| 摘要: | 在過去數十年以來大屯火山群中性溫泉的形成一直被關注，因為，在開發地熱資源時，中性溫泉對於管線的腐蝕程度較低。本研究為首篇以中性溫泉區的岩芯作為研究主題的文章，透過岩象學、X光繞射分析法及能量分散式螢光光譜分析法闡述大屯火山群中性溫泉區水與岩石間的反應關係。
本研究結果顯示，火山熔岩與火山碎屑岩之間的交界處為熱液蝕變最強烈的區域。中性溫泉區的蝕變礦物有方解石、蒙脫石、方矽石及氧化鐵-褐鐵礦，因為岩芯中出現大量氧化鐵-褐鐵礦沉澱，因此判斷有大量的地表水補注使得此地區的溫泉呈現中性。最後，本研究解釋大屯火山群中性溫泉區的水與岩石間之反應關係。第一階段為新鮮的淺灰色安山岩。第二階段岩石呈現中灰色且具有孔洞，以及方解石取代岩石中部分斜長石和石基。第三階段岩石呈現深灰色有方矽石，氧化鐵-褐鐵礦沉澱於岩石孔洞中，而蒙脫石為斜長石熱液蝕變下的產物。第四階段岩石呈現黃褐色有方矽石及蒙脫石，以及大量的氧化鐵-褐鐵礦沉澱於岩石孔洞之中。
The neutral thermal water of Tatun Volcano Group has seen increased attention in the last several decades, due to the neutral thermal water causes corrosion of pipeline less than acidic thermal water during developing geothermal resource. The firstly research focused on the characteristics of core of neutral thermal water area, and applied the petrography, X-ray diffraction and energy dispersive X-ray fluorescence to interpret water-rock interaction in the neutral thermal water area of Tatun Volcano Group.
This study shown that the significant alteration zone was between lava and pyroclastic rocks, and existed iron oxide-limonite and montmorillonite. Furthermore, the alteration mineral had calcite and, cristobalite. Base on a lot of iron oxide-limonite, this study recognized that the neutral thermal water was caused by mixing surface water in Tatun Volcano Group. Finally, this study interpreted water-rock interaction. First stage, it was fresh rock that is gray andesite. Second stage, it was medium gray andesite with empty space, and calcite has replaced part of plagioclase and groundmass. Third stage, it was dark gray andesite, had cristobalite, with iron oxide-limonite precipitated in empty space, and montmorillonite produced from plagioclase by hydrothermal alteration. Finally, it was brown andesite, had montmorillonite and cristobalite, with a lot of iron oxide-limonite precipitated in empty space and groundmass. |
