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SAMPLING STRATEGY

Shipboard and shore-based researchers should refer to the interim IODP Sample, Data, and Obligations policy posted on the Web at iodp.tamu.edu/curation/policy.html. This document outlines the policy for distributing IODP samples and data to research scientists, curators, and educators. The document also defines the obligations that sample and data recipients incur. As Expeditions 309 and 312 are both execution of the same proposal, we expect to consider the seagoing participants from both cruises as well as any approved shore-based researchers for either cruise as a single science party. Therefore, the Sample Allocation Committee (SAC) will consist of all four Co-Chief Scientists, both Staff Scientists, the IODP onshore Curator, and the curatorial representatives onboard the ship. This team will work with the entire science party from both expeditions to formulate a specific sampling plan for shipboard and postcruise sampling.

Owing to the short planning window for these expeditions, in order to coordinate all shipboard sampling shipboard scientists from both expeditions are expected to submit sample requests (iodp.tamu.edu/curation/samples.html) as soon as possible. Following good practice established during Leg 206, we strongly encourage collaboration among the shipboard and shore-based scientists so that the best use is made of the recovered core. Postcruise analytical programs should be coordinated to ensure that the full range of geochemical, magnetic, and physical property studies are undertaken on a representative sample suite. Sampling all but the most critical intervals will take place on board the ship, and, as few scientists will sail on both expeditions, scientists are encouraged to establish collaborations before Expedition 309 sails so that they have an interested party or group who can sample appropriate material during both cruises.

Based on sample requests (shipboard and shore based), the SAC will prepare a tentative sampling plan. The sampling plan will be subject to modification depending upon the actual material recovered and collaborations that may evolve between scientists during the expeditions.

For the purpose of developing sample requests, participating scientists could expect to receive on the order of 25–100 samples of no more than 25 cm3. This is based on historic precedent from ODP designed to enable scientists to complete a research program and meet the established publication deadlines. For these expeditions, all personal sample frequencies and sample volumes taken from the working half of the core must be justified on a scientific basis and will be dependent on core recovery, the full spectrum of other requests, and the project objectives. Postcruise research projects that require more frequent sampling or larger sample volumes should be further justified in sample requests. Some redundancy of measurement is unavoidable and even encouraged, but minimizing redundancy of measurements among the shipboard party and identified shore-based collaborators when recovery is sparse will be a factor in evaluating sample requests.

If some critical intervals are recovered (e.g., mineralization, veins, dikes or glassy margins, thin gabbroic intervals, melt lenses, etc.), there may be considerable demand for samples from a limited amount of cored material. These intervals may require special handling, a higher sampling density, reduced sample size, or continuous core sampling by a single investigator. A sampling plan coordinated by the SAC may be required before critical intervals are sampled.

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