Contrasting styles of gold mineralisation in Northwestern Territories of Argentina

JULIO C. AVILA; JOSÉ E. LAZARTE; MIGUEL GIANFRANCISCO

Mineplanning and equipment selection (MPES)

Singhal, Mehrotra, Fytas, Ge

Lugar: Banff, Alberta, Canadá; Año: 2009; p. 62 - 66

This paper deals about two styles of mineralisation of hydrothermal gold districts in NW Argentina. The districts have different age, tectonic setting, mineralogy and alteration pattern. Culampajá auriferous district is located in the north sector of the eastern edge of the homonymous hill, Catamarca province. In the studied area out crop mainly ortogneis rocks. The ore mineral is native gold with lesser amount of pyrite, chalcopyrite, hematite, limonite, malachite, azurite and covellite disseminated in quartz veins filling tension fractures that affect the ortogneis rocks. It is suggested that the deposit was formed during the late magmatic hydrothermal stage genetically liked to granitic rocks of Paleozoic age and can be comparable with intrusion-related gold system. Farallón Negro and Alto de la Blenda deposits are placed in the Agua de Dionisio mining district also in Catamarca province about 30 km east from Culampajá. The deposits are lodes of epithermal origin (adularia-sericite or low sulphidation type) closely related to mio-pliocene volcanism filling fractures in monzonitic and andesitic rocks. In the vein complex four mineralisation stages were defined. Ore minerals are manganese oxides, sulphides and sulphosalts associated with gold and silver in quartz and carbonates gangue. It is suggested that the deposits were formed during the late hydrothermal stage genetically liked to volcanic rocks of Neogene age and can be comparable with subduction-related low sulphidation epithermal gold system.