The La Gran Cruzada Cu-Au prospect (“La Cruzada” or the “Project”) is situated in the high Andes in the SW part of the Salta Province of Argentina, in the Department of the Andes, immediately adjacent to the border with Region II in Chile. The highest peaks are the Socompa volcano to the NE and the Llullaillaco to the SW with elevations of more than 6000 m MSL (Fig. 2). The region belongs to the Miocene metallogenic belt of the Andes (Sillitoe, 2010). The Salta province is well endowed with copper and gold mineralization including the Taca Taca deposit to the east and, Rio Grande to the south and the Arizaro project and the Lindero mine to the southeast of the La Gran Cruzada Project.

The geology of this region is dominated by Upper Miocene to Pliocene andesitic stratovolcanoes and dacite domes that are partly covered by Pliocene ignimbrites and pyroclastic sequences (Camus and Castelli, 2021). The geological basement consists of Mesozoic and Paleozoic meta-sediment units that are locally intruded by diorite and granodiorite stocks of the Taca Taca and Chuculaqui Formations.

There are also numerous hypabyssal porphyritic felsic to intermediate intrusions of the Llullaillaco intrusive complex and, more rarely, Mesozoic syenite stocks. These porphyritic intrusions are hornblende- and biotite‐phyric and have high-K calc-alkaline compositions (Kay et al., 1999; Camus and Castelli, 2021). Large parts of the region are concealed by Pliocene ignimbrites as well as andesitic to dacitic volcaniclastic sequences from the Quaternary Socompa volcano.

The structural setting of the region is dominated by regional deep-seated NE- trending basement structures of Paleozoic age that are locally intersected by NW‐trending high‐angle Triassic and N‐S oriented Tertiary faults (Camus and Castelli, 2021). During the Tertiary, compressive tectonics dominated the geological evolution of the area and is documented in N-S trending and west- dipping reverse faults. During intermittent phases of relaxation N-trending normal faults were formed and are best preserved in the higher parts of the region. The location of stratovolcanoes such as Villalobos and Socompa which dominate the morphology of the region appears to be structurally controlled by N‐S trending faults (Camus and Castelli, 2021). The area contains abundant ancient pirquinero workings and gold and copper showings.

The La Gran Cruzada Project comprises 6.568 hectares and it is situated about 15 km to the SW of Socompa volcano that dominates the topography of the area. The prospect geology is dominated by Tertiary andesitic to dacitic volcaniclastic
sequences that are covered by ignimbrites in places. The rocks are overprinted by widespread and texturally destructive hydrothermal alteration, especially along NW- or NE-trending structures or at their intersections. Vuggy textures of
andesite units are common (Figs 4 and 5). Airborne spectral analysis reveals that the hydrothermal alteration assemblages mainly consist of pyrophyllite as well as Ca‐ and K-alunite phases. The center of the prospect contains a large zone of
clay-sericite alteration, measuring about 3.5 km across.
Although part of the clay alteration could be attributed to late-stage volcanic activity and de-gassing of Socompa volcano, the formation of significant alunite-pyrophyllite alteration requires much higher temperatures, revealing a increased
potential for a concealed porphyry Cu system at La Cruzada.