Although the magnetic anomaly identifications on the rise are 

 somewhat tenuous, it does appear that they continue onto the rise from 

 the east, and they are certainly not continuous with the western 

 basin anomalies. 



Among the hypotheses offered, I favor the possibility that 

 the Eauripik Rise formed as a result of transform damming, blocking the 

 flow of mantle material along the spreading axis from a mantle plume 

 located to the east. The peculiar "collapsed arch" structure of the 

 proposed eastern spreading axis (Fig. 7) is quite different from the 

 structure of the proposed western axis (Fig. 4), and may be indicative 

 of a different spreading regime associated with a mantle plume environ- 

 ment. This is, however, a speculative proposal. 



With the evidence presently available it is not possible to 

 determine the origin of the Eauripik Rise, although the hypothesis 

 that it was a sea-floor spreading center can be discounted. A pos- 

 sible resolution of the rise origin may come from geochemical analysis 

 of the basalt recovered from DSDP Site 62. It has been found (Goslin 

 and Sibuet, 1975) that aseismic ridges such as the Ninety-east, Cocos, 

 Walvis, and Iceland-Faeroes ridges have unique rare-earth composi- 

 tions that differ markedly from spreading-ridge and island-arc basalts. 



Basin Margins 



The most notable feature of the Caroline Bcsin margins is that 

 with one exception they appear to be, or have been, subduction zones. 

 The kinematics of these zones presently ranges from inactive to 

 probably active. 



50 



