Magnetic susceptibility (MS) and sediment lightness (L*) data collected from Holes 1263A, 1263B, 1263C, and 1263D at 2.5-cm intervals were used to construct the composite section for Site 1263. The MS measurements were primarily used for core-to-core correlation and to construct the composite section (Figs. F4, F5). The depth offsets that define the composite section for Site 1263 are given in Table T2.
The composite depths of the top of the first six cores from Hole 1263A were calculated by assuming an 18% growth rate with depth. The composite data show that the cores from Site 1263 provide an almost continuous sequence from 48 to 340 meters composite depth (mcd), a few meters below the P/E boundary (Core 208-1263C-16X; upper Paleocene). The quality of the splice was limited by short cores; therefore, little overlap in some intervals and variable core quality resulting from APC and XCB coring (see example in Fig. F6), extremely disturbed cores resulting from the presence of chert and sediment flow (Cores 208-1263A-22H, 208-1263B-18H, and 208-1263C-4H), and two normal faults (Sections 208-1263A-4H-1, 20 cm, and 208-1263C-2H-2, 20 cm) affected our ability to make the spliced section. Nevertheless, the splice was created successfully, although some correlations between cores and their positions in the spliced record need to be handled with care. Cores 208-1263C-7H to 208-1263A-26H (~259 mcd), 208-1263C-9H to 208-1263A-28H (~283.5 mcd), 208-1263C-11H to 208-1263A-30H (~306 mcd), 208-1263C-27H to 208-1263D-1H (~318 mcd), and 208-1263B-9H, 208-1263A-27H, and 208-1263B-28X were appended to the base of the preceding cores (also see Table T3).
The top of Cores 208-1263B-18H and 19H and Core 208-1263C-4H were placed according to the growth rate for their depths (Fig. F7). The equivalent mcd for all cores below the splice (Table T3) was calculated by using the interpolated growth factor for the given mbsf depths. Following construction of the composite depth section for Site 1263, a single spliced record was assembled from the aligned core intervals from all four holes (Table T3).
Cores that had been significantly stretched, squeezed, or disturbed by the coring process were not used for the splice, with one exception, the base of Core 208-1263A-22H. Without a stretch or squeezing correction, all points in each core are offset equally. As a result, most of the cycles are not perfectly aligned between holes (e.g., Fig. F4). Thus, the mcd values of the different holes approximate but do not precisely correspond to the same stratigraphic horizon in alternate holes.
The P/E boundary interval in the composite was taken from Core 208-1263D-4H (~340 mcd) (Fig. F5). The Site 1263 splice (Table T3) can be used as a guide to sample a single sedimentary sequence between 48 and 340 mcd, and it was used to plot other data sets from this site. The mcd-to-mbsf growth factors for Holes 1263A, 1263B, and 1263C were 18%, 18%, and 19%, respectively (Fig. F7).