Abstract
This paper describes petrographically sections of drill core (YAR-06, YAR-017 and YAR-019) belonging to the Yarumalite Porphyritic System, in order to identify the lithology and hydrothermal alterations associated with gold mineralization in this system, owned of Colombian Mines Corporation, this project is located 4,3 Km south of the municipality of Valparaiso, Antioquia. The description of these sections bodies is made by the macroscopic analysis of drilling cores, optical petrography and electron microscopy (SEM); petrographically the hypoabisal bodies correspond to andesites and dacites with potassic, propylitic, quartz-sericite and serictic alterations; these alterations have distribution in halos of veins or to the interior of these and less occurs with a distribution pervasive in the rock. In the analyzed sections, the initial pulse corresponds to andesitic porphyries, with potassic, quartzsericitic and propylitic alterations, this pulse is followed by dacitic porphyries that presents the same alterations but with a greater intensity and finally these hypoabisal bodies are cut by small dacitic dykes whose main alteration is sericitic. The mineralogy of the porphyries provides data on the evolutionary stages of the system, for example it is observed as the initial pulse is more basic and progressively goes to compositions moderately more felsic; similarly to the textures of these bodies, which suggest relatively different levels of depth for the identified pulses; on the other hand the secondary textures and hydrothermal alterations presents, suggest a prominent interaction with fluids of magmatic-hydrothermal origin. Keywords: Petrography, hydrothermal alterations, porphyries, phyllosilicates, Porphyritic system Yarumalito.
Highlights
En este trabajo se presenta la descripción petrográfica de secciones de núcleos (YAR-06, YAR-017 y YAR019) pertenecientes al Sistema Porfirítico Yarumalito, con el objeto de identificar la litología y alteraciones hidrotermales asociadas con mineralizaciones de oro en este sistema, propiedad de Colombian Mines Corporatión, este proyecto se localiza a 4,3Km al sur del municipio de Valparaíso, Antioquia
Los depósitos porfiríticos concentran cantidades considerables de metales como cobre, molibdeno y oro, mineralizaciones que aparecen tanto en las zonas de alteración hidrotermal como en intrusivos porfiríticos asociados (Sillitoe, 2008, 2010)
Diversas dataciones realizadas en los cuerpos hipoabisales de esta formación sugieren edades del Mioceno Tardío, entre 12 y 6 Ma (K/Ar en hornblenda: Restrepo et al, 1981; Trazas de fisión en circones: Ramírez et al, 2006; U/Pb en circones: Henrichs et al, 2014)
Summary
Marcela Barrera-Cortes1*; José Carlos Frantz; Juliana Charão-Marques; Diana Sánchez-Celis. En este trabajo se presenta la descripción petrográfica de secciones de núcleos (YAR-06, YAR-017 y YAR019) pertenecientes al Sistema Porfirítico Yarumalito, con el objeto de identificar la litología y alteraciones hidrotermales asociadas con mineralizaciones de oro en este sistema, propiedad de Colombian Mines Corporatión, este proyecto se localiza a 4,3Km al sur del municipio de Valparaíso, Antioquia. El pulso inicial corresponde pórfidos de composición andesítica, con alteraciones potásica, cuarzo-sericitica y propilítica, este pulso es seguido por pórfidos dacíticos que presenta las mismas alteraciones pero con una intensidad mayor y finalmente estos cuerpos hipoabisales son cortados por pequeños diques dacíticos cuya alteración principal es sericitica. Palabras clave: Petrografía, alteraciones hidrotermales, pórfidos, filosilicatos, Sistema porfirítico Yarumalito
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