At Site 1081, three holes were cored with a maximum penetration of 448.2 mbsf. The maximum depth reached with the APC was 187.4 mbsf (Hole 1081B). Physical properties and color reflectance data were measured at 2-cm (Hole 1081A) and 4-cm (Holes 1081B and 1081C) intervals. The correlation of features present in the physical and visual properties measurements of adjacent holes was used to demonstrate the completeness of the local stratigraphic sequence drilled and to establish a depth scale in terms of meters composite depth (mcd) for Site 1081 (Table 8). The continuity of the stratigraphic sequence was shown to a depth of 215 mcd (Fig. 27).
At Site 1081, magnetic susceptibility and wet bulk density (GRAPE) were used to establish the mcd scale. The data sets were extensively processed before being used for correlation. Suspect measurements were eliminated by thresholding the data. The resulting data were smoothed using a Gaussian filter with a length of 12 cm. All data shown in Figure 27 and Figure 28 were processed as described above.
The resulting growth of the mcd scale compared with the standard ODP mbsf scale is ~7% (Section 175-1081A-23X-CC at 215 mcd and 201.5 mbsf). Figure 29 shows a linear growth of offsets applied to cores down to 130 mbsf. The growth of the mcd scale compared with the mbsf scale averages 10% in this depth interval. Below 130 mbsf, offsets are constant.
The gaps between successive cores of the same hole average ~2 m. Large intervals seem to be missing at Hole 1081A at 9.5 mcd (between Cores 175-1081A-2H and 3H, 4 m), 85.5 mcd (between Cores 175-1081A-14H and 15H, 2.5 m), 156.5 mcd (between Cores 175-1081A-16H and 18H, 2.5 m), and 192.5 mcd (between Cores 175-1081A-21X and 22X, 4.5 m).
Of special interest is the transition of APC cores to XCB cores from Hole 1081A and the correlation of XCB cores from Hole 1081A to adjacent APC cores from Hole 1081B. The quality of XCB cores from Hole 1081A compared with APC cores from Hole 1081B is good. Interhole correlation was possible for the entire APC-covered length at Hole 1081B, down to 215 mcd.
The spliced record presented in Figure 28 (also see Table 9) is continuous to 215 mcd for magnetic susceptibility and GRAPE wet bulk densities. The selection of cores to be included in the spliced record and the placement of tie points was carried out mainly using the composite section of magnetic susceptibility from Site 1081. The strategy for splicing was to construct a continuous spliced record with smooth transitions between individual cores for most of the triple APC–covered depth interval. Because of the disturbed Core 175-1081B-8H and a missing interval between Cores 175-1081B-9H and 10H, critical depth intervals were Cores 175-1081A-8H through 10H and Cores 175-1081B-8H through 10H. Also, the APC-to-XCB transition from Core 175-1081A-16H through 19X was problematic. Both depth intervals could be covered by the corresponding cores from Hole 1081C, thus emphasizing the importance of triple coverage to achieve a complete sedimentary sequence at a site.