FIGURES

Figure 1. Map showing the site locations for Leg 179 Part I (near Site 735) and Part II (near ODP Sites 756 and 757).

Figure 2. Hand-contoured Seabeam bathymetric map of the eastern transverse ridge of the Atlantis II Transform, showing the location of Site 732 and Hole 735B (Dick et al., 1991). Contour interval = 250 m. Solid contours include regions covered by seabeam swaths, whereas dashed contours are inferred. Proposed drilling region near the wavecut platform and Hole 735B, which was cored during ODP Leg 118. Solid dots and arrows indicate the starting point and approximate track of dredge hauls. Filled circles indicate the approximate proportions of rock types recovered in each dredge,: white=altered peridotite, +=gabbro, v=basalt and diabase, stippled = greenstone (Dick et al., 1991). Also shown are the proposed sites to be drilled during Leg 179.

Figure 3. Local survey track of video/sonar coverage at Site 735 showing the distribution of rock outcrop vs. sediment cover. Ratio of rock outcrop to sediment is proportional to distribution of patterns. Axes are in meters distance from Beacon 1 and time is annotated. Leg 118 drill hole locations and bathymetry (5 m contour interval, based on drill pipe measurements) are also shown.

Figure 4. Schematic diagram of water hammer drill-in casing system deployment. A. Initial deployment. B. Spud hole and drill ahead. C. Disengage hydraulic hammer and circulate fluid. D. Install free-fall reentry funnel. E. Retract bit and release casing running tool. F. Recover hammer drill and leave a cased reentry hole on the seafloor.

Figure 5. Site map in the Eastern Indian Ocean showing the location of Ninetyeast Ridge and NERO primary Site 757 and alternate Site 756 (from Peirce, Weissel, et al., 1989).

Figure 6. Sketch of the OFM/SISMOBS experiment (April-May 1992). OFM = Observitoire Fond de Mer (ocean bottom seismometer). OFP = Observitoire Fond de Puits (borehole seismometer).

Figure 7. Location of Federation of Digital Seismic Networks (FDSN) and GEOSCOPE stations in the world as of 1996.

Figure 8. Tomographic model AUM for depth = 100 km (from Montagner and Tanimoto, 1991). Triangles show existing broadband GEOSCOPE stations. Diamonds are proposed drilling sites.

Figure 9. Focal mechanisms of earthquakes that occurred in the Indian Ocean during the last 15 yr (from the Harvard database). It can be noted that the Australo-Indian plate is characterized by a high intraplate seismicity.

Figure 10. Survey tracks and bathymetric chart of the Site 757 operations area (after Shipboard Scientific Party, 1989b). Dashed line indicates survey track conducted during cruise 2707 of the Robert D. Conrad. Solid line indicates survey track of the JOIDES Resolution for ODP Leg 121.

Figure 11. Seismic dip line across the primary Site 757. A. Shipboard analog record, uninterpreted on left and interpreted on right. B. Same line reprocessed postcruise with less vertical exaggeration. The seismic units are discussed in the "Seismic Stratigraphy" section, Leg 121 Initial Reports (Shipboard Scientific Party, 1989c).

Figure 12. Seismic strike line across Site 757. A. Shipboard analog record, uninterpreted on left and interpreted on right. B. Same line reprocessed postcruise with less vertical exaggeration (after Shipboard Scientific Party, 1989c).

Figure 13. Bathymetric chart of the alternate Site 756 operations area (after Shipboard Scientific Party, 1989b). Dashed line indicates survey track conducted during cruise 2708 of the Robert D. Conrad, reference shotpoints are noted as tickmarks along the track line. Solid line indicates survey track of the JOIDES Resolution for ODP Leg 121.

Figure 14. Seismic profile of a proposed location for alternate Site 756. The seismic units are discussed in the "Seismic Stratigraphy" section, Leg 121 Initial Reports (Shipboard Scientific Party, 1989b).



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