basement surface found on the inner wall of the New Guinea Trench 

 (profile C) , and the peculiar zone of high basement relief found at 

 the southern end of the Eauripik Rise (profile G) . 



Figure 7 shows north-south seismic reflection profiles on the 

 Eauripik Rise (profile 8) and in the East Caroline Basin (profiles 

 9-11; L-D 5). The profiles are aligned (vertical dashed line labeled 

 A) about a magnetically defined extinct spreading axis. The magnetic 

 anomaly identifications used for this definition will be examined in a 

 later section. 



The Eauripik Rise (profile 8) exhibits a relatively smooth base- 

 ment surface south of 5°N, broken only by local relief in the form of 

 basement knolls, some of which penetrate the sediment surface. North 

 of 5° the profile shows considerable basement relief as the profile 

 approaches it's northern terminus in a purported extinct trench 

 (Bracey and Andrews, 1974) at 7°N. 



The remaining profiles in this figure exhibit varied and extensive 

 basement relief. On two of the profiles the proposed extinct spread- 

 ing axis appears as a collapsed basement arch (profile 9) or block 

 (profile 10) between bounding escarpments of about 1.0 sec relief. On 

 Profile 11 only the southern escarpment appears, as a trough-like 

 feature at 3°N. This trough, together with the southern-most trough 

 in Profile 10, forms the Kiilsgaard Trough shown in Figure 2. The 

 proposed extinct spreading axis location on this profile is marked 

 only by short-wavelength basement relief typified by numerous side- 

 echo reflections on the seismic record. 



19 



