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doi:10.2204/iodp.proc.331.105.2011

Physical properties

Physical property measurements were made at Site C0015 to nondestructively characterize lithologic units and states of sediment consolidation.

Density and porosity

Bulk density values at Site C0015 were determined from both gamma ray attenuation (GRA) measurements on whole cores (with the multisensor core logger for whole-round samples [MSCL-W]) and moisture and density (MAD) measurements on discrete samples from the working halves of split cores (see “Physical properties” in Expedition 331 Scientists, 2011b). A total of seven discrete samples were analyzed for MAD (five from Hole C0015B and two from Hole C0015C). Wet bulk density is essentially constant with depth (Fig. F19), whether determined from MAD measurements or from GRA. GRA-derived bulk density is generally lower than discrete MAD bulk density and exhibits a larger degree of scatter but the same overall pattern (Fig. F19). This measurement is expected of GRA-derived density, as GRA is very sensitive to incompletely filled core liners and the presence of voids and cracks.

The average bulk density in Holes C0015B and C0015C is 1.6 ± 0.1 g/cm³ (Table T14).

Grain density was determined from discrete MAD measurements. Grain density is also nearly constant with depth (average = 2.61 g/cm³) (Fig. F19; Table T14) with a slight excursion toward higher grain densities (~2.8 g/cm³) at ~4 mbsf.

Porosity was also calculated from MAD measurements. MAD-derived porosity is generally quite high (40%–60%) and decreases with depth in Hole C0015B (Fig. F20). In general, density and porosity results from the two holes (C0015B and C0015C) at Site C0015 reveal a consistent pattern with depth; however, the sparsity of data from this site prevents any firm conclusions.

Electrical resistivity (formation factor)

Formation factor is a measure of the connected pore space within the sediments and is used to calculate the bulk sediment diffusion coefficient. Electrical impedance measurements were made at eight specific locations (six from Hole C0015B and two from Hole C0015C). Formation factors calculated for Site C0015 ranged from ~3 to 11. Formation factor is constant with depth (Fig. F21) in Hole C0015B with an average value of 3.7 ± 0.42 (Table T14). The two values measured in Hole C0014C are 10.9 and 5.8, at 6.7 and 8.8 mbsf, respectively.

Thermal conductivity

Thermal conductivity measurements were conducted on whole-round cores. A total of eight measurements were made at this site (seven from Hole C0015B and one from Hole C0015C). Thermal conductivity at Site C0015 is generally low and ranges from 0.7 W/(m·K) at ~1.5 mbsf to 1.1 W/(m·K) at ~4.5 mbsf (Fig. F22). The average thermal conductivity for Site C0015 is 0.89 ± 0.15 W/(m·K) (Table T14). In general, thermal conductivity is relatively constant with depth.

MSCL-I and MSCL-C imaging

MSCL-derived core images and color analyses are presented in the visual core descriptions (VCDs).

MSCL-W derived electrical resistivity

MSCL-W based resistivity data are generally constant and low (~1 Ωm), but there is region of high resistivity (5–30 Ωm) at ~7.5 mbsf. There is no obvious relationship with the discrete measurements of formation factor (Fig. F23 versus Fig. F21).

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