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Gulf Coast Repository

Whole-Round Multisensor Core Logger (WRMSL)

Overview

Thumbnail image of Whole-Round Multisensor Core Logger Measurements of density, magnetic susceptibility and P-wave velocity provide basic physical properties and paleomagnetic data, which can be useful in the identification of lithologic units and stratigraphic correlation. While originally intended for whole-round core sections, the instrument can also be used to measure density and magnetic susceptibility of split core sections.

Maximum core diameter: 12 cm (o.d.)
Maximum core length: 155 cm

Instrument Make & Model

Custom-built track system.

Estimated Measurement Time

  • Sample Preparation: ~1 minute
  • Measurement Time: Scan time estimates are based on a 1.5 meter core length.
Estimated time based on measurement resolution.
Resolution Scan Time
0.5 cm 30 mins
1.0 cm 20 mins
2.0 cm 10 mins
2.5 cm 7 mins

Measurement Resolution

  • Highest resolution: 0.5 cm
  • Most commonly used resolution: 2 cm

Principles & Analytical Capabilities

The Whole-Round Multisensor Core Logger (WRMSL) has three primary capabilities: density by gamma ray attenuation (GRA), magnetic susceptibility, and P-wave velocity. All measurements are made sequentially as the core section is pushed through the track system. The first measurement of a core section measures the density (g/cm3) using GRA through a cesium source (137Cs) and a NaI scintillation detector. The second measurement collects magnetic susceptibility (in SI units) of the sample but is not volume corrected. To correct for dimensionless SI volume-specific magnetic susceptibility values, the instrument units must be multiplied by an empirical correction factor to compensate for the instrument scaling and the geometric ratio between the core and loop dimensions. The third measurement collects P-wave velocity (m/s) through the transmission of a 500kHz P-wave pulse across the core section at a set repetitious rate. The travel time is determined by the first arrival of the P-wave signal, with a precision of 50 ns. The resulting value is corrected for system propagation delay, liner thickness, and liner material velocity. The WRMSL is calibrated using a stepped aluminum bar in a whole round core liner, filled with deionized water (DI water) to check density on a calibration curve.

Data Generated

Data components:

  • Magnetic susceptibility
    • Magnetic susceptibility (instrument units): magnetic susceptibility of the sample, not volume corrected.

  • Bulk Density
    • Bulk density (g/cm3): computed bulk density of sample.

  • P-wave
    • Uncorrected P-wave velocity xy (m/s): velocity of pressure wave through sample in the x-y plane (dependent on orientation of the material).
    • Caliper separation (mm): displacement between the faces of the transducers in contact with the sample.
    • Sonic traveltime (µs): traveltime of the sonic wave from transducer to transducer through the sample.

Data files:

  • Magnetic susceptibility (CSV): tabular file of magnetic susceptibility results.
  • Bulk Density (CSV): tabular file of bulk density results.
  • P-wave (CSV): tabular file of P-wave results.

Raw files:

  • MS (instrument file): Data file containing WRMSL reduced data and metadata.
  • GRA (instrument file): Data file containing WRMSL reduced data and metadata.

Data Example

Graph of magnetic susceptibility, bulk density, and p-wave data from Hole U1619A. .
Magnetic susceptibility, bulk density, and p-wave data from Hole U1619A of IODP Expedition 403 in the Fram Strait. 1, 2, 3

Procedures & Manuals

References

1  Lucchi, R. G., St. John, K., Ronge, T. A., Barcena, M. A., De Schepper, S., Duxbury, L. C., Gebhardt, C., González-Lanchas, A., Goss, G., Greco, N. M., Gronmyr, V., Gruetzner, J., Haygood, L., Husum, K., Iizuka, M., Kapuge, A. K. I. U., Lam, A. R., Libman-Roshal, O., Liu, Y., … Zhong, Y. (2026). IODP Expedition 403 Magnetic susceptibility (whole round) [Data set]. International Ocean Discovery Program. https://doi.org/10.5281/zenodo.18437047

2  Lucchi, R. G., St. John, K., Ronge, T. A., Barcena, M. A., De Schepper, S., Duxbury, L. C., Gebhardt, C., González-Lanchas, A., Goss, G., Greco, N. M., Gronmyr, V., Gruetzner, J., Haygood, L., Husum, K., Iizuka, M., Kapuge, A. K. I. U., Lam, A. R., Libman-Roshal, O., Liu, Y., … Zhong, Y. (2026). IODP Expedition 403 Bulk Density (GRA) [Data set]. International Ocean Discovery Program. https://doi.org/10.5281/zenodo.18436007

3  Lucchi, R. G., St. John, K., Ronge, T. A., Barcena, M. A., De Schepper, S., Duxbury, L. C., Gebhardt, C., González-Lanchas, A., Goss, G., Greco, N. M., Gronmyr, V., Gruetzner, J., Haygood, L., Husum, K., Iizuka, M., Kapuge, A. K. I. U., Lam, A. R., Libman-Roshal, O., Liu, Y., … Zhong, Y. (2026). IODP Expedition 403 P-wave velocity logger (whole round) [Data set]. International Ocean Discovery Program. https://doi.org/10.5281/zenodo.18437064