长江口与黄河口沉积物角闪石和石英元素地球化学特征及物源意义

发布时间：2018-06-02 22:33

本文选题：角闪石 + 石英　；参考：《鲁东大学》2015年硕士论文

【摘要】：长江和黄河作为中国东部陆架海域海底沉积物主要的物质来源，输送大量的陆源碎屑物质，携带着源岩成因、流域环境、气候条件、沉积环境和过程等众多信息。长江和黄河入海沉积物的物源研究对研究中国东部陆架海域的源-汇系统意义重大，对认识环境变化、海洋通量、海岸带海陆相互作用等提供定性和定量的依据。目前，物源研究方法众多，结合矿物学和地球化学二者优点的矿物元素地球化学方法应用较少。基于矿物元素地球化学方法，寻找长江和黄河物源区分的新型指标，对研究长江和黄河物质来源和搬运机制、入海沉积物运移路线、认识中国东部陆架海域沉积物的物源和演化过程等问题有重要的科学意义。本文对长江口与黄河口沉积物角闪石、石英的元素地球化学特征分析，利用矿物学特征分析、常量元素、微量元素、稀土元素等方法，，找出区分长江和黄河物源指标。结果显示：（1）在长江口与黄河口沉积物矿物特征研究中，长江沉积物重矿物中闪石类矿物和金属矿物类含量高，黄河以云母类矿物和褐铁矿含量高，黄河故道云母类矿物含量较少，长江和黄河沉积物主要以云母类矿物、闪石类矿物和金属矿物类的含量为主要区分标准，重矿物中的磷灰石和榍石不能够很好的区分长江和黄河沉积物。轻矿物中长石/石英的比值黄河高于长江，由于长江的风化强度高于黄河，长石抗风化能力比石英弱，长江轻矿物中长石含量较少。黄河中的方解石可以作为黄河沉积物的特征矿物。（2）角闪石微量元素研究发现，长江角闪石成因类型复杂分散，壳型、壳幔型和幔型中均有分布，与其流域复杂的源岩成因相对应；黄河角闪石成因类型集中，以壳幔混合型为主，与物源单一的特点相一致。稀土元素中，黄河角闪石稀土元素总量高于长江，轻稀土差异较大，黄河和黄河故道配分曲线一致。角闪石的微量元素和稀土元素都能够较好的区分长江和黄河物源，利用角闪石微量元素进行聚类分析和Be-Ta图解，能够较好的区分长江和黄河沉积物，Be-Ta-Sc三角图作为长江和黄河物源区分的检验指标。（3）角闪石微量元素和稀土元素的前后两次测试结果存在一定的差异，黄河和黄河故道在两次测试中均能够较好的显示物源一致性，微量元素和稀土元素能够作为物源研究的重要指标。对角闪石在两次测试中差异较小的微量元素做标准差图，以标准差为元素含量浮动值，初步建立长江和黄河沉积物的物源指标。（4）石英元素地球化学研究发现，石英微量元素中的Be-Ta-Ge和Be-Ta-Sc图解可以较好的区分长江和黄河物源，石英稀土元素中，长江石英稀土总量高于黄河，长江和黄河之间重稀土差异高于轻稀土。
[Abstract]:The Yangtze River and the Yellow River are the main material sources of submarine sediments in the eastern continental shelf of China. They transport a large amount of continental clastic material and carry a lot of information such as source rock origin, basin environment, climatic conditions, sedimentary environment and process, and so on. The study on the provenance of sediments from the Yangtze River and the Yellow River is of great significance to the study of the source-sink system in the eastern shelf of China, and provides a qualitative and quantitative basis for the understanding of environmental changes, ocean fluxes and the interaction between sea and land in the coastal zone. At present, there are many methods for studying provenance, but few methods for mineral element geochemistry combining the advantages of mineralogy and geochemistry. Based on the method of mineral element geochemistry, a new indicator of the material source differentiation between the Yangtze River and the Yellow River is found, and the material source and transport mechanism of the Yangtze River and the Yellow River are studied, and the sediment transport route into the sea is also studied. It is of great scientific significance to understand the provenance and evolution process of sediments in the eastern shelf of China. In this paper, the geochemical characteristics of hornblende and quartz in the Changjiang Estuary and the Yellow River Estuary are analyzed. By means of mineralogical analysis, constant elements, trace elements and rare earth elements, the material source indexes of the Yangtze River and the Yellow River are found out. The results show that: 1) in the study of mineral characteristics of sediments in Changjiang Estuary and Yellow River estuary, the contents of amphibole minerals and metal minerals in heavy minerals of Yangtze River are high, mica minerals and limonite in Yellow River are high, and the contents of mica minerals in the Yellow River are less. The contents of mica, amphibole and metal minerals are the main criteria in the sediments of the Yangtze River and the Yellow River. The apatite and sphene in the heavy minerals can not distinguish the sediments of the Yangtze River and the Yellow River well. The ratio of feldspar to quartz in light minerals is higher in the Yellow River than in the Yangtze River. Because the weathering intensity of the Yangtze River is higher than that of the Yellow River, the weathering resistance of feldspar is weaker than that of quartz. Calcite in the Yellow River can be used as the characteristic mineral of the Yellow River sediment. The study of trace elements of amphibole shows that the genetic types of amphibole in the Yangtze River are complicated and dispersed, crustal, crust-mantle and mantle-type are distributed, corresponding to the complex origin of source rocks in its basin, and the genetic types of hornblende in the Yellow River are concentrated. The crust-mantle mixed type is the main type, which is consistent with the characteristics of single provenance. Among the rare earth elements, the total amount of amphibole rare earth elements in the Yellow River is higher than that in the Yangtze River, and the difference of the light rare earth elements is great. The distribution curves of the Yellow River and the Yellow River are consistent. The trace elements and rare earth elements of hornblende are able to distinguish the source of the Yangtze River and the Yellow River well. The trace elements of hornblende are used for cluster analysis and Be-Ta diagram. The Be-Ta-Sc triangulation can be used to distinguish the sediment from the Yangtze River and the Yellow River, which can be used as an index to distinguish the source of the Yangtze River and the Yellow River. (3) the results of trace elements and rare earth elements in hornblende are different before and after the two tests, and the Yellow River and Yellow River old road can show the consistency of the source of materials in the two tests. Trace elements and rare earth elements can be used as important indicators for the study of provenance. The trace elements with little difference in the two tests of amphibole were used as standard deviation map, and the source indexes of Yangtze River and Yellow River sediments were preliminarily established with the standard deviation as the floating value of element content. (4) the geochemistry of quartz elements shows that the Be-Ta-Ge and Be-Ta-Sc diagrams in quartz trace elements can distinguish the source of the Yangtze River from the Yellow River, and the total amount of rare earth elements in the quartz elements of the Yangtze River is higher than that of the Yellow River. The difference of heavy rare earth between Yangtze River and Yellow River is higher than that of light rare earth.
【学位授予单位】：鲁东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P595

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