Change in color of the hot spring deposits at the Chinoike-Jigoku hot pool, Beppu geothermal field
Change in color of the hot spring deposits at the Chinoike-Jigoku hot pool, Beppu geothermal field
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别府地热田茅池地狱温泉的温泉沉积物颜色变化
DOI：
10.1016/s0375-6505(01)00038-4
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Y. Yusa
中科院分区：
文献类型：
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作者：
Kazuthoshi Oue;S. Ohsawa;Y. Yusa
位于日本九州中部别府地热田的池池池，由于池底沉积了赤铁矿(Fe2O3)，呈现出血红色。用色度计测量了1990年10月1日、1995年3月27日和1996年3月6日收集的沉积物的颜色。结果表明，与1990年相比，1995年和1996年的红色沉积物变黄。X-射线衍射谱和沉积物化学成分分析表明，池池水变色是由于黄钾铁矾石[KFe3(SO4)2(OH)6]含量增加所致。据硬石膏化学地温计估计，在过去的25年里，Chinoike-Jigoku温池下地下热水的温度从200摄氏度下降到150摄氏度。池池县排出的温泉水中Na、Cl浓度降低，而SO4浓度升高。地下温度和溶解离子浓度的时间变化表明，在过去的25年里，形成奇诺池-地狱岛热水的高温中性Na-Cl型水和相对低温、酸性的H-SO4型水的混合比例发生了变化。对黄钾铁矾矿稳定性的水热研究证实，矿床中黄钾铁矾矿含量的增加是由于Chinoike-Jigoku水池下混合热水的降温引起的，这是由于较冷的H-SO4水型对热混合作用的贡献增加。
The Chinoike-Jigoku hot pool in Beppu geothermal field, Central Kyushu, Japan, displays a blood-red color due to the hematite (Fe2O3) deposited at the bottom of the pool. The colors of the deposits collected on 1 October 1990, on 27 March 1995, and on 6 March 1996 were measured with a colorimeter. The results show that the red deposits became yellower in 1995 and 1996 than they were in 1990. X-ray diffraction (XRD) patterns and chemical compositions of the deposits indicate that the discoloration of the Chinoike-Jigoku pool water is caused by an increase in the content of jarosite [KFe3(SO4)2(OH)6]. The temperature of the subsurface thermal water beneath the Chinoike-Jigoku hot pool, as estimated by the anhydrite chemical geothermometer, has declined from 200 to 150 °C over the past 25 years. The Na and Cl concentrations of the hot spring water discharging from Chinoike-Jigoku have decreased, while the SO4concentration has increased. The temporal variations in subsurface temperature and dissolved ion concentrations suggest that the mixing ratio between the high–temperature, neutral Na–Cl type water and the relatively low-temperature, acid H–SO4type water that form the thermal water of Chinoike–Jigoku has changed over the last 25 years. Hydrothermal studies of jarosite stability have confirmed that the increase in jarosite content in the deposits was caused by a temperature drop of the mixed thermal water beneath Chinoike-Jigoku pool, due to an increase in the contribution of the cooler H–SO4water type to the thermal mixture.