MATERIALS AND METHODS

Sediments for Hole 1017E were taken from Site 1017 (water depth, 967 m). The sampling location is 34°32.009´N, 121°6.430´W. This paper reports the analytical results of the uppermost core (1H) of Hole 1017E. The approximate age of the bottom of Core 167-1017E-1H is estimated to be 26.3 ka (calendar age; R. Tada, pers. comm., 1998).

Organic carbon, total nitrogen, and sulfur were determined for a powdered HCl-treated sediment sample (~100 mg) by a dry combustion method using a Fisons Instruments NA1500NCS elemental analyzer. Wet sediment samples were treated with 6-M HCl for carbonate removal, washed with distilled water until pH > ~ 4, and freeze dried. The combustion furnace was operated at 1000°C, and the reduction oven was operated at 650°C.

Stable carbon isotopic compositions for TOC in sediment samples were measured with a Finnigan/MAT delta-S mass spectrometer on CO₂ converted from TOC. A powdered HCl-treated sediment (40-350 mg) was placed in a thin quartz tube (6 mm o.d. × 70 mm). Powdered CuO (2 g) was added to it. This quartz tube was placed in another large quartz tube (9 mm o.d. × 300 mm) that had 1 g of Cu placed in the bottom, and then a small amount of thin Ag film was added to cover the top of the thin quartz tube. After evacuation, the outer quartz tube was sealed. TOC was oxidized completely into CO₂ by heating the tube first at 500°C for 30 min and then at 850°C for 2 hr. The CO₂ that was produced was purified cryogenically using both a dry ice-ethanol trap and a liquid nitrogen trap. The ¹³C is reported vs. the Chicago Peedee belemnite standard. Analytical precision for the isotope analysis was within 0.2.