詹涛^1,2,3,,
曾方明⁴,
杨业^1,2,
葛俊逸⁵,
马永法^1,2,
张俊^1,2,
姜侠^2,6,
黄荣富^1,2,
梁彦霞^1,2,
李峨¹,
王逊^2,6,
周鑫⁷,
邓成龙³
1. 黑龙江省生态地质调查研究总院, 黑龙江 哈尔滨 150030
2. 黑土地水土资源研究省级重点实验室, 黑龙江 哈尔滨 150036
3. 中国科学院地质与地球物理研究所, 岩石圈演化国家重点实验室, 北京 100029
4. 中国科学院青海盐湖研究所, 青海 西宁 810008
5. 中国科学院古脊椎动物与古人类研究所, 北京 100044
6. 黑龙江省地质矿产局, 黑龙江 哈尔滨 150036
7. 中国科学技术大学地球和空间科学学院, 安徽 合肥 230026

基金项目: 国家自然科学基金项目(批准号：41888101和41822707)、黑龙江省国土资源科研类项目(批准号：201407)和自然资源部公益性科研专项项目(批准号：201311137)共同资助


详细信息

作者简介: 詹涛, 男, 39岁, 教授级高级工程师, 第四纪地质环境研究, E-mail:hljzhantao@163.com

中图分类号: P532;P534.63⁺1

收稿日期:2020-05-29
修回日期:2020-08-30
刊出日期:2020-11-30

Decreasing summer monsoon precipitation during glacial at ca.900 ka: Evidence from grain size variation of lacustrine deposits from the Northeast Plain of China

Zhan Tao^1,2,3,,
Zeng Fangming⁴,
Yang Ye^1,2,
Ge Junyi⁵,
Ma Yongfa^1,2,
Zhang Jun^1,2,
Jiang Xia^2,6,
Huang Rongfu^1,2,
Liang Yanxia^1,2,
Li E¹,
Wang Xun^2,6,
Zhou Xin⁷,
Deng Chenglong³
1. The General Institute of Ecological Geology Survey and Research of Heilongjiang Province, Harbin 150030, Heilongjiang
2. Key Laboratory of Black Soil and Water Resources Research of Heilongjiang Province, Harbin 150036, Heilongjiang
3. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029
4. Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, Qinghai
5. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044
6. Heilongjiang Bureau of Geology & Mineral Resources, Harbin 150036, Heilongjiang
7. School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, Anhui


MSC: P532;P534.63⁺1

--> Received Date: 29 May 2020
Revised Date: 30 August 2020
Publish Date: 30 November 2020


摘要
摘要:中更新世转型(mid-Pleistocene Transition，简称MPT)期间，除了冰量周期由40 ka向100 ka的特征转变之外，约900 ka以后，高纬冰量、全球海平面和大气CO₂/大洋碳库的变幅也都发生了明显变化，这些因素对东亚夏季风的演化产生了深远影响。但关于此时期东亚夏季风降水的变化趋势及其驱动机制，目前尚存在不同看法。本文在前期古地磁和光释光(optically stimulated luminescence，简称OSL)年代框架的基础上，基于东北平原QAL钻孔上部71 m的沉积物粒度重建了夏季风降水演化序列。结果表明：1)时间跨度为1180~450 ka的林甸组和令字组均为较细颗粒的湖相沉积，且林甸组明显较令字组颗粒粗；2)粒度粗的层位代表低湖面阶段，反映降水少，为冰期，反之亦然；3)小波分析显示约900 ka后，100 ka周期特征明显，为通过与深海氧同位素对比获得更精细的年龄序列奠定基础；4)约900 ka后，冰期的降水有明显减弱的趋势。高纬冰量扩张造成的全球海平面下降导致更多陆地暴露出海平面，增加了大洋水汽的输送距离，可能是降水减少的一个影响因素。大西洋经向翻转流(Atlantic Meridional Overturning Circulation，简称AMOC)减弱，热带太平洋区域"热带辐合带"(Intertropical Convergence Zone，简称ITCZ)南移，可能是东亚夏季风降水减弱的另一重要原因。古湖相沉积能够用来重建长尺度夏季风降水变化，未来应加强东亚季风区不同区域古湖泊沉积研究，进而弥补长尺度夏季风演化研究存在的不足，这将有助于更好理解轨道尺度夏季风演化的动力机制。
关键词: 中更新世转型/
东亚夏季风降水/
东北平原/
湖相沉积/
粒度

Abstract:The mid-Pleistocene transition(MPT) is characterized by not only the transition of the ice cycles from 40 ka to 100 ka, but also changes in amplitude of high latitude ice sheet, global sea level and CO₂/ocean carbon storage after ca. 900 ka, which exert profound influence on the evolution of the East Asian summer monsoon. However, there are different views on the trend of the East Asian summer monsoon precipitation(EASMP) during this period and its driving mechanism. Previous studies based on grain size and pollen percentages in loess indicate a decreasing trend of the EASMP after MPT, which is supported by pollen record from alluvial sediments in North China. This trend was linked to the expansion of global ice volume. On the contrary, results of magnetic susceptibility, carbonate content, minerals and chemical weathering indices of loess show that the EASMP after MPT increased gradually. The increasing trend of the EASMP was related to different forcing factors, including the uplift of the Tibetan Plateau, and the increasing of the sea surface temperature variability in the tropical East-West Pacific Ocean and the frequency of La Ni?a phenomenon.
Upon published chronology from paleomagnetism and OSL(optically stimulated luminescence) dating, a new EASMP record was reconstructed in this paper on the basis of grain size in sediments from Core QAL(44°49'04″N, 123°48'46″E), with 120.54 m drilling depth. The grain size of the samples from 0~71 m were analysed with 10 cm intervals. The results show that:(1) There are relative fine-grained lacustrine sediments(19.5~71.0 m) during 1180~450 ka, with coarser grains, whose average value in silty sand layer is median particle size 36 μm, >32 μm percentage content 53%, >63 μm percentage content 29.7% in Lindian Formation and finer ones, whose average value in silty sand layer is median particle size 32 μm, >32 μm percentage content 46%, >63 μm percentage content 26.7% in Lingzi Formation; (2) Grain size of the sediments increased during the glacial periods, showing low lake levels and less EASMP; (3) 100-ka cycle is obvious after ca. 900 ka, corresponding well with benthic δ¹⁸O record; (4) Glacial precipitation decreased obviously after ca. 900 ka. The decreasing of the global sea level, caused by the expansion of ice sheet in high latitude, led to more land exposure and longer transport distance of ocean water vapor, might be the main cause of the EASMP reduction. In addition, the weakening of the Atlantic meridional overturning circulation(AMOC) will cause the southward movement of the Intertropical Convergence Zone(ITCZ) in the tropical Pacific, which will produce El Ni?o conditions in the southern tropical Pacific region, and weaken Walker circulation, but put the northern tropical Pacific region under La Ni?a conditions, strengthening the Walker circulation. ITCZ is more symmetrical along the equator. Thus, it weakens the intensity of the EASMP.
Paleolacustrine deposition can be applied to reconstruct long timescale EASMP changes. In the future, more studies on paleolacustrine deposition in different regions of the East Asian monsoon region should be carried out to reconstruct the long-term evolution of the summer monsoon, which will contribute to the understanding of the dynamic mechanisms of changes in summer monsoon on orbital timescale.
Key words:MPT/
summer monsoon precipitation in East Asia/
Northeast Plain/
lacustrine deposits/
grain size



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