The distribution of volcanic ash layers at four sites drilled during Leg 165, Site 999 on the Kogi Rise in the Colombian Basin, Site 998 on the Cayman Rise, Site 1000 on the upper Nicaraguan Rise, and Site 1001 on the Hess Escarpment. The data are not corrected for core recovery, as, in general, core recovery was excellent and close to complete in much of the cored section. The dispersed ash and terrigenous component in sediments drilled during Leg 165 calculated on the basis of geochemical normative models. Summary of correlations between seismic stratigraphy, depths, logging units, lithologic units, and ages at Site 999. Correlations with the reflection seismic record were constrained by calculations of two-way traveltime vs. depth derived from compressional velocities measured by downhole logging and laboratory instruments.
Velocities shown are averages derived from the downhole sonic tool within each major logging unit.
The total depth at Hole 999B of 1066.4 mbsf corresponds to 4.722 twt. The depth of volcanic basement is approximately 1400 mbsf if average velocities measured within seismic unit CB5 are extended to 4.936 s twt. At left is a lithostratigraphic summary of the boundary. The FMS image shows a claystone layer at the base of the limestone, which is about 8 cm thicker than the recovered claystone deposit. We propose that this represents the portion of the boundary deposit that was not recovered.