In the west basin, spreading at the older, eastern part of the axis 

 (profiles 4-7, Fig. 8) persisted for about 1.5 m.y, longer than the 

 youngest part of the east basin spreading axis. 



From the above observations it is clear that the spreading history 

 of the Caroline Basin is not comparable to the uniform spreading 

 histories of the larger ocean basins. It appears that the history is 

 very diverse, with hiatuses, episodic temporal incongruities, and pos- 

 sible reactivation of old spreading axes. 



Additional information on the source of the magnetic anomalies 

 can be gained from analysis of the component data perpendicular to (X'), 

 and parallel to (Y') the strike of the magnetic lineations. For exam- 

 ple, the model studies above are based on the premise that the magnetic 

 anomalies are essentially 2-dimensional (length :width> 3 :1) . Although 

 the anomalies appear to be 2-dimensional, in the absence of sufficient 

 data for contouring the only positive way to determine this is through 

 the Y' component, which only records anomalies due to 3-dimensional 

 sources (Blakely and others, 1973), and theoretically should be zero 

 over 2-dimensional sources. 



At the magnetic inclinations found in the Caroline Basin area (0 

 12 S), contributions to the total intensity vector (F) by the induced 

 magnetization from the vertical (Z) component should be minimal. The 

 major contribution should come from the horizontal (H) component. Sig- 

 nificant Z anomalies would therefore indicate strong remnant magnetiza- 

 tion. 



29 



