Previous   |    Next

doi:10.2204/iodp.proc.347.111.2015

Physical properties

This section summarizes the preliminary physical property results from Site M0067. Two holes were drilled at this site. Hole M0067A was drilled to 9.3 mbsf, and Hole M0067B extended to 10.9 mbsf. However, recovery from Core 347-M0067B-5H recorded >250%; it is unknown whether this is due to expansion of the sediments or coring of either fall-down or flow-in sediments or a combination of both. This does influence the results from the lower portion of Unit II, and depths quoted should be treated with caution.

Our analysis focuses on Hole M0067B (Fig. F13), which has the greatest recovery and penetration at this site. However, a combination of PCS and open holing was used for this hole to assess the extent of an unexpected lithology (see “Operations”). All physical property data from this site are thus sparse and discontinuous.

Natural gamma ray (NGR) increases through lithostratigraphic Unit I, and several meter-scale peaks that might reflect changes in lithology (see “Lithostratigraphy”) are observed (Fig. F13). Dry density also exhibits a progressive increase toward the base of lithostratigraphic Unit I. Magnetic susceptibility and noncontact resistivity (NCR) exhibit very little variation with depth in lithostratigraphic Unit I, except for a spike in NCR at ~3 mbsf. At the lithostratigraphic Unit I/II boundary, magnetic susceptibility, NCR, and dry density all abruptly increase. However, only the upper portion of lithostratigraphic Unit II was recovered, and thus no downcore trend for this unit can be inferred. From 9.7 mbsf in the lower interval of lithostratigraphic Unit II, coring operations resumed after an open-hole interval, and similarly high values of magnetic susceptibility and dry density are observed. NCR is generally low, and NGR is highly variable. Deeper than 10.9 mbsf (the official bottom of Hole M0067B), NGR and magnetic susceptibility values increase. We acknowledge that the data plotted appear to extend beneath the base of the hole because of expansion of the sediment/flow-in/fall-down. However, as it was unknown whether the expansion was linear or not, no compression corrections were applied. This will need to be taken into account if these data are used for postcruise analysis.

Top of page   |    Previous   |    Next