| 焦家式金矿水-岩交换作用——成矿流体氢氧同位素组成研究 |
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| 引用本文：.1994.Water-rock exchange in the Jiaojia type gold deposit: a study of hydrogen and oxygen isotopic composition of ore-forming fluids[J].Mineral Deposits,13(3):193~200 |
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| 基金项目:地质行业基金资助项目(89042) |
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| 中文摘要:焦家式金矿位于胶东半岛西北部，矿体赋存于花岗片麻岩-花岗闪长岩类岩石断裂带内，呈破碎黄铁绢英岩化浸染状矿石。矿体中均伴有富含金的成矿前、后中基性脉岩。成矿作用包括乳白色块状黄铁矿石英和（或）伟晶石英脉阶段、含金硫化物石英阶段和方解石石英阶段。三个阶段石英δ18O值平均为12.4‰、13.2‰和14.4‰。计算的石英δ18OH2O值平均分别为4.7‰、3.5‰和3.5‰。三个阶段石英流体包裹体水δ18OH2O值平均分别为-73‰、-80‰和-92‰。经反演计算，提出成矿流体是中生代大气降水(δ18O=-15.5‰，δD=-115‰)与5km以下深部中基性岩在350～400℃时，有效W/R比值从0.01至0.05之间交换作用形成。 |
| 中文关键词:焦家式金矿 水-岩交换 氢氧同位素 缓冲开放体系 |
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| Water-rock exchange in the Jiaojia type gold deposit: a study of hydrogen and oxygen isotopic composition of ore-forming fluids |
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| Abstract:The Jiaojia type gold deposit of eastern Shandong, characterized by disseminated ores, occurs in the Linglong granite or in the fractural shatter zone within the metamorphic rock of Jiaodong Group. There are three stages of mjneralization:Ⅰ-quartz small amounts of sulfides(280℃±); Ⅱ-quartz+sulfides(2500℃±); Ⅲ-calcite+quartz(220 ℃). Phyllic alteration is most intense and has much to do With gold mineralization. δ18O values of quartz are averagely 12.1±1‰ (12)for StageⅠ, 12.9±1.3‰ (19) for StageⅡand 14.4±2.0‰ (8) for Stage Ⅲ,whereasδ18OH2O values of fluid inclusions in quartz are -73±8‰ (5), -80±8‰ (9) and -97±8‰ (3) respectively. From StageⅠto Stage Ⅲ, the calculatedδ18OH2O values slightly decrease, whereas theδDH2O values decrease quite obviously, suggesting that the W/R ratio was relatively low at the time of water-rock exchange of tile hydrothermal solution but became higher towards the late stage. Supposing the temperature at depth was higher than 350℃ during the formation of the hydrothermal solution. It can be known from calculation that the ore-forming fluids were formed through the exchange between meteoric water (δ18O=-15‰, δD=-110‰) and basic rock (δ18O=-7.5‰, δD=-0‰)at W/R=0.01±. In fact, there are large quantities of basic dikes distributed in the Jiaojia type gold deposit. |
| keywords:Jiaojia type gold deposit, water-rock exchange, hydrogen and Oxygen isotopes, buffering open system |
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