Caracterización geoquímica y mineralógica de la alteración hidrotermal tipo “Steam-Heated" de sector Campanario, Franja el Indio, Región de Coquimbo, Chile
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Date
2021
Authors
Facultad/escuela
Idioma
es
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Journal ISSN
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Publisher
Universidad Andrés Bello
Nombre de Curso
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Abstract
Los depósitos epitermales de alta sulfuración albergan principalmente importante
mineralización de Au-Ag (-Cu). La franja de El Indio-Pascua es una franja metalogénica
de edad miocena que comprende importantes depósitos epitermales de alta sulfuración
tale como Pascua-Lama, Veladero, Sancarrón, El Indio, Tambo y Alturas (Figura 1.1).
Algunos de estos depósitos se caracterizan por tener una alteración tipo “steamheated” la cual es un manto estéril que se forma sobre el nivel freático (Schoen et al.,
1974), y en algunos de estos depósitos la mineralización yace bajo las zonas “steamheated”. Sin embargo, caracterizar esta alteración tipo “steam-heated” es importante
para definir diferentes aspectos para explorar estos depósitos.
Las rocas que se encuentran hospedadas en el sector de estudio corresponden a rocas
volcánicas y volcanoclásticas, incluyendo brechas freatomagmáticas y brechas
hidrotermales, y también cuerpos intrusivos hipabisales.
El sector de Campanario se caracteriza por presentar alteraciones hidrotermales
principalmente argílica avanzada con una zona “steam-heated” moderadamente
preservada, con un color blanco representativo debido a la abundancia de alunita y
caolinita. Datos espectrales de análisis PIMA evidencian la abundancia de alunita de
composición altamente potásica [KAl3(SO4)2(OH)6] demarcada por un índice espectral
≤1480 nm lo que podría indicar un posible vector de baja temperatura, esta alunita se
encuentra principalmente en la zona de alteración tipo “steam-heated”, la alteración de
cuarzo-alunita alunita-jarosita y la alteración de alunita-dickita. En cuanto a la
geoquímica presente en Campanario se clasifico en base a percentiles teniendo así los
últimos tres percentiles más altos los valores considerados “anómalos” tanto para
elementos “pathfinders” (As, Bi, Hg, Pb, Sb y Te) como los de relevancia económica
(Au y Ag) teniendo así una zona “steam-heated” con intereses prospectivos altos para
la continuación de la exploración hacia niveles más avanzados.
High sulphidation epithermal deposits host mainly important Au-Ag (-Cu) mineralization. The El Indio-Pascua belt is a metallogenic belt of Miocene age that comprises important high sulfidation epithermal deposits such as Pascua-Lama, Veladero, Sancarrón, El Indio, Tambo and Alturas (Figure 1.1). Some of these deposits are characterized by having a "steam-heated" type alteration which is a sterile mantle that forms above the water table (Schoen et al., 1974), and in some of these deposits the mineralization lies under the “steam-heated”. However, characterizing this "steam-heated" type alteration is important to define different aspects to explore these deposits. The rocks that are hosted in the study sector correspond to volcanic and volcanoclastic rocks, including phreatomagmatic breccias and hydrothermal breccias, and also hypabyssal intrusive bodies. The Campanario sector is characterized by hydrothermal alterations, mainly advanced argillic with a moderately preserved "steam-heated" zone, with a representative white color due to the abundance of alunite and kaolinite. Spectral data from PIMA analysis show the abundance of alunite with a highly potassium composition [KAl3(SO4)2(OH)6] demarcated by a spectral index ≤1480 nm which could indicate a possible low temperature vector, this alunite is found mainly in the steam-heated alteration zone, the quartz-alunite alteration, the alunite-jarosite alteration and the alunite-dickite alteration. Regarding the geochemistry present in Campanario, it was classified based on percentiles, thus having the last three highest percentiles the values considered "anomalous" both for "pathfinder" elements (As, Bi, Hg, Pb, Sb and Te) and those of economic relevance (Au and Ag) thus having a "steam-heated" zone with high prospective interests for the continuation of exploration towards more advanced levels.
High sulphidation epithermal deposits host mainly important Au-Ag (-Cu) mineralization. The El Indio-Pascua belt is a metallogenic belt of Miocene age that comprises important high sulfidation epithermal deposits such as Pascua-Lama, Veladero, Sancarrón, El Indio, Tambo and Alturas (Figure 1.1). Some of these deposits are characterized by having a "steam-heated" type alteration which is a sterile mantle that forms above the water table (Schoen et al., 1974), and in some of these deposits the mineralization lies under the “steam-heated”. However, characterizing this "steam-heated" type alteration is important to define different aspects to explore these deposits. The rocks that are hosted in the study sector correspond to volcanic and volcanoclastic rocks, including phreatomagmatic breccias and hydrothermal breccias, and also hypabyssal intrusive bodies. The Campanario sector is characterized by hydrothermal alterations, mainly advanced argillic with a moderately preserved "steam-heated" zone, with a representative white color due to the abundance of alunite and kaolinite. Spectral data from PIMA analysis show the abundance of alunite with a highly potassium composition [KAl3(SO4)2(OH)6] demarcated by a spectral index ≤1480 nm which could indicate a possible low temperature vector, this alunite is found mainly in the steam-heated alteration zone, the quartz-alunite alteration, the alunite-jarosite alteration and the alunite-dickite alteration. Regarding the geochemistry present in Campanario, it was classified based on percentiles, thus having the last three highest percentiles the values considered "anomalous" both for "pathfinder" elements (As, Bi, Hg, Pb, Sb and Te) and those of economic relevance (Au and Ag) thus having a "steam-heated" zone with high prospective interests for the continuation of exploration towards more advanced levels.
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Memoria (Geólogo)
Keywords
Geoquímica, Mineralogía, Alteración Hidrotermal, Chile, Región de Coquimbo