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doi:10.2204/iodp.proc.338.202.2015 ResultsPorosity data of MICP samples range from 0.21 to 0.56 and show a general decrease with increasing depth (Fig. F2; Table T1). Lithologic Unit II has the highest porosity (0.41–0.56) and Unit V has the lowest porosity (0.21–0.24). All MICP experimental data and injection pressure curves are provided in MICPDATA in Supplementary material (Tables S1–S19; Figs. S1–S19). MICP sample porosity is comparable to porosity of core samples and of intact undisturbed (formation) cuttings determined shipboard (Expedition 315 Scientists, 2009; Strasser et al., 2014b) by moisture and density measurements (Blum, 1997) but is consistently lower than porosity of bulk cuttings samples (Fig. F3). MICP sample porosity and shipboard porosity in lithologic Unit II are high and cover the same range. Near the Unit III/IV boundary, MICP sample porosity and shipboard porosity cover the same range and are generally lower than porosity of bulk cuttings. In Units IV and V, porosity of MICP samples and intact undisturbed cuttings are similar and lower than MAD-derived porosity on bulk cuttings. Shipboard comparison of (1) bulk cuttings, (2) intact undisturbed cuttings, and (3) core samples are used to interpret that elevated porosity in bulk cuttings is due to drilling disturbance (Strasser et al., 2014b). Further research is required to understand the amount of disturbance and the appropriate techniques for estimating in situ porosity where samples may be disturbed (i.e., bulk cuttings). Median pore throat radius (r50) determined from MICP measurements ranges from 0.0208 to 0.205 µm (Fig. F2; Table T1). Median pore throat radius in lithologic Unit II increases from 0.133 to 0.205 µm at 221–280 mbsf and then decreases to 0.0771 µm by 464 mbsf. In Units III–V (904–1980 mbsf), r50 decreases from 0.0764 to 0.0208 µm. Air-water capillary entry pressure (Pcentry) determined from MICP measurements ranges from 93 to 982 kPa (Fig. F2; Table T1). Pcentry data in lithologic Unit II may indicate an increase with increasing depth but are highly variable (93–599 kPa). Pcentry data in Units III–V are highly variable (119–982 kPa), show significant scatter, and do not indicate any trends with depth or with unit. |
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