The active part of Charlie‐Gibbs Fracture Zone: A study using sonar and other geophysical techniques

A short survey with Gloria side‐scan sonar and other geophysical instruments has revealed new information about Charlie‐Gibbs fracture zone between 29° and 36°W. The traces of two transform faults have been clearly delineated. They fit small circles about the pole of rotation with an rms error of only about 1 km, but they do not always follow the deepest parts of the transform valleys. The transforms are joined by a short spreading center at 31°45′W. The median transverse ridge appears to have been produced by normal seafloor spreading at this center and bears identifiable Vine‐Matthews magnetic anomalies. A transverse ridge along the eastern inactive part of the northern transform may be an intrusive feature. Considerable thicknesses of sediment appear to have been deposited in the northern transform valley from Norwegian Sea overflow water passing through the fracture zone, but transverse ridges have prevented the sediment reaching the southern valley.