东海内陆架泥质区EC2005孔沉积特征及古环境记录

IOCAS-IR > 海洋环流与波动重点实验室

	东海内陆架泥质区EC2005孔沉积特征及古环境记录
其他题名	Sedimentary characteristics and paleoenvironmental records of Core EC2005 in the mud area on the inner shelf of the East China Sea
	徐方建
学位类型	博士
	2009-05-21
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	东海内陆架末次冰消期与全新世沉积环境古气候 Ec2005孔
摘要	本论文通过对东海内陆架浙闽沿岸泥质沉积带EC2005孔沉积物岩性、粒度、AMS14C测年、粘土矿物以及全岩矿物衍射分析、沉积物常微量元素和稀土元素分析、总碳氮以及有机碳氮分析、磁化率测试和综合研究，以EC2005孔岩芯记录为依据分析了研究区的沉积环境演化、海平面升降、浙闽沿岸流形成历史以及蕴含的古气候信息，探讨了陆源物质矿物、地球化学成分与粒度的关系。 EC2005孔岩芯自底部至41.00 m（17.3~13.1 ka BP）为末次冰消期以来的湖泊三角洲沉积序列，物质来源主要是来自湖盆流域物质的输入。随着海平面逐渐上升，海水自13.1 ka BP开始侵入研究区，自12.3 ka BP开始海水深度加大，沿岸流的地位开始显现，7.3 ka BP以来，形成了高海平面以来主要受沿岸流控制的浅海沉积。稀土元素结果显示，东海内陆架EC2005孔12.3~9.8 ka BP是以湖盆流域近源物质为主向长江物质为主转变的过渡阶段，自大约10~9.8 ka BP开始，由于海水深度的进一步加大、沿岸流作用进一步增强，长江物质对研究区的物质供给成为主导。海平面的升高以及沿岸流的形成是物质来源发生变化的重要原因。东海内陆架泥质沉积物中全新世期间长达700 a（5.9~5.2 ka BP）的高分辨率细粒敏感组分资料揭示的东亚冬季风增强，与GRIP冰芯δ18O揭示的冷期具有良好的对应关系。5500 a BP前后东亚冬季风突然增强，与世界范围内的5500 a BP强降温事件非常一致。功率谱分析揭示出62 a和11 a的太阳活动周期以及与现代ENSO周期相似的6 a和5 a周期，因此，中全新世东亚冬季风演化可能是太阳活动以及古ENSO事件对全球气候系统的影响所致。东海内陆架区对末次冰消期至早全新世气候回暖的记录与该时期世界性的广泛记录相一致，应该是轨道时间尺度上太阳辐射增强与ITCZ北移以及太阳活动变化综合影响的结果。东海内陆架浙-闽沿岸泥质带EC2005孔存在的4个百年时间尺度上快速沉积事件：12.3~12.1 ka BP、7.5~7.3 ka BP、5.9~5.2 ka BP和1.5~1.3 ka BP，与新仙女木事件、7.3 ka BP冷事件、第二新冰期（5.5 ka BP强降温事件）以及北大西洋1.4 ka BP浮冰事件均有良好的对应，世界范围内广泛存在的8.2 ka冷事件对本钻孔沉积也形成了一定影响。 EC2005孔磁化率变化受到多种因素的制约，如岩性粗细、早期成岩作用以及人类活动等的影响。近3.6 ka以来，磁化率的剧烈波动可能是由于人类活动影响造成的。东海内陆架EC2005孔TOC、TN和TOC/TN的大小主要受控于岩性变化。此外，根据陆源物质粒度和矿物成分之间的关系，建立了陆源物质平均粒径与主要矿物成分含量大小的函数模型。地球化学成分与其所赋存单种矿物的相关性分析则进一步表明，陆源矿物种类和含量控制着地球化学成分及其含量，矿物种类和含量对地球化学成分的控制是决定性的，而粒度对元素（化学成分）的“控制”实际上是由于不同粒度的矿物组分不同而造成。
其他摘要	Based upon analysis of lithology, grain-size, AMS14C dating, clay and bulk minerals, geochemical compositions, rare earth elements (REE), total carbon (TC), total nitrogen (TN), total organic carbon (TOC) and magnetic susceptibility analysis for Core EC2005, located in the mud area off the Zhejiang-Fujian coast in the inner shelf of the East China Sea (ECS), the paleoenvironmental evolution, sea level change, formation of the Zhejiang-Fujian coastal current (ZFCC) and paleoclimatic change could be ascertained. The relationship among terrigenous mineral components, geochemical composition and grain-size distribution is also discussed. From the bottom 60.20 m to 41.00 m (17.3~13.1 ka BP), a lacustrine delta developed. The sea water arrived at the study area at 13.1 ka BP and a 41 m thick sediment formed from then on. From 12.3 ka BP, the study area was influenced by ZFCC, and Yangtze-derived materials had been transported southward from that time. Yangtze-derived materials played a dominant role from 10~9.8 ka BP while the sediments were mainly originated from the regional drainage area before. Since 7.3 ka BP, the sedimentary environment is dominated by the ZFCC, and the homogeneous mud sedimentation began to form. The important reason for material provenances change is sea level rise and the formation of coastal current. On the basis of environmentally sensitive grain-size population analysis of Core EC2005, a 700 a East Asian winter monsoon (EAWM) evolution between 5.9 and 5.2 ka BP was compared with the GRIP δ18O record. The good correlation suggested that inner relationship existed between the EAWM and the climatic changes disclosed by the GRIP ice core. The EAWM strengthened abruptly around 5500 a BP, which is corresponded to the worldwide cold event. The significant periodicities disclosed by power spectral analysis correspond to the solar activity such as the 62 and 11 a periodicities and the modern ENSO 3~8 a periodicity as 6 and 5 a. Theirfore, the EAWM evolution in the mid-Holocene and the 5500 a BP cold event may be influenced by solar and ENSO activities. The climatic warming from last deglaciation to the early Holocene in the inner shelf of the ECS has been worldwidely recorded, which may be the integrated results of orbital insolation forcing, the solar activities and the northward migration of intertropical convergence zone. Four rapid depositional periods such as 12.3~12.1 ka BP, 7.5~7.3 ka BP, 5.9~5.2 ka BP, and 1.5~1.3 ka BP disclosed by Core EC2005 well correspond to the worldwide Younger Dryas, 7.3 ka cold event, Neoglaciation or 5.5 ka cold event, and 1.4 ka ice rafted debris event, respectively. The worldwide 8.2 ka event is also well recorded in the core. The magnetic susceptibility variation is controlled by lithology, early diagenetic and human activity. The acute fluctuation since 3.6 ka BP may result from human activity. Variations of TOC, TN and TOC/TN in Core EC2005 are mainly controlled by lithology. A function model was built between grain-size and mineral components of terrigenous materials according to their inherent relationship. The mineral components show good correlation to geochemical compositions, suggesting the mineral constrains on the chemical elements in the sediments. The mineral constrains on the grain-size distribution and geochemical composition is crucial, whereas the grain-size distribution can only affect the geochemical composition via changes in mineral components.
页数	145
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1381
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	徐方建. 东海内陆架泥质区EC2005孔沉积特征及古环境记录[D]. 海洋研究所. 中国科学院海洋研究所,2009.

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