磁铁矿LA-ICP-MS分析在矿床成因研究中的应用

发布时间：2018-03-20 00:11

本文选题：微量元素　切入点：磁铁矿　出处：《地球科学进展》2017年03期 　论文类型：期刊论文

【摘要】：激光剥蚀电感耦合等离子体质谱(LA-ICP-MS),由于其原位、实时、低检测限、高空间分辨率等优点,在矿物原位微量元素分析方面具有独特的优势。磁铁矿作为多种矿床和岩石中的常见矿物,其化学组成一直是国内外学者关注的焦点。而大量的研究表明,在磁铁矿LA-ICP-MS分析过程中,基体效应不明显,一般采用富铁硅酸盐玻璃作为标样,就能够取得较为准确的结果。因此近年来磁铁矿原位微量元素研究进展迅速,并在反演成岩成矿条件、辅助判别矿床类型和间接指导找矿勘探等方面显示出广泛的应用前景。通过总结25个不同类型岩浆和热液矿床中磁铁矿微量元素数据,与前人在矿床类型判别上的研究进行了一定的对比,发现常用的磁铁矿判别图解可以用来区分多种不同类型的矿床,但是已经划分出的分类边界可能需要进一步细化和严格验证,并且事先仔细的岩相学观察是数据解释的重要基础。另外,通过磁铁矿微量元素分配对岩浆和热液过程一系列复杂物理化学条件(熔/流体成分、温度、冷却速率、压力、氧逸度、硫逸度和二氧化硅活度等)的响应进行了一定探讨。在岩浆阶段,磁铁矿成分与熔体组成及分异演化密切相关;而热液阶段,流体性质的变化也会显著改变磁铁矿的化学成分。并且后期流体的改造或者磁铁矿的亚固相再平衡作用会对磁铁矿的成因鉴别产生严重干扰。综述了近年来LA-ICP-MS在磁铁矿微量元素分析方面的发展以及在矿床学领域的重要应用,以期对成矿作用和成矿过程研究提供新的思路和方向。
[Abstract]:Laser denudation inductively coupled plasma mass spectrometry (LA-ICP-MS) has the advantages of in-situ, real-time, low detection limit and high spatial resolution. As a common mineral in many kinds of deposits and rocks, the chemical composition of magnetite has always been the focus of attention of scholars at home and abroad. In the process of LA-ICP-MS analysis of magnetite, the matrix effect is not obvious, so it is possible to obtain more accurate results by using ferrosilicate glass as standard sample. Therefore, in recent years, the research on trace elements in situ of magnetite has made rapid progress. It also shows a broad application prospect in inversion of diagenetic and metallogenic conditions, auxiliary discrimination of ore deposit types and indirect guidance for prospecting and exploration. The data of trace elements of magnetite in 25 different types of magma and hydrothermal deposits are summarized. Compared with the previous researches on ore deposit type discrimination, it is found that the commonly used magnetite discriminant diagram can be used to distinguish many different types of deposits. But the classified boundaries that have been delineated may need further refinement and strict verification, and careful petrographic observation in advance is an important basis for data interpretation. A series of complex physical and chemical conditions (melting / fluid composition, temperature, cooling rate, pressure, oxygen fugacity) for magmatic and hydrothermal processes through the distribution of trace elements in magnetite, In the magmatic stage, the composition of magnetite is closely related to the composition and evolution of the melt, while in the hydrothermal stage, the composition of magnetite is closely related to the evolution of melt composition and differentiation, while in hydrothermal stage, the composition of magnetite is closely related to the composition and evolution of the melt. The chemical composition of magnetite will also be significantly changed by the change of fluid properties, and the alteration of fluid or the rebalancing of subsolid phase of magnetite will seriously interfere with the genetic identification of magnetite in recent years. The development of trace element analysis of magnetite and its important application in the field of ore deposit, It is expected to provide new ideas and directions for the study of metallogeny and metallogenic process.
【作者单位】：中国科学院地质与地球物理研究所矿产资源研究重点实验室;中国科学院大学;
【基金】：国家自然科学基金面上项目“内蒙古毕力赫单金斑岩型矿床成矿作用研究”(编号:41572073)资助~~
【分类号】：P575;P611

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