Crest of the Mid-Atlantic Ridge at 26°N

Abstract

A relatively detailed investigation of the Mid-Atlantic Ridge crest at 26°N was conducted by using narrow-beam bathymetric data, total earth's magnetic field measurements, and underwater photographs. The Mid-Atlantic Ridge crest at 26°N appears to be hydrothermally active. The structural setting of this area is conducive to the occurrence of hydrothermal deposits. The walls of the rift valley are extensively faulted with blocks and steps ranging in size from kilometers to meters in width and relief. Underwater photographs show hydrothermal manganese associated with interpreted fault steps at depths between 3100 and 2500 m on the east wall, suggesting that the faults provide avenues for hydrothermal fluids. Small topographic highs in the floor of the rift valley are the sites of relatively recent volcanism and are believed to represent the top of an active dike emplacement zone. Bathymetric trend directions for this portion of the ridge crest are complex in comparison with plate rotation predicted trends for the Mid-Atlantic Ridge. The bathymetric grain is a function of processes active in the rift valley.