We built a meters composite depth (mcd) scale to Section 202-1242B-27X-6 (0.00-287.38 mcd) and a splice (as defined in "Composite Section" in the "Explanatory Notes" chapter) that documents complete recovery for the upper 196.37 mcd. The splice ranges from the top of Core 202-1242A-1H to the bottom of Section 202-1242A-19H-6 (see Tables T2, T3). All APC cores can be correlated to the splice at Site 1242. One XCB core (202-1242B-19X) can also be correlated into the splice records of Site 1242. Below the splice, Cores 202-1242A-20X and 202-1242B-21X are correlated to each other. Below these cores, a floating splice exists to the bottom of the XCB section (205.68-287.38 mcd).
The mcd scale and the spliced interval (0-196.37 mcd) are based on the stratigraphic correlation of Oregon State University Fast Track magnetic susceptibility (OSUS-MS) measurements collected at 5-cm intervals (Fig. F9A, F9B, F9D, F9E, F9F, F9G; Tables T4, T5, T6, T7). The floating splice interval (205.68-287.38 mcd) is based on whole-core multisensor track magnetic susceptibility (MST-MS) data (Fig. F9H, F9I, F9J, F9K). Tie points (Table T3) were then used to construct representative spliced records for MST magnetic susceptibility, gamma ray attenuation (GRA) bulk density, and, where available, natural gamma radiation (NGR) data (Fig. F10) and for color reflectance (L*, a*, and b*) data (Fig. F11).
We assumed that the uppermost sediment (the "mudline") in Core 202-1242A-1H was the sediment/water interface. A mudline was also recovered in Cores 202-1242B-1H and 202-1242C-1H. Core 202-1242A-1H is the "anchor" in the composite depth scale. From this anchor we worked downhole, correlating the stratigraphy on a core-by-core basis.
Correlation between holes in three areas of the composite section at Site 1242 is somewhat uncertain and should be confirmed by additional shore-based analyses. This also introduces uncertainty into the positioning of ties within the floating splice at Site 1242. The first problematic area is between 215 and 220 mcd and includes the tie between Section 202-1242B-21X-7, 70.0 cm, and Section 202-1242A-22X-2, 7.0 cm (Fig. F9, F9I). The second lies between 270 and 273 mcd and includes the tie between Sections 202-1242A-26X-6 and 202-1242B-26X-6 (Fig. F9J, F9K). The third area of uncertainty is from 278 to 282 mcd and includes the tie between Cores 202-1242A-27X and 202-1242B-27X (Fig. F9J, F9K).
A comparison of the mcd and mbsf depth scales (Fig. F12) shows that the mcd scale is on average 13% longer than the mbsf scale. To facilitate the calculation of mass accumulation rates (MARs), we provide corrected meters composite depth (cmcd) in Table T2 and in Table T3 for depths within the splice.