17000a以来冲绳海槽中部柱状样S10沉积学特征及其物源环境指示

发布时间：2018-01-17 01:05

本文关键词：17000a以来冲绳海槽中部柱状样S10沉积学特征及其物源环境指示　出处：《中国科学院研究生院(海洋研究所)》2016年硕士论文　论文类型：学位论文

【摘要】：基于AMS14C高精度定年,本文对冲绳海槽中部陆坡区岩芯S10展开粒度、微量元素和黏土矿物分析,分别从稀土元素和黏土矿物角度探讨冲绳海槽中部岩芯沉积物的物质来源。结果表明,岩芯S10记录了冲绳海槽中部约17 000 a以来沉积物的物源变化,沉积物主要由来自长江、黄河和台湾的陆源物质和火山物质组成,不同时期各源区物质贡献程度不同。16 500~11 600 a,长江、黄河陆源碎屑为主;11 600~7 750 a,海平面变化大,长江、黄河物质为主;7 750~6 450 a,沉积物全岩样稀土元素显示火山物质为主要物源,黏土矿物组成显示细粒沉积物以黄河碎屑为主,说明粗粒物质主要为火山物质,细粒物质主要为黄河碎屑物质;6 450~3 900 a,稀土元素显示沉积物在4 000 a左右受火山物质影响,黏土矿物显示细粒沉积物以长江、黄河陆源碎屑为主,台湾物质有一定影响;3 900~1 900a,岩芯碎屑物质主要来自长江和黄河,台湾物质略有增多;1 900 a至今,稀土元素显示黄河物质为主,而黏土矿物显示细粒物质以长江碎屑为主,台湾物质影响增强。本文利用稀土元素的物源判别公式DF计算得到长江、黄河、台湾和火山潜在物源的DF值,长江、黄河陆源DF值记录并反映了17 000 a以来冬季风的演变情况,可作为东亚冬季风强弱演化指标。黏土矿物中高岭石和蒙脱石形成条件独特,物源区相对单一,可将高岭石和蒙脱石含量做为东亚冬季风强弱演化的另一项指标。本文研究结果表明,冲绳海槽中部微量元素和黏土矿物研究可得到海槽17 000 a以来物源及东亚冬季风的演化情况,对于重建全新世以来冲绳海槽内部沉积物物源及古环境的演变历史具有重要意义。
[Abstract]:Based on the high precision dating of AMS14C, the grain size, trace elements and clay minerals of core S10 in the middle slope of Okinawa trough are analyzed in this paper. The material sources of core sediments in the middle of Okinawa trough are discussed from the point of view of rare earth elements and clay minerals respectively. Core S10 records the variation of sediment sources in the middle of the Okinawa trough over the past 17, 000 years. The sediments are mainly composed of terrestrial and volcanic materials from the Yangtze, Yellow and Taiwan. The contribution degree of material in different source areas is different in different periods, with the continental clastic of Yangtze River and Yellow River dominated by 11.600 a. The sea level changes greatly, the Yangtze River and the Yellow River are the main materials. 7 750 ~ 6 450 a, the REE in the whole rock samples of the sediments showed that volcanic material was the main source, and the clay mineral composition showed that the fine grain sediments were mainly of the Yellow River debris. It shows that the coarse grain material is mainly volcanic material and the fine grain material is mainly the Yellow River clastic material. The REE showed that the sediments were affected by volcanic materials at about 4 000 years, and the clay minerals showed that the fine sediments were mainly from the Yangtze River and the Yellow River. Taiwan material has certain influence; The core clastic material mainly came from the Yangtze River and the Yellow River, and the material from Taiwan increased slightly. Up to 1900a, the rare earth elements mainly show the Yellow River material, while the clay minerals show that the fine grained materials are mainly the Yangtze River debris. In this paper, the DF values of the Yangtze River, the Yellow River, Taiwan and volcanoes are calculated by using the material source discriminant formula of rare earth elements. The DF values of the terrestrial source of the Yellow River recorded and reflected the evolution of winter monsoon over the past 17 000 years, which can be used as an index for the evolution of the East Asian winter monsoon. The formation conditions of kaolinite and montmorillonite in clay minerals are unique. The source region is relatively single, so the contents of kaolinite and montmorillonite can be used as another index of the East Asian winter monsoon evolution. Trace elements and clay minerals in the central Okinawa trough can be obtained from the provenance of the trough and the evolution of the East Asian winter monsoon since 17000 years. It is of great significance to reconstruct the evolution history of sediment source and paleoenvironment in the Okinawa trough since Holocene.
【学位授予单位】：中国科学院研究生院(海洋研究所)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P736.2

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