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Priority:
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Alternate
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Position:
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18°20.167′N, 116°42.28′E
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Water depth (m):
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3906
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Target drilling depth (mbsf):
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1879
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Approved maximum penetration:
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Approved to basement + 100 m with full coring. Drilling through the top 900 m without coring is pending EPSP approval.
(Estimated total depth = 1879 mbsf)
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Survey coverage (track map; seismic profile):
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Bathymetric sketch and site track map (Figs. AF1, AF5)
Deep-penetration seismic reflection:
• Primary line: 08ec1602 (SP3300) (Fig. AF6)
• Crossing line: 08ec2696 (SP6098) (Fig. AF7)
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Objectives:
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Alternate for SCS-6A
• Date the oldest oceanic crust near the continent/ocean boundary of the South China Sea
• Measure magnetization, mineralization, and geochemical compositions of basement rocks
• Obtain basement rocks to ascertain the causes of sharp magnetic contrasts between different sub-basins
• Study the paleoceanographic response to the opening of the South China Sea
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Drilling program:
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Hole A (APC/XCB coring will only be completed if full coring is required by EPSP):
• APC to refusal with nonmagnetic core barrels, core orientation (FlexIT tool), and APCT-3
• XCB to refusal
Hole B:
• Jet-in test for reentry system
Hole C:
• Reentry system (20, 16, and 10¾ inch casing to ~900 mbsf)
• RCB with nonmagnetic core barrels to 1879 mbsf (one bit change at ~1779 mbsf)
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Downhole logging program:
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Hole A:
• Triple combo
• FMS-sonic
Hole C:
• Triple combo
• FMS-sonic
• VSI if time and hole conditions allow
• UBI/MMM if time and hole conditions allow
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Nature of rock anticipated:
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(Calcareous) mudstone, siltstone, sandstone, basalt
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