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Priority:
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1 |
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Position:
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6°44.19′N, 91°56.06′W |
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Water depth (m):
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3635 |
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Target drilling depth (mbsf):
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As deep as possible |
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Approved maximum penetration (mbsf):
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As deep as possible (EPSP reports as approved as proposed, and proposal requests >1700 m total penetration) |
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Survey coverage (track map; seismic profile):
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Acquired during Ewing cruise EW9903, March–April, 1999:
• MCS with 480 channels, 10 air guns
• Refraction shooting 20 air guns recorded on ocean bottom hydrophones (OBHs)
• 3.5 kHz reflection
• Hydrosweep multibeam bathymetry
• Site 1256 (proposed site GUATB-03C) is at the crossing of EW9903 Lines 22 and 27 (see Fig. F6).
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Objective(s):
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• Provide a reference with in situ samples through the extrusive volcanic and feeder dike section and into gabbroic rock in normal, intact oceanic crust formed at a very fast spreading rate at 15 Ma to constrain models of formation and alteration of oceanic crust.
• Maintain a "legacy hole" available for future deepening. |
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Drilling program:
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Continuous coring as deep as possible |
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Logging program: OR
Downhole measurements program:
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• Triple combo including MMT to determine borehole condition and temperature. If borehole has notably deteriorated, we may elect to conduct more logging runs with additional tools. If conditions permit, water sampling using WSTP.
• Full logging suite planned at the end of the expedition includes the following:
Triple combo
FMS-sonic
UBI: acoustic borehole images
VSI: normal-incidence vertical seismic profiling
MTT, HRLA, and HNGS: final temperature measurement
Final triple combo for second temperature log |
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Nature of rock anticipated:
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Gabbros and dikes |
