The Ollachea deposit, situated in north Region Puno, southeastern Peru, contains >2.4 Moz Au with an average grade of 3.5 g/t Au. Mineralisation is hosted within slates belonging to the Silurian-Devonian Ananea Formation, and locally within metamorphosed igneous dykes and sills. At a regional scale, the ore deposit is located in the western margin of an orogenic belt that extends along the northwest trending Eastern Cordillera of the Andes. The goal of this Master of Economic Geology project, funded by a PRONABEC Scholarship, is to document the characteristics of the Ollachea deposit, determine its genesis, and constrain the age of ore emplacement.
Major activities in 2017 were:
- completion of first-stage fieldwork in early January, which involved detailed mapping and sampling in the deposit area and extensions
- progress made on deposit characterisation and in determining a paragenetic sequence of vein formation. This led to an initial finding that suggests the deposit contains three main veining stages of which the ‘stage 1’ (the earliest) contains the economic gold grades.
Second-stage fieldwork is planned for January 2018, which will be followed up by petrology, geochronology and mineral chemistry studies.