Invisible Silver and Associated Elements in Sulfides from the Polymetallic Loma Galena Deposit, Navidad District, Argentinian Patagonia

VERÓNICA BOUHIER; MARTIN REICH; FRANCHINI MARTA; ANA LAURA RAINOLDI; LAURA MAYDAGÁN; FERNANDO BARRA; MATHIEU LEISEN

Santiago

Simposio; SEG-2019 -Conference- South America Metallogeny: Sierra to Craton; 2019

SEG -Society of Economic Geologist-

Loma Galena (6,410.8 t Ag, 997,130 t Pb) is one of the eight major deposits that constitute the world-class Ag + Pb ± (Cu, Zn) Navidad district (15.4 Mt with 137 g/t Ag and 1.44% Pb) in the western North Patagonian Massif, Argentina. The Loma Galena deposit was formed in an active continental rift basin during the Middle Jurassic. The epithermal polymetallic mineralization at Loma Galena occurs in veins and hydrothermal breccias, in autobreccias and chaotic breccias at the contact between volcanic and sedimentary units, and disseminated within the sedimentary rocks. The earliest mineral infill of veins and breccias consists of calcite1 and siderite followed by pyrite1, pyrite2 + marcasite, pyrite3, galena, and sphalerite. Chalcopyrite, bornite, and tennantite-tetrahedrite partially replaced the early sulfides. Sulfides are cemented by chalcedony with minor barite1 and late calcite2, barite2, quartz, and strontianite.