The composite section for Site 1124 yielded overlapping records for the upper ~171 mcd. Data from Holes 1124A and 1124B have been used to create a composite section between 0 and 11.66 mcd. Between 17.66 and ~174 mcd, a continuous section can be recreated using data from Holes 1124C and 1124D. Between 11.66 and 17.66 mcd there was no core recovered, perhaps because of the presence of thick, locally cemented tephra. Three high-resolution data sets proved most useful for correlation at this site: MS and gamma-ray attenuation porosity evaluator (GRAPE) density measured on whole cores on the MST and spectral reflectance at 550 nm (the center wavelength of the range measured), measured on split cores. Magnetic susceptibility and, unusually for this area, GRAPE records were useful for correlation between holes from 0 to 166 mcd. The least ambiguous record for correlation was reflectance, but below 124 mcd these data have a rather small variation and appear to be more noisy. The final composite section is illustrated in Figure F22.
In the light of coring failure toward the top of the section, the top core in the lower part (17.66-174 mcd) of the composite section (Core 181-1124C-2H) was positioned so that the topmost point corresponds to the drillers' mbsf value. Above ~20 mbsf, offsets between mbsf and mcd do not follow a clear trend, probably because of the variable coring disturbance (Fig. F23). Data were edited to remove information collected over voids as identified by very low GRAPE density values and are shown in Figure F22. Below ~20 mbsf, downhole core offsets in the composite section parallel a model of 10% stretch between the mbsf and mcd depth scales (Fig. F23). Table T12 (also in ASCII format) contains the offsets between the mbsf and mcd scales, which result from composite section construction.
The continuous spliced record, based on MS and reflectance data (Fig. F24), extends to 171 mcd. The top portion of the splice is composed entirely of records from Holes 1124A and 1124B, but the bulk consists of intervals from Holes 1124C and 1124D. Wherever possible, splice tie points (Table T13, also in ASCII format) were picked at well-defined maxima or minima where the overlap in data from Holes 1124A and 1124B or 1124C and 1124D are strongly 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.