Measurements of physical properties at Site 1133 followed the procedures outlined in "Physical Properties" in the "Explanatory Notes" chapter. These included nondestructive measurements of P-wave velocity (every 4 cm; Table T9, also in ASCII format), GRA bulk density (every 4 cm; Table T10, also in ASCII format), magnetic susceptibility (MS) (every 8 cm; Table T11, also in ASCII format), and natural gamma radiation (NGR) (every 16 cm; Table T12, also in ASCII format) using the multisensor track (MST). The P-wave logger was activated only on APC cores. A minimum of four discrete P-wave velocity measurements per section were made on the working half of the split cores (Table T13, also in ASCII format). Standard index properties (Table T14, also in ASCII format) and undrained shear strength (only in unconsolidated sediments) (Table T15, also in ASCII format) were measured at a frequency of one per section. Thermal conductivity was measured in unconsolidated sediment at a frequency of one per core (Table T16, also in ASCII format). Difficulties occurred with the pycnometer used for determination of dry volume for index properties measurements (see "Index Properties" in "Physical Properties" in the "Explanatory Notes" chapter).
The following sections describe the downhole variations in sediment physical properties and their relationships to lithology and downhole logging measurements. Variations in MS are described within "Paleomagnetism".
An offset was seen between discrete bulk density measurements and the GRA densiometry measurements of the MST (Fig. F15). This offset was corrected using the equation of Boyce (1976) (see "Index Properties" in "Physical Properties" in the "Explanatory Notes" chapter). Physical properties measurements at Site 1133 were limited because of poor core recovery. Despite this, data from Site 1133 closely reflect lithologic variations observed in the recovered sediments, and these data can be divided into two units with the boundary corresponding to the base of the Pleistocene section (see "Biostratigraphy") (Fig. F15).
Physical properties Unit (PP Unit) 1 (0-21.8 mbsf), which corresponds to lithostratigraphic Subunits IA and IB (see "Lithostratigraphy"), is characterized by increasing NGR to 19.5 mbsf (5-22 cps) and then a sharp decrease to the base of the unit (Fig. F15). This NGR profile may be diagenetic in origin, as the base of PP Unit 1 is correlated with the loss of aragonite and HMC in the sedimentary section (see "Inorganic Geochemistry"). Bulk density (1.65-1.95 g/cm3) and velocity (1.57-1.62 km/s) exhibit high variability but generally increase downward throughout PP Unit 1, as porosity decreases from ~62% to ~45% (Fig. F15). These trends result from an overall increase in lithification with depth in lithostratigraphic Unit I (see "Lithostratigraphy"). At the base of PP Unit 1, bulk density decreases to 1.8 g/cm3 and porosity increases to 53%. The lower boundary of PP Unit 1 correlates with a firmground marking the base of lithostratigraphic Unit IB (see "Lithostratigraphy").
The upper 6.2 m of PP Unit 2 (21.8-152.1 mbsf) is composed of calcareous ooze characterized by decreasing grain size and increasing lithification with greater depth. This change is reflected in the physical properties data as a decrease in NGR (9-5 cps) and bulk density (1.8-1.7 g/cm3) and an increase in porosity (52%-59%) (Fig. F15). The upper/middle Miocene boundary and the upper limit of lithostratigraphic Unit II occur at 28 mbsf and are marked by a firmground and the downcore appearance of neritic carbonates (see "Lithostratigraphy"). This lithostratigraphic boundary corresponds to an increase in bulk density and shear strength (Fig. F15), although it is not a major physical properties boundary. The remainder of PP Unit 2 is characterized by low NGR values (~5 cps) and variable density and P-wave velocity. This variability is the result of alternations between silicified limestones and partially lithified/unlithified packstones (see "Lithostratigraphy"). The lack of recovery in this interval hinders the complete characterization of this unit.
Undrained peak and residual shear strength were measured on unconsolidated sediments from 0 to 47 mbsf (Fig. F16). Shear strength increases downhole from 5 to 26 kPa as a result of compaction, punc-tuated by increased variability within PP Unit 2 (Fig. F16). This variability is, in part, caused by alternations in sediment lithification. However, in some intervals, shear strength variability may also result from drilling disturbance and cracking of the sediment before sediment failure, producing lower values for peak strength.
Thermal conductivity measurements were made from 0 to 76 mbsf at Site 1133. Values increase throughout PP Unit 1 from 0.985 to 1.215 W/(m·K) (Fig. F17; Table T16). Within PP Unit 2, thermal conductivity decreases from 1.21 to 1.01 W/(m·K) (Fig. F17). This trend is likely to be biased by the low recovery within the unit. In general, thermal conductivity data correlate well with other sediment physical properties, particularly bulk density.