Previous   |    Next

doi:10.2204/iodp.proc.319.201.2014

Methods and materials

Hole C0009A was spudded on 19 May 2009 at 33°27.4704′N, 136°32.1489′E. We collected three cuttings samples (Fig. F1) from lithologic Unit IV (1287.7–1603.7 mbsf), which is composed mainly of silty claystone with minor silt interbeds, as described in the “Site C0009” chapter (Expedition 319 Scientists, 2010c). Samples 319-C0009A-130-SMW, 193-SMW, and 213-SMW were collected from 1305.2, 1592.2, and 1595.2 mbsf, respectively. Each of these samples was stored immersed in drilling mud in a polyethylene bottle (~500 cm³) in a shipboard refrigerator at 4°C and later archived at the Kochi Core Center under the same storage conditions. We removed 45 cm³ samples from the original bottles on the day of collection and then 6 months and 33 months later. We followed sample treatment procedures described in the “Methods” chapter (Expedition 319 Scientists, 2010b). The procedure can be briefly described as follows. Cuttings and mud were gently washed in freshwater and then sieved to obtain three size fractions (>4, 1–4, and 0.25–1 mm). During sieving, a magnet was used to remove iron contaminants from drilling tools and casing. We used only the 1–4 mm fraction for geochemical analysis. The >4 and 0.25–1 mm fractions were excluded to avoid contamination by particles that may have traveled downward through the mud column from shallower in the drilled sequence: coarse particles (>4 mm) may have been fragments of boulders encountered higher in the drilled sequence, and fine particles (0.25–1 mm) may have been transported downward by mud circulation.

The 1–4 mm fraction was washed 10 times with deionized water and then soaked in deionized water for 12 h. Washed cuttings were then dried for 24 h in an oven at a constant temperature of 40°C. The dried cuttings were powdered and homogenized with an agate mortar and then stored in clean polyethylene vials. Approximately 50 mg of powdered sample was sequentially digested in nitric acid, perchloric acid, and hydrofluoric acid (Fig. F2) using a closed digestion procedure modified from that of Totland et al. (1992). Commercially available high-purity acids (TAMAPURE-AA-100 grade; Tama Chemicals Co. Ltd., Tokyo) and ultrapure water (18.2 MΩ·cm; Millipore) were used for sample preparation. Major and minor element concentrations (Al, Ba, Ca, Cr, Fe, K, Li, Mg, Mn, Na, Sr, and Zn) were determined by inductively coupled plasma–atomic emission spectroscopy (ICP-AES) (Perkin Elmer Optima 4300 at Kochi University; HORIBA Jobin Yvon Ultima 2 aboard the Chikyu). ICP-AES conditions are summarized in Table T1. Element concentrations were quantified by calibration curve fitting using a standard solution prepared by dilution of ICP multielement standard Solution IV (Merck, Darmstadt, Germany) with 1% nitric acid. Recovery ratios from sample digestion (average of three runs) for each element were obtained by using geological standard materials JA-3 and JMS-1 supplied by the National Institute of Advanced Industrial Science and Technology of Japan (Table T2).

Top of page   |    Previous   |    Next