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UNDERWAY GEOPHYSICS
Standard ODP practice is to collect magnetometer and 3.5- and 12-kHz echo-sounder data during transit to each site. Additionally, Leg 191 will likely conduct a short air-gun survey (~6 hr) to ensure that the location of Site WP-2 is on top of a high in the oceanic basement, where the anticipated chert-chalk sequence is thinner.
SAMPLING PLAN
The Sample Distribution, Data Distribution, and Publications Policy is posted at: http://www-odp.tamu.edu/publications/policy.html. The Sample Allocation Committee (SAC), which consists of the two co-chiefs, the staff scientist, the ODP curator onshore, and the curatorial representative on board ship, will work with the entire science party to formulate a formal Leg 191-specific sampling plan for shipboard and postcruise sampling.
During Leg 191, we expect to recover < 1 km of sediment, sedimentary rock, and basalt. All 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 cruise objectives. All sample requests must be made on the standard Web sample request form and approved by the SAC. Leg 191 shipboard scientists may expect to obtain as many as 100 samples of no more than 15 cm3 in size. Additional samples may be obtained upon written request onshore after initial data are analyzed. Depending on the penetration and recovery during Leg 191, the number of samples taken may be increased by the shipboard SAC. For example, studies requiring only small sample volumes (1 cm3 or less, e.g., for veins, fluid inclusions, etc.) may require > 100 samples to characterize a long section of core. The SAC will review the appropriate sampling interval for such studies as the cores are recovered. Samples larger than 15 cm3 may also be obtained with approval of the SAC. Request for large samples must be specified on the sample request form. Sample requests may be submitted by shore-based investigators as well as the shipboard scientists. Based on sample requests received two months precruise, the SAC will prepare a temporary sampling plan, which will be revised on the ship as needed. Some redundancy of measurement is unavoidable, but minimizing redundancy of measurements among the shipboard party and identified shore-based collaborators will be a factor in evaluating sample requests.
If some critical intervals are recovered (e.g., fault gauge, ash layers, basement veins, 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 sampling size, or continuous core sampling by a single investigator. A sampling plan coordinated by the SAC may be required before critical intervals are sampled.