IODP

doi:10.2204/iodp.sp.329.2010

Site summaries (continued)

Site SPG-10A

Priority: Primary
Position: 39°18.6158′S, 139°48.0381′W (WGS 84) (39.3103°S, 139.8006°W)
Water depth (m) 5283
Target drilling depth (mbsf): 21
Approved maximum penetration (mbsf): Until basement is encountered
Previous drilling in area: Closest drilling:
• DSDP Leg 92 Site 597, 1350 nmi away
Comments: International waters; 750 nmi from Rapa, French Polynesia Preferred weather window: November–December
Survey coverage (track map, seismic profile): High-resolution seismics:
• Primary Line(s): MCS Line 6 - Shotpoint 15516 (Fig. AF25)
• Crossing line(s): MCS Line 4 - Shotpoint 14861 (Fig. AF26)
• Subbottom profile, 3.5 kHz: Line 6 - JDay 013 at 16:03 GMT
• Detailed bathymetry and site location (swath bathymetry: collected with SIMRAD EM120) (Fig. AF27)
Sediment cores: Two piston cores, three trigger cores, one gravity core, and seven cores of an eight-barrel multicore
Objectives (see text for complete details): • 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.
Drilling/Coring program: • Triple to quadruple APC to basement
• Temperature measurements: APCT-3
Downhole logging program: None specified
Anticipated lithology: Homogeneous brown clay with yellowish brown circular mottles; baseball-sized manganese nodules present at top