. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 236 McGregor et al.: Magnetics Mid-Atlantic Ridge bJ a. HI a 400 2001- 0 -200 -400 _ A :^ 2000 3000 4000 m I iiiiiiiii i m Is -56" 56' -56" 0= I80» 0» 180' 5A/M 15 25 15 ?- -H- •> _L I 5 A/M a UJ 400 200 0 -200 -400 5 2000 X K Q. 3000 UJ a 4000. 1= ; ' D=» '' m M a te^^inir 5»"isle* 5 A/M 15 25 15 56" » Qo 2264' 5 A/M -t-H- 10 20 30 40 50 60 DISTANCE (KM) Fig. 7. Models using the forward method with
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 236 McGregor et al.: Magnetics Mid-Atlantic Ridge bJ a. HI a 400 2001- 0 -200 -400 _ A :^ 2000 3000 4000 m I iiiiiiiii i m Is -56" 56' -56" 0= I80» 0» 180' 5A/M 15 25 15 ?- -H- •> _L I 5 A/M a UJ 400 200 0 -200 -400 5 2000 X K Q. 3000 UJ a 4000. 1= ; ' D=» '' m M a te^^inir 5»"isle* 5 A/M 15 25 15 56" » Qo 2264' 5 A/M -t-H- 10 20 30 40 50 60 DISTANCE (KM) Fig. 7. Models using the forward method with Idealized blocks of sea floor to show the effect of (a) normal direction of magnetization and (b) direction of magnetization rotated 45°. Blocks are numbered sequentially away from the axis of spreading, with normally magnetized blocks shaded. Directions' and intensities of magnetization used are shown. shows the anomaly generated by tilting the blocks 45" as suggested by Moore et al. [1974] (declina- tion °, inclination ° for the east side of the ridge and declination °, inclination ° for the west side). The intensities of magnetization used are shown and are in agreement with those reported by Macdonald et al. [1975], which were determined by inverting deep tow magnetic field data. The shape of the axial anomaly and the shapes of the flanking lows differ considerably (Figures 7a and 7b). From the shape of the axial anomaly measured at 26°N (Figures 4 and 5) it does not appear that tilting of the blocks in the rift valley has occurred as Moore et al. [l974] suggested for 36°N. Further confirmation of rotation as suggested by Moore et al. [1974] must await analysis of magnetic anomalies which are less variable in shape than the ones discussed here. It seems unlikely that rotation by 45° is a general feature of the mag- netic blocks, because then the paleomagnetic pole positions obtained from the shapes of the anomalies [Larson and Chase, 197
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