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首页> 外文期刊>Journal of Asian earth sciences >Paleoenvironmental changes in the northern South China Sea over the past 28,000 years: A study of TEX_(86)-derived sea surface temperatures and terrestrial biomarkers
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Paleoenvironmental changes in the northern South China Sea over the past 28,000 years: A study of TEX_(86)-derived sea surface temperatures and terrestrial biomarkers

机译：过去28,000年南海北部的古环境变化：TEX_（86）衍生的海面温度和陆地生物标志物的研究

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摘要

We have generated a record of TEX_(86) (TEX_(86)~H)-derived sea surface temperatures (SSTs) over the last 28 ka for core MD97-2146 from the northern South China Sea (SCS). The TEX_(86)~H-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 Boiling-Allerφd period, a plateau across the Younger Dryas period, and an abrupt rise at the beginning of the Holocene. The glacial-interglacial contrast in TEX_(86)~H-derived temperature is almost the same as that in foraminiferal Mg/Ca ratio-derived temperature, but it is larger than those in U_(37)~(K') 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 TEX_(86)~H, and (3) the underestimation of temperature change by U_(37)~(K') and transfer function approaches. The similar variation in TEX_(86)~H-derived temperature at the study site and Chinese stalagmite δ~(18)O during the last deglaciation suggests that changes in TEX_(86)~H-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.
机译：对于南海北部（SCS）的MD97-2146核心，我们在最后28 ka上已经生成了TEX_（86）（TEX_（86）〜H）衍生的海面温度（SSTs）的记录。核心层样品的TEX_（86）〜H衍生温度对应于温暖季节的SST。 SST记录显示，在最古老的树妖时期期间下降，在沸腾-Allerφd时期开始时突然上升，在年轻的树妖时期期间处于平稳状态，并且在全新世初期突然上升。 TEX_（86）〜H衍生温度下的冰晶间对比与有孔虫Mg / Ca比衍生温度下的冰晶间对比几乎相同，但大于U_（37）〜（K'）和传递函数衍生的温度。可能的解释是：（1）甘油二烷基甘油四醚（GDGT）产量的季节性变化；（2）TEX_（86）〜H高估了温度变化；（3）U_（37）低估了温度变化〜（K'）和传递函数方法。研究地点的TEX_（86）〜H衍生温度与中国石笋δ〜（18）O在最后一次冰消期的相似变化表明，这一时期TEX_（86）〜H衍生温度的变化反映了大气和海洋在千年的时间尺度上进行重组。长链正构烷烃主要来自约14 ka之前的高等植物起源，以及约14 ka之后的高等植物和石质起源的混合物。长链与短链正脂肪酸的丰度比在约15 ka时降低，表明在约14-15 ka时沉积物来源发生了急剧变化。我们将〜14-15 ka之前新鲜的高等植物正构烷烃和长链正构脂肪酸的含量较高归因于增强的风沙运输和/或干旱环境。在约14-15 ka之后，夏季季风增强可能导致降水增加，这加剧了沉积岩的侵蚀并增加了正构烷烃的贡献。

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