Site summaries (continued)

Proposed Site PEAT-5C (Oligocene Equator)

Primary for Expedition 320, alternate for Expedition 321
07°42.075’N, 128°15.254’W (WGS-84)
Water depth (m):
4311 (5.748 s TWT)
Target drilling depth (mbsf):
253 then tag basement
Approved maximum penetration (mbsf):
300 (approved by TAMU safety panel based on EPSP June 2006 recommendation)
Survey coverage
(track map; seismic profile):
Roger Revelle (31 March 2006):
• Simrad EM-120 multibeam system
• Knudsen 320B subbottom profiler
• Dual 150 c.i. GI seismic sources
• 4-channel streamer
Piston core: 11.1 m (RR0603-07JC)
Primary seismic line: PEAT-5 Line 6
Crossline: PEAT-5 Line 1 (Figs. F23, F24, F25, F26) (see also report to the EPSP panel, available at
Site PEAT-5C targets lower Oligocene crust to
• Obtain well-recovered and well-preserved equatorial sections during a time of relatively deep CCD to extend and supplement existing astronomical time calibrations
• Investigate how a "one cold pole" world might impact the inter-hemispheric temperature imbalance on pole-to-Equator temperature gradients and on the symmetry of the global wind systems
• Gain new information on the position of trade winds, the position of the ITCZ, and the seasonal shifts in this zone, as reflected by the wind-driven currents of the equatorial region
• Form a limited depth transect with Sites PEAT-4C and 6C
Drilling program:
• Holes A, B, and C: APC with core orientation to refusal; XCB to basement; logging in Hole A
• Hole A: APC/XCB to basement
• Holes B and C: wash to 100 m; APC/XCB to basement
Downhole measurement program:
• Wireline logging: triple combo, FMS-sonic, possibly check shot
• Temperature measurements: 3 APCT-3, 2 DVTP
Nature of rock anticipated:
Clay, radiolarian/nannofossil ooze, nannofossil ooze/chalk, possibility of thin diatom layers, hydrothermically altered ridge basalt. Low possibility of chert strings