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以康滇地轴古元古代拉拉铁氧化物-铜-金(IOCG)矿床中不同期次萤石的稀土元素为研究对象,讨论其地球化学特征及指示意义。研究结果表明:拉拉IOCG矿床中有变质期和热液期2期萤石产出,变质期萤石分为早晚2个阶段,与铜钼矿化关系密切,形成温度较高,为同源不同阶段产物;热液期萤石与变质期不同源,为后期热事件产物。萤石整体表现出REE总量高的特征;从早期到晚期,萤石稀土总量呈逐渐减少趋势;变质期萤石是矿床中主要的REE载体之一。变质期成矿流体稀土含量较高,热液期成矿流体稀土含量较低。稀土配分模式呈LREE富集、HREE亏损的右倾型,轻重稀土分异明显,萤石的稀土配分模式受溶液体系中REE络合物稳定性的影响。变质期萤石继承了钠质火山岩的Ce、Eu异常特征,形成变质期萤石的高温变质流体具有负Ce异常且同时存在Eu2+和Eu3+;热液期萤石成矿流体具有温度低、氧逸度高的特征。Y的含量变化可能是引起本矿床萤石颜色变化的原因之一,其含量与颜色深浅呈负相关关系。
Taking the rare earth elements of fluorite from different periods in the Paleoproterozoic Lala iron oxide-copper-gold (IOCG) deposit of the Kangdian Dianhe axis as the research object, the geochemical characteristics and their significance are discussed. The results show that the Lala IOCG deposit has metamorphic stage and hydrothermal stage 2 fluorite output. The metamorphic stage fluorite is divided into two stages, sooner or later, which are closely related to the copper-molybdenum mineralization and form the higher temperature, Different stages of products; hydrothermal fluorite and the different sources of the deterioration of the late thermal events. Fluorite shows the characteristics of high total REE. From early to late stage, the total amount of fluorite rare earths decreases gradually. In the metamorphic period, fluorite is one of the main REE carriers in the deposit. In the metamorphism period, the RE ore-forming fluid has a higher RE content and a lower REE content in the hydrothermal fluid. The LREE enrichment is the pattern of RREE distribution. The right-leaning HREE depletion and the variation of light and heavy REEs are obvious. The REE complex patterns of fluorite are affected by the stability of REE complexes in the solution system. The metamorphic fluorite inherited the Ce and Eu anomalous characteristics of the sodium-bearing volcanic rocks. The metamorphic fluid of high temperature metamorphic fluorite has a negative Ce anomaly with the simultaneous presence of Eu2 + and Eu3 +. The hydrothermal fluorite mineralization fluid has the characteristics of low temperature, oxygen fugacity High characteristic. The variation of Y content may be one of the causes of fluorite color change in this deposit, and its content is negatively correlated with the color depth.