The formation of auriferous quartz-sulfide veins in the Pataz region, northern Peru: A synthesis of geological, mineralogical, and geochemical data

Abstract

The Pataz region in the eastern part of the North Peruvian Department La Libertad hosts a number of important gold mining districts like La Lima, El Tingo, Pataz, Parcoy, and Buldibuyo. Economic gold mineralization occurs in quartz-sulfide veins at the margin of the calc-alkaline Pataz Batholith, that mainly consists of granites, granodiorites, and monzodiorites. The batholith is of Paleozoic age and cuts the Precambrian to Early Paleozoic low-grade metamorphic basement series. Its intrusion was controlled by a NNW-trending fault of regional importance. The gold-bearing veins are characterized by a two-stage sulfide mineralization. Bodies of massive pyrite and some arsenopyrite were formed in stage 1, and after subsequent fracturing they served as sites for deposition of gold, electrum, galena, sphalerite, and chalcopyrite. It is concluded that gold was transported as a AuCl -2 -complex by oxidizing chloride solutions and deposited near older pyrite by micro-scale redox changes and a slight temperature decrease. Mineralogical, textural, geochemical, and microthermometric features are interpreted as a consequence of mineralization at considerable depth produced by a hydrothermal system linked with the emplacement of the Pataz Batholith. acteristics in order to outline a general physicochemical model of the hydrothermal ore-forming processes.