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Figure 1. Proposed drill sites (white circles with black rims) and alternates (solid circles) for ODP Leg 199. Site PAT-13C, however, will be drilled during Leg 200 if time becomes available. Arrows show the probable shiptrack of the JOIDES Resolution and light shaded rectangle boxes mark the approximate position of magnetic anomaly 25R, the crustal target age for the late Paleocene transect. Base map is by Mammerickx and Smith (1985).

Figure 2. Map of the Pacific equatorial sediment bulge and a schematic of ages of sediment within the bulge, from Mitchell (1998) and Mitchell (unpubl. data). The axis of the equatorial sediment bulge is displaced north of the equator because of the northward drift of the Pacific plate. Because of Pacific plate motion, Paleogene equatorial sediments are easily accessible by APC beneath a thin veneer of red clay and early Neogene sediments.

Figure 3. Position of the axis of the early Miocene equatorial bulge with respect to the hotspot predicted position of the equatorial region, from Knappenberger (2000). The hotspot position is about 2° north of the equatorial position defined by the sediment bulge. The sediment mass accumulation rate was estimated from physical properties of sediments and the distance between seismic reflectors in profiles collected on the EW9709 site survey. The ages of reflectors (20-16.3 Ma) were dated using the Mayer et al. (1985) Neogene equatorial Pacific seismic stratigraphy.

Figure 4. A schematic of the equatorial sediment bulge from seismic lines taken during the Leg 199 site survey cruise (EW9709). Note how the early Eocene section thickens north of the predicted early Eocene equatorial position. The Miocene stratigraphy is based upon Mayer et al. (1985) constrained at the surface by sediment cores. The Eocene seismic stratigraphy is based upon our best estimates but with no real age control. Leg 199 drilling will test the model shown here and in Figure 5. TWTT = two-way traveltime.

Figure 5. Tentative seismic stratigraphy of the Leg 199 56-Ma transect, from Moore et al. (manuscript submitted to Paleoceanography). Horizons "G" through "O" are identified based on comparisons with the work of Mayer et al. (1985) in the equatorial Pacific. Horizons "M" through "E3" were identified by Moore et al. (manuscript submitted to Paleoceanography). Arrows indicate the locations and ages of near-surface sediments recovered at the base of piston cores taken along the transect on EW9709. These ages were used to check our correlation with horizons identified in Mayer et al. (1985). Dashed vertical lines indicate the location of major fracture zones. TWT = two-way traveltime. FZ = fracture zone.

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