Report and preliminary results of METEOR-Cruise M 23/2, Rio de Janeiro - Recife, 27.2.-19.3.1993.

METEOR Cruise 23 was projected to take samples fram the water column and the sea floor as well as to record the sediment structures using geoacoustic methods for the long-term special research project Sonderforschungsbereich 261 aimed at reconstructing the mass budget and current systems of the South Atlantic during the late Quaternary. Micropaleontological, geochemical, geophysical and isotopic characteristics of the sampled materials are determined both on board and subsequent to the cruise in the laboratories at Bremen University. Cruise M 23/2 primarily concentrates on sediment sampling and geochemical in situ measurements along profiles over the Brazilian continental margin south and north of the Vema Channel and in the Vitoria-Trindade Seamount area. These materials and data should pravide records of the paleoceanographic variability imposed by water masses from high northern and southern latitudes on the sedimentation processes in this key region of the western South Atlantic. A high resolution regional bathymetrie survey on the continental slope northeast of Rio de Janeira was designed by Brazilian colleagues to document in detail the pathways of sediment transport fram the shelf into the deep ocean basin. To analyse the specific sedimentary regime, which to a large extent is dominated by intensive bottom currents, additional echographie profiling and sediment sampling was planned in a field of large sediment waves north of the Rio Grande Rise.