IODP

doi:10.2204/iodp.sp.320321.2008

Site summaries (continued)

Proposed Site PEAT-2C (early Eocene Equator and climatic optimum)

Priority:
Primary for Expedition 321, alternate for Expedition 320
Position:
11°54.711’N, 141°02.744’W (WGS-84)
Water depth (m):
4941 (6.588 s TWT)
Target drilling depth (mbsf):
162 then tag basement
Approved maximum penetration (mbsf):
250 (approved by TAMU safety panel based on EPSP June 2006 recommendation)
Survey coverage
(track map; seismic profile):
Roger Revelle (6 April 2006; 6 kt):
• Simrad EM-120 multibeam system
• Knudsen 320B subbottom profiler
• Dual 150 c.i. GI seismic sources
• Scripps 48-channel Geometrics GeoEel
Piston core: 11.31 m (RR0603-10JC)
Primary seismic line: PEAT-2 Line 6
Crossline: PEAT-2 Line 1 (Figs. F14, F15, F16) (see also report to the EPSP panel, available at eprints.soton.ac.uk/45921)
Objective:
Sites PEAT-1C and 2C are located above 49–50 Ma basement to provide material from previously poorly recovered early and middle Eocene material at times of a very shallow CCD, during and after the early Eocene Climatic Optimum. This time period represents true Cenozoic "greenhouse" conditions followed by gradual climatic cooling.
Drilling program:
Preferred:
• Holes A, B, and C: APC with core orientation to refusal; XCB to basement. Logging in Hole A.
Minimum:
• Hole A: APC/XCB to basement
• Holes B and C: wash to 100 m; APC/XCB to basement
Downhole measurement program (low priority at this site):
• Wireline logging: triple combo, FMS-sonic, possibly check shot
• Temperature measurements: 3 APCT-3, 2 DVTP
Nature of rock anticipated:
Clay, radiolarian ooze, nannofossil ooze/chalk, possibility of chert strings, hydrothermically altered ridge basalt