Abstract Magnetite is the most important iron ore in iron oxide-apatite (IOA) deposits which represent the Cu-poor end-member of the iron oxide-copper–gold (IOCG) clan. Magnetite chemistry has been used as a petrogenetic indicator to identify the geological environment of ore formation and as a fingerprint of the source reservoir of iron. In this study, we present new textural and microanalytical EPMA and LA-ICP-MS data of magnetite from Carmen, Fresia, Mariela and El Romeral IOA deposits located in the Cretaceous Coastal Cordillera of northern Chile. We also provide a comprehensive summary and discussion of magnetite geochemistry from Andean IOAs including Los Colorados, Cerro Negro Norte, El Romeral (Chilean Iron Belt) and the Pliocene El Laco IOA deposit located in the Central Volcanic Zone of the Chilean Andes. Microtextures coupled with geochemical data were used to define and characterize the occurrence of different magnetite types. Magnetite exhibits a variety of textural features including oscillatory zoning, colloform banding, re-equilibration textures, exsolution lamellae and symplectites. The magmatic vs. hydrothermal origin of the different magnetite types and the evolution of IOA deposits can be assessed using diagrams based on compatible trace elements. However, magnetite is very susceptible to hydrothermal alteration and to both textural and compositional re-equilibration during magmatic and superimposed hydrothermal events. Based on the data presented here, we conclude that V and Ga are possibly the most reliable compatible elements in magnetite to trace ore-forming processes in the Andean IOA deposits. Magnetite chemistry reveals different conditions/events of formation for each IOA deposit ranging from high-temperature, low-oxygen fugacity (ƒO2), purely magmatic (>600 °C) conditions; to lower temperature and higher ƒO2 magmatic-hydrothermal (300–600 °C) to low-temperature hydrothermal (

中文翻译：

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智利氧化铁磷灰石 (IOA) 矿床磁铁矿地球化学综述及其对成矿过程的影响

摘要 磁铁矿是氧化铁-磷灰石 (IOA) 矿床中最重要的铁矿石，IOA 矿床代表了氧化铁-铜-金 (IOCG) 族的贫铜端元。磁铁矿化学已被用作确定成矿地质环境的岩石成因指标和铁源储层的指纹。在这项研究中，我们展示了位于智利北部白垩纪沿海山脉的 Carmen、Fresia、Mariela 和 El Romeral IOA 矿床磁铁矿的新结构和微分析 EPMA 和 LA-ICP-MS 数据。我们还提供了对安第斯 IOA 磁铁矿地球化学的全面总结和讨论，包括 Los Colorados、Cerro Negro Norte、El Romeral（智利铁带）和位于智利安第斯山脉中央火山带的上新世 El Laco IOA 矿床。微观结构结合地球化学数据被用来定义和表征不同磁铁矿类型的出现。磁铁矿表现出多种结构特征，包括振荡分区、胶体条带、再平衡结构、出溶片层和辛晶石。可以使用基于兼容微量元素的图表评估不同磁铁矿类型的岩浆与热液成因以及 IOA 矿床的演变。然而，磁铁矿非常容易受到热液蚀变以及岩浆和叠加热液事件期间的结构和成分重新平衡。根据此处提供的数据，我们得出结论，V 和 Ga 可能是磁铁矿中最可靠的兼容元素，可用于追踪安第斯 IOA 矿床的成矿过程。磁铁矿化学揭示了每个 IOA 矿床的不同形成条件/事件，包括高温、低氧逸度 (ƒO2)、纯岩浆 (>600 °C) 条件；降低温度和升高 ƒO2 岩浆热液 (300–600 °C) 到低温热液 (