| MIS2期南海北部粘土矿物记录的东亚夏季风快速变化 |
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| 引用本文： | 赵绍华,刘志飞.MIS2期南海北部粘土矿物记录的东亚夏季风快速变化[J].第四纪研究,2019,39(4):894-904. |
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| 作者姓名： | 赵绍华 刘志飞 |
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| 作者单位： | 同济大学,海洋地质国家重点实验室,上海200092;自然资源部第三海洋研究所,海洋与海岸地质实验室,福建 厦门361005;同济大学,海洋地质国家重点实验室,上海200092 |
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| 摘 要： | 运用伊利石结晶度线性剥离法,定量计算了华南、台湾和吕宋这 3 个主要物源区对南海北部陆坡MD12-3432和MD12-3434两个岩芯(分别为50. 80 m和8. 33 m)MIS 2期粘土相对贡献量的时间序列变化.结果显示,台湾对两个岩芯的贡献最大(36%~62%),吕宋的贡献次之(28%~50%),二者之和一般大于90%,而来自华南的贡献最小(3%~17%).台湾和吕宋的贡献量呈现显著反向的千年时间尺度快速波动,二者贡献量随东亚夏季风增强或减弱而显著变化,因此,吕宋/台湾贡献量比值可以用于指示东亚夏季风的快速演化.吕宋/台湾粘土贡献量比值在B?lling-Aller?d和Dansgaard-Oeschger 2事件期间的增加,反映了同时期东亚夏季风的快速增强;而在Heinrich 1和Heinrich 2事件期间的减小,则指示了东亚夏季风的减弱.吕宋/台湾贡献量比值对东亚夏季风快速变化的指示,在一定程度上要明显优于蒙脱石/(伊利石+绿泥石)比值.南海北部MIS 2期粘土矿物对东亚夏季风快速变化的响应具有明显的空间差异性,受洋流搬运扰动和物源控制作用影响,陆坡相对浅水区粘土矿物记录的东亚夏季风快速变化信息相对有限,而深水稳定的沉积环境则更有利于保存东亚夏季风快速变化信息.
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| 关 键 词： | 粘土矿物 东亚季风 相对贡献量 快速气候变化 南海 氧同位素2期 |
Rapid variations in the East Asian summer monsoon during marine isotope stage (MIS) 2recorded in clay minerals of the northern South China Sea |
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| Zhao Shaohua,Liu Zhifei.Rapid variations in the East Asian summer monsoon during marine isotope stage (MIS) 2recorded in clay minerals of the northern South China Sea[J].Quaternary Sciences,2019,39(4):894-904. |
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| Authors: | Zhao Shaohua Liu Zhifei |
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| Institution: | (State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092;Laboratory of Ocean and Coast Geology, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, Fujian) |
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| Abstract: | Clay mineralogy, as reflected by smectite/(illite + chlorite) ratio, provides a powerful tool to reconstruct high-resolution paleoclimatology and paleoceanography variations in the northern South China Sea. However, some proportion of South China-sourced illite and chlorite are strongly controlled by sea-level fluctuations that will further mask or obscure some climate change signals. To better reveal such an issue, a linear separation method for illite crystallinity was used to obtain time series of relative clay contribution from various sources at cores MD12-3432 and MD12-3434 during marine isotope stage (MIS) 2 based on their published available clay mineralogical data. These two sediment cores, retrieved from the northeastern part of the Pearl River canyon on the continental slope of northern South China Sea, are 50.80 m and 8.33 m long that can encompass the temporal records extending to 400 ka B. P. and 60 ka B. P. with average sedimentation rates of 12.7 cm/ka and 10.7 cm/ka, respectively. During MIS 2, a total of 31 and 78 clay mineralogical data points were obtained at depth intervals of 10 cm and 2 cm with average temporal resolution of 387 a and 154 a, respectively. The results of these data revisited show that Taiwan contributes the most clay minerals to these two sediment cores (36%~62%), followed by the contribution from Luzon (28%~50%). The sum of clay mineral contribution from these two sources is normally > 90%, while South China provides the lowest clay mineral contribution (3%~17%). Temporal variations of clay mineral contribution from Taiwan present clear millennial-scale changes that are anti-phased with that of clay contribution from Luzon. The abrupt increases or decreases of clay mineral contribution from Taiwan and Luzon are mostly attributed to rapid changes in the East Asian summer monsoon, and thus the Luzon/Taiwan clay contribution ratio provides an excellent proxy for such rapid climate changes. Abrupt increases of the Luzon/Taiwan clay contribution ratio indicate strengthened summer monsoon happened during Dansgaard-Oeschger 2 and B?lling-Aller?d interstadials. Whereas rapid decreases of this ratio indicate relatively weakened summer monsoon occurred during Heinrich 1 and 2 stadials. By comparison with the smectite/(illite + chlorite) ratio, the Luzon/Taiwan clay contribution ratio is much better to constrain those rapid changes in the East Asian summer monsoon. The abrupt responses of clay minerals in the northern South China Sea to rapid changes in the East Asian summer monsoon indicate distinct spatial differences that are mainly under the influence from bottom current transportation and provenance control. In the relatively shallow water region, rapid changes in the East Asian summer monsoon documented by clay mineral are limited, while such abrupt climate change information can be better preserved in calm deeper-water sedimentary environments. |
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| Keywords: | clay mineral East Asian monsoon relative contribution rapid climate change South China Sea Marine Isotope Stage 2 |
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