The Magnetostratigraphy of Northwest Pacific Sediments, Deep Sea Drilling Project Leg 86

Abstract

Results of paleomagnetic analyses of pelagic sediment sequences recovered in the Northwest Pacific during Deep Sea Drilling Project Leg 86 are presented. On the basis of these data, almost complete late Cenozoic magnetostratigraphies are established for each drill site. At Site 577, on the Shatsky Rise, a stratigraphic duplication of Late Cretaceous to middle Eocene sequences was achieved using the hydraulic piston coring technique. For the first time, a detailed paleomagnetic study of this period using largely undisturbed and complete sedimentary columns from the Pacific region was possible. Available biostratig-raphy and stable isotope stratigraphy data allowed a positive correlation of the downhole magnetic reversal patterns with a calibrated geomagnetic polarity time scale. In general, the results obtained are in remarkable agreement with oth-er recently published magnetostratigraphies from various parts of the world. Therefore, they represent a high quality framework for an early Tertiary magnetobiochronology including the Cretaceous/Tertiary boundary interval.