Deep Meteoric Water Circulation and Magmatic Fluid Discharge at an Active Volcano

通过对温泉水和富马尔蒸汽冷凝物的氢、氧同位素研究，证明了日本九州久州岩山火山深部循环地热水存在明显的地下沸腾。(1)单级和连续蒸汽分离导致残液的氯和同位素含量相差很大。由于高温下的相分离，温泉中的氚含量高于补给水，观测到的氧同位素漂移的一部分可能是由于沸腾以及水-岩反应。在温泉水中观察到的最高氯、氧-18和氘含量被认为是在其临界点深层热水单级蒸汽分离时浅层沸腾的结果。较低的氯、氧-18和氘含量可能是由于热水的多级蒸汽分离下的沸腾，加上大气水的稀释。(2)因此…。此外，我们还提出，在通过火山的水文循环过程中，部分大气水被加热到水的临界点，形成单相层。富马酸凝析油的线性DeltaD-Delta^^&lt；18&gt；O、DeltaD-Cl和Delta^&lt；18&gt；O-Cl关系似乎是火山深处岩浆蒸汽和大气水来源的超临界蒸汽混合的结果。(3)富马酸凝析油中的氚含量表明，大气降水在蒸汽区的停留时间很短(约6年)，而在温泉水中的氚含量对应于液态区很长的停留时间，超过100年。因此，富马酸的排泄物被认为是来自火山中含有蒸汽主控带的主水循环系统，温泉的排放一定是来自蒸汽主控系统周围的液态水循环子系统。(4)高温溶液中硫的水解可能是温泉水中强硫酸形成的可能机制。通过硬石膏-水体系的水热实验，利用其主要化学成分研制了一种新型的强酸性温泉水地热测温仪。较少

Significant subsurface boiling of the deep circulating geothermal waters in Kuju-Iwoyama Volcano, Kyushu, Japan, was demonstrated by the hydrogen and oxygen isotopic study of hot spring waters and fumarolic steam condensates.(1) Single-stage and continuous steam separations result in greatly different chloride and isotope contents of remaining liquid. Because of phase separation at high temperatures, deuterium contents of hot spring arehigher than those recharge waters, and part of the observed oxygen isotope shift may be due to boiling as well as water-rock reactions. The highest contents of chloride, oxygen-18 and deuterium observed in hot spring waters are considered to have resulted from boiling at shallow levels under single-stage steam separation of deep thermal water at its critical point. The lower contents of chloride, oxygen-18 and deuterium may have resulted from boiling under multi-stage steam separation of thermal waters, coupled with dilution with meteoric waters.(2) Thus … More , we proposed that part of meteoric water is heated to the critical point of water during a hydrologic cycle through the volcano, forming a single-phase seam. The linear deltaD-delta^<18>O,deltaD-Cl, and delta^<18>O-Cl relationships for fumarolic condensates appear to have resulted from mixing at depths of the volcano between a magmatic steam and the super-critical steam of meteoric water origin.(3) The tritium contents in fumarolic condensates suggest a short residence time (within about 6 years) of meteoric water circulating in the steam region, while those in hot spring waters are corresponded to a very long residence time over 100 years for the liquid region. The fumarolic discarge, therefore, is considered to be from the main water circulation system containing a vapor-dominated zone in the volcano and the hot spring discharge must be from the subsystem of liquid water circulation surrounding the vapor-dominated system.(4) A sulfur hydrolysis in high temperature solution may occur as a possible mechanism of the formation of strongly sulfuric acid in the hot spring water. The new geothermometer for strongly acidic hot spring water by using its main chemical composition was developed by hydrothermal experiments of anhydrite-water system. Less