Site summaries (continued)

Site UMK-4D (Umnak Plateau): Pliocene–Pleistocene

54°40.2′N, 169°58.9′W (WGS 84)
Water depth (m)
Target drilling depth (mbsf):
Approved maximum penetration (mbsf):
Previous drilling in area:
DSDP Site 185
Relocated from Site UMK-4C to Shotpoint 3275 on Line 2 of USGS R/V Lee Cruise L6-80 (EPSP December 2005)
Survey coverage (track map, seismic profile); sediment cores:
USGS R/V Lee Cruise L6-80 (1980):
• Single-channel seismic: Line 2 (Figs. AF52, AF53)
• Crossing Line 5 (Figs. AF54, AF55)
• Seismic velocity: DSDP Site 185 measurement; ref. interval velocity by R/V Lee Cruise L6-80, Line 6
R/V Hakuhou-maru Cruise KH99-3 Leg 3 (1999):
• Regional overview map with track line (Fig. AF55)
• 3.5 kHz (Fig. AF56)
• Swath bathymetry (Fig. AF57)
• Multiple cores (30 cm)
Objective (see text for complete details):
Monitor surface water exchange from the Pacific into the Bering Sea and surface conditions in the easternmost part of the Bering Sea.
Reconstruct Pliocene–Pleistocene high-resolution paleoceanography and investigate Bering/Arctic Gateway history and sea ice and water mass distribution, distal to Pacific water.
Drilling/coring program:
Holes A, B, and D: APC with core orientation to ~200 m, Hole C to 25 mbsf
Temperature measurements: 3 APCT-3
Downhole logging program:
Wireline logging: triple combo, FMS-sonic
Anticipated lithology:
Hemipelagic silty clay with siliceous and calcareous microfossils. Estimated bottom age = Pliocene.

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