The J-Anomaly in the central North Atlantic Ocean.

Abstract

The J anomaly is a linear zone of high-amplitude magnetic anomalies, observed in the eastern North Atlantic north of the Canary Island lineament and the western North Atlantic north of the New England seamounts. Analyses of these anomalies show that the anomalous amplitude zones were formed at the Mid-Atlantid Ridge axis and thus define isochrons. Along strike, the J anomaly can be separated into two regions, one of high and one of intermediate anomaly amplitudes. In the eastern Atlantic where these amplitude variations are best documented, the boundary between the two regions occurs at a change in strike in the magnetic lineation pattern. The anomalous distribution of magnetization which is responsible for the unusual shape of the J anomaly includes crust slightly younger than M-1 to slightly younger than M-0. The J anomaly was probably caused by a large increase in the intensity of magnetization. DSDP Site 384 is between anomalies M-2 and M-3, and thus does not lie within the inferred zone of anomalous magnetization.-Authors