AMEx’s founder acquired the La Cruzada property in 2018, built the investment thesis and performed a series of desktop tasks, spectral analysis, and A+I algorithm testings to stress test the concept. With a reinvigorated junior exploration market in 2020, AMEx decided to take on and allocate capital to convert La Cruzada into an exploration asset. During the first ever expedition to the property in June 2021, the company recovered a significant sample discovering a lithocap with politmetalic mineralization at surface. The company is building on that initial success aiming at advancing the La Cruzada prospect through exploration to discovery either through self-financing or partnering.
|Geology||Cu-Au porphyry and epithermal style alteration|
|Location||Westernmost part of the Province of Salta, Los Andes Department, NW Argentina, 450 km west of the City of Salta|
|Discovered||Andes Mineral Exploration S.A.|
|Elevation||Between 4,100 m and 5,100 m|
|Exploration to date||
Desktop Studies: spectral analysis and target-modeling.
Confirmation of mineralization at surface from float chip samples.
|Reconnaissance exploration program Target Area I complimented with field mapping.|
|Ownership||100% by AMEx|
|Major Projects in the Puna Atacama
|Lindero Au porphyry, mine commissioned and in production (Fortuna Silver) 70 km SW; Taca Taca Cu-Mo deposit (First Quantum) 70 km due West; Escondida Cu Mine (BHP JV) 75 km to the WNW in Chile|
La Cruzada regional geology
The La Cruzada Cu-Au prospect is situated in the high Andes south of the Salar de Atacama and near the border between Chile and the western Salta Province of Argentina. The Salta province is well endowed with copper-gold mineralization including the Taca Taca and Lindero deposits to the east and southeast of La Cruzada.
The geological basement consists of Ordovician meta-sedimentary rocks that are locally intruded by Paleozoic to Mesozoic diorite and granodiorite stocks of the Taca Taca and Chuculaqui Formations. The area also comprises abundant felsic to intermediate porphyry intrusions of the large Llullaillaco intrusive complex and, more rarely, Mesozoic syenite stocks. These porphyritic intrusions are hornblende-phyric and have high-K calc-alkaline compositions. They post-date and intersect rhyolitic to dacitic volcanic and volcaniclastic sequences of the Laguna de Aracar Formation. Part of the area is concealed by Tertiary rhyolitic ignimbrites dated at about 3.2-2.5 Ma as well as andesitic to dacitic volcaniclastic sequences from the Quaternary Socompa volcano.
The structural setting is dominated by regional deep-seated NW-trending lineaments. During the Tertiary, compressive tectonics dominated the geological evolution of the area and is documented in north-trending and west-dipping reverse faults. During intermittent phases of relaxation N-trending normal faults were formed and are best pre-served in the higher parts of the region. Historical mine workings targeted occurrences of copper and gold.
La Cruzada prospect geology
La Cruzada is situated about 5 km to the SW of the Socompa volcano, the preeminent topographic feature of the area. The prospect geology is defined 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. Airborne spectral analysis reveals that the significant structurally controlled alteration assemblages mainly consist of Na-alunite, pyrophyllite and, less commonly, 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 degassing of Socompa volcano, the formation of significant alunite-pyrophyllite alteration requires much higher temperatures and revealing a high potential for a concealed porphyry Cu system at La Cruzada.
Work performed to date
Spectral (Desktop Exercise, second half of 2020)
Our team has used algorithm-based remote sensing analyses of multi- and hyperspectral data to detect surface lithologies and hydrothermal alteration types as well as to model theoretical attributes of a potential copper-bearing orebody underground. Surface alteration zonation at La Cruzada favourably compares with the Taca-Taca gold deposit in the vicinity.
Create a site-specific spectral library in subsequent exploration efforts improving the reliability of mapping and bettering the understanding of the variety of site-mineralogy covered by sufficient samples and geological ground-truthing.
Reconnaissance Phase I (Field, May 2021)
Two reconnaissance trips were made to follow-up on hyperspectral vector-targeting and tracking down porphyry-type hydrothermal alteration assemblages at La Cruzada during the late Autumn season. AMEx hired a group of professional, High-Andes mountaineers to conduct the first ever ascent to the Cerro Tecar. During the campaign only a limited amount of rock chip samples were collected and brought to Salta for further analysis. Initial (pXRF) studies of one float chip sample revealed significant Cu, Au and Ag values. Whole-rock ICP-MS analyses and polymetalic mineralization confirmation followed. Sample RCH-CR-001 is considered the first piece of proof of the AMEx investment thesis. Segemar geophysical map showings indicate magnetic anomalies that call for systematic large-scale field exploration efforts on the property.
Lithocap, polymetallic mineralization and magnetic “doughnut”-shaped anomalies make La Cruzada a prime porphyry and HSE exploration target.