Most of the core material to be recovered during Leg 175 will be retrieved by APC, generally by triple coring for the first priority sites and by double coring for any secondary priority sites drilled. One half of the first hole at each site will be the permanent archive half. Micropaleontology and sedimentology sampling will be done after a composite sampling splice is constructed from the two or more holes drilled at that site. High-resolution sampling is anticipated for most sites (5 cm interval), with 10 to 20 cm3 needed for each sample, depending on the abundance of fossils (especially benthic foraminifers). Sampling schedules will be worked out between the parties involved to optimize stratigraphic coverage and to minimize overlap. Geochemical sampling, which calls for larger volumes, will be done on material from the third hole if it interferes with micropaleontology and sedimentology sampling. Also, whole-round samples will be available for pore-water studies from the third copy, as long as a sample's position is not crucial to filling gaps in the continuous stratigraphic record. If there is a need for a rapid decision on the location of a whole-round sample, but information is insufficient to place critical intervals for continuous stratigraphy, whole-round sections that would result in gaps greater than 15 cm will be avoided. Such sections should be separated by at least 1 m. Sampling for microbiological studies also will follow this strategy. Sampling for physical properties should be done so as not to interfere with stratigraphically sensitive sampling sequences, and to take advantage of available continuous nondestructive measurements. U-channel sampling for high resolution paleomagnetic and rock-magnetic studies will be carried out along the composite sampling splice (temporary archive), where appropriate.

Ultra-high Resolution Sites
There is a possibility that varves will be encountered in some sites, notably in Walvis Basin. Detailed sampling will be necessary to achieve objectives in such sections. The sampling allocation committee ([SAC], consisting of the Co-chiefs, Staff Scientist, and Curator's representative) will determine details of the sampling pattern in these cases.

Sampling Time Table
Detailed sampling of cores from a given site will proceed after a composite stratigraphy is constructed from cores from the two or more holes drilled at the site. The splice will be constructed, and the stratigraphic information will be distributed to the scientific party in advance of post-cruise sampling to facilitate planning and scientific collaboration. Requests to sample on board, for pilot studies or for projects requiring lower stratigraphic resolution, will be considered by the SAC.

General Sampling Procedure
Investigators should avoid sampling the center of core halves. Sample plugs should be taken as close to the edges of a core half as is feasible, given the purpose of sampling. Samples may also be taken with the "scoop" tool, which inherently takes samples from the edges of the core half. Large samples taken with the "cookie-cutter" tool, for example for lamina-scale studies, should be shared among interested scientific party members.

The permanent archive will be the ODP-defined "minimum permanent archive." Once the working half of a section is depleted, the temporary archives for that section will be accessible for sampling. Wherever possible, one quarter of such temporary archives should be preserved by sampling off-center to one side.

Special Core Handling
Large numbers of samples for organic geochemistry analysis may be taken and may need to be frozen.


A total of four sites will be logged during Leg 175 (Sites SAB-2, WB-B, NCB-2B, and SCB-1). Possibly one other site will be logged at the end of the leg, if time is available (e.g., SCB-A). Variations in biogenic carbonate, opal, and detrital deposition associated with climatic, oceanographic, and eustatic changes will be reflected in terms of corresponding changes in physical and geochemical properties. Coring may be discontinuous over deeper intervals because of gas expansion or XCB-coring disturbance. Consequently, downhole log data present an excellent resource for developing a quantitative paleoclimatic and paleoceanographic time series. Special software for core-core and core-log data integration (CLIP) will be used during Leg 175 to etablish composite sedimentary sections vs. depth.

Only holes deeper than 250 m will be logged with a combination of geophysical sensors: Triple combo tool, the Formation MicroScanner (FMS) associated with the sonic tools, and the geological high-sensitivity magnetic tool (GHMT). The Triple-combo provides measurements of gamma ray, porosity, density, and electrical resistivity, which will be used to describe the lithology, sedimentary fabric, degree of lithification, and fluid composition. The FMS tool string produces high-resolution electrical resistivity images of the borehole wall that can be used to study the structure of bedding, diagenetic features, hiatus, and cyclicity recorded by sediments. The sonic tool coupled to the FMS can be useful to establish synthetic seismograms. By combining acoustic velocity with density evaluations and then convolving them with appropriate wavelet techniques, we can accurately calibrate the seismic lines. The GHMT provides continuous measurements of magnetic susceptibility and the vertical component of the total magnetic field. This latter measurement provides a magnetic reversal stratigraphy, if the magnetization of the sediments is sufficiently strong.

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