Chemical characteristics of sedimentary rocks and meta-sedimentary rocks of tectonic belts in Japanese Islands and geological environments of their formations

我们安装了一台电感耦合等离子体原子发射光谱仪(Seiko SPS-1500R)，并建立了不同类型沉积岩中稀土元素加Y的测定。应用本方法测定了石灰岩、白云岩、变质岩、前寒武纪铁矿和深海铁锰结核中的稀土元素和稀土元素。本文从稀土元素和Y元素分析入手，重点对日本群岛构造带碳酸盐岩进行了化学分类。划分出三种类型：(1)珊瑚礁型，(2)大陆缘型，(3)深水型。其碳酸盐岩建造的地质环境与前人的沉积学和地质分析结果吻合较好，并对“四极效应”进行了重要的理论研究，这将是认识低温下沉积物-水体系中稀土元素行为的重要依据。从这一观点出发，开展了稀土元素Y在Fe-Mn氢氧化物-氯化钠体系中分配的实验研究。阐明稀土元素不仅在沉积岩建造中的行为，而且在水生地球环境中的行为也是第一步。

We have installed an ICP-AES spectrometer (Seiko SPS-1500R) and established REE plus Y determinations in various types of sedimentary rocks. We have applied our ICP-AES method to determining REE and Y in limestones, dolostones, metamorphic rocks, Precambrian iron ores, and deep-sea ferromanganese nodules. We focused on the chemical classification of carbonate rocks in the tectonic belts in Japanese Islands from REE and Y analyzes. The three types of (1) coral reef-type, (2) continental margin-type, and (3) deep-see type are distinguished. Their geological environments of carbonate rock formations inferred from our geochemical data are in good agreements with previous sedimentological and geological analyzes.We also made an important theoretical study of "Tetrad effect", which must be an important basis to understand REE behaviors in sediment-water systems in low temperatures. From this viewpoint, experimental study on partitioning of REE and Y in the system of FE-Mn hydroxide and NaCl solution have been initiated. It is the first step to elucidate the REE behaviors not only in sedimentary rock formations but also in aquatic earth's environments.