Hydrography above the mid-atlantic ridge (33-degrees-40-degrees-n) and within the lucky-strike segment

As part of the French-American Ridge Atlantic program the French-American Zero-Angle Photon Spectrometer and Rocks (FAZAR) cruise conducted water column studies between 33 and 40 degrees N along the Mid-Atlantic Ridge (MAR)) to detect hydrothermal activity and map its influence, This paper describes the large-scale hydrography within the axial valley, with particular emphasis on the hydrothermally active Lucky Strike segment (37 degrees 17'N). The FAZAR study area is affected be the presence of the Azores Current and Mediterranean Water (MW). Although the MW core has been mapped as far north as 50 degrees N off the ridge; the northern boundary Of the MW within the MAR in the FAZAR study area exists as a strong front south of the Azores platform. This front is most likely caused by the shallower ridge crest becoming a physical barrier to the MW. The Lucky Strike segment lies within this front and, as a result, has complicated hydrography which can obscure hydrothermal temperature and salinity anomalies.