Minimum Permanent Archive
The minimum permanent archive will be the standard archive half of each core.
Shipboard scientists may nominally expect to obtain up to 100 samples up to 15 cm3 in size. Additional samples may be obtained upon written request onshore soon after the cores return to the ODP Repository. This guideline will be adjusted upward or downward by the shipboard SAC, depending on the penetration and recovery during Leg 176. All sample requests of whatever number and volume must be justified in writing on the standard sample request form and approved by the SAC.
Samples larger than 15 cm3 may be obtained with approval of the SAC but shall be considered the equivalent of multiple samples in partial or complete increments of 15 cm3. Requests for large samples must be specified on the sample request form except where they are for detailed stratigraphic studies of specific intervals of the core in which case they must be approved on an individual basis for each interval by the co-chief scientists.
Redundancy of Studies
Some redundancy of measurement is unavoidable, but minimizing redundancy of measurement among the shipboard party and identified shore-based collaborators will be a factor in evaluating sample requests. Requests for independent shore-based studies that substantially replicate the intent and measurements of shipboard participants will require the approval of both those shipboard investigators and the SAC.
Shipboard Samples and Data
Following core labeling, measuring nondestructive properties, and splitting, samples will be selected from core working halves by members of the shipboard party for routine measurement of physical and magnetic properties, bulk chemical analyses by X-ray fluorescence (XRF) and carbon-hydrogen-nitrogen-sulpher (CHNS) analyzer, and X-ray diffraction as necessary. Polished thin sections will be prepared for identification of minerals, determination of mineral modes by point counting, and studies of texture and fabric.
We shall identify a suite of samples for full measurement characterization. At approximately 9.5 m intervals (once per full core), slabs measuring 10 x 6 x 1.5 cm, with a previously-sampled central mini-core, will be cut to be used for all shipboard measurements, then subdivided and split appropriately for further shore-based geochemical, mineralogical, and petrographic studies. Where necessary to avoid or include features like veins and alteration, full half-round slices or quarter slices may be taken instead of slabs.
Data from all shipboard studies, regardless of method or observer, including all core descriptions and measurements and the nondestructive measurements of physical and magnetic properties, are the property of the entire shipboard party and may be used exclusively by them in publication and for preparation of manuscripts with proper citation to the Initial Report up until the publication of the Initial Report or 12 months post cruise, whichever is later.
Shipboard Thin Sections
Shipboard thin sections will be selected from representative sections of the core and at some critical intervals. These sections will remain the property of ODP. The thin section chips from which the sections are made will be retained by ODP and should normally be thick enough to allow for the production of additional sections unless the sampling plan for a critical interval precludes this. Members of the shipboard party can request the production of a thin section from these thin section chips for their personal use at their own expense as part of their nominal 100 sample limit, but must arrange for the prepaid manufacture of these thin sections with a third-party commercial service unless otherwise approved by the ODP core lab curator. The thin-section chip will then be sent directly to the commercial service and returned directly to ODP by them.
Sampling for Shore-based Studies and Sampling Parties
To minimize the time and physical effort required for additional sampling for shore-based studies, we shall organize sampling consortia among the principal scientific teams (igneous, metamorphic, structural, physical and magnetic properties), who will identify locations for similarly large (10 x 6 x 1.5 cm--a mini-core) or even larger samples, and also averaging approximately once per 9.5 m of core. The actual size will depend on the number of investigators in the group, and it will be subdivided among them, to count against the nominal 100-sample limit of each consortium investigator. Follow-up sampling will be organized as short sample parties during reentries or logging runs, for individuals using the second-look lab, or at the ODP Repository as necessary.
Short intervals of unusual scientific interest (e.g., veins, ores, narrow trondhjemite dikelets, a knife-edge crust/mantle transition) may require a higher sampling density, reduced sample size, or sampling techniques not available on board ship. These will be identified during the core description process, and the sampling protocol established by the interested scientists and shipboard SAC.
Studies requiring only small sample volumes (1 cm3 or less, e.g., for veins, fluid inclusions, etc.) may require more than 100 samples to characterize the long section of core we anticipate recovering, and might be possible to obtain while the cores are being described. We shall review the appropriate sampling interval for such studies periodically as the cores are recovered. Ideally, many of these studies will be coordinated with the shipboard and shore-based sampling protocols outlined above.
Storage and Shipping Needs
The usual labeling, orientation, core-placement, and storage procedures should be all that is necessary for safe transportation to the ODP Repository. Core handlers should wear back supports while lifting and handling individual archive or working halves, and especially when maneuvering core storage boxes.
To 176 References
176 Table of Contents