GRA bulk density, magnetic susceptibility, NGR emission, and P-wave velocity were measured with the MST on whole-core sections recovered from Site 1094. Color reflectance and resistivity were measured on the working half of all split APC cores using the Oregon State University Split Core Analysis Track (OSU-SCAT) (see "Explanatory Notes" chapter). Other physical properties measurements conducted on discrete core samples included moisture, density, and P-wave velocity. Measured parameters were initial wet bulk mass (Mb), dry mass (Md), and dry volume (Vd). Velocity was measured on split-core sections using the P-wave velocity sensor 3 (PWS3). Table T18 and Figure F23 summarize the physical properties measurements performed at Site 1094.
At previous Leg 177 sites, sedimentary physical properties were controlled largely by changes in the proportion of carbonate vs. siliceous components. At Site 1094, terrigenous material is much more common and has considerably more influence. At previous sites, high GRA and discrete-sample (moisture and density [MAD] method) bulk densities were observed within carbonate layers. GRA and MAD bulk densities generally agree very well (Fig. F24). At Site 1094, greatest densities are generally associated with muddy intervals (as determined from smear slide analysis; see "Lithostratigraphy").
The characteristics of the reflectance spectrum for sediments from Site 1094 are somewhat different from those of the more northerly Leg 177 sites. As with previous sites, high blue reflectance at Site 1094 is caused by an increase in carbonate, but red/blue values do not show the decrease toward 1.0 in carbonate-rich intervals that characterized the previous sites. The reason for this is that the carbonate layers are not as pure at Site 1094 (<40% carbonate; see "Lithostratigraphy"), and other components, either diatoms and/or mud, impart the carbonate layers with a salmon-pink color that causes red overprinting of the reflectance signal. The red/blue values do, however, show a marked increase when diatoms dominate the sediment. In core photographs, it can be observed that the diatom-rich layers directly underlie the carbonate layers, and this is clearly evident in the lead of high red/blue peak values relative to blue reflectance peak values in Figure F23.
Porosity decreases and bulk density increases downhole because of compaction. The decrease in porosity is closely mirrored by an increase in resistivity. Superimposed on the general trend is a cyclic variability related to alternations between muddy diatom ooze and layers of less muddy foraminifer- and nannofossil-bearing diatom ooze (see "Lithostratigraphy"). The muddy diatom ooze layers also contain dispersed sand and gravel that indicate ice-rafting (see "Lithostratigraphy"). In the upper 90 mcd, the cyclicity has a dominant period of ~20 m (Fig. F23). The cyclicity is also clearly evident in the records of magnetic susceptibility, NGR, and spectral reflectance. The shipboard age-depth model (see "Chronostratigraphy") indicates that these cycles represent the 100-k.y. climatic cycles of the late Pleistocene.
Above 90 mcd, NGR, GRA bulk density, and reflectance all display a prominent saw-tooth signal, although the relationship is inverted in the reflectance record (Fig. F23). GRA density and NGR show a steady increase with time following the deposition of each diatom-rich layer, which is low in mud content. The steady increase culminates at a maximum value (minimum in reflectance), and then abruptly decreases at the base of the next low-mud interval. Furthermore, there is an abrupt increase and decrease in magnetic susceptibility during the transition into and out of the muddy diatom-rich layers. The saw-tooth pattern of GRA and NGR signals probably represents either a gradual increase in terrigenous influx (probably through ice-rafting) or a gradual decrease in biogenic input. In any case, the abrupt decrease in each signal suggests a rapid termination of the environmental conditions characterized by increased terrigenous components. A similar pattern was observed at Site 1093, where carbonate layers are overlying sediments with high magnetic susceptibility that has been attributed to a greater concentration of IRD (see "Physical Properties" in the "Site 1093" chapter).
Below 90 mcd, there is an abrupt decrease in the red/blue values, probably as a result of increased carbonate content compared with the upper section (see "Lithostratigraphy"). In addition, the period of cyclicity recorded in physical properties decreases to ~5 m, as a result of more frequent alternations between carbonate-bearing intervals and muddy diatom-rich intervals that were deposited at reduced sedimentation rates (see "Lithostratigraphy" and "Chronostratigraphy").
Figure F23 shows P-wave velocities measured with the PWS3 velocimeter and P-wave logger (PWL) at Site 1094. PWL velocities are somewhat lower than PWS3 velocities by a mean difference of ~35 m/s. Overall, velocity is inversely correlated with fluctuations in GRA bulk density. PWL velocities range from 1510 to 1525 m/s (median = 1518 m/s) and PWS3 velocities range from 1521 to 1575 m/s (median = 1553 m/s).
Measurements on discrete porcellanite/chert pieces with the PWS3 probe provided velocities between 3000 and 4000 m/s.
As with the diatom oozes at Sites 1091 and 1093, the total of 65 thermal conductivity measurements gave values within a narrow range (0.61-0.79 W/[m·K]; Table T19, also in ASCII format in the TABLES directory; Fig. F25). The frequency distribution of the measured values resembles a normal distribution and the mean of 0.68 W/(m·K) appears to be characteristic for this lithology. The standard deviation of 0.04 W/(m·K) can be attributed to analytical error, indicating that there is very little variability in the measured material in terms of thermal conductivity.
At Site 1094, seven successful downhole temperature measurements were obtained using the APCT shoe (Adara tool), one in bottom water and six in sediment between 33 and 147 mbsf. One additional measurement was taken at 159 mbsf using the DVTP. As at Site 1093, measurements at Site 1094 were also slightly to severely affected by frictional heat and/or downhole flow of cold water during deployment (Fig. F26). The temperature-time series was evaluated using shipboard processing programs to derive equilibrium temperatures. The relatively large measurement errors of ±0.3º to ±0.5ºC were estimated from repeated application of decay models to different intervals of the temperature curve, and consideration of the heating and cooling disturbance during deployment (Fig. F26).
The depth-temperature relationship reveals a consistent, anomalously low temperature gradient of 8.3º± 0.5ºC/km (Fig. F27). Using an average thermal conductivity of 0.7 W/(m·K) for the sedimentary section, a very low average heat flow of 6 ± 1 mW/m2 is calculated for the drilled interval. This anomalously low heat flow has important implications for the origin of young porcellanites at Site 1094 (see "Lithostratigraphy") and supports their formation at low temperature (Bohrmann et al., 1994; Botz and Bohrmann, 1991).