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The Cerro Lindo volcanogenic massive sulphide zinc-lead-copper-silver deposit is located ~175 km SE of Lima, in Ica department, at an elevation of 1850 m.a.s.l., within the arid coastal range of southern Peru (#Location: 13° 4' 45"S, 75° 59' 31"W).
The deposit was initially discovered as outcrop of barite by SMRL Cerro Lindo/Milpo geologists, followed by geophysical (induced polarization) surveys which outlined five anomalies possibly reflecting massive sulphides, followed by geochemical sampling of outcrops of the barite and surrounding rocks which delineated base metal anomalies. These anomalies were tested between 1982 and 1987. Continued exploration in the form of drilling and underground development between 1992 and 2002, with Minera Phleps Dodge as joint venture partner from 1995, resulted in a mineral resource of 34 Mt @ 5.2% Zn, 0.6% Pb, 0.8% Cu, 36.1 g/t Ag being outlined, with an inferred additional 10 Mt. Mining operations commenced in 2007.
Cerro Lindo was emplaced within a marginal extensional back-arc setting, part of the Huarmey-Cañete trough, which occupies the western slopes of the Cordillera Occidental and the Coastal Plains of Peru. The mineralisation is hosted by the Cretaceous (Albian) volcano-sedimentary Huaranguillo Formation of the Casma Group. At a smaller scale, the host rocks were deposited within an intra-basin graben and strike at ~300° and mainly dip to the SW. They are preserved as a roof pendant within the Albian to Paleocene Coastal batholith of western Peru.
The Huaranguillo Formation has an estimated thickness of ~3000 m, and is divided into two members:
• Lower member, composed of laminated slates, shales and volcanic ash, alternating with andesitic layers and occasional fine limestones;
• Upper member that consists of 5 to 40 cm thick black limestone layers interspersed with horizons of shales and volcanic beds.
The Cerro Lindo is a deposit is oriented NW, and dips at ~65°SW, with an approximate length of 800 m, thickness of 200 m and a and down-dip extent of ~450 m, split into three main orebodies OB-1, OB- 2 and OB-5, which are structurally controlled by synvolcanic faults of the graben and intruded by andesitic dykes that follow faults which offset the ore.
Published ore reserves and mineral resources at 31 December, 2014 (Milpo, 2015) were:
Proved + probable reserve - 39.9076 Mt @ 2.67% Zn, 0.27% Pb, 0.72% Cu, 24.6 g/t Ag;
Measured + indicated resource - 45.8625 Mt @ 2.28% Zn, 0.27% Pb, 0.66% Cu, 23.0 g/t Ag;
Inferred resource - 9.1832 Mt @ 2.01% Zn, 0.17% Pb, 0.71% Cu, 17.73 g/t Ag;
Reserves + resources - 94.9533 Mt @ 2.41% Zn, 0.26% Pb, 0.69% Cu, 22.1 g/t Ag.
The most recent source geological information used to prepare this summary was dated: 2014.
This description is a summary from published sources, the chief of which are listed below.
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