D . Survey Results 



1 . Enroute Data 



The enroute magnetic survey data are presented in Figures 33 through 66 

 as a series of magnetic total intensity profiles with corresponding bathymetric pro- 

 files and detailed plots of the ship's track. A detailed analysis of these single- 

 profile magnetic data is not possible because of insufficient knowledge of the 

 geomagnetic and bathymetric trends. Some of the more significant magnetic fea- 

 tures do warrant brief descriptions, however, and are discussed in the following 

 paragraphs . 



Hawaiian Islands to New Zealand (Figs. 29 and 30) 



A negative anomaly of 700 gammas is associated with a sharp bathy- 

 metric feature north of the Christmas Island Ridge (Fig. 34). There is excellent 

 correlation between an 800-gamma anomaly and a steep bathymetric feature on 

 the Samoa Island Rise (Fig. 36). There is a noticeable lack of significant 

 anomalies over the seamounts north of the Tonga Trench (Figs. 36 and 37), 

 There are, however, small anomalies (175 gammas) over the Trench itself. In 

 the vicinity of 31° S, 178* W, on the western side of the Kermadec Trench, 

 there are broad magnetic features with amplitudes of 450 gammas that have no 

 significant bathymetric association (Fig. 39). 



South of New Zealand (Fig. 31) 



At approximately 45° 45' S, 173° 45' E, on the New Zealand Plateau, 

 there is a broad 1200-gamma anomaly which has no bathymetric correlation 

 (Fig. 40). This lack of bathymetric correlation is characteristic of the anomalies 

 (some of which are very steep) that occur over the plateau . An anomalous zone 

 begins with a 250-gamma anomaly over the slope at the edge of the plateau and 

 continues across it (Figs. 40, 41, 42, and 59, 60, 61). A large, complex 

 anomaly (1750 gammas) is present over the Pacific-Antarctic Ridge (Fig. 57). 



The Ross Sea (Fig. 32 ) 



There is an extremely steep, high amplitude anomaly (2500 gammas) 

 north of Ross Island. This anomaly (Fig. 50) is associated with a small bathy- 

 metric feature in approximately 50 fathoms of water. 



Cook Strait to Australia (Fig. 30) 



No anomalies were observed in the passage through Cook Strait (Fig. 62). 

 Anomalies exceeding 400 gammas occur on the Lord Howe -New Zealand Rise 

 between latitudes 38° and 39° South (Fig. 64). An anomaly with an amplitude 

 of 1000 gammas occurs over a broad seamount of 2500 fathoms relief east of 

 Brisbane, Australia (Fig. 66). 



44 



