TABLE 1
PROPOSED SITE INFORMATION AND DRILLING STRATEGY
SITE: BON-8A PRIORITY: 1 POSITION: 31° 18.5´N, 142° 57.5´E
WATER DEPTH: 6000 m SEDIMENT THICKNESS: 600 m TOTAL PENETRATION: 900 m
SEISMIC COVERAGE: Conrad 2005, Line 39, shotpoint #2936 at 1613Z on 10/13/76
Objectives: (1) Provide estimates of the sediment inputs and altered basalt inputs (geochemical fluxes) into the
Izu-Bonin subduction zone. (2) Contrast crustal budgets here with those for the Marianas to test whether along-strike
differences in the volcanics can be explained by along-strike variations in the crustal inputs. (3) Compare basement
alteration characteristics with those at Hole 801C (also in old Pacific crust). (4) Provide constaints on the Early
Cretaceous paleomagnetic time scale. (5) Provide constraints on mid-Cretaceous CCD and equatorial circulation
fluctuations.
Drilling Program: APC, XCB, MDCB, RCB
Logging and Downhole Operations: Triple combo, GLT, FMS/Sonic, GHMT, ARI, Permeability
Nature of Rock Anticipated: Pelagic clay with volcanic arc ash (150 m); cherty porcellanites and chalks (450
m); basaltic pillows, flows, breccia, and possibly dikes (>300 m)
SITE: 801C PRIORITY: 1 POSITION: 18.642°N, 156.36°E
WATER DEPTH: 5674 m SEDIMENT THICKNESS: 460 m TOTAL PENETRATION: 960 m
SEISMIC COVERAGE: MESOPAC II, Line 10 at 0600, 8/26/89
Objectives: (1) Characterize the geochemical fluxes and geophysical aging attending the upper oxidative alteration
of the oceanic crust at Hole 801C. (2) Compare igneous compositions, structure, and alteration with other drilled
sections of in situ oceanic crust (in particular Hole 504B, contrasting a young site in Pacific crust with the oldest
site in Pacific crust). (3) Help constrain models for seafloor alteration that depend on spreading rate and age (Hole
801C is the world's oldest oceanic crust and was formed at a fast-spreading ridge, so it embodies several end-member
characteristics). (4) Test models for the Jurassic Magnetic "Quiet" Zone.
Drilling Program: RCB
Logging and Downhole Operations: Triple Combo, GLT, FMS/Sonic, ARI, Permeability
Nature of Rock Anticipated: Basaltic pillows, flows, breccia, and possibly dikes (>350 m)