SAMPLING STRATEGY AND SAMPLING PLAN
Sampling of the recovered cores will be subject to the rules described in the ODP Sample Distribution Policy (http://www-odp.tamu.edu/curation/sdp.htm). Based on the sample requests received by 15 November 1998, the Sample Allocation Committee (SAC) will prepare a temporary sampling plan, to be revised on the ship according to actual coring results. In the final shipboard sampling plan, sample requests will be closely linked to proposed postcruise research. Postcruise studies can also be proposed by shore-based investigators who do not participate in the cruise.
The core sampling logistics are three-fold: (1) shipboard sampling for shipboard measurements, (2) shipboard sampling for postcruise studies, and (3) postcruise sampling for postcruise studies. Some sampling for shipboard measurement of ephemeral properties must occur immediately, before stratigraphic correlation information is available (see below). These measurements include organic geochemistry for safety monitoring (free gas and 20 cm3 sediment samples), interstitial water chemistry (whole-round of 5-15 cm length), and moisture content (10 cm3 sediment). In addition, core catchers will be analyzed for biostratigraphic datums.
Shipboard sampling for postcruise studies will be kept to a reasonable minimum, trying to balance the need for an initial set of samples for immediate postcruise laboratory work against the need for avoiding redundant or "frenzy" sampling before the composite section and splice are constructed (see below). The SAC may decide to sample the upper few cores on the ship because high porosity sediments could be disturbed during transport to the Texas A&M University (TAMU) core repository. Samples that need to be frozen or sealed for shore-based analysis also must be taken onboard. All shipboard scientists will participate in shipboard sampling according to a shift schedule.
Because of the large number of requested samples that are expected, most investigators will be encouraged to participate in a postcruise sampling meeting in the core repository ~4 months postcruise. The ODP repository staff will fill the remaining requests.
Most of the material to be recovered is expected to be hemipelagic mud with moderate carbonate content and low abundance of organic material. Sedimentation rates are expected to range typically between 2-20 cm/k.y., although some sites may have substantially higher rates.
Coverage, MCD, and the Splice
Complete stratigraphic coverage will be attempted at all sites. Because coring gaps occur, even between successive cores with nominally 100% recovery, complete sections will be achieved by triple coring with the APC system (typically the uppermost 150-250 m). Double XCB coring of the deeper intervals may be considered, depending on the priority of the section and the available time. In addition to ensuring complete coverage, multiple-hole coring also provides significantly more core material for sampling.
The shipboard stratigraphic correlators will be responsible for constructing a composite depth section for each site in near-real time. The "meters composite depth" (mcd) scale correlates the cores from multiple holes based on core logging data. All investigations from any hole can then be linked by using the mcd scale. A shipboard "splice" will be defined by the correlators, which is one continuous stratigraphic core section for a site composed of core intervals from different holes. The splice can be used by most investigators for sampling. However, because of the short distance from the final site to port, the "mcd splice" for the last few sites may not be available for sampling until the postcruise sampling party.
At any time during the cruise, the SAC will determine whether special circumstances for a certain interval warrant either a sampling moratorium or solicitation of a special sampling program.
To 184 References
To 184 Table of Contents