New data on the geology of the Romanche F.Z., equatorial Atlantic: PRIMAR-96 cruise report

An oceanographic expedition was carried out in May and June 1996 with the R/V Gelendzhik to the Romanche Fracture Zone (F.Z.), in the frame of an Italian-Russian joint program for the geological study of the equatorial Atlantic (PRIMAR). We present here a cruise report, with some preliminary data and scientific results. The choice of the ship was determined mostly by the availability of a new, state of the art oceanic multibeam system (SIMRAD EM-120-S). The '96 expedition focused on the Romanche F.Z. western ridge/transform intersection (RTI) and complemented a 1994 expedition that covered the eastern RTI. Multichannel seismic reflection, gravimetric and magnetometric profiles were collected, as well as bottom rock samples. Moreover, we acquired over 10,000 nautical miles of high resolution multibeam bathymetry. With these new data the entire active part of the Romanche transform (> 900 km) has been covered by multibeam morphobathymetry