A multiple and propagating rift model for the NE Atlantic

Two stages of propagating rift behaviour can be pro-observed within the seafloor-spreading history of the NE Atlantic. Spreading started along one virtually continuous spreading ridge (early axis in Fig. 1) from S of Greenland and northward to the Greenland-Senja Fracture Zone. This ridge showed a locally sinuous trend with linear to the S and to the N (later Reykjanes and Mohns Ridge respectively), and a curved segment in the middle showing partly oblique spreading (later Aegir Ridge). Spreading was initiated above sea-level and apparently gressed from the S towards the N between anomaly 25 and 24 with an apparent propagation rate of around 1 m per year. The suggestion of a propagating behaviour of the early axis is based on the northward narrowing zone of pre-anomaly 24 oceanic crust (Fig. 1) and is not confirmed segments stratigraphically. Initial but unsuccessful attempts at spreading along one straight axis may be correlated with a line of intraplate volcanism in E Greenland (see Fig. 1) including the source area for the lower part of the E Greenland plateau basalts. An almost successful attempt at straightening the early axis took place around anomally 24 time and is recorded along part of the E Greenland coast by dyke intrusion, rotation of fault blocks and linear magnetic anomaly formation (E Greenland extinct axis in Fig. 1). Spreading, however, continued along the sinuous axis. By the time of anomaly 22 to 20, the southern straight segment of the axis started to propagate above sea-level, from the position