Sedimentation in the Atlas Gulf II: Mid-Cretaceous Events

Abstract

According to paleogeographic research in the Cretaceous sequence of western Morocco, a funnel-like Atlas Gulf existed between Agadir and Safi, stretching farther toward the east in the present High Atlas region. Bordered by structural highs of the Anti-Atlas in the south, and the Moroccan Meseta in the north, the Atlas depression subsided slowly and continuously. Within the Atlas Gulf transgressions and regressions of the Cretaceous Atlantic can be recorded by an almost synchronous migration of the littoral zones. Distribution of shallow-marine, littoral, lagoonal, deltaic, coastal plain and fluvial facies are pointed out. Regimes, processes and kinematics of sedimentation are discussed by a sedimentation model. Significant events in Barremian, Aptian, and Turonian time are explained by an accelerated rise of the sea level. Our sedimentation model proposes eustasy as a major cause for the Mid-Cretaceous events, documented in the sedimentary record. Relations to similar rock sequences in the Sahara Basin, at the opposite margin of the Atlantic Ocean, and in the deep-sea basins, are discussed with regard to the Atlas Gulf sedimentation model.