Exploration of the Huanzalà mine, Republic of Perù -The discovery of a deep mineralized zone.

Abstract

The Huanzala mine is a poly-metallic mineral deposit associated with copper-silver-lead-zinc in the Peruvian Andes. The ores have replaced certain horizons of limestone beds of the Lower Cretaceous, and the ore bodies are platy or lenticular in form and concordant with the host-rock stratigraphy. During the recent deep DDH exploration program, which was planned and implemented based on a reanalysis of existing geological information, a prominent mineralized zone with large potential was discovered 200m below the current operating zone. This new mineralized zone occurs in limestone blocks which are the downward continuation of the current operating zone. These blocks were thrust downward by the reverse fault (the so-called “Lower Fault”) and then subjected to hydrothermal metasomatism. Mineralization is in the form of copper-silver and copper-zinc minerals occurring with skarn and massive pyrite. The Huanzala mine consists of two independent districts: the north deposits, and the south deposit. In addition, the mineralization is interpreted to have occurred in two stages: in the first stage, the pyritic ore and the skarn ore formed mainly with silver-lead-zinc mineralization accompanying the granodiorite porphyry, and in the second stage, so-called “Shiroji” ore containing copper-silver-lead-zinc mineralization accompanying quartz porphyry was deposited. From 1964 until recently, systematic exploration and development of the Huanzala mine had focused on the strike-extension zones horizontally to the north and to the south of the known deposits. However, the strike extension exploration program was recently completed and the remaining potential zones in the operating area are running out. As production is depleting the ore reserves, the discovery of a new exploration target area has significantly contributed additional ore reserves for the Huanzala mine.