Polymetallic mineralization-Sedex Type

The Quebrada Ordoñez Prospect is located in Region II, on the eastern edge of the Cordillera de la Costa, just 10km NW of Puntillas Porphyry, within the Cretaceous belt. It has a district basic geology stage, which had geochemical samples that showed strong anomalies of Zn, Pb, As and minor Cu and Ag (specifically analyzed), in the Quebrada Ordoñez sector. Later, trenches were made in the sector, 112 RC drillings with lengths of 50 to 400m, all distributed in a 3.5x2km strip. The area with polymetallic anomalies was then delimited, with Zn being the most constant, with the highest intensity and areal distribution, reaching maximum values of 29.4%.
Lines were drawn with strong anomalies, mostly Zn> 300ppm, coinciding with Pb> 300ppm and Cu> 500ppm (Fig. 1).
Polymetallic mineralization is associated with stockwork of quartz veinlets of possible metamorphic origin, which would have reconcentrated early mineralization, Sedex type, deposited in sedimentary rocks of the El Toco Fm (Devonian), composed of a sequence of silicoclastic conglomerates, sandstones and shales (phyllites), affected by strong regional metamorphism and intensely folded.

Figure N° 1: Polymetallic anomalies of Zn, Pb and Cu
Figure N° 2: Location of new sectors

The mineralization is finely disseminated and forming halos, mainly in centimeter veinlets of quartz. Using a magnifying glass marmatite, and minor sphalerite, galena and occasionally green Cu oxides have been identified, mostly associated with coarse-grained (millimeter) silicoclastic strata, medium-grained sandstones and quartzites.

Microscopic studies were made, identifying sphalerite, galena, chalcopyrite, pyrite and arsenopyrite. Another 2 zones have sectors with strong siliceous veins and are located 5km and 9km ENE of Quebrada Ordoñez (Fig 2).
District-wise, the size of the El Toco Fm, where the Quebrada Ordoñez prospect is located, is approximately 50x20km NS, which makes it highly prospective to search for better areas and concentrations of Zn-Pb-Ag (?)

Jose Dias Cifuentes
New Metal Business Director
jose.dias.cifuentes@sqm.com
+56 9 7465 7359

Ricardo Gonzalez Montecinos
Exploration and New Metal Business Manager
ricardo.gonzalez.montecinos@sqm.com 


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