Seismic evidence of bottom current controlled sedimentation in the Ceará Rise region (central Atlantic)

Abstract

This study is based on the seismoacoustic data (3.5 kHz) collected during cruise 9209 of the RV Maurice Ewing (1992), organized within the framework of preparation for ODP drilling – leg 154. The analysis of the acquired data helped distinguish major acoustic facies and their spatial distribution in the study area. It was found out that almost the entire northern segment of the Ceará Rise is covered by a vast field of contourite sediment waves. The distribution of sediment wave heights is suggested to be controlled by geostrophic currents of AABW and NADW as well as by processes on the boundaries between water masses. Contourite erosional features are not widespread and generally resulted from the interaction of the bottom current with prominent topographic obstacles like western scarp of the Ceará Rise or basement outcrops.