A minimum program of shipboard physical properties measurements was carried out at Site 1086. Measurements with the MST were conducted at a low resolution on GRAPE wet bulk density, magnetic susceptibility, and P-wave velocity on all recovered whole-round core sections.
Gravimetric wet bulk density, porosity, and moisture content data were determined from one sample point in every half-split core section. Method C was used at Site 1086 (see "Explanatory Notes" chapter, this volume). Undrained vane shear strength was not measured because of time constraints at this alternate site.
Discrete compressional (P-wave) velocity measurements were made at a resolution of one sampling point per section. For these P-wave velocity measurements, the modified Hamilton Frame was used on split sections of cores between 0 and 207 mbsf.
Thermal conductivity was determined on every fifth unsplit section in every core by inserting a thermal probe into the sediment (see "Explanatory Notes" chapter, this volume).
GRAPE density (Fig. 24), P-wave velocity (Fig. 25), and magnetic susceptibility (Fig. 26A) were recorded every 10 cm for the entire depth at Hole 1086A. MST data are included on CD-ROM (back pocket, this volume). Compressional velocities were stored at an amplitude threshold of 50 incremental units. The MST P-wave logger recorded signals over the entire depth of 207 mbsf at Hole 1086A (Fig. 25). This long MST P-wave profile indicates a low gas content and low signal attenuation in the sediments. MST velocity and discrete velocities correlate well over the entire depth range, although discrete velocities were mostly higher (Fig. 25).
Magnetic susceptibility (Fig. 26A) shows a similar trend compared with GRAPE and index properties wet bulk density (Fig. 24, Fig. 27A).
GRAPE density and index properties wet bulk density display a high degree of similarity. GRAPE density shows an overall increase from 1530 to 1950 kg/m3 because of sediment compaction. Long-term variations in GRAPE density may correspond to lithologic boundaries (see "Lithostratigraphy" section, this chapter). Unlike at other Leg 175 sites, higher values in GRAPE density than in the wet bulk density can be observed over the entire depth range at Site 1086.
Between 0 and 207 mbsf, most of the MST P-wave values are lower than the discrete velocities (Fig. 25). Because of the much lower gas content observed at Hole 1086A (see "Organic Geochemistry" section, this chapter), the recovered sediments were much less disturbed. Thus, velocity data from Hole 1086A are of better quality than velocity data from previous Leg 175 sites, where higher gas content caused numerous voids and cracks. Discrete velocities reveal high values in the top portion of Hole 1086A (Fig. 25), which may be caused by coarser grained particles (see "Lithostratigraphy" section, this chapter).
Data from discrete measurements of wet bulk density, porosity, and moisture content are displayed in Fig. 27A, Fig. 27B, and Fig. 27C, respectively (also see Table 12 on CD-ROM, back pocket, this volume). The density values vary between 1500 and 1870 kg/m3, indicating a coarser grain-size distribution in the sediments compared with previous Leg 175 sites.
The wet bulk density profile shows an overall increase, which can be mostly assigned to compaction. Hole 1086A consists mainly of foraminifer-nannofossil ooze (see "Lithostratigraphy" section, this chapter). This sediment composition is reflected in higher velocities (Fig. 25), although maximum values in the velocity profile do not necessarily correspond to maximum wet bulk density values (Fig.24).
In general, porosity and moisture profiles are inversely correlated with the wet bulk density. Porosities decrease from 70% in the top section to 52% at 207 mbsf (Fig. 27B). Moisture content varies between 48% at the top of Hole 1086A and 28% at 207 mbsf (Fig. 27C).
The thermal conductivity profile (Fig. 26B) at Hole 1086A was measured in every second and fifth core section above 40 mbsf and in every fifth section below 40 mbsf (see "Explanatory Notes" chapter, this volume). Values range between 0.8 and 1.32 W/(m·K) and are higher than at any other Leg 175 site. Despite the low resolution sampling, a good match among thermal conductivity, magnetic susceptibility, and GRAPE density can be observed (Fig. 24; also see Table 12 on CD-ROM, back pocket, this volume). Elevated values in thermal conductivity appear to be related to sediments composed of coarser grained particles such as quartz minerals (see "Lithostratigraphy" section, this chapter).