Sulphate, clay, silica and oxide-hydroxide minerals were identified by means of fieldwork, XRD and SEM, both in the active and fossil zones of the Cerro Apacheta volcano, (Cerro Pabellón geothermal field, northern Chile). Mineral assemblages and their spatial distribution in the active zone allow defining Superficial advanced argillic alteration facies associated with Argillic alteration facies, consistent with an acid-sulphate steam-heated environment. Poor crystallized kaolinite and cristobalite (opal-C), alunite in the steaming ground, alunogen and Mg-Zn-Cu-rich smectite in the fumarolic deposits represent the main mineralogical associations of this zone. The same two facies are defined in the fossil zone, interpreted as related to a superficial epithermal environment, with well crystallized kaolinite, alunite-natroalunite, pyrophyllite, mixed opal-A-opal C/T-quartz and Mg-Zn-Cu-rich Illite/Smectite (I/S). The presence and distribution of Mg-Zn-Cu rich montmorillonites and beidellites in the active and fossil zones are used as indicative of the hot mineralized vector fluids. In the active zone they would be interpreted alternatively as the result of an in situ argillic alteration, overlapping steam-heated typical assemblages and mineral associations formed in the fumarolic zones, or having an “allochthonous” origin, being formed at depth within the superficial part of the clay cap, and subsequently transported to the surface during phreatic eruptions or fluidized events. The distribution of the hydrothermal alterations is likely related to the intersection of NW-SE and NE-SW structures, linked to the Pabelloncito graben, a primary feature in the control of the circulation of hydrothermal fluids towards the surface (cf. Veloso et al., 2020; Baccarin et al., 2021).

通过野外工作、XRD 和 SEM，在 Cerro Apacheta 火山（智利北部 Cerro Pabellón 地热田）的活动区和化石区中发现了硫酸盐、粘土、二氧化硅和氢氧化物矿物。矿物组合及其在活动区的空间分布允许定义与泥质蚀变相相关的表层高级泥质蚀变相，与硫酸-硫酸盐蒸汽加热环境一致。结晶较差的高岭石和方石英（蛋白石-C）、蒸腾地面中的明矾石、富马岩矿床中的铝矾土和富含 Mg-Zn-Cu 的蒙脱石代表了该区域的主要矿物组合。在化石区定义了相同的两个相，解释为与浅表超热环境有关，具有结晶良好的高岭石、明矾石-钠铝榴石、叶蜡石、混合蛋白石-A-蛋白石 C/T-石英和富含 Mg-Zn-Cu伊利石/蒙脱石 (I/S)。活动区和化石区中富含 Mg-Zn-Cu 的蒙脱石和贝得石的存在和分布被用作热矿化载体流体的指示。在活动区，它们将被解释为原位的结果泥质蚀变，在喷气带中形成的重叠蒸汽加热的典型组合和矿物组合，或具有“外来”起源，在粘土盖的表层部分深处形成，随后在潜水喷发或流化过程中运输到地表事件。热液蚀变的分布可能与 NW-SE 和 NE-SW 结构的交叉点有关，与 Pabelloncito 地堑相连，这是控制热液流向地表的主要特征（参见 Veloso 等人，2007 年）。 ，2020 年；巴卡林等人，2021 年）。