Both to the north and to the south of the interprovincial limit that crosses the Cordillera del Tigre, and throughout the Eastern edge of Cordillera frontal are known wide zones of argillic alteration, of Miocene age. Part of them, include areas such as the Cerro Blanco, Los Gemelos and the former Fabricaciones Militares zone of Leoncito. These zones are associated to smaller manifestations of altered rhyolites like those of the gorge La Fortuna, Despoblados and El Tigre (Figure 3), that displayed geochemical anomalies of Cu, Zn, Pb and Mo.

It is noticeable the colors of oxidation of the zone of the Leoncito and the argillic alteration of the Cerro Blanco. The last one shows a fracture of northwest bearing (possibly of transtensional origin), that links this zone with the intrusive centre of the Gemelos. The continuation of this fracture or fracture zone leads to the zone of Yalguaraz, former area of Reserve 2 Nº "Yalguaraz" of Fabricaciones Militares. In this zone are intrusive of dacitic and andesitic composition, which were evaluated as copper porphyries.

Mineralización

"Although in the region of Leoncito slightly altered to fresh andesitic porphyries seem to superficially lack of disseminated mineralisation of sulfides, the presence in the strongly altered sectors, of a vast dissemination of limonite and sporadic manifestations of turquoise, malachite and in smaller degree azurite, determined the concentration of the greater efforts in investigating this area." The area covered by the tenements that Entropy resources has negotiated for the Cerro Blanco project, covers a surface of 12,000 has.

Satellite image of the exploration leases of the Cerro Blanco project.