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Priority:
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Primary
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Position:
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23°51.0508′S, 165°38.6538′W (WGS 84)
(23.8508°S, 165.6442°W)
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Water depth (m)
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5697
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Target drilling depth (mbsf):
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171 (including 100 m of basement)
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Approved maximum penetration (mbsf):
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Up to 100 m basement penetration
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Previous drilling in area:
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DSDP Leg 91 Site 596, <1 nmi away
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Comments:
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International waters; 365 nmi off Palmerston Island, Cook Islands
Preferred weather window: November–December
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Survey coverage
(track map, seismic profile):
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High-resolution seismics:
• Primary line(s): MCS Line 1 - Shotpoint 1167 (Fig. AF1)
• Crossing line(s): MCS Line 3 - Shotpoint 2280 (Fig. AF2)
• Subbottom profile, 3.5 kHz: Line 1 - JDay 354 at 19:48 GMT
• Detailed bathymetry and site location (swath bathymetry: collected with SIMRAD EM120) (Fig. AF3)
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Sediment cores:
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Two piston cores, two trigger cores, one gravity core, and one eight-barrel multicore taken at site location
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Objectives
(see text for complete details):
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• Document the habitats, metabolic activities, genetic composition, and biomass of microbial communities in subseafloor sediments with very low total activity.
• Test how oceanographic factors (such as surface ocean productivity) control variation in sedimentary habitats, activities, and communities from gyre center to gyre margin.
• Quantify the extent to which these sedimentary communities may be supplied with electron donors by water radiolysis, a process independent of the surface photosynthetic world.
• Determine how the basement habitats, potential activities, and communities vary with crust age and hydrologic regime (from ridge crest to abyssal plain).
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Drilling/Coring program:
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• Quadruple APC to basement, RCB to 100 m of basement
• Temperature measurements: APCT-3
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Downhole logging program:
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Wireline logging: triple combo, FMS-sonic
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Anticipated lithology:
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Dark brown to dark yellowish brown clay; manganese nodules present at top
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