Peter Blum, October 2022 (another update)

Purpose of stratigraphic correlation on the JOIDES Resolution

Shipboard (during expedition)

1. Minimize coring gaps
   1. Provide rapid correlations when drilling multiple holes (starting with the top cores of hole B) to ensure coring gaps in existing holes are covered by core in the newest hole.
   2. Use of the secondary core logger (Special task multisensor logger, STMSL) in addition to the primary logger (whole-round multi-sensor logger, WRMSL) for "out of sequence" rapid logging of selected sections is highly recommended.
   3. This tasks requires effective real-time communication with the "core tech" from the drilling crew to achieve immediate drilling depth corrections when needed to mitigate coring gaps.
2. Construct core composite depth scale below seafloor (CCSF)
   1. Provide a first order correlation of all cores from multiple holes by depth shifting (affine translation without scaling).
   2. Shifts can be accomplished by multiple methods, the primary method being a tie point between a reference core and a shifting core (more on that later).
   3. Make the CCSF scale available to the entire science team via the LIMS database.
3. Construct sampling splice
   1. Provide a primary spliced section, consisting of core intervals from multiple holes.
   2. The primary splice shall represents as much as possible of the stratigraphic section at a drill site, using the best-quality core intervals.
   3. Sample locations in the curated core at the core depth below seafloor, method A (CSF-A) depth scale can be mapped easily to the splice using the core offsets that define the CCSF depth scale.

Typically on shore (post-expedition - optional)

• Map non-splice intervals into the the primary splice (includes stretching and squeezing).
• Scale the CCSF depth scale, and/or a modified/mapped variant of it, to other depth scale(s) to match the drillers depth below seafloor (DSF) scale or a wireline logging depth scale.
• Astronomical tuning of the final depth scale.

Workflow and tools

• The workflow for the correlation of stratigraphic records obtained from scientific ocean drilling cores requires multiple applications.
• The workflow summarized here is primarily for the shipboard tasks. However, most of it can be done on shore before and/or after an expedition.

Table 1. Tasks and tools for stratigraphic correlation on and off the JOIDES Resolution.

Figure 1-1. Stratigraphic correlation support (SCORS) workflow and tools.

Correlation Downloader (get non-image data)

Download core logging data from the LIMS database for use in Correlator.

• Select the data types you want
• Select the hole and core(s) you want
• Note: the relevant section summary required for accurate computations in Correlator is downloaded automatically.
• IMPORTANT: Check the Append core data to hole button for iterative addition of data to the hole file.
• Click the Download correlation data button.

LORE (get image data)

Batch-download trimmed section half images for use in Correlator.

ImageResample

Batch-process the images, cropping the peripheral ~1 cm from the images and reducing the image to ~200 kb, suitable for Correlator.

Correlator

Stratigraphic correlation of cores from multiple holes at a drill site, by

• depth shifting cores using high-resolution core logging data to construct a core composite depth below sea floor (CCSF) depth scale;
• splicing selected core intervals to construct the most complete stratigraphic representation possible at a site.

Correlator can be used as a stand-alone application, but efficacy and support is maximized when it is used in conjunction with the SCORS support applications in the JRSO LIMS infrastructure.

SCORS Uploader and Manager

Load affine tables and splice interval tables created by an external application (e.g., Correlator) to the LIMS database where the information can be reported and applied to all data in LIMS.

LORE again (get correlated data)

Provide (A) lists of existing affine tables and splice interval tables, with links to uploaded user files; (B) detailed, LIMS-computed affine and splice interval tables; (C) CCSF (alternate) depths for any data set in the LIMS; and (D) data sets by selected splice.