A study of part of the eastern flank of the mid-Atlantic ridge

Abstract

A continuous seismic reflection profile along the eastern flank of the mid-Atlantic ridge between the latitudes of 47°N and 48°N is discussed. Excellent resolution and multiple recording techniques yield an unusually clear view of both sediment thickness and structure along this line. The sediments filling many intermontane basins on the ridge and the surface sediments in the Porcupine abyssal plain appear to have a similar genesis—horizontal transport of sediment. Some abyssal hills in the abyssal plain predate the surrounding overlapped sedimentary horizons; others appear to be the result of compressional forces and unrelated to basement irregularity. The basement relief below the upper and part of the middle step is very rough (amplitude approximately 500 meters, wavelength about 8 km). Below the remainder of the middle step and the western part of the lower step, the basement is more nearly level. Eastward of this the topography of the basement appears to have a shorter wavelength and a decreased amplitude.