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Table of Contents

Table of Contents
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Core Description area on the Core Deck.




Overview

A description of each core recovered on the JR is among the primary deliverables of the shipboard science party. Core describers are also responsible for other tasks related to description, including instrument measurements, sampling of core sections, and general core handling. The core description team typically includes 5-10 scientists, and up to 15 have sailed on expedition with ambitious description objectives. Depending on the types of materials expected, specialists in sedimentology, igneous petrology, metamorphic petrology, volcanology and/or structural geology may be included.

Tasks that core describers are fully responsible for, or may be assisting technical staff with:

  • Section half preparation
  • Whole-round and section half imaging
  • Measurement of diffuse color reflectance and magnetic susceptibility
    • Standard core logging
    • Handheld color reflectance measurements
  • Core description
    • Macroscopic description of section halves, including structural measurements as appropriate
    • Microscopic description of smear slides and thin sections
  • SEM and/or EDS measurements
  • Sampling for shipboard analyses
  • XRD interpretations
  • Writing the lithostratigraphy and related sections for the site chapters (Proceedings), site summaries and preliminary report, including a descriptive summary of all observations, preliminary interpretations, and suitable illustrations.

Section half preparation

Video Tutorials (Windows Media Player)

Section Half Imaging Logger (SHIL)

SHIL

For soft sediment cores, the surface textural effect of core splitting can be mitigated by scraping the surface using glass slides and paper wipes. This process can be laborious and it should only be applied if the benefits outweigh the effort. In some material, scraping may created artificial effects that counter the purpose of making sedimentary structures more visible. The decision whether to scrape or not is the scientists'. If scraping, be sure to avoid contamination down or up the core section.

For igneous rocks, the question often arises whether to image the archive section half surface wet or dry. Wetting the surface 'ust right' before imaging is laborious.

Whole-round and section half imaging

Whole-round imaging using the section half image logger (SHIL) is typically only done on igneous rocks, although it could could also be done on sedimentary rocks if scientifically justified and time is available. Technicial support personnel typically carries out this type of imaging due to the equipment configuration changes needed.

Section half imaging is done on all sections and the core describers are typically doing it.

The detailed user guides are:

Section Half Multisensor Logger (SHMSL)

Measurement of diffuse color reflectance and magnetic susceptibility

Standard core logging

The physical properties (PP) specialists are typically analyzing and reporting the data from the magnetic susceptibility point sensor (MSP) and reflectance spectrophotometry and colorimetry (RSC) measured on the section half multisensor logger (SHMSL). However, given the physical locatin of the logger, general workflow, and often small PP team, the core describer are operating the systems.

The detailed user guides are:

Scanning Electron Microscope (SEM)

Handheld color reflectance measurements

The old Minolta Spectrophotometer from the 90ies never went completely away. It may still be around as a backup if you ask a technician:

Core description

The primary responsibility of the core describers is - core description! This includes

  • Macroscopic description of section halves, including structural measurements as appropriate
  • Microscopic description of smear slides and thin sections



SEM and/or EDS measurements

If you have time and purpose, you can enjoy scanning electron microscopy (SEM) and/or

Minolta Spectrophotometer



Video Tutorials (Windows Media Player)