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doi:10.2204/iodp.proc.324.102.2010 Methods1Expedition 324 Scientists2ProceduresNumbering of sites, holes, cores, and samplesDrilling sites are numbered consecutively from the first site drilled by the Glomar Challenger in 1968. Integrated Ocean Drilling Program (IODP) Expedition 301 began using the prefix "U" to designate sites occupied by a U.S. Implementing Organization (USIO) vessel. For all IODP drill sites, a letter suffix distinguishes each hole drilled at the same site. The first hole drilled is assigned the site number modified by the suffix "A," the second hole takes the site number and the suffix "B," and so forth. For Expedition 324, each site has only one hole (A). The cored interval is measured in meters below seafloor (mbsf) according to the core depth below seafloor, method A (CSF-A), depth scale (see IODP Depth Scale Terminology at www.iodp.org/program-policies/). In general, the depth below seafloor is determined by subtracting the water depth estimated from the initial drill pipe measurement to the seafloor from the total drill pipe measurement. The depth interval assigned to an individual core begins with the depth below seafloor at which coring began and extends to the depth that coring advanced. Each coring interval is generally ~9.5 m, which is the length of a core barrel; however, coring intervals may be shorter. During Expedition 324, some of the overlying sediment succession was drilled without coring. Coring at all sites started ~50–70 m above the expected basement contact. During Expedition 324, unless otherwise noted, all core depths below seafloor were calculated as CSF-A. For ease of communication of shipboard results, all depths are reported in this volume as "meters below seafloor" unless otherwise noted. Cores taken from a hole are numbered sequentially from the top of the hole downward. Core numbers and their associated cored intervals are unique in a given hole. Generally, maximum recovery for a single core is 9.5 m of rock or sediment contained in a plastic liner (6.6 cm internal diameter) plus ~0.2 m (without a plastic liner) in the core catcher, which is a device at the bottom of the core barrel that prevents the core from sliding out when the barrel is being retrieved from the hole. In certain situations, recovery may exceed the 9.5 m maximum. In soft sediments, this is normally caused by core expansion resulting from depressurization. In hard rock cores, this probably happens when a pedestal of rock fails to break off and is grabbed by the next core barrel. A recovered core is divided into 1.5 m sections that are numbered serially from the top. When full recovery is obtained, the sections are numbered 1 through 7, with the last section usually being shorter than 1.5 m. Rarely, an unusually long core may require >7 sections. When the recovered core is shorter than the cored interval, the top of the core is equated with the top of the cored interval by convention to achieve consistency in handling analytical data derived from cores. All pieces recovered are placed immediately adjacent to each other in the core tray. Samples and descriptions of cores are designated by distance, measured in centimeters from the top of the section to the top and bottom of each sample or interval. By convention, material recovered from the core catcher is placed below the last section when the core is described and is labeled with the suffix "CC." In sedimentary cores, the core catcher section is treated as a separate section. The core catcher is placed at the top of the cored interval in cases in which material is recovered only in the core catcher. However, information supplied by the drillers or by logging may allow more precise interpretation as to the correct position of core catcher material within an incomplete recovered cored interval. A complete identification number for a sample consists of the following information: expedition, site, hole, core number, core type, section number with the interval in centimeters measured from the top of the section, and piece number (assigned only for hard rock). For example, a sample identification of "324-U1350A-26R-8 (Piece 1, 4–7 cm)" indicates a 3 cm sample of Piece 1 removed from the interval between 4 and 7 cm below the top of Section 8 of Core 26 ("R" designates that this core was taken with the rotary core barrel [RCB]) in Hole A at Site U1350 during Expedition 324. Core handlingCores recovered during Expedition 324 were extracted from the core barrel in plastic liners. These liners were carried from the rig floor to the core processing area on the catwalk outside the core laboratory, where they were split into ~1.5 m sections. Liner caps (blue = top, colorless = bottom) were glued with acetone onto liner sections on the catwalk by the curator. Hard rock pieces were pushed to the top of the liner sections and total rock length was measured. The length was entered into the database using the Sample Master application as "created length." This number is used to calculate recovery. The 1.5 m sections were transferred to the core splitting room, where the plastic liners were split lengthwise to expose the core. Oriented pieces of core were marked on the bottom with a red wax pencil to preserve orientation, either before they were extracted from the core barrel or when they were removed from the split core liner. In some cases, pieces were too small to be oriented with certainty. Adjacent but broken core pieces that could be fit together along fractures were curated as single pieces. The structural geologist on shift confirmed piece matches and corrected any errors. The structural geologist also marked the split line on the pieces, which defined how the pieces were cut in two equal halves. The aim was to maximize the expression of dipping structures on the cut face of the core while maintaining representative features in both archive and working halves. A plastic spacer was secured to the split core liner with acetone between individual pieces or reconstructed contiguous groups of subpieces. These spacers may represent a substantial interval of no recovery. The length of each section of core, including spacers, was entered into the curation database as the curated length. Curated length commonly differs by a few to several centimeters from the created length measured on the catwalk. The database then recalculates the assumed depth of each piece based on the curated length. Each section was allowed to equilibrate to ambient room temperature (3 h for hard rock, 4 h for sediment) and first scanned using the shipboard Whole-Round Multisensor Logger (WRMSL) (see "Physical properties"). The whole-round core sections were next measured with the Natural Gamma Ray Logger (NGRL) (see "Physical properties"). Each piece of core was then split with a diamond-impregnated saw into an archive half and a working half, with the positions of plastic spacers between pieces maintained in both halves. Pieces were numbered sequentially from the top of each section, beginning with number 1. Separate subpieces within a single piece are assigned the same number but were lettered consecutively (e.g., 1A, 1B, 1C). Pieces were labeled only on the outer cylindrical surfaces of the core. If it was evident that an individual piece had not rotated around a horizontal axis during drilling, an arrow was added to the label, pointing to the top of the section. The oriented character of the piece was then recorded in the database using the Sample Master application Digital images of the dry, cut faces of the archive halves were captured with the Section Half Imaging Logger (SHIL). Measurements of point magnetic susceptibility and color reflectance were performed with the Section Half Multisensor Logger (SHMSL) on the archive half of the cores. This instrument also includes a laser calibration system. The data from the laser (e.g., the location of gaps in the core and rubble intervals) was used to aid data filtering of multisensor measurements (see "Physical properties"). The archive half of each core was described for magmatic lithology and structural features, and observations were recorded using the descriptive data capture application, DESClogik. Specialized templates and spreadsheets were developed for this application by the individual descriptive laboratory groups (for details, see individual disciplinary sections in this chapter). Finally, digital color close-up images were taken of particular features, as requested by individual scientists. During the crossover of both day and night shifts, a sample meeting was held to discuss the sections described and to select key intervals for shipboard analyses sampling. Samples were taken on working halves for shipboard physical property, paleomagnetic, thin section, X-ray diffraction (XRD), and geochemical analyses, as described in the sections below. Each extracted sample was logged into the Sample Master database program by location, sample type, and intended shipboard study (e.g., thin section, XRD, etc.). Records of all removed samples are kept by the IODP Curatorial Specialist. Sampling for personal postcruise research was delayed until the transit at the end of the expedition. This allowed for a more careful sample selection because it was based on the integrated shipboard data set (e.g., geochemical analyses, thin section descriptions, and other observational or analytical data stored in the database). At the end of Expedition 324, all cores were transferred from the ship for permanent storage at the IODP Gulf Coast Repository in College Station, Texas (USA). Authorship of site chaptersThe separate sections of the site chapters and methods chapter were written by the following shipboard scientists (authors are listed in alphabetical order; no seniority is implied):
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