Chronological study on the cretaceous igneous rocks and related ore deposits by Rhenium-Osmium method

(1)由于对分析方法的改进花费了大量的时间，因此分析的样品仅限于Kuroko矿石和其他一些矿石矿物。但是，本文在分析方法方面取得了一些重要的成果，这些成果将对该领域的进一步研究做出重要贡献。购买了光子计数装置，并对计算机程序进行了改进，以获得快速和精确的测量。引入了降噪变压器和电磁屏蔽，效果良好。为了减少化学空白，已经通过反复试验作出了很大努力。Os空白成功地降低到0.2pg以下，但Re空白仍然很高（ca.17ph）。除了这种毛坯问题外，灯丝中的Re和源污染问题仍然很严重，需要进一步开发。(4)将矿物等时线方法应用于黑子矿。18.6 Ma的年龄比先前推荐的15 Ma略大。然而，这些数据并不可靠，需要进一步研究。(5)花岗岩中其他矿石硫化物矿物和铁钛矿物进行了尝试。低浓度的Re和Os阻碍了准确的分析，但进一步降低空白的努力将保留有希望的结果。

(1)Much time has been spent for improving the analytical methods, and thus, the analyzed samples were limited to the Kuroko ores and other some ore minerals. However, important aspects were obtained concerning the analytical methods, and those will much contribute to further studies in this field.(2)The photon-counting unit was purchased, and the computer programs were refined to attain speedy and precise measurements. Noise-cut transformer and electro-magnetic shield were introduced and worked effectively.(3)In order to diminish the chemical blanks, much effort has been made by repeated trials. Os blanks were successfully reduced to below 0.2pg, but Re blanks are still high (ca.17ph). In addition to such blank problem, Re in the filament and source contamination remained serious problem, and further development should be needed.(4)The mineral isochron method was applied to the Kuroko ores. The age of 18.6 Ma obtained is somewhat older than the previously recommended value of 15 Ma. However, this data is not so reliable and further study is necessary.(5)Other ore sulfide minerals and Fe-Ti minerals in granitic rocks were attempted. The low concentrations of Re and Os prohibit accurate analyses, but further efforts for lowering the blank would reserve promising results.