MINERÍA la mejor puerta de acceso al sector minero EDICIÓN 572 / MAYO 2025 51 as blackish silica with fine-grained pyrite and partly as creamy silica. The silicification also fills interstitial open spaces between grains of the sandstone, fractures in sandstones, and as cement of breccias. The porphyry style mineralization at Cuypampa displays minor quartz - pyrite veinlets (D vein) mostly cutting fine-grained sandstone of Carhuaz Formation and the main mineralization occurs inner feldspar porphyry developing quartz- moly-pyrite (B vein) and traces of remaining chalcopyrite in white mica + pyrite ± quartz stockwork zone. Geochronology This study collected 16 samples for dating: 7 alunite (Ar-Ar), 1 molybdenite (Re-Os) for alteration-mineralization and 8 Zircon (U-Pb) for magmatic rocks. The dating shows that although both the La Virgen Domain and the Escalerilla block of the Escalerilla-Cuypampa Domain have HS mineralization and related AA alteration, they formed in two different events (ca. 18-17 Ma vs. ca. 22- 21 Ma) and are unrelated. The HS mineralization-alteration in Escalerilla block has similar ages as the porphyry-style mineralization in the Cuypampa block, therefore, it is inferred that the Escalerilla HS is related to the Cuypampa porphyry (ca. 22-21 Ma), while in La Virgen domain the HS mineralization-alteration is developed ca. 18-17 Ma (Figure 1). Discussions and Conclusions AAA in siliciclastic rocks At LVD is largely cryptic to the naked eye. The AA1 alteration develops intensely in hydrothermal breccias, with silica (hydrothermal quartz) cementing open spaces and percolating tiny interstices between grains in quartz sandstones. Alunite forms platy crystals, and as we move away from the breccia zone, its occurrence increases, filling microfractures and interstices of quartz grains. Additionally, dickite appears, while silicification decreases. In more distal areas, dickite and kaolinite dominate, eventually, this transition leads to the IA zone, where fresh sandstones contain minor pyrite veins filling fractures as distal escape fluids. The major mineralization is associated with the AA1 assemblage. The rocks, especially sandstones, with AA alteration appear fresh, mainly due to the lack of vuggy texture, the low abundance of alunite, dickite and pyrophyllite, and the small grain sizes as such minerals could only grow in the tiny interstices between sandy grains. Traditionally, pyrophyllite is used to indicate a higher temperature and deeper position than alunite (e.g., Chang et al., 2011). This study shows that this vector should be used more carefully in siliciclastic terranes, because pyrophyllite may preferably replaces clay-rich lithologies therefore there is an additional lithological control in addition to temperature/depth/acidity control. As a result, it would not indicate transition zones to high-temperature areas. This idea should be validated through further studies in other similar deposits. Magmatic rocks show visible alteration through mineral changes, while quartz sandstones appear fresh but may have cryptic alteration, undetectable to the eye but present at a microscopic level. SWIR spectral analysis is highly effective for detecting alteration minerals. A dry, hand-sized sample is enough for quick reconnaissance, while a detailed sampling grid is ideal for district mapping. Two Domains in the LVD: La Virgen and Escalerilla-Cuypampa LVD has only been explored, recognized, and mined under the concept of a single HS mineralization since its discovery (Noble and Mckee, 1999; Ristorcelli and Prenn, 2001). This study found that it is actually composed of two domains, based on mapping and dating of alunite, molybdenite, and zircon. In the La Virgen Domain, the hypogene alunite Ar-Ar dates are 18.1 ± 0.4 to 17.1 ± 0.4 Ma, whereas in the Escalerilla-Cuypampa Domain, the hypogene alunite Ar-Ar dates are 22.1 ± 0.4 to 21.4 ± 0.4 Ma (related HS mineralization), and the molybdenite
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