Advanced argillic (AA) alteration produced by hydrothermal activity and subsequent supergene alteration in the Potrerillos district, Atacama Desert, Chile, includes sulfate-bearing and aluminosilicate alteration minerals. These alterations commonly contain alunite supergroup minerals (e.g., alunite, jarosite, and aluminum-phosphate-sulfate (APS) minerals) of both hypogene and supergene origin. In this contribution, we investigate the mineralogical and geochemical characteristics of these minerals, to decipher the physicochemical parameters of formation, as well as the composition, source, and evolution of the fluids that produced the AA alteration in the area. Field observations, optical microscopy, and geochemical analyses provide insights into the geochemical evolution of the hydrothermal system and its later supergene weathering. Three precipitation environments with different sulfur sources and characteristics of alunite group minerals have been defined at Potrerillos as follows: (i) hypogene environment with sulfur originating from H₂S disproportionation and tabular alunite (> 200 µm); (ii) steam-heated environment with sulfur from oxidation of distilled H₂S above the water table, tabular alunite (< 100 µm), and pseudocubic APS; and (iii) supergene environment with sulfur from the oxidation of hydrothermal sulfides and dissolution of alunite and APS in the vadose zone represented by pseudocubic alunite, jarosite (≤ 5 µm) and APS minerals. Hydrothermal and supergene minerals have endmember and intermediate compositions in the alunite-jarosite solid solution series, respectively. Divalent exchange in alunite and jarosite, and the precipitation of APS minerals reflect variations in the redox and pH conditions, chemical composition, and elemental concentration in the supergene fluids, these variations also were observed to a lesser extent in steam-heated solutions. The temperature of hypogene alteration is estimated to range from to 120 to 200 °C; lower temperatures are possible for the steam-heated environment.

智利阿塔卡马沙漠 Potrerillos 地区由热液活动和随后的表生蚀变产生的高级泥质 (AA) 蚀变包括含硫酸盐和铝硅酸盐蚀变矿物。这些蚀变通常包含浅成生和表生成因的明矾石超群矿物（例如明矾石、黄钾铁矾和磷酸铝硫酸盐 (APS) 矿物）。在这篇文章中，我们研究了这些矿物的矿物学和地球化学特征，以破译形成的物理化学参数，以及在该地区产生 AA 蚀变的流体的组成、来源和演化。实地观察、光学显微镜和地球化学分析为热液系统的地球化学演化及其后来的表生风化提供了见解。₂ S歧化和板状明矾石（> 200 µm）；_{(ii) 蒸馏 H 2}氧化产生硫的蒸汽加热环境S 高于地下水位、板状明矾石 (< 100 µm) 和伪立方 APS；(iii) 以拟立方明矾石、黄钾铁矾 (≤ 5 µm) 和 APS 矿物为代表的包气带中热液硫化物氧化和明矾石和 APS 溶解产生的硫的表生环境。热液矿物和表生矿物分别具有明矾石-黄钾铁矾固溶体系列的端元和中间成分。明矾石和黄钾铁矾中的二价交换以及 APS 矿物的沉淀反映了表生流体中氧化还原和 pH 条件、化学成分和元素浓度的变化，在蒸汽加热溶液中也观察到了较小程度的这些变化。低基因改变的温度估计在 120 到 200 °C 之间；