Three holes were cored at Site 1084 with the APC/XCB to a maximum depth of 604 mbsf. MST measurements of magnetic susceptibility and GRAPE density were taken at 4-cm resolution for all cores, except the upper 11 cores of Hole 1084A, which were measured at 2-cm intervals. Measurements of spectral reflectance using the Minolta spectrophotometer were done using the same intervals. Quantitative and graphic correlation of the physical parameter measurement of adjacent holes were used to establish depth continuity of the stratigraphic sequence. This process is used to determine intercore depth offsets of adjacent holes and to establish a common composite depth scale (expressed as meters composite depth, or mcd). The stratigraphic sequence was demonstrated to be a continuous from the core top to 175 mcd (Fig. 17; Table 10).
Cores recovered from Site 1084 show a high number of small voids of a few centimeters in size, beginning with Cores 175-1084A-8H, 175-1084B-8H, and 175-1084C-8H. The abundance of voids below 75 mcd is reflected in the MST data collected (see "Physical Properties" section, this chapter). The scatter introduced in the physical properties logs partly masks features suitable for interhole correlation. Thus, total color reflectance (lightness L*) was primarily used to construct the composite section. Magnetic susceptibility and GRAPE density were also used to supplement the correlations. To establish the composite depth record, Gaussian smoothing was applied to the data over a 31-cm window.
Once converted to the mcd scale, a complete spliced sedimentary sequence of magnetic susceptibility and color reflectance was constructed (Fig. 18). On the mcd scale, features of the magnetic susceptibility appear to be inversely related to features in the color reflectance data. By using Table 11 as a reference, a chronologically complete downcore record can be constructed by sampling adjacent holes and filling intercore gaps documented in the primary sampling hole.
Documentation of the composite section was generally good to very good; however, the noise in the deeper portions of the hole made parts of the composite section more speculative. Growth of the mcd scale relative to the mbsf scale drilled was ~17% (Fig. 19).