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Revista de la Asociación Geológica Argentina
Print version ISSN 0004-4822On-line version ISSN 1851-8249
Abstract
BIGLIA, Marco E; LIRA, Raúl and SFRAGULLA, Jorge A. Nuevos datos mineralógicos, petrográficos y metalogenéticos del distrito minero Agua de Ramón, departamento Minas, Córdoba. Rev. Asoc. Geol. Argent. [online]. 2016, vol.73, n.2, pp.225-241. ISSN 0004-4822.
The Agua de Ramón tungsten mining district is located northwest of Córdoba province, in the sierra de Guasapampa; numerous inactive mines are distributed in three main zones (North, Central and South). Except for a few mines in the South zone of stratabound scheelite, the rest are represented by wolframite-bearing, quartz-muscovite-schorl veining, which are emplaced in extensional structures within an Ordovician tonalite-granodiorite and in Neoproterozoic-Cambrian metasedimentary host rocks. New minerals described for the district, and some for Argentina, include sanmartinite, russellite, stolzite, galenobismutite, kettnerite, bismoclite, molybdenite, galene, covellite, mottramite, chrysocolla, Na-bearing jarosite and gypsum. The Fe/Mn ratios of wolframite mineral series are compositionally intermediate, slightly richer in molar ferberite in the South zone. Geobarometric computations suggest a pressure of ~1.9 kbars during greisenization and W± Bi (± Zn, Cu, Pb, Mo) mineral deposition. According to fluid inclusion homogeneization temperatures in vein quartz, acquired by previous studies, the yield trapping temperatures are between 410-450ºC. Replacement of ferberite-hübnerite by scheelite, stolzite, sanmartinite and russellite suggests significant changes in fluid composition by decrease of the temperature, particularly of ƒO2. A muscovite already dated, from an altered wall-rock, has an age of 366 ± 1 Ma, so the alteration-mineralization event belongs to the Devonian Metallogenetic Epoch, related to an extension associated with the Achalian tectono-magmatic event; however, boron-rich mineralizing fluids would derive from felsic highly-evolved hidden intrusions. The quartz-wolframite (± Bi) veins of the southern neighbor La Bismutina district, assigned to the Panasqueira type, could be metallogenetically linked, as was interpreted by other authors.
Keywords : Greisen; Tungsten; Geobarometry; Devonian-Carboniferous; Sierra de Guasapampa.