168 Prospectus

Site: PP-5A

Priority: 1
Position: 47°45.76´N; 127°45.55´W
Water Depth: 2679 m
Sediment Thickness: 230 m
Total Penetration: 260 mbsf (with option for deepening)
Seismic Coverage: Line 95-26, SP 340 (Fig. 6B, Appendix 1B)

Objectives: At the Permeable Penetrators site relatively rugged relief of the igneous crust is buried by sediment everywhere, except at three small volcanic edifices where fluids vent through the seafloor. Holes spanning the primary basement relief will allow the buoyancy forces that drive fluid flow to be determined; holes into one of the permeable basement outcrops will allow the rate and history of discharge to be determined. The holes will extend the overall drilling transect to 3.5 Ma. This CORK reentry hole is situated in a structurally similar location to Site PP-3A; together with those made at Site PP-4A, these observations will allow determination of the degree of thermal and chemical homogeneity of basement fluids and the pressure gradient driving fluid flow.

Drilling Program: RCB only with approximately 40 m of basement penetration, but it may be selected for deeper penetration

Logging and Downhole: Approximately five temperature probe trips, packer/flowmeter testing, Quad-combo logging run, possible FMS and GLT logging runs, CORK installation

Nature of Rock Anticipated: Turbidite sediments; altered basement

To Site PP-6A

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