We built a meters composite depth (mcd) scale to Section 202-1239A-54X-7, 40 cm (0.00-556.82 mcd) and a splice (as defined in "Composite Section" in the "Explanatory Notes" chapter) that documents complete recovery for the upper 188.85 mcd. The splice ranges from the top of Core 202-1239A-1H to the bottom of Section 202-1239A-19H-7 (0.00-188.85 mcd) (see Tables T2, T3). All APC cores can be correlated to the splice at Site 1239.
The mcd scale and the splice are based on the correlation of whole-core Oregon State University Fast Track magnetic susceptibility (OSUS-MS) measurements collected at 5-cm intervals (Fig. F9; Tables T4, T5, T6). Tie points (Table T3) were used to construct a representative spliced record for multisensor track magnetic susceptibility (MST-MS), gamma ray attenuation (GRA) bulk density, and natural gamma radiation (NGR) data (Fig. F10), and color reflectance (L*, a*, and b*) data (Fig. F11). Magnetic susceptibility was the most useful tool for stratigraphic correlation at Site 1239.
We assumed that the uppermost sediment (the "mudline") in Core 202-1239A-1H was the sediment/water interface. Core 202-1239A-1H, the "anchor" in the composite depth scale, is the only core with depths that are the same on the mbsf and mcd scales. From this anchor, we worked downhole, correlating records on a core-by-core basis. Core 202-1239B-1H was assigned a negative offset because the uppermost few centimeters of sediment in this core has unrealistically high magnetic susceptibility that indicates possible contamination. Core 202-1239C-1H, even though it has a -0.95 m negative offset relative to Core 202-1239A-1H, is not the anchor in the splice because Cores 202-1239A-1H and 202-1239B-1H both clearly recover sediment from above the top of Core 202-1239C-1H. This negative offset is related to the general uncertainty in drillers depth estimates.
The mcd scale is on average 8% longer than the mbsf scale (Fig. F12). Given that the growth factor of 1.08 in the APC section was inferred to be constant and that no obvious lithologic changes occur in the recovered section, we placed the XCB cores on an approximate mcd scale using the observed expansion in the APC section. Thus, the 1.08% growth factor was applied to the XCB cores from Site 1239 (Fig. F12).
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.
Downhole logging operations at Site 1239 produced records of borehole density and NGR that could be correlated to GRA density and NGR measurements in sediments from Hole 1239A (Fig. F13). An estimated log depth (eld) scale was produced using these correlations (see "Core-Log Integration" in "Composite Section" in the "Explanatory Notes" chapter). This eld scale accounts for differential stretching and squeezing within cores as well as for the gaps between cores and is the most accurate depth scale for sediments below the spliced section. The Site 1239 eld file (see the "Supplementary Material" contents list) allows the application of the eld depth scale to sample depths in either the mbsf or mcd scale using the "Sagan" software package available from the Borehole Research Group at LDEO.