Jurassic sediments, Site 547, Northwest African margin: remarks on stratigraphy, facies, and diagenesis, and comparison with some Tethyan equivalents.

Abstract

The Jurassic sedimentary sequence recovered shows many analogies to Tethyan sequences, thus confirming inferences drawn from Mesozoic sequences in the Alpine-Mediterranean area. After initial rifting in the Late Traissic and earliest Liassic, the Sinemurian-Pliensbachian sediments at Site 547 record for the first marine transgression in the central Atlantic with a rapid passage from a continental to a basinal and hemipelagic regime. Gradual sinking of the margin in Middle and Late Jurassic times is reflected at Site 547 by decreasing sedimentation rates. There is a relative increase in pelagic sediments and components in gravity flow sediments with respect to redeposited shallow-water material.-from Authors