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doi:10.2204/iodp.sp.343.2012

Sampling and data sharing

Sample and data requests (research proposals)

All shipboard scientists must submit at least one data or sample request in advance of the drilling expedition. Since Expedition 343 will not recover any observatory monitoring data until the observatories are revisited, sample requests for observatory data should be submitted in collaboration with other research vessels following this expedition. Currently, the first observatory data retrieval expedition is planned for a non-IODP cruise.

A Sample Allocation Committee (SAC) composed of co-chief scientists, expedition project manager, and IODP curator on shore (and curatorial representative on board ship) will work with the entire scientific party to formulate a formal expedition-specific sampling plan for shipboard and postcruise sampling. The SAC must approve access to data and core samples requested during the expedition and during the one-year moratorium period, which starts at the end of the drilling expedition. Modifications to the sampling plan during the expedition require the approval of the SAC.

Additional requests also may be submitted during or after the expedition if appropriate.

The initial sample requests provide the basis for the SAC to develop an integrated sampling program of both shipboard and postcruise sample requests. The initial sampling plan, of course, will be subject to modification depending upon the actual material/data recovered and on collaborations that may evolve between scientists before and during the expedition. To provide time for the SAC and Specialty Coordinators to develop a detailed and integrated sampling strategy, data requests are due by the end of February 2012.

The IODP Sample, Data, and Obligations Policy (www.iodp.org/program-policies/) outlines the policy for distributing IODP samples and data and defines the obligations incurred by both ship board and shore-based scientists. Both groups of scientists should also use the Sample/Data Request form (smcs.iodp.org:8080/smcs/) in submitting their requests.

Core flow for onboard measurements, sampling, and storage

We will follow IODP standard measurements and archival sampling procedures in the shipboard laboratory. Upon recovery, core will be cut into 1.5 m sections and will be sampled for interstitial water (whole round 20–50 cm in length, from Section 4) and archival routine microbiological sample (RMS) (whole round from next to the interstitial water sample as recommended by the Subseafloor Life Task Force), for micropaleontology (from core catcher), and for safety monitoring (headspace). The RMS will be sampled at a frequency of 1 every 20 m, core recovery permitting. All core sections will be scanned using the X-ray CT facility; X-ray CT image analysis will be used to identify critical intervals (e.g., localized fault zones) and for planning any whole-round core measurement and sampling for microbiological study, interstitial water extraction, geotechnical testing, anelastic strain recovery measurements, and thermal conductivity measurements. All whole-round samples will be taken after completing whole-round sample measurements (e.g., whole-round multisensor core logging [MSCL-W]) unless whole-round sampling is time sensitive (e.g., microbiological). Standard cluster samples for physical properties and mineralogical/chemical analyses will be taken from adjacent to whole-round samples if possible.

After whole-round sampling is completed, cores will be split into working and archive halves per standard procedures. Archive halves will be used for visual core descriptions and image/color scan. Working halves will be used for physical properties measurements, such as thermal conductivity and shear strength. Additional discrete samples will be used for measurements of moisture and density, P-wave velocity, and bulk chemistry.

Additional sampling/data handling guidelines

Acquiring core samples from the slipped fault zone is a high priority of the expedition, but there may be a limited amount of core material and high demand for samples, particularly in critical intervals. For these intervals (e.g., highly sheared zones of the fault) special handling and sampling plans may be required, and it will not be possible to finalize plans until after core recovery occurs. The SAC may require an additional formal sampling plan before critical intervals are sampled for postcruise studies.

The working half is available for sampling by shipboard and shore-based scientists, which will likely be completed shipboard. Samples of whole-round cores can be requested following IODP policy. Sampling whole rounds is particularly valuable for geotechnical and rock mechanical testing (e.g., permeability, consolidation, triaxial, ring shear, etc.), for study of ephemeral features or properties (e.g., pore fluid chemistry and microbiological studies), and for special preservation and study of sediment and rock structures (e.g., delicate shear zones) that would be destroyed by conventional splitting of cores in working and archive halves. Use of X-ray CT imaging has proven particularly useful for selecting intervals ideal for whole-round sampling and informing sample planning.

The overarching science goals of Expedition 343 focus primarily of the mechanics of earthquake faulting, secondly on thermal and fluid flow processes, and thirdly on microbiological activity associated with fault zone environments. As such, sample plans will follow this prioritization in resolving sampling conflicts. Ideally, core recovery will allow extensive sampling to achieve research objectives within a range of disciplines. If core recovery permits, it would be ideal to make as many measurements as possible on common (or nearly colocated) samples, thus maximizing correlation of different data types (e.g., physical and mechanical properties, pore water, carbon carbonate, moisture and density, bulk X-ray diffraction, clay X-ray diffraction, and bulk chemistry).

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