SAMPLING STRATEGY
New sampling guidelines specify that a formal, leg-specific sampling strategy must be prepared by the Sample Allocation Committee (SAC: co-chiefs, staff scientist, and ODP curator onshore‹curatorial representative on board ship) for each prospectus. Any modification of the sampling strategy during Leg 185 must be approved by the SAC following evaluation of sample requests by the shipboard party at each site.
Nominal
Sample Limit
Leg 185 shipboard scientists may expect to obtain up to 100
samples of no more than 15 cm3 in size. Additional
samples may be obtained upon written request onshore soon after
the cores are sent to the ODP Repository. Depending on the
penetration and recovery during Leg 185, the number of samples
taken may be increased by the shipboard SAC. All sample requests
must be made 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 will be considered as 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.
Multiple
Analysis of Samples
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. For Leg 185, we anticipate the
preparation of samples for which splits will be analyzed in
different laboratories. We stress the importance of having a
coherent data set on the same powdered or solid samples.
Shipboard
Samples and Data
Following core labeling, measuring nondestructive properties,
and splitting, samples will be selected from core working halves
by members of the Leg 185 shipboard party for routine measurement
of physical and magnetic properties, bulk chemical analyses by
X-ray fluorescence (XRF) and carbon-hydrogen-nitrogen-sulfur
(CHNS) analyzer, and X-ray diffraction (XRD), 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. In most cases these samples will
serve as the shore-based material for full analysis by multiple
laboratories.
Shipboard thin sections, selected from representative sections of the core and at some critical intervals, 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 Leg 185 shipboard party can request the production of a thin section from these thin-section chips for their personal use, at their own expense, and as part of their nominal 100-sample limit. Scientists 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.
Critical
Intervals
If critical intervals of unusual scientific interest are
identified during the core description process, a sampling
protocol will be established by the interested scientists and
shipboard SAC.
Small
Samples
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 a long section of core. The
SAC will review the appropriate sampling interval for such
studies as the cores are recovered. Ideally, many of these
studies will be coordinated with the shipboard and shore-based
sampling protocols.