Figure 8 also shows that a gap is required between the model 

 profile reversed polarity period between anomalies 12 and 13 in order 

 to match the observed data. To match the observed data during this 

 time the reversal period must be decreased by about 1.5 m.y. Whether 

 this is the result of a slowing of the spreading rate over the 3.0 

 m.y. reversal period, or a complete cessation of spreading for 1.5 

 m.y. cannot be determined. 



It is also evident from Figure 8 that the southward extent of 

 identifiable anomalies diminishes to the west. This may be due to the 

 relative increase in basement disturbance in this area indicated on the 

 seismic profiles. This basement disturbance may have been caused by 

 the arching of the oceanic crust as it approached the New Guinea Trench. 



Figure 9 shows magnetic anomaly identifications in the East 

 Caroline Basin and on the Eauripik Rise. Because of apparent dif- 

 ferences in the time of cessation of spreading indicated by the pro- 

 files, those profiles showing older cessation time are "split" at 

 the axis of symmetry in order that they may be compared to the youngest 

 profile. 



It is apparent that spreading in the East Caroline Basin ceased 

 at different times in different parts of the basin. In general it can 

 be said that the cessation of spreading progressed from west to east 

 across the basin, stopping at about 31 m.y. B.P. in profile 9, and 

 about 28.5 m.y, B.P. in profile L-D 5 (Weissel and Anderson, 1978). 



The inception of spreading seems to have been synchronous in both 

 the East and West Caroline Basins, at a time prior to anomaly 13 time. 



27 



