Measurements of physical properties at Site 1132 followed the procedures outlined in "Physical Properties" in the "Explanatory Notes" chapter. These included nondestructive measurements of P-wave velocity (every 4 cm; Table T7, also in ASCII format), gamma-ray attenuation (GRA) bulk density (every 4 cm; Table T8, also in ASCII format), MS (every 8 cm; Table T9, also in ASCII format), and natural gamma radiation (NGR) (every 16 cm; Table T10, also in ASCII format) using the MST. The P-wave logger (PWL) was activated only on APC cores. Thermal conductivity was measured in unconsolidated sediment at a frequency of one determination per core (Table T11, also in ASCII format), with two additional samples analyzed after deployments of the DVTP and Adara temperature tools. Four in situ measurements of formation temperature were made (Table T12, also in ASCII format). A minimum of two discrete P-wave velocity measurements per section were made on the working half of split cores (Table T7), and measurement frequency was increased to five per section after the PWL was turned off. Standard index properties (Table T13, also in ASCII format) and undrained shear strength (only in unconsolidated sediments) (Table T14, also in ASCII format) were measured at a frequency of one per section. Magnetic susceptibility data are discussed in "Paleomagnetism".
The following sections describe the quality of the data obtained, downhole variations in sediment physical properties, and their relationships to lithology and downhole logging data (see "Lithostratigraphy" and "Downhole Measurements").
Multisensor track data also include measurements of coarse-grained sediment that cascaded into the hole between coring and was generally present in the first section of Cores 182-1132B-1H to 15H at depths shallower than 139 mbsf. For some cores, this sediment fill occupied more than the first section. Affected data were omitted from figures in this report but are included in the data tables (Tables T8, T9, T10, T15, also in ASCII format). High-quality NGR and GRA bulk density data were obtained using the MST, although problems occurred with P-wave velocity and MS measurements (see "Paleomagnetism"). The former was affected by voids between core and liner as a result of the presence of H2S in the sediments. Difficulties also 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).
A close correlation was seen between downhole logging data (see "Downhole Measurements") and sediment physical properties measurements. Gamma-ray attenuation bulk densities have similar values to the downhole logging data in the interval 100 to 150 mbsf and exhibit similar patterns. For instance, cyclicity in bulk density in the interval 140-150 mbsf is also seen in both records (Fig. F20) (see "Downhole Measurements").
Physical properties data can be separated into five units on the basis of trends in the measured parameters. Physical properties Unit (PP Unit) 1 (0-5 mbsf) is characterized by a high bulk density near the sediment/water interface (>2.0 g/cm3), which decreases rapidly with depth (Fig. F20). Natural gamma radiation increases from 3 to 10 cps. P-wave velocity remains unchanged and porosity increases (41%-58%) within this unit (Fig. F20). Physical properties Unit 1 corresponds to a thin package of grainstones that caps lithostratigraphic Unit I (see "Lithostratigraphy").
Physical properties Unit 2 (5-142 mbsf) exhibits an overall increase in bulk density with depth (1.7-1.95 g/cm3), with a corresponding but more gradual increase in P-wave velocity (~1.6-1.7 km/s) and a decrease in porosity (~58%-41%) (Fig. F20), although there is considerable variation in porosity associated with differences in lithology. Average NGR values generally increase within this unit from ~5 to ~20 cps, with high-frequency cycles superimposed on this trend. PP Unit 2 may be divided into two subunits separated by an apparent firmground at 42 mbsf (Fig. F20).
Physical properties Subunit 2A (5-42 mbsf) exhibits increasing NGR (5-22 cps) and GRA bulk density (1.75-1.8 g/cm3) with depth. A decrease in NGR at 33 mbsf corresponds to a packstone at the boundary between lithostratigraphic Subunits IA and IB (see "Lithostratigraphy"). P-wave velocity and porosity remain nearly constant within PP Subunit 2A (Fig. F20). The base of PP Subunit 2A is marked by an abrupt decrease in NGR (20-10 cps) and an increase in P-wave velocity (1.6-1.7 km/s; Fig. F20).
Physical properties Subunit 2B (42-142 mbsf) is characterized by cyclic and generally increasing NGR, bulk density (1.8-1.95 g/cm3), and P-wave velocity (1.6-1.7 km/s), and decreasing porosity (50%-38%; Fig. F20). The amplitude of the high-frequency NGR cyclicity is greater in this unit relative to PP Subunit 2A. A low in NGR values within Subunit 2B corresponds to the disappearance of HMC from the sediments (see "Inorganic Geochemistry").
Physical properties Unit 3 (142-248 mbsf) is characterized by highly variable P-wave velocity and bulk density data superimposed on an increasing trend (Fig. F20). Natural gamma radiation data within PP Unit 3 show a distinct cyclicity on a slightly increasing trend (Fig. F20) that corresponds well to an interval of high NGR variability in the downhole logs (see "Downhole Measurements"). Porosity decreases throughout PP Unit 3 (43%-38%). Within this unit, peaks in GRA bulk density are generally correlated to more lithified sections recognized in the split-core sections (see "Lithostratigraphy"). Below 150 mbsf, GRA density is lower than in situ measurements because of incomplete filling of core liners during XCB and RCB coring. The base of PP Unit 3 correlates well to the base of logging Unit 1 (see "Downhole Measurements"), lithostratigraphic Unit III (see "Lithostratigraphy"), and the upper/middle Miocene boundary (see "Biostratigraphy").
Core recovery within PP Unit 4 (248-603 mbsf) was poor because of numerous chert layers in the sedimentary section alternating with softer carbonate sediment (Fig. F20; see "Lithostratigraphy"). Recovered cherts had high P-wave velocities alternating with lower velocities characteristic of the less indurated sediments. All measured parameters show high variability near the base of PP Unit 4 (Fig. F20).
Shear strength at Site 1132 was measured from 1 to 168 mbsf, and values ranged between 2 and 48 kPa (Fig. F21). Although shear strength exhibits an increasing trend with greater depth, the data are highly variable because of differences in lithification and grain size within the upper portion of the recovered sedimentary section (see "Lithostratigraphy"). However, in some intervals, variability may result from drilling disturbance and cracking of the sediment before failure, resulting in lower values for peak strength. Peaks in shear strength near the base of PP Unit 2 (Fig. F21) correlate to partially lithified intervals within lithostratigraphic Unit 2 (see "Lithostratigraphy").
At Site 1132, thermal conductivity was measured between 10 and 250 mbsf (Fig. F22). Values increase from 0.82 W/(m·K) near the top of the hole to 1.24 W/(m·K) within PP Unit 3 (195 mbsf). Below 195 mbsf, thermal conductivity values are highly variable, corresponding to an interval of increasing sediment lithification (see "Lithostratigraphy"); thus, some values may be invalid as a result of poor contact between sediments and the measurement probe. Overall, thermal conductivity data are significantly controlled by sediment bulk density as demonstrated by the close relationship between the two data sets (Fig. F22).
Four in situ temperature measurements were made at Site 1132, three using the Adara tool and one using the DVTP. There was some variation in estimates of mudline temperature from 14.5°C to 15.4°C. An additional estimate of seafloor temperature (12.6°C) was obtained using an expendable bathythermograph (XBT). This value was lower than those obtained from the in situ temperature tools, possibly because of calibration differences. None of the in situ temperature measurements was affected by postemplacement movement of the probe, and differences between lower and upper data fits to the decay curve yielded only minor differences in temperature (Table T12).
The three deepest in situ temperature measurements define a linear relationship with depth (r2 = 0.99; N = 4) that passes close to the average of all mudline values (14.9°C ± 0.4°C; Fig. F23) but not to the XBT-derived seafloor temperature. If the XBT seafloor temperature is used, it is difficult to explain the magnitude of the geothermal gradient nonlinearity, given the very small change of thermal conductivity with depth at Site 1132. Thus, the XBT temperature was not used (Fig. F23).
The geothermal gradient derived using Adara mudline temperatures is 41.6°C/km. The defined linear trend does not pass through the first Adara measurement at 35.5 mbsf, where the formation is similar in temperature to the highest estimates of seafloor temperature. This pattern strongly suggests that there is some circulation of seawater within the relatively coarse facies occurring in this interval. This conclusion is consistent with the presence of pore fluids of near-seawater salinity from 0 to 35 mbsf (see "Inorganic Geochemistry"). The geometric mean of thermal conductivity between 0 and 169 mbsf was used to determine heat flow at the site (0.99-0.074 W/[m·K]). Using this value and the geothermal gradient determined above, heat flow at the site is estimated to be 42-44.7 mW/m2. This value is identical to that determined at Site 1131, which has similar low thermal-conductivity sediments and is in a similar position, although somewhat deeper on the shelf margin.