RESULTS 



Currents on the shelf were in line with other studies: mean flow 

 southwest along the isobaths at 10 to 21 cm/s and relatively uniform flow 

 throughout the water column. In the canyon, the currents were decoupled from 

 the shelf flow, running up and down the axis with a net up-canyon movement. 



Sediment analysis showed up to 95 percent sand on the shelf, 50 percent 

 at about 350 m, and around 3 percent at 550 m in midcanyon. The silt/clay 

 ratio in most of the samples was about 2. Pre-drilling metals analysis for 

 the upper 3 cm of sediment showed background levels consistent with earlier 

 studies--barium at 156 to 303 ppm, chromium at 8 to 45 ppm and vanadium at 16 

 to 49 ppm. The higher levels were found in the canyon, reflecting the higher 

 concentration of fine sediments. During drilling, the barium levels in the 

 upper 3 cm of sediment were elevated to almost 5,000 ppm in the immediate 

 vicinity of the wellsite, but were down to background levels within 1 to 

 1.5 km downcurrent. Chromium and vanadium levels were not elevated above 

 background even at the wellsite. 



The sedimentation rates, as measured by the traps ranged from 32 to 

 347 mg/mVday near the sea surface (20-m depth), 98 to 800 mg/mVday at 

 middepth {140-m depth), and 121 to 5,792 mg/mVday in the canyon axis at 540 

 water depth, with one anomalously high value over 1.1 million mg/mVday at 

 this location. Barium levels in the sediment traps were elevated above 

 sediment background with higher values occurring in the traps near the 

 wellsite. However, the percentage of mud solids in the sediment traps ranged 

 from about 10 percent at the 20-m depth and 1,500 m from the wellsite, to less 

 than 0.1 percent in the canyon--at the 540-m depth and 7 km from the wellsite. 



CONCLUSIONS 



■ Mud solids were transported to the canyon but not in sufficient 

 quantity to affect the natural sedimentation rate or be detected in 

 canyon sediments. 



m 



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