| Journal: | Andean geology |
| Database: | PERIÓDICA |
| System number: | 000459986 |
| ISSN: | 0718-7092 |
| Authors: | Espeche, María J1 Lira, Raúl1 Viñas, Nicolás A2 |
| Institutions: | 1Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Físicas y Naturales, Córdoba. Argentina 2Michelotti e Hijos S.R.L., La Calera, Córdoba. Argentina |
| Year: | 2020 |
| Season: | Ene |
| Volumen: | 47 |
| Number: | 1 |
| Pages: | 14-45 |
| Country: | Chile |
| Language: | Español |
| Document type: | Artículo |
| Approach: | Analítico, descriptivo |
| Spanish abstract | resumen está disponible en el texto completo |
| English abstract | On-going mining operations in a marble quarry (Cantera Centro) from Malagueño, Sierra Chica de Córdoba, Argentina, have unearthed veins, veinlets and lenses of sulfides (pyrrhotite>pyrite≅chalcopyrite> >sphalerite). These veins and lenses are up to 0.3 m thick and 2-3 m long, although intermittently can extend about a hundred meters. They are associated with skarns. The metasedimentary host sequence, largely composed of gneisses, amphibolites and marbles, was intruded by amphibolic metagabbro and metadiorite dykes, metatonalite plutons and alkali-feldspar metagranites; the whole complex was metamorphosed into medium to high amphibolite facies and strongly deformed as a result of the a regional event M2-D2/D3 that affected the Neoproterozoic-Cambrian basement during the Pampean orogeny. Except for gneisses, all the other metamorphic lithologies register evidence of differential alteration into skarn, although the process was preferentially developed on marbles, amphibolites and metagranite, and to a lesser extent on mafic and mesosilicic dykes. The metasomatic rocks are characterized by a garnet˃˃pyroxene skarn (Grs27-48Adr22-34Alm15-27Sps9-21), formed after the replacement of the metagranite; a pyroxene-rich skarn (Hd42-63Di32-50Jo3-5) developed after para-amphibolite, and a garnet (Adr54-71Grs22-40Alm4-7Sps1-2) (±wollastonite) skarn that replaced a calcic marble. The dykes show poor metasomatic replacement and lack sulfides of metasomatic-hydrothermal origin. Retrograde mineral associations include hastingsite, ferroactinolite, epidote, clinozoisite, sericite, plagioclase (An18), chamosite and calcite. The sulfide mineralization is paragenetically associated with late-stage, infilling skarn-hydrothermal minerals that were sequentially deposited as: calcite→clinochlore→quartz→pyrite→pyrrhotite→chalcopyrite+sphalerite; these phases occur as veins and veinlets within the garnet-pyroxene skarn, and as massive pyrrhotite lenses in the piroxen |
| Disciplines: | Geociencias |
| Keyword: | Geología, Mineralogía, petrología y geoquímica, Skarn, Sulfuros, Orogenia Pampeana, Inclusiones fluidas, Isótopos de azufre, Sierra Chica, Argentina |
| Keyword: | Geology, Mineralogy, petrology and geochemistry, Skarn, Sulfides, Pampean orogeny, Fluid inclusions, Sulfur isotopes, Sierra Chica, Argentina |
| Full text: | Texto completo (Ver HTML) Texto completo (Ver PDF) |
