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Priority:
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1
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Position:
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32°42.3402’S; 57°16.6910’E
North-central part of Atlantis Bank wave-cut platform
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Water depth (m):
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695
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Target drilling depth (mbsf):
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As deep as possible (>3 km)
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Approved maximum penetration (mbsf):
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To be agreed; but >3 km
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Survey coverage (track map, seismic profile):
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Seabed drill core Site JR31-BR-8
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Objective(s):
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Drill deep section through gabbro to crust–mantle transition
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Drilling program:
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Re-entry system:
Plan A: 15-m long 13.375-inch drill-in casing
Plan B conventional 15-m long 16-inch casing. RCB core to 220 mbsf; set 200-m long 10.75 inch casing (after logging).
RCB core as deep as time permits. Log.
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Logging/downhole measurements program:
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Three runs with triple combo, FMS-sonic, and UBI before setting 200 m long 10.75 inch casing; same three runs plus VSI from 200 mbsf to maximum depth achieved.
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Nature of rock anticipated:
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Gabbro, possible rare diabase; ultimately serpentinized
and thence fresh peridotite
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