台灣北部發現頭城金面山鉛鋅礦之初步研究

北宜高速公路坪林隧道導坑發現的金面山鉛鋅礦，礦體以礦脈侵入於漸新世四稜砂岩及其硬頁岩互層中。礦脈內含有方鉛礦、閃鋅礦、黃鐵礦、黃銅礦與磁黃鐵礦等金屬礦物，非金屬礦物則有方解石、石英、綠泥石和螢石等。礦石微量元素分析顯示有鉛、鋅、銀、鎘及汞之明顯異常。石英脈液包體具有液、氣兩相及含液體CO_2之三相液包體。前者的均一溫度介於210°C至270°C之間，鹽度為3.7至9.7 wt%NaCl eq.；後者的均一溫度較高，為237°C至339°C，而鹽度則較低為0.4至4.1 wt%NaCl eq.。上述結果顯示在熱液演化的過程中壓力曾急劇降低，並產生沸騰作用。金面山礦床生成之大地構造背景與金瓜石金銅礦床類似，可能均與島弧安山岩的入侵有關。

關鍵字

方鉛礦；閃鋅礦；螢石；液包體；均一溫度

並列摘要

Sulfide-containing veins, injected in the Oligocene Szeleng Sandstone and intercalated argillite beds, are discovered in the prospective tunnel of Taipei-Ilan expressway. Galena, sphalerite, pyrite, pyrrhotite, chalcopyrite, quartz, calcite, chlorite, and fluorite are found in the veins. Two -phase inclusions with liquid + vapor and three-phase inclusions with liquid + vapor + Iiquid-CO_2 are found in quartz veins. The former may be homogenized between 210°-270°C with salinities varying from 3.7 to 9.7 wt% NaCl eq., while the latter may be homogenized between 237°-339°C with salinities ranging from 0.4 to 4. 1wt% NaCI eq. The results of fluid inclusion analysis indicate the loss of CO_2 and CH_4 (?)during fluid vaporization. The results of preliminary mineralogical and chemical analyses indicate this deposit may be related to an underneath deep-seated igneous body, with a geotectonic background similar to the nearby Chinkuashih gold-copper deposits.

並列關鍵字

Galena ； Sphalerite ； Fluorite ； Fluid inclusions ； Homogenization temperature

國際替代計量

台灣北部發現頭城金面山鉛鋅礦之初步研究

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