| 江西永平铜矿矽卡岩矿物特征及其地质意义 |
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| 引用本文： | 田明君,李永刚,万浩章,张宇,高婷婷.江西永平铜矿矽卡岩矿物特征及其地质意义[J].岩石学报,2014,30(12):3741-3758. |
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| 作者姓名： | 田明君 李永刚 万浩章 张宇 高婷婷 |
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| 作者单位： | 中国科学院地质与地球物理研究所, 北京 100029;中国科学院大学, 北京 100049;中国科学院地质与地球物理研究所, 北京 100029;江西地矿局九一二大队, 鹰潭 35000;中国科学院地质与地球物理研究所, 北京 100029;中国科学院大学, 北京 100049;中国科学院地质与地球物理研究所, 北京 100029;中国科学院大学, 北京 100049 |
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| 基金项目： | 本文受大中型企业委托项目(Y118305183)资助. |
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| 摘 要： | 永平铜矿含矿岩石主要为绿帘石透辉石石榴石矽卡岩,这种岩石类型是与斑岩体有关的矽卡岩铜矿的典型赋矿岩石。通过对这一主要赋矿矽卡岩的研究,我们发现石榴石生长分为两个阶段:(1)早期石榴石:主要分布在石榴石颗粒核部,XAdr=1.0,主要以钙铁榴石为主,说明早期流体中可能含有较多的铁,是在较氧化条件下形成的;(2)晚期石榴石,沿石榴石裂隙重新成核或者在靠近流体通道的早期石榴石表面生长,出现震荡环带,XAdr=0.46~0.99,为钙铁-钙铝石榴石系列。石榴石发生变化的期间也形成新的矿物,如绿帘石、萤石、方解石和石英等。共存石榴石和绿帘石矿物中存在Fe3+-Al3+之间的替代,说明流体的氧逸度、组分浓度或aFe3+/aAl3+可能发生了变化。金属矿物也可能是在这一阶段形成的。永平铜矿矽卡岩从接触带到大理岩空间上有分带现象。从岩体到围岩的变化趋势为:石榴石含量减少,颜色存在红棕色-棕色-棕绿色-黄绿色-浅黄色的变化趋势;矿石品位降低,这与石榴石中Al2O3含量的变化较一致。我们认为这种变化是含矿热液对早期矽卡岩进行再交代改造的结果,表现为石榴石和绿帘石中Fe3+-Al3+含量的变化,并将Cu等金属沉淀下来。根据矽卡岩矿物的这些特征,在矿床勘探时,可依据棕色石榴石来追踪主矿体的位置。
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| 关 键 词： | 永平铜矿 石榴石 绿帘透辉石榴石矽卡岩 矿床分带 江西 |
| 收稿时间： | 2014/2/13 0:00:00 |
| 修稿时间： | 2014/10/17 0:00:00 |
Characteristics of skarn minerals in Yongping copper deposit, Jiangxi Province, and geological significances |
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| TIAN MingJun,LI YongGang,WAN HaoZhang,ZHANG Yu and GAO TingTing.Characteristics of skarn minerals in Yongping copper deposit, Jiangxi Province, and geological significances[J].Acta Petrologica Sinica,2014,30(12):3741-3758. |
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| Authors: | TIAN MingJun LI YongGang WAN HaoZhang ZHANG Yu and GAO TingTing |
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| Institution: | Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;University of Chinese Academy of Sciences, Beijing 100049, China;Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;912 Geological Party of JBEDGMR, Yintan 35000, China;Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;University of Chinese Academy of Sciences, Beijing 100049, China;Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The main ore skarn in Yongping copper deposit is epidote diopside garnet skarn, which is typical ore-bearing skarn related to porphyry intrusion. On the basis of study on the main ore-bearing garnet skarns, we divided the garnets into two generations: (1) an early generation of garnets, distributing at the core of garnet crystal, XAdr=1.0, and mainly of andradite, indicating an oxidized state; (2) a late generation of garnets, which is generally nucleated along garnet cracks, or on the surface of the early garnets near the fluid channels, with oscillatory zonation, and belongs to andradite-grossularite series with XAdr=0.46~0.99. Other minerals formed during garnet replacement process include epidote, fluorite, calcite, quartz and so on. Partitioning of Fe3+-Al3+ among coexisting garnet and epidote solid solutions may reflect variations of oxygen fugacity, component concentration and/or aFe3+/aAl3+. Metal minerals would also precipitate from this period. Skarn in the Yongping deposits has a general spatial zonation-within the contact zone between skarn and marble. From the pluton to wall rock, the content of garnet decreases, and its color changes from red-brown, brown, brown-green, yellow-green, to light-yellow. Moreover, the ore grade decreases coincidently with the Al2O3 content of garnet. We consider that these changes are result of metasomatism between ore-bearing hydrothermal fluid and early skarns, represented by Fe3+-Al3+ substitution in garnet and epidote. This trend of skarn minerals in ore deposits may be used as a guide for deposits exploration. |
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| Keywords: | Yongping copper deposit Garnet Epidote diopside garnet skarn Mineral zonation Jiangxi Province |
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