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%CaCO3, %TOC, %N, δ13C, and δ15N concentrations in sediment samples are plotted for Sites U1426, U1427, and U1429 in Figures F2, F3, and F4, respectively. These data are also recorded in Tables T1, T2, and T3. Tada et al. (1999) indicated that sedimentary units that were typically deeper blue and had relatively less carbonate were deposited during glacial periods. Sites U1426 and U1427 show decreased %CaCO3, %TOC, and %N and relatively depleted δ13C and δ15N values (approximately –26‰ to –24‰ and ~2‰–7‰, respectively) when compared with other sediments deposited during the interglacials (e.g., periods with higher carbonate content [δ13C and δ15N values of approximately –20‰ to –23‰ and ~6‰–8‰, respectively]), corroborating previous studies in the area. Cyclic variation of these geochemical proxies corresponds strongly to glacial–interglacial cycles (Tada et al., 1999; Hyun et al., 2007). Migration of the Yellow and Yangtze Rivers toward the Japan Sea/East Sea and the exposure of the continental shelf during glacial periods likely caused an increase in terrestrial input, leading to depleted δ13C and δ15N (Khim et al., 2007).

Site U1429 (Fig. F4) does not share geochemical trends similar to the other two sites because it is located outside of the Japan Sea/East Sea and is not isolated during glacioeustatic sea level changes. Site U1429 in the East China Sea is also unique in that it lacks the dark–light sediment alternations found at other Expedition 346 sites, likely caused by limited variation in nutrient supply and resulting paleoproductivity levels as well as oxic bottom water conditions.

Glacial periods reduce the inflow of the TWC into the restricted marginal sea, which in turn freshens the surface water and increases stratification in the water body while decreasing productivity (Khim et al., 2007; Xing et al., 2011). Therefore, during interglacial and interstadial periods, the influx of the TWC brings warmer, more nutrient-rich water that increases productivity in the water column. The increased productivity is inferred by increased %CaCO3, %TOC, and %N and enriched δ13C and δ15N values during the interglacial periods.