Caracterización petrográfica e hidrotermal, su relación con las fallas Lechuza y el Alamo y el emplazamiento magmático cretácico en el sector Cruz de Caña y Mollaco, Región de Coquimbo, Chile
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Archivos
Fecha
2023
Profesor/a Guía
Facultad/escuela
Idioma
es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
El presente trabajo se llevó a cabo con el fin de caracterizar y delimitar
en superficie las zonas de alteración y litologías en un área aproximada de 15 km2
la cual se encuentra en la región de Coquimbo, a 26km aprox desde el centro de la
ciudad homónima, inmersa en la Franja metalogénica Cretácica inferior también
llamada Franja Ferrífera; el área abarca parte de los sectores Cruz de Caña (norte)
y Mollaco (sur). A través de la integración de diferentes metodologías, entre ellas
teledetección, petrografía, calcografía y trabajo de campo. Petrográficamente el
área está constituida por litologías ígneas básicas, junto a volcanosedimentarias.
Los minerales metálicos responden a un sistema polimetálico con presencia de oro,
plata, cobre, manganeso y hierro. El sector Cruz de Caña difiere con Mollaco debido
a su mayor ocurrencia de minerales asociados a Cu y menor cantidad de Fe. Este
estudio se enfoca en las menas de hierro predominantes en el área; magnetita ±
hematita, las cuales tienen una ocurrencia diseminada, brechosa y en diques
masivos, respondiendo a un patrón estructural de tendencias N-S NNE-SSW
asociadas probablemente a un dúplex extensional definido por las ramificaciones
de la falla Lechuza. Las alteraciones observadas se caracterizan por ensambles
mineralógicos sódica-cálcica (Carten, 1986) de diferentes temperaturas, potásicas,
fílicas y supérgenas, los cuales se encuentran sobre impuestos. Integrando los
datos del área, se evidencia que el sistema guarda relación con el modelo que
plantea Barra et al. (2017) en el cual se presenta una zonación vertical para
depósitos tipo IOCG. Correspondiendo la presente área de trabajo a una zona de
transición entre IOA-IOCG.
The present work was carried out in order to characterize and delimit on surface the alteration zones and lithologies in an area of approximately 15 km2 which is located in the region of Coquimbo, approximately 26km from the center of the city of the same name, immersed in the Lower Cretaceous metallogenic belt also called Ferriferous Belt; the area includes part of the Cruz de Caña (north) and Mollaco (south) sectors. Through the integration of different methodologies, including remote sensing, petrography, chalcography and field work. Petrographically, the area is constituted by basic igneous lithologies, together with volcanosedimentary ones. The metallic minerals respond to a polymetallic system with the presence of gold, silver, copper, manganese and iron. The Cruz de Caña sector differs from Mollaco due to its higher occurrence of Cu-associated minerals and lower amount of Fe. This study focuses on the predominant iron ores in the area; magnetite ± hematite, which have a disseminated, brecciated and massive dykes occurrence, responding to a structural pattern of N-S NNE-SSW trends probably associated to an extensional duplex defined by the branches of the Lechuza fault. The observed alterations are characterized by sodic-calcic mineralogical assemblages (Carten, 1986) of different temperatures, potassic, phyllic and supergene, which are over-taxed. Integrating the data of the area, it is evident that the system is related to the model proposed by Barra et al. (2017) in which a vertical zonation for IOCG type deposits is presented. The present work area corresponds to a transition zone between IOA-IOCG.
The present work was carried out in order to characterize and delimit on surface the alteration zones and lithologies in an area of approximately 15 km2 which is located in the region of Coquimbo, approximately 26km from the center of the city of the same name, immersed in the Lower Cretaceous metallogenic belt also called Ferriferous Belt; the area includes part of the Cruz de Caña (north) and Mollaco (south) sectors. Through the integration of different methodologies, including remote sensing, petrography, chalcography and field work. Petrographically, the area is constituted by basic igneous lithologies, together with volcanosedimentary ones. The metallic minerals respond to a polymetallic system with the presence of gold, silver, copper, manganese and iron. The Cruz de Caña sector differs from Mollaco due to its higher occurrence of Cu-associated minerals and lower amount of Fe. This study focuses on the predominant iron ores in the area; magnetite ± hematite, which have a disseminated, brecciated and massive dykes occurrence, responding to a structural pattern of N-S NNE-SSW trends probably associated to an extensional duplex defined by the branches of the Lechuza fault. The observed alterations are characterized by sodic-calcic mineralogical assemblages (Carten, 1986) of different temperatures, potassic, phyllic and supergene, which are over-taxed. Integrating the data of the area, it is evident that the system is related to the model proposed by Barra et al. (2017) in which a vertical zonation for IOCG type deposits is presented. The present work area corresponds to a transition zone between IOA-IOCG.
Notas
Tesis (Geólogo)
Palabras clave
Petrografía, Litología, Alteración Hidrotermal, Chile, Región de Coquimbo