A composite section for Site 1120 was constructed using data from Holes 1120B, 1120C, and 1120D. Holes 1120B and 1120C yielded overlapping records for the upper ~52 mcd, although at least one gap in continuity exists in the composite record for this interval. Sediment composition at this site limited APC recovery to the upper ~50 m, thus the double-cored upper interval is relatively short. Holes 1120B and 1120D displayed some overlap between ~158 and 185 mcd, as planned by the drilling strategy at Hole 1120D. Four high-resolution data sets proved useful for correlation at this site: magnetic susceptibility (MS), natural gamma-ray intensity (NGR), and gamma-ray attenuation porosity evaluator (GRAPE), all measured on whole cores on the MST, and spectral reflectance at 550 nm (the center wavelength of the range measured), measured on split cores. Variations in all of these parameters decreased in amplitude downhole, yielding the best correlations in the upper section.
All four data sets defined the composite section from 0-52 mcd (Fig. F11). Low recovery in Core 181-1120B-3H (4.9 m) produced a break in continuity of the recovered section between Cores 181-1120B-3H and 181-1120C-3H (Fig. F11). Another gap may exist between Cores 181-1120B-4H and 181-1120C-4H, although we show an overlap between these two cores. This correlation, based on magnetic susceptibility records, includes only a small number of points, and may be suspect. The small section of overlap between Holes 1120B and 1120D from ~158 to 185 mcd also includes gaps between Cores 181-1120B-19X and 181-1120D-2X and between Cores 181-1120D-2X and 181-1120B-21X.
Downhole core offsets relative to mbsf depths roughly follow a model of 10% stretch between the mbsf and mcd depth scales in the upper section. Where gaps exist in the record, we assigned the top of the deeper core in one hole an mcd value equal to that at the base of the overlying core in the other hole. Such an artificial closure of the gap between Cores 181-1120B-3H and 181-1120C-3H produced a shift in offsets for Cores 181-1120B-4H through 6H, although these cores follow a trend parallel to the ten-percent-stretch model (Fig. F12). Offsets for sections deeper than 50 mbsf are merely cumulative from cores above, producing a vertical trend in Fig. F12. Table T9 (also in ASCII format) contains the offsets between the mbsf and mcd scales resulting from composite section construction.
The spliced record, based primarily on GRAPE and reflectance data (Fig. F13), extends to 52 mcd. Wherever possible, splice tie points (Table T10, also in ASCII format) were picked at well-defined maxima or minima where the overlap in data from Holes 1120B and 1120C are correlated. Typically, parameter values differed by less than 10% at tie levels. In all cases, ties were selected so that the spliced record was as free from noise (high-frequency variability) as possible.