| Abstract: | 本研究首先利用岩石的岩象和蝕變礦物相組合探討大屯火山群的龍鳳谷和硫磺谷區域的岩石在氣-水-岩之間的反應之下礦物的轉變過程。
本研究結果顯示，遠離火山噴氣位置的安山岩含由普通輝石、紫蘇輝石、普通角閃石和斜長石；部份蝕變的安山岩則含有蛋白石、方矽石和少量斜長石；而近火山噴氣位置的安山岩含蛋白石、方矽石和極少量斜長石。
本研究最後綜合電子顯微鏡、X-射線繞射光譜儀和能量分散式螢光光譜儀資料結果顯示，在遠離火山氣體的岩石其岩石組織保存相當好，且樣品中的二氧化矽含量低於近火山氣體的岩石，而樣品中的氧化鋁和氧化鈣的含量高於近火山氣體的岩石。另外，從白色外觀環狀紋路岩石中發現硫含量多寡與礦物相種類成正相關，因此，本研究推測火山氣體中硫成份在蝕變過程伴演很重要的角色。
This study firstly applies the petrography and alteration mineral assemblages of rocks to study mineralogical facies transition under the gas-water-rock interaction in Longfengku and Liuhaungku of the Tatun Volcano Group (TVG).
The results showed that the andesite consists of augite, hypersthene, hornblende, plagioclase and these samples far away from fumarolest; a partial altered andesite composes of opal, cristobalite and less plagioclase; and he andesite includes opal and a little plagioclase in the closer fumaroles area. The sulfur element does not exist in samples far away from fumaroles.
In addition, the results of SEM, EDS and ED-XRF displayed that samples are well texture and lower silica content, and higher of aluminum and calcium elements of samples in the far away fumaroles area. Finally, this study infers to the sulfur component plays important role during alteration process. |
