A longitudinal seismic reflection profile of the Reykjanes Ridge: Part I — Evidence for west-flowing bottom water

A longitudinal seismic reflection profile along the east flank of Reykjanes Ridge, from Charlie fracture zone to the vicinity of Iceland, has important implications both for bottom water movement and for hypotheses of crustal generation at the axis of the mid-oceanic ridge. In this paper bottom water movement is considered. Between 52°N and 57°N Reykjanes Ridge is cut by about 12 fractures whose trend, inferred from other data, is approximately east-west. North of 57° there is little or no indication of east-west fracturing. Fracture valley bottoms are typically 1 km below the surrounding basement level; sediment fills are about 0.5 km; present bottoms are 2.1 to 2.8 km below sea level. Depositional asymmetry is apparent in 9 cases, 7 of which have the deepest and generally least reflective bottom at the northern edge. This suggests predominately west-flowing bottom currents, carrying Norwegian Sea overflow water through the fracture valleys, a result consistent with previously published data.