长江中下游宁芜-庐枞火山岩盆地内产出大量铁矿床。前人对其进行了成岩成矿时代、地球化学特征及矿床成因等工作，提出了著名的“玢岩铁矿”成矿模式，并形成独特的透辉石(阳起石)-磷灰石-磁铁矿组合。目前硫同位素是研究三叠纪膏盐层与铁矿化关系的主要手段，但是由于地质过程的复杂性和硫同位素的多解性，导致对以上关系的认识不全面，因此有必要引入新的分析手段对其进行研究。钙是膏盐层和玢岩铁矿含钙矿物中的主体元素，其同位素组成在表生过程中分馏尺度大，是区分表生和岩浆过程的良好指示剂。本项目拟对长江中下游三叠纪膏盐层和陶村玢岩铁矿不同成矿阶段含钙矿物以及同一成矿阶段共生平衡的含钙矿物对进行钙同位素分析，结合硫化物和石膏原位硫同位素，以期获得成矿过程中的钙同位素信息及分馏行为，限定膏盐层在成矿过程中的贡献，为膏盐层是否参与成矿、贡献大小等提供判别指标，对揭示其成矿机制和扩大钙同位素在矿床中的应用具有重要意义。

A large number of iron deposits occur in the Ningwu-Luzong volcanic basins in the Middle-Lower Yangtze River. Many researchers have investigated diagenetic and metallogenic ages, geochemical characteristics and genesis of deposits, and they have established the famous “Porphyrite iron ore” metallogenic model, which has the unique diopside (actinolite)-apatite-magnetite assemblage. At present, the sulfur isotope is the main mean to study the relationship between the Triassic evaporite and the porphyrite iron mineralization. However, due to the complexity of geological processes and the multiplicity of sulfur isotopes, the understanding of the contribution of evaporites in the porphyrite iron ore is not comprehensive. Therefore, it is necessary to introduce a new analytical method to study it. Calcium is one of the main elements of evaporites and calcium-bearing minerals in the porphyrite iron deposit. Calcium isotopes have a large fraction scale in the supergene process, which is a good indicator to distinguish the supergene process from the magmatic process. In this project, we will determine calcium isotopic compositions of the Triassic evaporite and calcium-bearing minerals in the different metallogenic stages or symbiotic equilibrium of calcium-bearing mineral pairs in the same metallogenic stages of Taocun iron deposit in the Middle-Lower Yangtze River, combined with in situ sulfur isotope analysis of sulfides and gypsum, to obtain the calcium isotope information and fractionation behaviors in the metallogenic process, constrain the contribution of evaporites in the metallogenic process, and provide the discriminant index for the participation of evaporites in the deposit and the degree of the contribution. It is of great significance to reveal its metallogenic mechanism and expand the application of calcium isotopes in ore deposits.