open access

https://hdl.handle.net/2115/51239

Paleoenvironmental changes in the northern South China Sea over the past 28,000years: A study of TEX86-derived sea surface temperatures and terrestrial biomarkers

英語

Late Quaternary

2011-04-02

Elsevier

Journal of Asian Earth Sciences

40(6)

1221-1229

We have generated a record of TEX86 (TEXH86)-derived sea surface temperatures (SSTs) over the last 28 ka for core MD97-2146 from the northern South China Sea (SCS). The TEXH86-derived temperature of a core-top sample corresponds to the SSTs in warmer seasons. The SST record shows a drop during the Oldest Dryas period, an abrupt rise at the onset of the Bølling–Allerød period, a plateau across the Younger Dryas period, and an abrupt rise at the beginning of the Holocene. The glacial–interglacial contrast in TEXH86-derived temperature is almost the same as that in foraminiferal Mg/Ca ratio-derived temperature, but it is larger than those in UK'37 and transfer function-derived temperatures. Possible interpretations are: (1) the seasonal shift of glycerol dialkyl glycerol tetraether (GDGT) production, (2) the overestimation of temperature change by TEXH86, and (3) the underestimation of temperature change by UK'37 and transfer function approaches. The similar variation in TEXH86-derived temperature at the study site and Chinese stalagmite δ18O during the last deglaciation suggests that changes in TEXH86-derived temperature in this period reflected atmospheric and oceanic reorganization on a millennial timescale. The long-chain n-alkanes are mainly of higher plant origin before ∼14 ka and a mixture of higher plant and lithic origins after ∼14 ka; the abundance ratio of long-chain to short-chain n-fatty acids decreases at ∼15 ka, suggesting a drastic change in sediment sources at ∼14–15 ka. We attribute the higher content of fresh higher plant n-alkanes and long-chain n-fatty acids before ∼14–15 ka to enhanced aeolian transportation and/or arid environments. Increased precipitation likely due to intensified summer monsoon after ∼14–15 ka enhanced the erosion of sedimentary rocks and increased the contribution of lithic n-alkanes.

学術雑誌論文

Accepted Manuscript

1367-9120

AA11138796