Physical properties at Site 1207 were measured on both whole-round sections and discrete samples from split-core sections. Whole-round measurements included the continuous determination of magnetic susceptibility, gamma ray attenuation (GRA) bulk density, compressional P-wave velocity, and natural gamma radiation, using the multisensor track (MST) as well as discrete measurements of thermal conductivity. Discrete compressional P-wave velocity was measured at a frequency of at least one measurement per split-core section in both Holes 1207A and 1207B. Index properties were measured on discrete samples from split-core sections at a frequency of one measurement per section throughout Hole 1207A and on Cores 198-1207B-4R through 6R.
All core sections from Holes 1207A and 1207B were routinely measured on the MST for magnetic susceptibility and GRA density at 2.5-cm intervals (Figs. F44, F45). MST P-wave velocity was routinely measured at 2.5-cm intervals in all Hole 1207A APC cores (Fig. F46) but was not measured for any XCB, MDCB, or RCB cores, because of the poor contact between the sediment and core liner. During the collection of P-wave data, it was noted that erroneous values were being recorded by the MST P-wave logger (PWL) (e.g., Fig. F46A). Subsequently, these anomalies were traced to a faulty transducer, which was replaced following the completion of MST data collection from the Site 1207 cores. Consequently, archived MST P-wave data from Hole 1207A should be used with extreme caution. Natural gamma radiation was measured routinely on the MST at 30-cm intervals and then at 10-cm intervals in some Cretaceous cores (Fig. F47). All collected MST data are archived in the ODP Janus database.
Magnetic susceptibility data (Fig. F44) are generally higher in magnitude in the uppermost 20 m of the Site 1207 sedimentary column, compared to the relatively lower values evident from 20 to 130 mbsf (these depth intervals are located within lithologic Subunit IA; see "Lithologic Unit I" in "Lithostratigraphy". Such a change in magnetic susceptibility values is probably related to the oxidation state of iron in these sediments, as pyrite is commonly found in sediments in the interval below 20 mbsf (see "Lithologic Unit I" in "Lithostratigraphy"), reflecting reduced conditions. Furthermore, the low magnetic susceptibility values in the lower sedimentary interval resulted in the collection of weak magnetic inclination data from these sediments (see "Paleomagnetism"). Peaks in magnetic susceptibility in lithologic Subunit IA may correlate with distinct ash layers (see "Lithologic Unit I" in "Lithostratigraphy"). In the Pleistocene-Pliocene section, an excellent correlation is observed between magnetic susceptibility data and color reflectance measurements, the latter primarily the total reflectance value (L*) and the 550-nm wavelength (see "Lithologic Unit I" in "Lithostratigraphy"). Both magnetic susceptibility and color reflectance data in this interval reveal a pronounced cyclicity, which may be useful in identifying astronomically controlled depositional processes. Magnetic susceptibility values are higher in lithologic Subunit IB, relative to values between 20 and 130 mbsf in Subunit IA, with a peak value in Subunit IC delimiting the ferromanganese nodule (see "Lithologic Unit I" in "Lithostratigraphy") recovered close to the Campanian-Miocene unconformity (see "Biostratigraphy") at ~163 mbsf. Magnetic susceptibility values are generally close to background values in lithologic Unit II (Campanian) and do not exhibit any consistent downhole variation.
MST GRA bulk density data exhibit a general downhole increase in magnitude (Fig. F45), resulting from sediment compaction and dewatering processes with increased overburden pressure. In addition to the overall downhole trend, GRA bulk density data also show distinct variations that relate to lithologic changes at several distinct horizons (see "Lithostratigraphy"). GRA bulk density values exhibit a change in magnitude at ~130 mbsf, across the boundary between lithologic Subunits IA and IB. Cyclical variation in GRA bulk density values, similar to that evident in magnetic susceptibility (see above) and color data, is also found within Pleistocene-Miocene lithologic Subunit IA. A further increase in the GRA bulk density values occurs at ~165 mbsf, the boundary between lithologic Subunit IC and Unit II, and correlates with the Campanian-Miocene unconformity (see "Biostratigraphy"). However, GRA bulk density values are consistently higher than the discrete wet bulk density measurements (Table T18) throughout Hole 1207A. These overestimated GRA bulk density values can be explained by the relatively high carbonate content, porosity, and moisture content of sediments; the calibration procedure for the MST GRA sensor is optimized for mixed-lithology sediments. Consequently, the GRA method overestimates the density in carbonate-rich sediments of all lithologic units and is most pronounced in Unit II because this unit has the highest carbonate contents (see "Lithostratigraphy" and "Inorganic Geochemistry").
MST P-wave velocities were recorded at 2.5-cm intervals in Hole 1207A sections to a depth of ~182 mbsf (Fig. F46). Despite many obviously high P-wave velocities recorded by the MST PWL, a general trend to higher velocities with increased depth in the sediment column can be discerned from values lying between 1500 and 1600 m/s. MST P-wave velocities also exhibit a stepped increase in magnitude at ~165 mbsf, across the boundary between lithologic Subunit IC and Unit II that represents the Campanian-Miocene unconformity (see "Biostratigraphy") at Site 1207. The magnitude of the reliable MST PWL values also compare well with the discrete measurements of P-wave velocity (Table T19; Fig. F48), as illustrated in the right-hand plot of Figure F46.
Natural gamma radiation data were collected using the MST for Hole 1207A cores at 30-cm intervals and at 10-cm intervals in some cores of Cretaceous age recovered from Hole 1207B (Fig. F47). In the upper 225 m of Hole 1207A, natural gamma radiation generally decreases downhole, with a marked peak value highlighting the presence of the Mn nodule (see "Lithologic Unit I" in "Lithostratigraphy") at ~163 mbsf, close to the Campanian-Miocene unconformity (see "Biostratigraphy"). Natural gamma radiation also exhibits cyclical variation in the Pleistocene-Miocene sediments of lithologic Subunits IA, IB, and IC. Within lithologic Unit II (Campanian), natural gamma radiation values are considerably lower in magnitude and approach background values, compared to those data from higher in the stratigraphic section. At the base of Hole 1207B, in lithologic Unit III, natural gamma radiation increases to values comparable to those in lithologic Subunit IA.
Discrete measurements of compressional P-wave velocity were obtained on Site 1207 split-core sections using the modified Hamilton Frame (PWS3) velocimeter. These data are listed in Table T19 and illustrated in Figure F48. Data were collected at a routine sampling frequency of one measurement per section, with additional measurements made on a single Mn nodule, and chert and black-shale sediments. The P-wave velocity values measured for the cherts range from 4322.4 to 5842.5 m/s (mean P-wave velocity = 5306.7 m/s). The Mn nodule (see "Lithologic Unit I" in "Lithostratigraphy") recovered proximal to the Campanian-Miocene unconformity (see "Biostratigraphy") had a P-wave velocity of 2257.5 m/s. The P-wave velocity data obtained for chert samples are not plotted in Figure F48 because of their higher magnitude relative to proximal sediments and the limitations of axis scaling. Velocities vary between ~1500 m/s in the soft surface sediments and ~1600 m/s in the more consolidated sediments found in Hole 1207A. Discrete P-wave measurements show an increase in velocity with depth, between 0 and ~225 mbsf, which is similar to that evident in the reliable data obtained with the MST PWL (see the caveat detailed in "MST Measurements"). The magnitude of discrete Hamilton frame velocimeter and useful MST PWL determined P-wave velocities are comparable. The lack of evidence for early diagenetic cementation near the seafloor, as shown by high-percentage porosity in the interval 0-225 mbsf (Fig. F49), suggests that increasing P-wave velocity with depth in the upper 225 m of the sedimentary column is primarily the consequence of compaction and pore fluid expulsion. An increase in discrete P-wave velocities through this stratigraphic interval broadly correlates with an increase in the magnitude of discrete bulk density values (Fig. F50). P-wave values then increase to ~1800-3050 m/s in the lithified sediments recovered at the base of Hole 1207B. P-wave velocities recorded for the deepest sediments recovered in Hole 1207B exhibit significant variability in magnitude and are dependent on the lithology (excluding chert) of the sampled sediment (see "Lithologic Unit I" in "Lithostratigraphy").
Thermal conductivity data from Site 1207, obtained using the TK04, are listed in Table T20 and shown in Figure F51. Measurements were made on Sections 1, 3, and 5 of each core from Hole 1207A, and on Sections 1, 3, and 5 of Cores 198-1207B-1R through 6R, 9R, and 28R. Average thermal conductivity for the 79 data points is 1.01 W/(m·K), with a standard deviation of 0.18. Site 1207 thermal conductivity values also exhibit a general increase in magnitude with depth below seafloor, increasing from ~0.85 W/(m·K) near the seafloor to ~1.20 W/(m·K) at ~210 mbsf. The downhole increase in thermal conductivity values broadly correlates with a decrease in porosity (see values in Table T18 and also Fig. F49) with increased sediment burial depth (Fig. F52), as would be expected from increased sediment consolidation at greater depths.
Index properties were determined only for discrete samples from Hole 1207A and Cores 198-1207B-4R through 6R. These data are listed in Table T18 and shown in Figures F49 and F53. Index properties primarily reflect progressive sediment compaction and fluid expulsion with depth in the sediment column, but also indicate changes in sediment composition as defined by lithologic units and subunits (see "Lithostratigraphy"). Bulk and dry density increase slightly in magnitude between the seafloor and ~125 mbsf, within lithologic Subunit IA. The greatest increase in bulk and dry density at Site 1207 occurs within lithologic Subunit IB, between ~125 and ~160 mbsf, and values then remain approximately constant to ~225 mbsf through lithologic Subunit IC and Unit II. By comparison, grain density exhibits a small downhole increase in magnitude and does not change at the boundary between lithologic units. Water content, porosity, and void ratio all exhibit a general downhole decrease in magnitude in lithologic Unit I (Pleistocene-Miocene), between the seafloor and ~160 mbsf. No further significant downhole decrease in these properties occurs within lithologic Unit II (Campanian). The lack of any sharp transition in water content, porosity, and void ratio between lithologic Units I and II suggests that the Campanian sediments may not have been overlain by a significant thickness of sediments older than those currently of Miocene age.
Physical properties data at Site 1207 show variation with depth below seafloor that suggests progressive compaction and fluid expulsion are the dominant controlling factors. Offsets in certain physical properties data, such as GRA bulk density, indicate that the dominant properties are also influenced by lithologic changes.