Heat flow, bathymetry, and the Mid-Atlantic Ridge at 43°N

Abstract

A detailed profile of heat-flow values across the mid-Atlantic ridge near 43°N is typical of mid-oceanic ridge areas, except for low values (about 1.0 μcal/cm2 sec, or 42 mw/m2) 100–300 km east of the ridge crest. The mid-Atlantic ridge south of 43°N has a heat-flow distribution and bathymetric profile consistent with the hypothesis of rigid-plate tectonics with a spreading rate of less than 1.0 cm/yr for the last 40 m.y. and in conflict with the spreading-rate history deduced from magnetic anomalies. The ridge north of 43°N is abnormally flat, is unusually elevated in a region of low heat flow to the west, and has an abnormally low axial magnetic anomaly. These features cannot be explained by a simple model of rigid-plate motion.