Rhenium-Osmium geochemistry for the mantle plume and the Kuroko ore deposits formed at the time of the opening of the Japan Sea

在本研究中，对所使用的质谱计进行了改造和布置，以测量负离子束并提高其稳定性。测定了几种岩石和矿物的Re、Os含量和Os同位素组成。这些数据以及空白值表明，目前一些元素含量较高的岩石和矿物可以为地质讨论提供有用的数据，但有些岩石和矿物的这些元素含量不足以进行分析。要降低空白值，需要付出很大努力。尽管对分析方法的研究还不够完善，但还是可以从浓度相对较高的物质中获得一些有用的信息。在本研究中，发现黑子矿床的初始Os同位素比值约为海水的值，表明黑子矿物是从海水中沉淀出来的。此外，还测量了其他一些地质标岩和从花岗岩中分离出来的磁铁矿。

In this study, the mass-spectrometer used was reconstructed and arranged to measure negative ion beams and to improve the stability. Re and Os concentrations and Os isotopic compositions were measured for several rocks and minerals. These data as well as the blank values indicate that at present some rocks and minerals which has relatively high concentrations of these elements can provide usable data for geological discussion, but some rocks and minerals do not contain enough amounts of these elements for analyzes. Much efforts should be necessary for lowering the blank values. Despite such incomplete attainment for analytical methods, some useful information can be drawn from relatively high concentration materials. In the present study, the initial Os isotopic ratio for the Kuroko ore deposits were found to be around the values of the seawater, suggesting that the Kuroko minerals had been precipitated from the seawater. Moreover, some other geological standard rocks and magnetites separated from the granitiv rocks were measured.