Lithostratigraphic boundaries at Site 1176 can be correlated with reflections on 3-D seismic line 277 (Fig. F32). Specific correlations should be considered preliminary at this time because the velocity structure at this site is not well known. Any inaccuracies in velocity will produce errors in depth conversion. Additional velocity work will be carried out postcruise to improve depth conversions and stratigraphic correlations.
Lithostratigraphic Unit I is recognized on the seismic line as a sequence bounded at the top by the seafloor and at the bottom by a strong reflector that dips northwest, intersecting Site 1176 at ~180 mbsf (Fig. F32). Reflections within the upper 800 m of the sequence are generally continuous and dip slightly to the southeast (seaward), but the lower reflections are somewhat discontinuous and dip northwest (landward). The unit thickens to the northwest and exhibits an overall wedge shape.
Seismic Unit II is correlated with lithostratigraphic Unit II and is bounded by a sharp reflection at its top and onlaps the underlying sequence at its base. Internal reflections are strong and continuous northwest of Site 1176 but are discontinuous and lower amplitude southeast of Site 1176.
The lowest identified seismic stratigraphic unit correlates with lithostratigraphic Unit III. It is defined by an angular unconformity at its top. Internal reflections exhibit high amplitudes, are laterally continuous, and dip steeply to the northwest (landward).
The major out-of-sequence thrust that was a significant target for this site is interpreted to lie ~10-20 m below the base of Hole 1176A.