| 赵富远.贵州盘县架底金矿稀土元素和同位素特征及成矿物质来源探讨[J].地质与勘探,2018,54(3):465-478 |
| 贵州盘县架底金矿稀土元素和同位素特征及成矿物质来源探讨 |
| REE and isotopic features of the Jiadi gold deposit in Panxian county of Guizhou Province and its ore-forming material source |
| 投稿时间：2017-11-20 修订日期：2018-03-20 |
| DOI：10.12134/j.dzykt.2018.03.003 |
| 中文关键词: 玄武岩 稀土元素 同位素 成矿物质来源 架底金矿 盘县 贵州 |
| 英文关键词: basalt,REE, isotope, ore-forming materialsource , Jiadi gold deposit, Panxian county, Guizhou |
| 基金项目:贵州省地质矿产勘查开发局地质科研项目（黔地矿科合( 2014 )06号）和贵州省地质矿产勘查开发局地质科研项目（黔地矿科合( 2017 )12号）联合资助 |
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| 中文摘要: |
| 架底金矿位于贵州西部峨眉山玄武岩分布区，首次在该区发现产于峨眉山玄武岩组第二段中部的以蚀变火山角砾岩为主的层间破碎带中的原生金矿体，赋矿围岩主要为玄武岩和凝灰岩，容矿岩石主要为蚀变火山角砾岩，其下层矿产于中二叠统茅口组与上二叠统峨眉山玄武岩组间的不整合界面附近的构造蚀变体中。本文通过稀土元素和氢、氧、硫同位素来探讨架底金矿体与围岩的关系及成矿物质来源，矿体ΣREE值的变化范围为151.11×10-6～321.52×10-6，平均值为221.21×10-6，明显小于围岩，LREE/HREE值的变化范围为2.9～8.53，平均值为6.84，LaN/YbN值的变化范围为5.55～12.33，平均值为9.13，略小于围岩。除了个别矿体样品的δEu值小于1，其他样品基本远大于1，暗示与成矿作用相关的流体可能经历过高温和还原的深部环境，矿体继承了围岩稀土配分曲线的部分特征，说明部分成矿物质可能来自围岩。辉锑矿δ34S值的变化范围为-0.80‰～-0.90‰，极差为0.1‰，平均值为-0.85‰，数据变化范围较窄，均一化程度较高，主要在0‰附近，指示成矿相关矿物辉锑矿的硫可能主要来源于深部。石英氢氧同位素的δDV-SMOW值的变化范围为-70～-56‰，δ18OV-SMOW值的变化范围为23.20～23.60‰，按200℃作为本区金矿的成矿温度，根据石英-水在自然体系中的分馏方程式，可计算得出石英中与之相平衡的水的δ18OH2O值变化范围为11.49～11.89‰，投图的结果说明与成矿作用相关的流体均落在岩浆水和变质水之间，显示两者相混合的特征，但研究区基本没有变质作用的发生，并且4件石英样品的δDV-SMOW均落在正常岩浆水范围内，指示架底金矿中成矿流体来源具有岩浆水的特点。 |
| 英文摘要: |
| The Jiadi gold deposit is located in the Mount Emei basalt distribution area of western Guizhou Province. The work for the first time discovered primary gold ore bodies in the middle of second member in Mount Emei basalt formation, which occur in interlayer fracture zone dominated by altered volcanic breccia. The ore-hosted surrounding rocks are mainly basalt and tuff, and ore-hosted rocks are mainly altered volcanic breccia. The underlying ores are hosted in structural alteration rocks near the unconformity between the Middle Permian Maokou Formation and the Upper Permian Mount Emei basalt formation. This work discussed the relationship between the Jiadi gold ore bodies and surrounding rocks and also the ore-forming material source through REE and hydrogen-oxygen-sulfur isotopes. The ΣREE values of the orebodies range from 151.11×10-6 to 321.52×10-6, the average=221.21×10-6, much smaller than that of surrounding rocks, LREE/HREE=2.9~8.53, the average=6.84, LaN/YbN=5.55~12.33, the average=9.13, slightly smaller than surrounding rocks. Except for some individual sample with δEu <1, other samples generally have δEu >1, implying the ore-forming fluid may be mainly come from the deep through high temperature and reducing environment. The ore bodies inherit part of the rare earth distribution curve of surrounding rocks, which indicates that part of the ore-forming material may be come from surrounding rocks. The δ34S values of stibnite lie in -0.80‰~-0.90‰, with extreme difference range of 0.1‰ and an average value of -0.85‰; the range of data changes is narrow, and the degree of homogenization is high, mostly around 0‰, indicating that the sulfur of ore-related mineral stibnite may be mainly come from the deep. The quartz hydrogen and oxygen isotope show δDV-SMOW=-70‰~-56‰ and δ18OV-SMOW=23.20‰~23.60‰. Taking 200℃ as the metallogenic temperature of gold deposits in this area, according to the quartz-water fractionation equations, we calculated the δ18OH2O of balance H2O to be 11.49‰~11.89‰ in quartz. The plotted diagram shows that the ore-forming fluid is located between magmatic hydrothermal and metamorphic water, indicative of a mixed characteristic. However, there is no metamorphism occurred in this region, and four samples of quartz's δDV-SMOW all fall in normal magma water, which implies that the ore-forming fluid in the Jiadi gold deposit has magma water characteristics. |
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