The physical properties program at Site 1169 included multisensor track (MST) and thermal conductivity measurements of whole-round cores and compressional wave (P-wave) velocity, moisture and density (MAD), and vane shear-strength measurements of split cores. Because of the extensive disturbance of the cores and the pervasive flow-in, the quality of sediments recovered is poor and the available physical properties data set is limited.
All core sections from Hole 1169A were measured on the MST (for magnetic susceptibility, P-wave velocity, and gamma-ray attenuation [GRA] density) at 2-cm intervals. P-wave velocities were recorded at 2-cm intervals in Hole 1169A to a depth of ~197.9 mbsf. P-wave velocities were not recorded in the XCB-cored sections.
The combination of flow-in and high carbonate content of the sediments is reflected in the relatively unvarying downcore magnetic susceptibility profile (Fig. F15A). GRA density values and discrete wet bulk-density data exhibit similar downhole trends (Fig. F15B). The GRA and MAD density data, however, show more variability than the magnetic susceptibility data. Because of the ubiquitous flow-in, it is difficult to determine whether the downcore variations result from lithologic variation or disturbance. A significant decrease in GRA density at ~200 mbsf corresponds to the switch from APC to XCB coring.
GRA values are higher than the discrete density values (Fig. F15B) reflecting the MST calibration procedure. The calibration procedure for the MST is optimized for mixed sediments, so the GRA-density measurements are overestimated in the carbonate-rich sediments at Site 1169.
Discrete compressional velocity measurements (PWS1, PWS2, and PWS3) were performed at a sample frequency of one per section, when sections were not characterized completely by flow-in or disturbed sediments (Fig. F16; Table T14). A comparison of the filtered continuous MST velocity profile with the discrete values is shown in Figure F16. PSW3 (x- [across core] direction) velocities are higher than expected for the sediment type (Fig. F16). The velocity measurements perpendicular (PSW1; z- [along core] direction) and parallel to the bedding (PSW2; y- [perpendicular to the core] direction) are similar, ranging between 1500 and 1620 m/s. Although discrete velocity measurements were always attempted in less disturbed intervals, data interpretation is difficult because of the high degree of disturbance and presence of flow-in throughout much of the core.
Vane shear strength was measured in sections with relatively low amounts of flow-in and disturbance in Hole 1169A. However, the data quality is unknown considering the high degree of disturbance. The shear strength results are displayed in Figure F17 and Table T15. With the exception of several high shear-strength values at ~80 mbsf, the data fluctuate around an average of ~20 kPa.
Thermal conductivity was measured on Section 3 of Cores 1H-6H and 14H-18H in Hole 1169A (Fig. F18; Table T16). Thermal conductivity measurements are made before core splitting; therefore, it is impossible to assess sediment quality when taking measurements. The data are limited and of suspect quality because of the highly disturbed sediments and the presence of flow-in.
The density data from discrete samples (Fig. F19; Table T17) have a strong first-order correlation with the GRA data (Fig. F15B). MAD samples were chosen only from sections that appeared to display minimal disturbance or flow-in. However, because flow-in and disturbance were so prevalent, it is difficult to assess the quality of the data.