刘磊, 管红香, 冯俊熙, 许兰芳, 茅晟懿, 刘丽华. 南海北部31 ka以来GDGTs组成及其对古温度和季风变化的响应[J]. 海洋地质与第四纪地质, 2020, 40(3): 144-159. DOI: 10.16562/j.cnki.0256-1492.2020021101
引用本文: 刘磊, 管红香, 冯俊熙, 许兰芳, 茅晟懿, 刘丽华. 南海北部31 ka以来GDGTs组成及其对古温度和季风变化的响应[J]. 海洋地质与第四纪地质, 2020, 40(3): 144-159. DOI: 10.16562/j.cnki.0256-1492.2020021101
LIU Lei, GUAN Hongxiang, FENG Junxi, XU Lanfang, MAO Shengyi, LIU Lihua. Composition of glycerol dibiphytanyl glycerol tetraethers (GDGTs) and its responses to paleotemperature and monsoon changes since 31ka in northern South China Sea[J]. Marine Geology & Quaternary Geology, 2020, 40(3): 144-159. DOI: 10.16562/j.cnki.0256-1492.2020021101
Citation: LIU Lei, GUAN Hongxiang, FENG Junxi, XU Lanfang, MAO Shengyi, LIU Lihua. Composition of glycerol dibiphytanyl glycerol tetraethers (GDGTs) and its responses to paleotemperature and monsoon changes since 31ka in northern South China Sea[J]. Marine Geology & Quaternary Geology, 2020, 40(3): 144-159. DOI: 10.16562/j.cnki.0256-1492.2020021101

南海北部31 ka以来GDGTs组成及其对古温度和季风变化的响应

Composition of glycerol dibiphytanyl glycerol tetraethers (GDGTs) and its responses to paleotemperature and monsoon changes since 31ka in northern South China Sea

  • 摘要: 南海因受到高纬度气候、低纬度大洋以及东亚季风等多种因素的影响而成为研究古温度和季风变化的理想区域。本文通过研究QH-CL11柱状沉积物的GDGTs组成、含量变化特征及其延伸的86个碳原子的四醚指标(TEXH86),分析南海北部GDGTs来源,并定量计算QH-CL11柱状沉积物记录的海洋表面温度(SST),从而探讨31 ka以来南海北部古温度变化的驱动机制。通过甲烷指数和支链/异戊二烯类指标等,确定isoGDGTs主要来自于奇古菌,适用于古温度重建。TEXH86温度显示出明显的冰期—间冰期旋回,与南海北部有孔虫和UK’37 SSTs具有很好的相似性。出现在TEXH86 SST中的海因里希冷事件(H1-3)和Bølling–Allerød暖期之前的温度大幅度上升事件(14.6 ka)反映了高纬度气候对南海的影响。南海SSTs和北太平洋MD01-2421 UK’37 SST的差异(ΔSSTs)可以用来反映东亚冬季风强度的变化。ΔSSTs显示东亚冬季风强度在Bølling–Allerød暖期前增加,在新仙女木时期达到最大值,在全新世早期再次下降,然后在全新世中晚期缓慢增加,这与前人对东亚冬季风强度的认识具有很好的一致性。该方法对重建长周期东亚冬季风强度具有重要的指导意义。

     

    Abstract: The South China Sea (SCS), under the control of multiple climate patterns, is an ideal region for studies of paleo-climate and the East Asian monsoon. In this paper, we studied the composition and characteristics of isoGDGTs to further identify their sources and used the outspread TEXH86 index to reconstruct the sea surface temperature (SST) of the northern SCS for the past 31 ka quantificationally. By calculating the Methane Index and BIT indexes, we found that the isoGDGTs mainly came from Thaumarchaeota, and are suitable for TEXH86 appliance. TEXH86 temperatures exhibit distinct glacial–interglacial cycles, and is very similar to the SSTs from foraminifera and UK'37 in the northern SCS. TEXH86 SSTs showed a decline trend during the Heinrich events (H1-3) and an abrupt rise at 14.6 kaBP before Bølling–Allerød (BA) warming, suggesting a tight climate teleconnection between the northern SCS and the North Atlantic region in last Deglaciation. The SST differences (ΔSSTs) between the SCS and the core MD01-2421 in the North Pacific was calculated and used to reveal the intensity of East Asian Winter monsoon. ΔSSTs showed that the EAWM intensity firstly increased before the BA warming, reached a maximum in the Younger Dryas period, decreased again in early Holocene and slowly increased in Late and Middle Holocene. The ∆SSTs results coincide with previous findings on the EAWM variations and constitute a feasible means of long-term EAWM intensity reconstruction.

     

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