125 22 



PLA1NH — BENCHH MARGINAL RIDGE- 







BASIN 



■4- SECOND RIDGE 



VENTS 



PROJECTION OF 

 SUBMARINE CANYON 



B 



OCEANIC PLATE 



DECOLLEMENT- 



KM 



Figure 4. (Top diagram) Alvin submersible transects and Sea 



Beam bathymetry map across the lower continental slope (see 

 fig . 1 , dive area ) . Contours in meters ; numbered dives 

 commence at the solid dots. Asterisks indicate fluid 

 venting sites and carbonate chimneys (i.e., northern site 

 1428 and southern site 1426 on marginal ridge); triangle 

 indicates carbonate chimneys at site 1423 on the second 

 ridge. (Bottom diagram) Interpretive structural depth 

 section of the deformation front along profile A-B (dashed 

 line across contour map at top). (From Kulm et al. 1986, 

 their fig. 2. ) 



157 



