The preliminary study of hydrothermal alteration of andesite at Tayukeng, Taiwan

臺灣大油坑地區安山岩熱液蝕變作用初步研究

方建能(Jiann -Neng Fang) ； 陳耀麟(Yaw-Lian Chen) ； 余國彥(Tony Yu) ； 林義傑(I-Chich Lin)

《國立臺灣博物館半年刊》 52卷2期 (1999/12) Pp. 103-111

https://doi.org/10.6532/JNTMA.199912_52(2).0009

摘要

The alteration andesite at the Tayukeng area is the main research object in this study. With systematically sampling and analyzing, we tried to understand the variation and distribution of the alteration minerals of the andesite in this area after hydrothermal alteration. Furthermore, we discussed the geothermal exploration by the quantitative analysis of Hg, Sb, As, three elemenls of the alteration andesite at Tayukeng. The experimental results indicated that the hydrothermal alteration andesite along the three sampling paths produced quartz, pyrophyllite, kaolinite, low-temperature cristobalite, and alunite five different secondary alteration mineral s. These mineral s composed three different mineral associations which showed an outward zoning from the fumarole. The mineral associations distributed inwardly from quartz+kaolinite, to quartz+alunite+pyrophyllite, and finally quartz+alunite+low-tcmperalure cristobalilc, appears. According to the analysis of the quantity of three kinds Hg, Sb, and As ofelements ofthe alteration andesite at Tayukeng. We realized that the closer to the fumarole the sampling location was, the (Hg X Sb) / As became higher. Therefore, the abnonnal phonomena of the geothermal at Tayukcng area could be indicated.

關鍵字

Taiwan ； alteration minerals ； Tayukeng ； geothermal exploration

並列摘要

本研究選擇臺灣大屯火山群的大油坑地區蝕變安山岩為研究對象，有系統的取樣分析，以瞭解此地區的安山岩經由熱液蝕變作用後，所出現的蝕變礦物種類及分布情況，並由大油坑蝕變安山岩所含汞、銻、砷含量進行此區之地熱探勘。研究結果顯示，本地區三條採樣路線的安山岩經熱液蝕變作用後，產生石英、葉蠟石、高嶺石、低溫方英石、明礬石等5種次生的蝕變礦物，呈現3個礦物群的帶狀變化;即以大油坑硫氣孔為中心，由外往內分布為：石英－高嶺石、石英－明礬石－葉蠟石、石英－明礬石－低溫方英石。由大油坑蝕變安山岩所含汞、銻、砷含量分析顯示，愈接近硫氣孔，（汞×銻）/砷數值愈大，如此可顯示出大油坑地熱異常的現象。

並列關鍵字

臺灣 ； 大油坑 ； 蝕變礦物 ； 地熱探勘