of any longitudinal flow along the spreading axis. The major charac- 

 teristics of such a "transform dam" would be: (1) Accumulation of 

 ultrabasic slushes and increased basic volcanism along the upstream 

 side of the dam. (2) A transform fault along only one side of the 

 constructional ridge formed by the basalt discharge. (3) The con- 

 structional ridge would have the same age as the adjacent accretional 

 crust on the upstream side of the fracture. 



The Eauripik Rise demonstrates all the above characteristics. 

 The presence of extrusive basalt at DSDP Site 62 as well as other 

 nearby igneous features (Winterer and others, 1971) indicates that 

 volcanism was occuring on the rise even after the cessation of spread- 

 ing in the East Caroline Basin. This fact is somewhat puzzling, con- 

 sidering that spreading at this location ceased at about 31 m.y. B.P. 

 (although continuing until 28.5 m.y. B.P. to the east). A possible 

 explanation is that the old spreading axis still served as a conduit 

 for basalts formed at a still marginally active hotspot located to the 

 east, but that the discharge volume was insufficient to support spread- 

 ing. 



The 325 km offset of magnetic anomalies along the western flank 

 of the rise indicates that this flank was the site of the most exten- 

 sive transform faulting in the Caroline Basin. Those faults on the 

 eastern flank of the rise are relatively minor and are discontinuous. 

 The relatively steep bathymetric gradients (Fig. 2) on the west flank 

 of the rise also indicate that this was the locus of extensive faulting 



49 



