Geología de la veta Ángela, proyecto Inmaculada Ayacucho - Perú

Abstract

The study area called Inmaculada Project is located in southern Peru between the provinces of Parinacochas and Páucar del Sara Sara in the department of Ayacucho, approx. 210 km southwest of the city of Cusco. The Inmaculada project is located on the west flank and central part of the Au-Ag epithermal metallogenic strip of Puquio-Caylloma. In the project study area, two volcanic series have been differentiated. The first is formed at the base by alternations of andesitic lavas and debris flow, under lapilli tuffs and andesitic lithic tuffs that emerge from the Anta-Patari area and continue to the Minascucho area; which have been grouped and assigned to the Tacaza Group. A second volcanic series is the outcrops of the Quellopata area formed by andesitic lavas of porphyritic texture and violet green debris flow; which are regionally correlated with the Saycata Formation. The Inmaculada project is located in a tectonic regime dominated by regional faults of NW direction intersected with trans-Andean faults of NE direction. The placement of the veins in Quellopata took place in an extensional context with normal NE-SW faults, with opening of spaces by subsidence of blocks towards the SE. Initially, these spaces were filled by Ag mineralization associated with base metals (Pb, Zn). The veins-failures continued in activity, being affected in turn by horizontal movements of dextral course, with the development of pull-apart type depressions, riedel and sigmoid fractures, which are observed in the outcrops. This event probably facilitated the placement of a second pulse of Au type bonanza mineralization with filonian quartz filler. The Inmaculada project presents two styles of epithermal mineralization. The first corresponds to the low sulfidization style represented by the filonian filler quartz veins; which emerge in Quellopata, Anta-Patarí and Pararani. The second corresponds to the style sulfate acid or high sulfidization, which occur in Minascucho-San Salvador and Tararunqui. The Inmaculada project has 20 quartz veins, 07 veins (Teresa, Lourdes, Juliana, Rebeca, Verónica, Marina and Organa) correspond to the type of intermediate sulfidization with mineralization of Ag + Pb-Zn and the other 13 veins (Martha, Ángela, Roxana, Shakira, Lucy, Sara, Karina, Pirita, Jimena, Melissa, Kattia, Rosario and Claudia) are of the low sulfidization type with mineralization of Au + Ag. The diamond drilling campaign focused on continuing the exploration in the NE extension of the Ángela vein and continuing with the infill drilling program in zones I and II of the same vein. As a result of the exploration program of the year 2010, the extension of the Ángela vein mineralization has been defined in approximately 2.5 km along the course (open towards the NE), a vertical depth of more than 300 m. and economic contents of Au and Ag much higher than those obtained in previous campaigns.