Figure 2. (A) Bathymetric map and location of drill sites. (B) Peak seismic amplitude on décollement (after Shipley et al., 1994; Moore et al., 1995). Bold line on both A and B indicates location of seismic line in Figure 3. Bathymetry is derived from mapped seafloor reflection in migrated 3-D seismic records.
Figure 3. Cross section from seismic depth section extending from west of Site 1045 to Site 1044. Solid lines below level of décollement and proto-décollement show approximate limits of underthrust terrigenous sequence.
Figure 4. (A) Shaded relief image of the seafloor within the 3-D seismic survey area. The seismic horizon was interpreted along the zero crossing between the first negative and first positive seafloor reflections on a grid of roughly every 10th line and every 50th common midpoint. Between interpreted lines, the horizon was mapped using the LandmarkTM Zone Autopicker algorithm, which extends horizon interpretations throughout the data set by following the specified trace characteristics. The resultant horizon contains a value for every line and common midpoint of the 3-D survey (bin spacing is 25 m x 15 m respectively). Illumination is from the southeast, and gray scale shades are histogram equalized. Overall bathymetry is increasing to the east, but small scale bathymetric variations reveal at least three distinct structural regions. Within the first region, between common midpoints 480 and 920, a series of south-southwest-trending lineations are visible downstepping to the north-northwest. The second region, from common midpoint 920 to 1386, encompasses south-southeast-trending lineations related to thrusting in the toe of the prism. East of common midpoint 1386, within the third structural region, bathymetric changes are subdued but a series of south-southwest-trending lineations is visible. These downstep to the north-northwest and are related to the topography of the underlying oceanic crust. (B) 200% zoom of the area between common midpoints 153 and 986 showing locations of Leg 110 sites. (C) 200% zoom of the area between common midpoints 986 and 1781 showing the locations of sites drilled during Legs 110, 156, and 171A.
Figure 5 (A, B). Summary of LWD data from Site 1044 compared to core data from Site 672. Shaded bar across diagram shows the proto-décollement zone.
Figure 6 (A, B). Summary of LWD data from Site 1045. Décollement zone (log Unit 7) in this region is characterized by a high-amplitude negative polarity seismic reflection.
Figure 7 (A, B). Summary of LWD data from Site 1046 compared to core data from Holes 959B and 949C. Shaded bars across diagram show fault zones identified in cores.
Figure 8 (A, B). Summary of LWD data from Site 1047 and core data from Site 676. Log units for Hole 1047A can be compared to lithologic units of Site 676. Shaded bars across diagram show fault zones as identified in core and décollement zone as inferred from interval of low density (log Unit 3c).
Figure 9 (A, B). Summary of LWD data from Site 1048 compared to core data from Site 672 and the Site 1044 density curve. Log units for Site 1048 can be compared to the lithologic units of Site 672. Shaded bars across diagram show proto-décollement zone as inferred from low-density log Unit 3.
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