| LA-ICP-MS原位分析白钨矿稀土元素 |
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| 引用本文： | 郝宇杰,商青青,任云生,刘小禾,陈聪.LA-ICP-MS原位分析白钨矿稀土元素[J].吉林大学学报(地球科学版),2020,50(4):1029-1041. |
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| 作者姓名： | 郝宇杰 商青青 任云生 刘小禾 陈聪 |
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| 作者单位： | 1. 吉林大学地球科学学院, 长春 130061;2. 自然资源部东北亚矿产资源评价重点实验室, 长春 130061;3. 防灾科技学院, 北京 101601;4. 中国地质调查局沈阳地质调查中心, 沈阳 110034 |
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| 基金项目： | 国家自然科学基金项目（41802078）；国家重点基础研究发展计划项目（2017YFC0601304）；自然资源部东北亚矿产资源评价重点实验室自主基金项目（DBY-ZZ-18-05） |
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| 摘 要： | 白钨矿是各类矿床中较为常见的副矿物，通过分析白钨矿的稀土元素质量分数及其标准化配分模式图，可为矿床成矿流体特征及演化提供重要的判别依据。本文对东北地区羊鼻山矽卡岩型矿床和杨金沟热液脉型矿床两个典型钨矿床的白钨矿样品中的稀土元素进行了激光剥蚀-电感耦合等离子体质谱（LA-ICP-MS）原位分析。其中：羊鼻山矽卡岩型矿床白钨矿LA-ICP-MS分析方法所获得的稀土元素配分曲线模式与前人用传统的溶液-ICP-MS分析方法所获得的结果完全吻合，表明采用剥蚀束斑44 μm和剥蚀频率7 Hz的193 nm ArF激光器，NIST 610作外部标样，Ca作内标元素，对基体效应影响最小，所获数据可靠，方法可行；而杨金沟热液脉型矿床白钨矿溶液-ICP-MS分析方法与LA-ICP-MS分析法所获得结果既具有相似性又具有差异性。原因在于羊鼻山白钨矿的成因类型为矽卡岩型、粒度较小且形成时间短，因此不同矿物颗粒间、同一矿物不同部位间稀土元素的配分模式一致；而杨金沟白钨矿的成因类型属于热液脉型、粒度较大、沉淀结晶时间长，因此同一矿物不同部位的稀土元素的配分模式因成矿流体早晚阶段不同而不同。基于以上对比研究发现，无论是在取样和测试过程方面，还是数据准确度方面，相比传统溶液-ICP-MS分析法，LA-ICP-MS原位分析法均具有明显的优势，主要表现在样品形式简单、粒度和质量分数要求低、测试周期短、费用低且结果精确度高；同时其可对不同成矿阶段或白钨矿不同部位成分进行精细测定，从而得出不同成矿阶段或白钨矿不同部位的稀土元素质量分数，以及在更高的空间分辨率下获得更详细准确的数据信息。此外，对白钨矿（尤其是无明显环带者）进行LA-ICP-MS原位分析时，既可采用电子探针微量分析（EPMA）准确测定Ca的质量分数，也可直接采用标准化学式计算Ca的质量分数，分析所得数据同样可以获得合理的地质解释。
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| 关 键 词： | 白钨矿 稀土元素 LA-ICP-MS 羊鼻山矽卡岩型矿床 杨金沟热液脉型矿床 |
| 收稿时间： | 2019-05-16 |
In Situ Analysis of Rare Earth Element Composition of Scheelite by LA-ICP-MS |
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| Hao Yujie,Shang Qingqing,Ren Yunsheng,Liu Xiaohe,Chen Cong.In Situ Analysis of Rare Earth Element Composition of Scheelite by LA-ICP-MS[J].Journal of Jilin Unviersity:Earth Science Edition,2020,50(4):1029-1041. |
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| Authors: | Hao Yujie Shang Qingqing Ren Yunsheng Liu Xiaohe Chen Cong |
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| Institution: | 1. College of Earth Sciences, Jilin University, Changchun 130061, China;2. Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Natural Resources, Changchun 130061, China;3. Institute of Disaster Prevention, Beijing 101601, China;4. Shenyang Center, China Geological Survey, Shenyang 110034, China |
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| Abstract: | Scheelite is a common accessory mineral in all kinds of deposits. The analysis of its rare earth element (REE) and the standardized distribution patterns can provide important discrimination basis for the evolution of ore-forming fluids. Laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) in situ analysis of REE in scheelite was conducted by taking the samples from the two typical deposits in Northeast China, Yangjingou hydrothermal vein deposit and Yangbishan Skarn deposit. The REE distribution curves obtained by LA-ICP-MS of Yangbishan scheelite is completely consistent with the results obtained by the traditional solution-ICP-MS analysis, which show that using 193 nm ArF laser with denudation frequency of 7 Hz and denudation spot of 44 μm, the NIST 610 as the external standard and Ca as the internal standard element, the method is proved to be feasible with the least effective matrix and the reliable obtained data. The results of Yangjingou scheelite solution-ICP-MS and LA-ICP-MS analysis have similarities and differences, while the REE distribution patterns in different mineral particles and different parts of the same mineral of Yangbishan scheelite is consistent. The result is that Yangbishan scheelite is of skarn-type with small size, and short-term formation; while Yangbishan scheelite is of hydrothermal vein type with large grain size, and long-term precipitation and crystallization. Based on the above comparative study, the LA-ICP-MS in situ analysis method has obvious advantages over traditional solution-ICP-MS analysis method, in aspect of sampling, testing process, and data accuracy. The advantages mainly display in that the simple sample form, low requirements in particle size and content, short test period, low cost, and high precision results, at the same time the contents of REE are obtained under the fine determination for different ore-forming stages or in a different part of scheelite, more detailed and accurate data information can be obtained at a higher spatial resolution. In addition, in the process of LA-ICP-MS in situ analysis of scheelite (especially those without obvious zonation), the content of Ca can be accurately determined by electron probe microanalysis (EPMA) or directly calculated by standard chemical formula. The data obtained from the analysis also can be reasonably geologically interpreted. |
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| Keywords: | the scheelite rare-earth element LA-ICP-MS Yangbishan Skarn deposit Yangjingou hydrothermal vein deposit |
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