OCEANOGRAPHER FRACTURE ZONE

The U.S.C.G.S. Oceanographer, using a narrow beam echo sounder and satellite navigation, conducted a 1500 mile survey of the Mid-Oceanic Ridge at 35°N, 35°W in an area where the earthquake epicenter belt was offset. The survey revealed that the ridge crest is offset 80 miles in apparent right lateral sense by a steep-walled fracture zone that has a maximum depth of 2400 fms and that strikes N75°W. Analysis of magnetometer data showed that the axial growth rate of the ridge on either side of the offset is approximately 1 cm/yr. Serpentinites with lesser amounts of gabbros and basalts were recovered in two dredge hauls from the southern wall of the fracture zone. © 1969.