spreading centers on, and parallel to, the Eaurlpik Rise, separated 

 by numerous northeast-striking transform faults. 



Mammerickx (1978) offered another interpretation, based heavily 

 on the significance of bathymetric features. She too proposed a 

 two-phase sea-floor spreading scheme in which the Kiilsgaard and 

 West Caroline Troughs (Fig. 2) are remnants of a former continuous 

 spreading axis, active from about 38 m.y. B.P. until 31 m.y. B.P. 

 and 28 m.y. B.P. , respectively. At approximately 31 m.y. B.P., 

 she proposed that the spreading center jumped to the axis of the 

 Eauripik Rise, and persisted at a rate of 5 cm/yr until 26 m.y. B.P. 

 This axis consisted of a series of short northeast-oriented spreading 

 segments separated by northwest-striking transform faults. She also 

 proposed a triple ridge-j unction at the location of DSDP site 62 

 (Fig. 2), with a bifurcation of the spreading axis extending south- 

 east to the Manus Trench along the present bath3Tnetric axis of the rise. 



Weissel and Anderson (1978), using additional geophysical data, 

 identified a spreading axis on the extreme eastern margin of the 

 basin. This axis was active from about anomaly 13 to anomaly 9 

 time (approximately 28.5 - 36 m.y. B.P.). The axis is associated 

 with a bathymetric trough which the authors identified as an exten- 

 sion of the Kiilsgaard Trough. They also concur with Mammerickx 

 that the West Caroline Trough is an inactive spreading center, although 

 they did not assign any age to the magnetic anomalies flanking the 

 trough. The authors further contend, on the basis of morphology and 

 sediment thickness, that the Ayxi Trough (Fig. 2) is a spreading center, 



