sedimentation of the boundary beds. Paleomagnetic objectives were to refine the Paleogene/Cretaceous biochronology and magnetochronology of the Paleogene/Cretaceous period and constrain Eocene paleomagnetic poles for the North American plate.
To 171B Summary of Primary Blake Nose Drilling Results
To 171B Table of Contents