The Lindero deposit is located in the Puna plateau, northwest Argentina, at the southern end of the Central Volcanic Zone of the Central Andes. The high-K calc-alkaline dioritic composition of the subvolcanic intrusions, the shallow emplacement depth (< 1.5 km), and the gold-rich and copper-depleted mineralization style suggest that the Lindero deposit is a porphyry gold deposit. Porphyry gold deposits are scarce worldwide and the factors controlling their formation are still poorly known. Here we present a detailed study of fluid inclusions in order to characterize the mineralizing fluids that precipitated the Au mineralization at Lindero. Different types of fluid inclusions in quartz veins (A-type and banded quartz), which are associated with the K-silicate alteration, were analyzed using Raman spectroscopy, microthermometry, and LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry). Four inclusion types can be recognized in quartz veins: (i) Salt melt inclusions, which are characterized by a dense packing of daughter minerals (mainly Fe-chloride, sylvite, halite, anhydrite, and hematite), by a distorted vapor bubble, and by the lack of liquid phase; (ii) Halite-bearing inclusions which contain liquid, vapor, and halite; (iii) Two-phase aqueous inclusions that contain liquid and vapor; (iv) Vapor-rich inclusions containing only vapor. The inclusion types are related to different stages of hydrothermal evolution. Stage 1 is the main mineralization stage, characterized by vapor-rich inclusions coexisting with salt melt inclusions. Salt melt inclusions commonly show total homogenization temperature (Th_L) > 1000 °C. This Na-K-Fe-Cl-rich highly saline brine (~ 90 wt% NaCl eq.) was of magmatic origin and responsible for the Au mineralization. Two later stages involving cooler fluids (Th_L < 300 °C) and gradually lower salinities (from 36.1 to 0.2 wt% NaCl eq.) trapped by halite-bearing and two-phase aqueous inclusions during stages 2 and 3, respectively, correspond to a late magmatic-hydrothermal system, that is probably related to a deep supercritical fluid exsolution. Salt melt inclusions represent the most likely parental fluid of K-silicate alteration and associated Au mineralization at Lindero. This uncommon type of fluid must have played an important role in Au transport and precipitation in shallow porphyry gold deposits.

Lindero矿床位于阿根廷西北部的普纳高原，安第斯山脉中部火山带的南端。火山侵入体的高钾钙碱性闪长岩成分、侵位深度浅（< 1.5 km）以及富金贫铜矿化样式表明 Lindero 矿床为斑岩金矿床。斑岩金矿床在世界范围内都很稀有，并且控制其形成的因素仍然知之甚少。在这里，我们对流体包裹体进行了详细研究，以表征在 Lindero 沉淀金矿化的矿化流体。使用拉曼光谱、显微测温法和 LA-ICP-MS（激光烧蚀电感耦合等离子体质谱法）对石英脉中与钾硅酸盐蚀变相关的不同类型的流体包裹体（A 型和带状石英）进行了分析。石英脉中可识别出四种包裹体类型：（i）盐熔体包裹体，其特征是子矿物（主要是氯化铁、钾盐、岩盐、硬石膏和赤铁矿）致密堆积，并具有扭曲的蒸气泡；由于缺乏液相； (ii) 含石盐夹杂物，其中含有液体、蒸气和石盐； (iii) 含有液体和蒸气的两相水包裹体； (iv) 仅含有蒸气的富含蒸气包裹体。包裹体类型与热液演化的不同阶段有关。第一阶段是主要成矿阶段，以富水蒸气包裹体与盐熔体包裹体共存为特征。盐熔体包裹体通常表现出总均化温度 (Th _L ) > 1000 °C。这种富含 Na-K-Fe-Cl 的高盐度盐水（约 90 wt% NaCl eq.）源自岩浆，是金矿化的原因。两个后期阶段涉及较冷的流体（Th _L < 300 °C）和逐渐降低的盐度（从 36.1 到 0.2 wt% NaCl eq.），分别在阶段 2 和阶段 3 期间被含石盐和两相水包裹体捕获，对应于晚期岩浆热液系统，可能与深层超临界流体溶出有关。盐熔体包裹体代表了 Lindero 钾硅酸盐蚀变和相关金矿化最可能的母体流体。这种不常见的流体类型必定在浅层斑岩金矿床的金迁移和沉淀中发挥了重要作用。