TOC varied between 0 and 1.27 wt% of dry sediment, with an average of 0.20 wt% at Site 1237 (Fig. F2; Table T1). CaCO3 varied between 0.3 and 94.9 wt% of dry sediment, with an average of 67.2 wt%. Below ~110 mcd, TOC contents were very low and CaCO3 values were higher than 89 wt% with an exception at 160.08 mcd (ash layer). Above ~110 mcd, TOC gradually increased and CaCO3 gradually decreased with decreasing depth. The increase of TOC and the decrease of CaCO3 were marked above ~41 mcd.
In Site 1239 samples, TOC varied between 0.21 and 3.35 wt%, with an average of 1.22 wt% (Fig. F3; Table T2). CaCO3 varied between 18.9 and 82.4 wt%, with an average of 60.0 wt%. Below ~90 mcd, TOC gradually increased and CaCO3 gradually decreased upward. TOC maximized at 89.71 mcd, and CaCO3 minimized at 84.51 mcd. TOC abruptly decreased at 84.51 mcd, and CaCO3 was almost constant in the uppermost 84.51 mcd.
Normal alkanes were analyzed for Site 1237 sediments. The concentration of LNAs (n-C25–C33) varied between 0.18 and 5.18 µg/g of sediment, with an average of 1.46 µg/g (Fig. F4; Table T1). LNAs were below detection limit in the sediments below 125.51 mcd. CPI varied between 2.4 and 5.9, with an average of 4.1. ACL varied between 29.0 and 30.0, with an average of 29.8. The concentration of LNAs and CPI gradually increased uphole, and they maximized at 15.02 mcd. Above ~15 mcd, the concentration of LNAs and CPI decreased. ACL was almost constant throughout the range of the site.
The increase of LNAs uphole is associated with the increase of TOC and the decrease of calcium carbonate, which is attributed to the increasing contribution of terrestrial organic matter together with Aeolian dusts. The variation of CPI presumably reflects the changes of terrestrial organic matter compositions such as mixing ratio of the fresh higher plants with high CPI and the diagenetic products with low CPI in weathered sedimentary rocks.
Total alkenone (C37–C39 alkenones) concentrations in dry sediment varied between 0.14 and 18.03 µg/g, with an average of 3.54 µg/g in Site 1237 samples (Fig. F5; Table T1). The alkenones were below detection limit in the sediments below 118.56 mcd. Total alkenones increased uphole and maximized at 15.02 mcd. Alkenone-based paleotemperature varied from 17.3° to 25.4°C. The temperature decreased uphole and minimized at 15.02 mcd. The temperature increased uphole above 15.02 mcd. The core-top temperature (0.01 mcd) was 20.3°C, which agrees with the present mean annual sea-surface temperature (~20°C) (Levitus and Boyer, 1994).
In Site 1239 samples, total alkenone concentration varied between 1.41 and 22.28 µg/g, with an average of 11.17 µg/g (Fig. F6; Table T2). The alkenones were below detection limit in the sediments below 450.59 mcd. Below ~300 mcd, total alkenones increased uphole and maximized at 300.62 mcd. The total alkenone content decreased gradually above ~300 mcd with a single peak at 100.31 mcd. The paleotemperature varied from 24.2° to 27.9°C. The temperature gradually decreased uphole. The core-top temperature (0.01 mcd) was 25.3°C, which is ~1°C higher than the present mean annual sea-surface temperature (~24°C) at Site 1239 (Levitus and Boyer, 1994).