本研究藉由不同高程且連續性的採樣，以岩象學、X光繞射分析及能量分散式X光螢光分析等方式試圖了解紗帽山各種火山熔岩的特徵，並且提出紗帽山火山穹丘的來源及其形成過程。
紗帽山總共有4種型態火山熔岩，分別為白色粗面石英安山岩、灰色石英安山岩、紫紅色及灰色玄武質安山岩。其中以紫紅色玄武質安山岩分布範圍最廣。就地球化學分析資料顯示4種型態火山熔岩的來源一致。最後，本研究推論紗帽山火山穹丘形成有四個階段。第一階段為白色粗面石英安山岩形成，礦物顆粒可達15 um-80 um，且石英顆粒呈現六角形。第二階段為灰色石英安山岩形成且石英顆粒呈現港灣狀，此階段與第一階段的白色粗面石英安山岩之間形成尖形構造的接觸形狀。第一階段和第二階段為大屯火山群大規模噴發前的產物。第三階段為紫紅色玄武質安山岩形成，此類岩石為大屯火山群大規模噴發的產物。第四階段為灰色玄武質安山岩的形成，此階段火山熔岩僅分布於紗帽山山頂。
This study systematically collects lava samples along main road and hiking trail of Shamaoshan, and analyzes the samples by petrography, x-ray diffraction, and energy dispersive x-ray fluorescence spectrometer. Finally, this study aims to understand the characteristics of lava flow, source and process of lava dome on the Shamaoshan.
In the Shamaoshan, the lava flow has four types that are white trachydacite, gray dacite, red purple basaltic andesite and gray basaltic andesite, respectively, and the red purple basaltic andesite is widely distribution on the mountain. Based on the geochemistry data, four lava flow present same magma source. Finally, this study infers that four stages construct lava dome of the Shamaoshan. First stage is white trachydacite that grain sizes of minerals are around 15 um-80 um, and quartz grains present hexagonal. Second stage forms gray dacite and quartz grains show embay texture, and they display cuspate structure between gray dacite and white trachydacite. Third stage is red purple basaltic andesite which is main eruption of the Tatun Volcano Group. The gray basaltic andesite displays on the fourth stage of lava dome of Shamaoshan.
