大屯火山群是著名的溫泉區且在東北季風的影響範圍，倘若要了解風化作用與熱液蝕變作用對岩石特性的影響，此地區提供了一個很好研究場所。因此本研究利用岩象學、X光繞射分析及能量散射式X射線螢光分析對於火山熔岩進行礦物組成、組織及地球化學含量進行研究，探討在風化作用與熱液蝕變作用下岩石特性的轉變。 本研究結果顯示，安山岩依據礦物組成可分出三種類型，一為含角閃石兩輝石玄武質安山岩，一為含角閃石兩輝石安山岩，一為兩輝石玄武質安山岩。本研究範圍內新鮮的火山熔岩之風化指數呈現與岩象結果一致性的變化，而風化最嚴重的安山岩其風化指數 (WIP)只有27，代表此岩石受到最強烈的風化作用及熱液蝕變作用。另外，本研究所有種類安山岩之蝕變礦物為方矽石及禾樂石。
The Tatun Volcano Group is famous area of hot spring and belongs to northeast monsoon zone that provide a well site to study the topic of influence of weathering and hydrothermal alteration on rock properties. This study applies petrology, X-ray diffraction and energy dispersive X-ray fluorescence on mineral assemblages, texture, and geochemistry of lava flow. The results show that there have three types of andesite which include two pyroxenes basaltic andesite with hornblende, two pyroxenes andesite, and two pyroxenes basaltic andesite. The weathering indices (CIA, CIW, PIA, and WIP) of fresh lava flow display consistent results, and plagioclase mostly haven’t change to alteration minerals. The WIP is 27 that indicates the rock has mostly influence by weathering and hydrothermal alteration. In addition, all kinds of andesite produce same alteration minerals which are cristobalite and halloysite.
