近 a 南海北部陆架沉积物的东亚季风记录

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1 近 a 南海北部陆架沉积物的东亚季风记录 田旭 1, 徐方建 2, 徐微 3 4, 刘喜玲 (1., ; 2. ( ), ; 3., ; 4., ) 摘要 : 对位于海南岛南部陆架的 S20 孔沉积物进行了岩性 AMS 14 C 年代 粒度和微量元素分析, 提取了东亚季风演化的代用指标, 初步探讨了该沉积区蕴含的亚洲季风演化信息 结果表明, 近 a 以来, S20 孔研究区受相对稳定的水动力条件控制 主要富集于相对粗粒和细粒物质的 Zr/Rb 陆源元素比值和 <19 μm 细粒敏感粒度组分平均粒径可以作为冬季沿岸流和东亚冬季风强度的代用指标 二者与东海内陆架 PC-6 孔以及南海 孔海水表层温度变化表现出良好的相似性, 说明中国东南部不同地区季风代用指标揭示出的东亚冬季风演化具有一致性 因此, 相对于陆地和深海而言, 南海陆架区沉积物中同样蕴含着丰富的季风演化信息, 后续高分辨率研究工作亟待开展 关键词 : 陆架 ; 南海 ; 地球化学元素 ; 粒度 ; 亚洲季风 ; 全新世中图分类号 : P 文献标识码 : A 文章编号 : (2015) doi: /hykx ,, [1] [2] [3] [4], [2] [5-8] [9-12], [13-15],, [16-18],,, [19-20], [21-22], [23], S20, 1 材料与方法,,, [24] ( 1a 1b) S ( E, N, m, 1), 222 cm, 23, 10 cm 30% 3 mol/l, 3 Malvern 2000, 0.02~2 000 μm, 2% Zr Rb 60, 250, X-, PW2440,, 2 μg/g : ; : : ( , ); (14CX02038A, 12CX02003A); ( jch) : (1989-),,,,, : , tianxuaq@163.com;,,, : , xufangjiangg@163.com 62 / 2015 / 39 / 9

2 Fig.1 1 Seasonal current variations in northern South China Sea and core locations a. 2 ; b. 8 ; c. a. February; b. August; c. core locations,, GSD-9 GSD-10, 100% 3 AMS 14 C CALIB [25] ( 1), ( ) 2 结果, S20, (71%), 67.6%~ 77.3%, (16%), 12.5%~22.8%, (13%), 4.9%~18.9%,,,, (30 μm) ( 2) S20 Rb , ~ , Zr , ~ , μm, 17.42~35.77 μm, Zr, Rb ( 3) AMS 14 C, a BP 4 118~2 354 a BP, 77 cm/ka, a BP, 29 cm/ka 3 元素比值与敏感粒度组分平均粒径的地质意义 [26-28],, S20 ( 2) [24] (63~250 μm),, 1, 2 -, 8 [24], S20,, [29], 表 1 S20 孔 AMS 14 C 年龄数据 Tab.1 AMS 14 C dating of Core S20 (cm) AMS 14 C (abp) (abp) 68~ ± ~ ± ~ ± Marine Sciences / Vol. 39, No. 9 /

3 Fig.2 2 S20 The content of clay, silt and sand and frequency distributions of sediment grain-size in Core S20 3 S20 Rb Zr Fig.3 Profiles of contents of Rb, Zr and mean grain size in Core S20,, 3.1 Zr/Rb 元素比值,, Rb, Zr [30] S20 Zr, Rb, ( 3),,, [31],, Zr/Rb [32-34] Zr Rb [32], Zr/Rb, Zr/Rb S20 Zr/Rb Spearman, a=0.01( P=0.99) ( R=0.21),, Zr/Rb,,, Zr/Rb, 64 / 2015 / 39 / 9

4 [35] 3.2 敏感粒度组分平均粒径, - [3, 10, 12, 36] ( 4), 8 μm 71 μm, 19 μm 19 μm 4 近 a 东亚季风信息 S20 19 μm ( 5a) Zr/Rb ( 5b) PC-6 ( 5c, 1c) [12],,, (SST, 5d, 1c) [26-27],, S20 Zr/Rb a, 17940, S20 Zr/Rb 19 μm, Fig.4 4 S20 - Standard deviation vs. grain-size of Core S20,, [10, 12, 24],, S20,, [10, 12] 19 μm, : n X ( Xa)/ a n = å å, X i i i i i= 1 i= 1 ; a i ; i S20 Zr/Rb, ( 5), Spearman, a=0.01( P=0.99) ( R=0.63),,,, S20, S20 Zr/Rb 19 μm 5 Fig.5 Comparison of different proxies a. S20 ; b. S20 Zr/Rb ; c. PC-6 ; d a. mean grain-size of fine population of Core S20; b. Zr/Rb ratio of Core S20; c. mean grain-size of fine population of Core PC-6; d. seasurface temperature of Core 17940, - [37],,, [38] Marine Sciences / Vol. 39, No. 9 /

5 ,,, PC-6 [12] S20 Zr/Rb, [26-27],, ( ),, 5 结论 S20, S20 Zr/Rb 19 μm a, S20 Zr/Rb PC ,,,,,, : [1] Liu Jianguo, Li Anchun, Chen Muhong, et al. Sedimentary changes during the Holocene in the Bohai Sea and its paleoenvironmental implication[j]. Continental Shelf Research, 2008, 28(10-11): [2] Yang Zuosheng, Liu Jingpu. A unique Yellow River-derived distal subaqueous delta in the Yellow Sea[J]. Marine Geology, 2007, 240(1-4): [3] Xiang Rong, Yang Zuosheng, Saito Y, et al. East Asia Winter Monsoon changes inferred from environmentally sensitive grain-size component records during the last 2300 years in mud area southwest off Cheju Island, ECS[J]. Science in China (Series D), 2006, 49(6): [4] Liu J P, Liu C S, Xu K H, et al. Flux and fate of small mountainous rivers derived sediments into the Taiwan Strait[J]. Marine Geology, 2008, 256(1-4): [5],,. Li/Ba Rb/Sr [J]., 2014, 38(1): [6],,,. [J]., 2000, 18(2): [7] Yang Shouye, Youn J S. Geochemical compositions and provenance discrimination of the central south Yellow Sea sediments[j]. Marine Geology, 2007, 243(1-4): [8],,. 50 ka [J]., 2013, 37(1): [9],,. [J]., 2013, 37(10): [10] Xu Fangjian, Li Anchun, Xu Kehui, et al. Cold event at 5500 a BP recorded in mud sediments on the inner shelf of the East China Sea[J]. Chinese Journal of Oceanology and Limnology, 2009, 27(4): [11] Liu Jian, Saito Y, Wang Hong, et al. Sedimentary evolution of the Holocene subaqueous clinoform off the Shandong Peninsula in the Yellow Sea[J]. Marine Geology, 2007, 236(3-4): [12] Xiao Shangbin, Li Anchun, Liu J P, et al. Coherence between solar activity and the East Asian winter monsoon variability in the past 8000 years from Yangtze River-derived mud in the East China Sea[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2006, 237(2-4): [13] Wei Gangjian, Li Xianhua, Liu Ying, et al. Geochemical record of chemical weathering and monsoon climate change since the early Miocene in the South China Sea[J]. Paleoceanography, 2006, 21(4): PA4214, doi: /2006PA [14] Sun Youbin, Wu Feng, Clemens S C, et al. Processes controlling the geochemical composition of the South China Sea sediments during the last climatic cycle[j]. 66 / 2015 / 39 / 9

6 Chemical Geology, 2008, 257(3-4): [15] Tian Jun, Wang Pinxian, Cheng Xinrong. Development of the East Asian monsoon and Northern Hemisphere glaciation: oxygen isotope records from the South China Sea[J]. Quaternary Science Reviews, 2004, 23(18-19): [16],, Stuut J B W,. ODP Ma [J]. : D, 2007, 37(6): [17], Trentesaux A, Clements S C,. ODP1146 : [J]. : D, 2003, 33(3): [18],,,. 1.8 Ma [J]., 2010, 55(34): [19],,,. [J]., 2006, 26(3): 1-5. [20]. [J]., 2008, 27(6): [21] Sun Xiangjun, Li Xu, Luo Yunli, et al. The vegetation and climate at the last glaciation on the emerged continental shelf of the South China Sea[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2000, 160(3-4): [22] Wang Xiaomei, Sun Xiangjun, Wang Pinxian, et al. Vegetation on the Sunda Shelf, South China Sea, during the Last Glacial Maximum[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2009, 278(1-4): [23] Steinke S, Kienast M, Hanebuth T, et al. On the significance of sea-level variations and shelf paleo-morphology in governing sedimentation in the southern South China Sea during the last deglaciation[j]. Marine Geology, 2003, 201(1-3): [24]. [M]. :, [25] Hughen K A, Baillie M G L, Bard E, et al. Marine04 Marine radiocarbon age calibration, 0-26 cal kyr BP[J]. Radiocarbon, 2004, 46(3): [26] Huang Yue, Jiang Hui, Sarnthein M, et al. Diatom response to changes in palaeoenvironments of the northern South China Sea during the last years[j]. Marine Micropaleontology, 2009, 72(1-2): [27] Wang Luejiang, Sarnthein M, Erlenkeuser H, et al. Holocene variations in Asian monsoon moisture: A bidecadal sediment record from the South China Sea[J]. Geophysical Research Letters, 1999, 26(18): [28] Zong Yongqiang. Mid-Holocene sea-level highstand along the Southeast Coast of China[J]. Quaternary International, 2004, 117(1): [29],,, [J]., 2014, 34(3): [30],. [M]. :, [31] Wronkiewicz D J, Condie K C. Geochemistry of Archean shales from the Witwatersrand Supergroup, South Africa: Source-area weathering and provenance[j]. Geochimica et Cosmochimica Acta, 1987, 51(9): [32],, 旸,. 130 ka Zr/Rb [J]., 2001, 47(9): [33],,,. Zr/Rb [J]., 2003, 23(4): [34] Dypvik H, Harris N B. Geochemical facies analysis of fine-grained siliciclastics using Th/U, Zr/Rb and (Zr+Rb)/Sr ratios[j]. Chemical Geology, 2001, 181(1-4): [35] Chen Jun, Chen Yang, Liu Lianwen, et al. Zr/Rb ratio in the Chinese loess sequences and its implication for changes in the East Asian winter monsoon strength[j]. Geochimica et Cosmochimica Acta, 2006, 70(6): [36],,,. [J]., 2009, 31(3): [37] Ding Zhongli, Liu Tungsheng, Rutter N W, et al. Marine Sciences / Vol. 39, No. 9 /

7 Ice-volume forcing of East Asian winter monsoon variations in the past 800, 000 Years[J]. Quaternary Research, 1995, 44(2): [38] An Zhisheng. The history and variability of the East Asian paleomonsoon climate[j].quaternary Science Reviews, 2000, 19(1-5): a East Asian monsoon record from sediments in the continental shelf of the northern South China Sea TIAN Xu 1, XU Fang-jian 2, XU Wei 3, LIU Xi-ling 4 (1. Institute of Mineral Resources and Geoscience, China University of Mining & Technology, Xuzhou, , China; 2. School of Geosciences, China University of Petroleum, Qingdao , China; 3. Overseas Evaluation Center of CNOOC Research Institute, Beijing , China; 4. CNOOC International Limited, Beijing , China) Received: Apr., 23, 2014 Key words: continental shelf; the South China Sea; geochemical elements; grain-size; Asian monsoon; Holocene Abstract: Lithology, AMS 14 C dating, grain-size and trace element analysis were carried out for Core S20, which was retrieved from the continental shelf in the northern South China Sea (SCS). The monsoonal proxies were investigated and the evolution history of East Asian monsoon was discussed in this paper. The results show that since a BP, the hydrodynamic conditions in the study area are relatively stable. The Zr/Rb ratio of which enriched mainly in the relatively coarse and fine materials and mean grain-size (MGS) of the finer population are sensitive to the strength of the coastal current, and could be adopted to rebuild the evolution history of the East Asian winter monsoon (EAWM). Both of the Zr/Rb ratio and the finer population MGS correspond well to the sedimentary record of Core PC-6 on the inner shelf of the East China Sea, and sea-surface temperature of Core from the northern slope of the SCS. This similarity indicates the consistency of EAWM evolution in different areas of the southeast China. Compared with the land and deep-sea proxies, the sediments in the continental shelf area also contain a wealth of information on the Asian monsoon evolution. Therefore, more research with higher resolution need carry out urgently. ( 本文编辑 : 刘珊珊 ) 68 / 2015 / 39 / 9