Late Quaternary clay minerals off Middle Vietnam in the western South China Sea: Implications for source analysis and East Asian monsoon evolution
Late Quaternary clay minerals off Middle Vietnam in the western South China Sea: Implications for source analysis and East Asian monsoon evolution
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DOI：
10.1007/s11430-007-0115-8
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发表时间：
2007-11
期刊：
影响因子：
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通讯作者：
Zhifei Liu;Yulong Zhao;Jianru Li;C. Colin
中科院分区：
文献类型：
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作者：
Zhifei Liu;Yulong Zhao;Jianru Li;C. Colin
报道了南海中国海西部越南中部近海MD052901孔近450ka以来的高分辨率粘土矿物记录，并结合氧同位素地层学，重建了东亚季风演化史。伊利石、绿泥石和高岭石含量的变化指示了强烈的冰期-间冰期旋回性，而蒙脱石含量的变化则表现出更高的频率旋回性。物源分析表明，南中国海周围有多种来源的粘土矿物混合而成。蒙脱石主要来自印尼诸岛的舜他陆架及其主要物源区。伊利石和绿泥石主要来自湄公河和红河。高岭石主要由珠江提供。高岭石/(伊利石+绿泥石)比值的谱分析显示出100ka的强烈偏心周期，暗示着冰盖强迫的冬季季风演化，而蒙脱石含量的高频变化显示出冰盖强迫的倾斜期为41ka，进动周期为23和19ka，半岁差周期为13ka，表明热带强迫的夏季风演化。冬季季风演变与冰期-间冰期旋回性基本一致，冰期冬季季风风增强，间冰期冬季季风风减弱；夏季风演变对北半球低纬夏季日照几乎呈线性响应，高日照时夏季风增强，低日照时夏季风减弱。结果表明，高纬冰盖和低纬热带因素可分别驱动东亚冬季风和夏季风的晚第四纪演化，暗示了它们的双重强迫机制和自给自足的强迫机制。
High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are reported to reconstruct a history of East Asian monsoon evolution. Variations in Illite, chlorite, and kaolinite contents indicate a strong glacial-interglacial cyclicity, while changes in smectite content present a higher frequency cyclicity. The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea. Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands. Illite and chlorite originated mainly from the Mekong and Red rivers. Kaolinite was provided mainly by the Pearl River. Spectral analysis of the kaolinite/(illite+chlorite) ratio displays a strong eccentricity period of 100 ka, implying the ice sheet-forced winter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka, and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well, implying the tropical-forced summer monsoon evolution. The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity, with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere, with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation. The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons, respectively, implying their diplex and self-contained forcing mechanism.