著者

村上 浩康 佐藤 比奈子 石山 大三 石原 舜三

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.61, no.2, pp.129-137, 2011-05-25

参考文献数

23

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High-grade REE ores containing acid-resistant minerals, which are common in the Nolans Bore REE-P-U deposit, Northern Territory, Australia, were analyzed by ICP-MS after decomposition of two different preparation methods before the analyses; Li-borate-fusion in a commercial laboratory and multi-acid digestion in our organization. The result derived from multi-acid digestion method shows higher values on LREE relative to the other fusion method, yet Y and Zr showed us higher values on the fusion method. The high-grade REE ores are enriched in light-REE, especially Ce, La and Nd, with a maximum total REE value around 7 wt %. The quantitative analysis by multi-acid digestion seems highly reliable for a wide range of REE concentration when using suitable dilution ratio and digestion sequence with several types of acids which could totally dissolve acid-resistant minerals such as monazite. On the other hand, analysis by Li-borate-fusion at a commercial laboratory potentially gives lower values than that of multi-acid digestion; a given sample is extremely concentrated in light REE. It is necessary to examine the upper as well as the lower detection limits by a conventional analytical method in a commercial laboratory.

著者

佐藤 比奈子 石山 大三 水田 敏夫 松葉谷 治 村上 史一

出版者

資源地質学会

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.60, no.1, pp.15-24, 2010 (Released:2013-06-14)

参考文献数

13

被引用文献数

3

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Tamagawa hot spring is a volcanic gas-bearing hydrothermal system derived from Quaternary andesitic to dacitic magma beneath Yakeyama volcano. Thermal waters and precipitates of Tamagawa Hot Spring in 2002 and 2007 were investigated to clarify the geothermal structure of the area. Thermal waters in Tamagawa Hot Spring area are divided into three types: Cl-SO4type (Ohbuki Hot Spring: pH 1.2), SO4type (pH 1.8 to 2.9) and neutral-type (pH 6.1). Concentrations such as F, Cl, SO4, Na, K, Mg and Ca in Cl-SO4type Ohbuki thermal water are ten to several hundred-times higher than those of elements in SO4type thermal waters. The concentrations of elements in SO4 type thermal waters also varied according to changes in geothermal structures supplying steam and the flow system of groundwater and vapor in Tamagawa geothermal system from 2002 to 2007.The oxygen and hydrogen isotopic ratios of the thermal waters in the system suggest that SO4 type thermal waters are formed by heating of shallow groundwater by the steam separated from Ohbuki thermal water below Tamagawa Hot Spring area. On the other hand, the small variation of chemistry and hydrogen and oxygen isotopic ratios of Cl-SO4 type Ohbuki thermal water from 2002 to 2007 suggests that the Cl-SO4 type Ohbuki thermal water originates from a deeper part of Yakeyama Volcano. The flow rate of Cl-SO4 type Ohbuki thermal water below Tamagawa hot spring area was estimated to be 13,000 l/min.