Multisensor track (MST) and spectral reflectance (L*) data collected from Holes 1171A, 1171B, and 1171C were used to determine depth offsets in the composite section. Magnetic susceptibility, gamma-ray attenuation (GRA) bulk density, and spectral reflectance measurements were the primary parameters used for core-to-core correlation at Site 1171. GRA bulk density and magnetic susceptibility data were collected at 2-cm intervals on all APC cores recovered from Holes 1171A, 1171B, and 1171C and at 2- to 4-cm intervals on XCB cores from Holes 1171A, 1171B, and 1171C. Spectral reflectance data were collected at 2-cm intervals on cores from Holes 1171A, 1171B, and 1171C (see "Physical Properties" and "Lithostratigraphy" for details about MST and spectral reflectance data).
The data used to construct the composite section and determine core overlaps are presented on a composite depth scale in Figure F29. The depth offsets that comprise the composite section for Holes 1171A, 1171B, and 1171C are given in Table T15. The composite data show that the APC cores from Site 1171 provide a continuous overlap to 118 mcd (base of Core 189-1171A-12H). GRA bulk density data were the primary basis for interhole correlation. Spectral reflectance measurements were used in the upper 50 mcd to provide additional support for composite construction. The interhole correlations (Fig. F29) show that ~50 cm to 1 m of material is missing between cores in each hole.
Stretching and compression of sedimentary features in aligned cores indicate distortion of the cored sequence. Because significant distortion occurred within individual cores on depth scales of <9 m, it was not possible to align every feature in the MST and color reflectance records accurately by simply adding a constant to the mbsf core depth. Core-scale changes will require postcruise processing to align smaller sedimentary features. Only after allowing variable adjustments of peaks within each core can an accurate estimate of core gaps be made.
Following construction of the composite depth section for Site 1171, a continuous spliced record was assembled for the aligned cores over the upper 120 mcd (base of Core 189-1171A-12H). Intervals having significant disturbance or distortion were avoided. The Site 1171 splice (Table T16) can be used as a sampling guide to recover a single sedimentary sequence between 0 and 120 mcd. The splice primarily utilizes cores from Holes 1171A and 1171B, except for a short interval around 32 mcd (Core 189-1171A-4H), where the splice was constructed from cores from Holes 1171B and 1171C. The variations in GRA bulk density, magnetic susceptibility, and spectral reflectance data from Core 189-1171A-4H do not match the data from equivalent cores and depths in Holes 1171B and 1171C. The cause of this difference in data quality is problematic as Core 189-1171A-4H does not contain any significant disturbance. Because of this apparent data mismatch, the sampling splice does not include Core 189-1171A-4H.