Anomalously shallow magnetic inclinations, most less than ¿20¿, occur throughout the deep hole at Deep-Sea Drilling Project site 332 on the mid-Atlantic ridge. This was the first hole penetrating more than 500 m into the oceanic crust. Inversion of the magnetic anomaly recorded on a deep-tow traverse near the site indicates that hole 332 was not drilled in the negative anomaly between 2' and 3 as was thought but was drilled in a broad polarity transition zone between the Gauss and Gilbert epochs. The duration of the transition may have been longer than is usual owing to the proximity of a major reversal and an event (or short reversal). Thus the anomalously shallow inclinations may be explained by episodic volcanism during the polarity reversal(s) at a rate consistent with studies of volcanism in the nearby Famous rift. The shallow inclinations may reflect dominance of the nondipolar component or some other erratic behavior of the magnetic field during the reversal(s). |