Análisis de los parámetros que controlan la mineralización del Yacimiento Cuprífero Mirador Norte

Abstract

The Mirador Norte project is a porphyry copper deposit located southeast of Ecuador, Tundayme parish, el Pangui canton, and province of Zamora-Chinchipe. This project and Mirador Project will begin the new industrial cooper mining in our country. At the time the deposit has been delimited on the basis of advanced exploration. A short term later phase of infill drilling is considered, so a deepening knowledge of the geological model and resource estimation can be obtained from new drilling works. Events and styles mineralization, alteration, lithology and main structures, were considered of high importance to define the control of mineralization in the deposit. For this purpose all information existing on drill log files and core drilling from 140 boreholes was reviewed and interpreted to elaborate profiles and thematic maps at various levels that defined at the first time the presence of at least two main mineralization events with distinctive styles (disseminated and veinlets). An uncommon alteration model corresponds to an alternation of potassic and propylitic (cloritic) bands with an NWSE tendency that coincides with porphyritic bodies emplacement, potassic areas are more developed towards the west, meanwhile cloritic ones are all over the System. There was a single sub-volcanic intrusion event called the early porphyry that petrographically reported a mineralogical composition ranging from granodiorite (dacite) to granite, textural variations by hydrothermal alteration processes may occur. As for the structural parameter, some main NWSE tendency structures were interpreted to run parallel to the ore body and displaced by less important late transverse structures. The parameters described above are related to the presence of copper grade and its distribution in the deposit, to define mineralization control. The fact that the emplacement of the early porphyries with mineralizing fluids have a similar trend to the main structures (NWSE), the development of alteration like strips or bands with the same trend and the apparent dominance of one style of mineralization in veinlets (structural) in 2 phases, evidence there was an constant and decisive tectonic factor during geological processes and thus on the occurrence and distribution of the copper mineral.