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doi:10.2204/iodp.sp.323.2009

Site summaries

Site BOW-12B (Bowers Ridge): upper Miocene

Priority:
 Primary
Position:
 53°24.0′N, 179°31.3′W (WGS 84)
Water depth (m)
 1313
Target drilling depth (mbsf):
 700
Approved maximum penetration (mbsf):
 745
Previous drilling in area:
 DSDP Site 188
Comments:
 Relocated from Site BOW-12A to Shotpoint 910 on Line Stk6-1 during Cruise KH99-3, 1999 (EPSP December 2005)
Survey coverage (track map, seismic profile); sediment cores:
 R/V Hakuhou-maru Cruise KH99-3 Leg 3 (1999):
• Location and track map (Figs. AF1, AF2)
• Swath bathymetry: Line Stk6-1 (W–E) and Stk6-3 (S–N) (Fig. AF3)
• MCS profile: Line Stk6-1 (W–E) (Figs. AF4, AF5)
• Crossing Line Stk6-3 (S–N) (Figs. AF6, AF7)
• Subbottom profile, 3.5 kHz: Line Stk6-1 (W–E) (Fig. AF8)
• Piston core (9 m)
Objective (see text for complete details):
 Provide records from the shallowest part of vertical depth transect to slightly deep water (2166 m)
to evaluate vertical water mass gradients when compared to other sites.
Used to represent surface water and climate conditions in the southernmost part of the Bering Sea and
to monitor the exchange of North Pacific and Bering Sea water from the upper Miocene through the Pleistocene.
Drilling/coring program:
 Triple APC to refusal, XCB and RCB if needed:
• Holes A, B, and C: APC with core orientation to refusal (~200 mbsf)
• Hole C: XCB to ~500 mbsf
• Hole D: drill to ~500 mbsf, RCB to ~700 mbsf; logging
Temperature measurements: 3 APCT-3, 2 DVTP if required
Downhole logging program:
 Wireline logging: triple combo, FMS-sonic, possible check shot survey
Anticipated lithology:
 Hemipelagic silty clay with siliceous and calcareous microfossils

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