We built primary and secondary meters composite depth (mcd) scales and splices at Site 1233. A secondary splice was necessary because of the unusually high density of sampling requests at Site 1233. Because most of the site was quadruple cored, creation of a secondary splice was feasible. The mcd scale is constructed to align tie points between cores in the splice. Gas expansion of cores recovered at Site 1233 was unusually high and also spatially variable. Because the two splices have different tie points, when constructing a secondary splice, it was also necessary to construct a secondary mcd scale. When using one of the splices, it is critical to use the correct mcd scale.
The primary mcd scale and primary splice (as defined in "Composite Section" in the "Explanatory Notes" chapter) ranges from the top of Core 202-1233C-1H to the bottom of Section 202-1233C-13H-8 (0.00-135.72 mcd) (see Tables T2, T3). Given the available data we conclude that 100% of the cored interval at Site 1233 was recovered in the five APC holes drilled at the site. All cores from the five holes can be placed into the composite section using the core offsets listed in Table T2.
The secondary mcd scale and secondary splice (as defined in "Composite Section" in the "Explanatory Notes" chapter) ranges from the top of Core 202-1233B-1H to 202-1233C-13H-5, 39 cm (0.00-130.14 mcd). (See Tables T4, T5; also see the "Supplementary Materials" contents list for Splicer compatible affine and splice tables.) All cores from the five holes can be placed into the secondary composite section using the core offsets listed in Table T4. The secondary splice is discontinuous at five tie points because of a lack of two copies of the sedimentary sequence. The first gap in the secondary splice is between Section 202-1233E-4H-6, 65 cm, and Section 202-1233B-4H-1, 0 cm (39.29-39.47 mcd). The second gap is between Section 202-1233B-7H-7, 40 cm, and Section 202-1233C-9H-1, 0 cm (81.50-81.89 mcd). The third gap occurs between Section 202-1233B-10H-6, 85 cm, and Section 202-1233C-12H-1, 0 cm (113.09-114.13 mcd). The fourth gap lies between Section 202-1233C-12H-3, 65 cm, and Section 202-1233B-11H-1, 0 cm (116.58-117.05 cm). The fifth gap is between Section 202-1233D-13H-3, 20 cm, and Section 202-1233C-13H-1, 0 cm (124.72-125.05 mcd). The secondary splice ends 4.4 m before the primary splice because of the fact that this section of the sedimentary sequence at Site 1233 was recovered only once. The five gaps and the missing bottom of the splice mean that the secondary splice is missing 6.81 m (5%) of the sedimentary sequence at Site 1233.
The mcd scales and the splices are based on the stratigraphic correlation of whole-core OSU Fast Track magnetic susceptibility data (OSUS-MS) collected at 5-cm depth intervals using 1-s integration times. OSUS-MS data for Holes 1233A, 1233B, 1233C, 1233D, and 1233E and the primary splice constructed from them are presented on the primary mcd scale in Figure F4 and in Tables T6, T7, T8, T9, and T10. Correlations were checked using multisensor track data (MST-MS) collected at 5-cm depth intervals. The primary splice tie points (Table T3) were then used to construct representative spliced records for gamma ray attenuation (GRA) bulk density and natural gamma radiation (NGR) data. The spliced records of reflectance (L*), NGR, GRA, and magnetic susceptibility (MS) are presented in Figure F5.
Magnetic susceptibility was the most useful tool for stratigraphic correlation at Site 1233. GRA bulk density was helpful in intervals where MS structure was ambiguous. Correlation between cores from different holes was sometimes poor in the top and bottom ~1 m of cores. We interpret this lack of correlation as evidence for disturbance resulting from the effects of the coring process at Site 1233. For the primary mcd scale, we assumed that the uppermost sediment (the "mudline") in Core 202-1233C-1H was the sediment/water interface. For the secondary mcd scale, we assumed that the uppermost sediment (the "mudline") in Core 202-1233B-1H was the sediment/water interface. Comparison with site survey core GeoB3313-1 suggests that the top of Cores 202-1233C-1H and 202-1233B-1H successfully recovered near-surface sediments.
Cores 202-1233C-1H and 202-1233B-1H, the respective anchors in the primary and secondary composite depth scales, are the only cores in which depths are the same on the mbsf and mcd scales. From these anchors, we worked downhole, correlating records on a core-by-core basis. A comparison of the primary mcd and mbsf depth scales (Fig. F6) shows that the primary mcd scale is, on average, 18% greater than the mbsf scale. Note that Core 202-1233E-1H was assigned a negative offset (-0.34 m) because its top is not correlative with the other two realizations of the near-surface sediments that we recovered (Sections 202-1233B-1H-1 and 202-1233C-1H-1).
To facilitate the calculation of the mass accumulation rate (MAR), we provide corrected meters composite depth (cmcd) in Tables T2, T3, T4, and T5. The mcd growth factor for the spliced interval at Site 1233 is 1.18.