Magnetic anisotropy and sediment transport directions in North Atlantic Early Cretaceous black shales and Eocene mudstones cored on DSDP Leg 48.

Abstract

Cretaceous black shales in the Bay of Biscay reveal a well-developed magnetic lineation. It is proposed that this lineation was produced by a strong and persistent bottom transport mechanism, oriented perpendicular to the contemporaneous continental margin. This makes it unlikely that the high organic carbon content of these sediments results from their deposition in a stagnant basin, and supports the alternative view that their organic-rich nature results from an unusually high influx of terrigenous plant material. The magnetic anisotropy of glauconitic mudstones and volcaniclastic siltstones near the W margin of Rockall Plateau, also reveals a strong preferred grain alignment approximately perpendicular to the present continental margin. -from Authors