Hydrography above the Mid-Atlantic Ridge (33°-40°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°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°17'N). The FAZAR study area is affected by the presence of the Azores Current and Mediterranean Water (MW). Although the MW core has been mapped as far north as 50°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.

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