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doi:10.2204/iodp.proc.347.111.2015

Stratigraphic correlation

Two holes were drilled at Site M0067: Holes M0067A (9.30 mbsf) and M0067B (10.90 mbsf). Recovery was poor deeper than ~5 mbsf, and reliable correlation downhole from this point was not possible. The meters composite depth (mcd) scale for Site M0067 was constructed by correlating magnetic susceptibility between holes (Fig. F16). Despite its relative proximity to Site M0059, at Site M0067 only a thin fine-grained sediment cover on top of gravels and sands was retrieved. The depth offsets that define the composite section for Site M0067 are given in Table T9 (affine table). For the topmost ~5 mbsf, one splice was created (Table T10).

Seismic units

By integrating seismic data with lithostratigraphy (see “Lithostratigraphy”), seismic sequence boundaries were correlated with sediment core and multisensor core logger (MSCL) log (magnetic susceptibility) boundaries (Fig. F17). Two-way traveltime values for each lithostratigraphic unit boundary were calculated using sound velocity values measured offshore (see “Physical properties”; Table T11).

Seismic Unit I

• Two-way traveltime: 0.037 ms
• Lithology: faintly laminated sapropel and clay (lithostratigraphic Unit I)
• Depth: 0–3.30 mbsf (M0067A), 0–4.42 mbsf (M0067B)

The lower boundary of seismic Unit I coincided with a group of strong reflectors. This seems plausible, as changes in lithology and physical properties data are quite distinctive.

Seismic Unit II

• Two-way traveltime: 0.039 ms
• Lithology: clast-rich mixed sand and silt (upper part of lithostratigraphic Unit II)
• Depth: 3.30–4.80 mbsf (M0067A), 4.42–6.30 mbsf (M0067B)

Seismic Unit II does not correlate with a distinct change in the seismic image. This could be due to uncertainties in the estimated velocity values.

Seismic Unit III

• Two-way traveltime: 0.045 ms
• Lithology: massive sand with minor silt content (lower part of lithostratigraphic Unit II)
• Depth: 6.30–10.9 mbsf (M0067A)

Seismic Unit III correlates with a more massive seismic unit, from which no good physical properties data could be obtained.

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