Análisis estructural del distrito El Asiento, San Felipe (32°41’-32°42’ S; 70°47’-70°48’ W) . Implicancias para el desarrollo minero de la zona
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2021
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es
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Universidad Andrés Bello
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Resumen
El distrito minero El Asiento, corresponde a una zona minera de pequeña escala con una extensa historia caracterizada por minerales metálicos de alta ley, sin embargo, no existe conocimiento que permita definir el tipo de depósito, así como sus características, por ende, este estudio en base a un análisis geológico-estructural presenta las principales características que controlan la mineralización en esta zona minera, aportando a una mejor optimización de la labor extractiva llevada a cabo.
Este distrito se ubica al noreste de la Ciudad de San Felipe, posee una serie de depósitos polimetálicos desarrollados en rocas Volcanoclásticas del cretácico, pertenecientes a la Formación Las Chilcas, enmarcadas dentro de la franja metalogénica del Cretácico. La mina ―La Platina‖ corresponde a un sistema de vetas masivas polimetálicas de Cobre-Plata y en menor medida Oro, Plomo y Zinc, las que poseen una morfología tabular lineal semi-continua, con una orientación general NNW-SSE y una elongación (σ2) subvertical hacia el SSW. El Análisis estructural y geológico realizado en el yacimiento, muestra las diferentes características que pose este depósito, donde el factor de mayor influencia en la distribución de las vetas es el control estructural.
El análisis de este sistema estructural y su posterior integración a un modelo 3D, permitió determinar un sistema de deformación tipo Riedel de cinemática dextral. Las estructuras principales dextrales (NNW-SSE) controlan la disposición de las veta mientras que las estructuras secundarias sinistrales (R’) generan la dislocación de las mismas dando lugar a los saltos de falla que modifican la trayectoria lineal de las vetas hacia el oeste, pero también favorece la intersección de estructuras, aumento de permeabilidad y el desarrollo de clavos mineralizados de mayor ley con orientación NNE.
La mineralogía de mena está compuesta principalmente por sulfuros de Cobre hipógenos tales como Bornita y calcopirita, también por sulfuros de cobre supérgenos como Covelina-Calcosina, además de Óxidos de cobre. La mineralogía de ganga y los minerales de alteración sugieren un pH de formación neutro a alcalino, en un ambiente mesotermal, características semejantes a los depósitos epitermales de sulfuración intermedia a baja. Las características obtenidas permiten definir el yacimiento como un deposito veta-falla, con orientación NNW-SSE y una dimensión de aproximadamente 16.140 toneladas de material rico en metales.
Este análisis en conjunto con la utilización de modelos geológicos 3D, otorga una mejor visión, además de un dimensionamiento más preciso de los cuerpos minerales y corresponde a una importante herramienta de optimización para la labor extractiva.
The El Asiento mining district, corresponds to a small-scale mining area with an extensive history characterized by high-grade metallic minerals, however, there is no knowledge that allows defining the type of deposit, as well as its characteristics, therefore, this study based on a geological-structural analysis, it presents the main characteristics that control mineralization in this mining area, contributing to a better optimization of the extractive work carried out. This district is located northeast of the city of San Felipe, has a series of polymetallic deposits developed in Cretaceous Volcanoclastic rocks, belonging to the Las Chilcas Formation, framed within the Cretaceous metallogenic band. The ―La Platina‖ mine corresponds to a system of massive polymetallic veins of Copper-Silver and to a lesser extent Gold, Lead and Zinc, which have a semi-continuous linear tabular morphology, with a general NNW-SSE orientation and an elongation (σ2) subvertical towards the SSW. The structural and geological analysis carried out in the deposit shows the different characteristics of this deposit, where the factor with the greatest influence on the distribution of the veins is structural control. The analysis of this structural system and its subsequent integration into a 3D model, made it possible to determine a Riedel-type deformation system with dextral kinematics. The dextral main structures (NNW-SSE) control the arrangement of the veins while the sinister secondary structures (R’) generate their dislocation, giving rise to fault jumps that modify the linear trajectory of the veins towards the west. but it also favors the intersection of structures, increased permeability, and the development of higher-grade mineralized nails with a NNE orientation. The ore mineralogy is mainly composed of hypogen copper sulphides such as Bornite and chalcopyrite, also by supergen copper sulphides such as Covelina-Calcosina, in addition to copper oxides. The gangue mineralogy and alteration minerals suggest a neutral to alkaline formation pH, in a mesothermal environment, characteristics similar to intermediate to low sulphidation epithermal deposits. The characteristics obtained allow the deposit to be defined as a vein-fault deposit, with a NNW-SSE orientation and a dimension of approximately 16,140 tons of material rich in metals. This analysis, together with the use of 3D geological models, provides a better vision, as well as a more precise dimensioning of the mineral bodies and corresponds to an important optimization tool for extractive work.
The El Asiento mining district, corresponds to a small-scale mining area with an extensive history characterized by high-grade metallic minerals, however, there is no knowledge that allows defining the type of deposit, as well as its characteristics, therefore, this study based on a geological-structural analysis, it presents the main characteristics that control mineralization in this mining area, contributing to a better optimization of the extractive work carried out. This district is located northeast of the city of San Felipe, has a series of polymetallic deposits developed in Cretaceous Volcanoclastic rocks, belonging to the Las Chilcas Formation, framed within the Cretaceous metallogenic band. The ―La Platina‖ mine corresponds to a system of massive polymetallic veins of Copper-Silver and to a lesser extent Gold, Lead and Zinc, which have a semi-continuous linear tabular morphology, with a general NNW-SSE orientation and an elongation (σ2) subvertical towards the SSW. The structural and geological analysis carried out in the deposit shows the different characteristics of this deposit, where the factor with the greatest influence on the distribution of the veins is structural control. The analysis of this structural system and its subsequent integration into a 3D model, made it possible to determine a Riedel-type deformation system with dextral kinematics. The dextral main structures (NNW-SSE) control the arrangement of the veins while the sinister secondary structures (R’) generate their dislocation, giving rise to fault jumps that modify the linear trajectory of the veins towards the west. but it also favors the intersection of structures, increased permeability, and the development of higher-grade mineralized nails with a NNE orientation. The ore mineralogy is mainly composed of hypogen copper sulphides such as Bornite and chalcopyrite, also by supergen copper sulphides such as Covelina-Calcosina, in addition to copper oxides. The gangue mineralogy and alteration minerals suggest a neutral to alkaline formation pH, in a mesothermal environment, characteristics similar to intermediate to low sulphidation epithermal deposits. The characteristics obtained allow the deposit to be defined as a vein-fault deposit, with a NNW-SSE orientation and a dimension of approximately 16,140 tons of material rich in metals. This analysis, together with the use of 3D geological models, provides a better vision, as well as a more precise dimensioning of the mineral bodies and corresponds to an important optimization tool for extractive work.
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Tesis (Geólogo)
Palabras clave
Mineralización, Depósitos Minerales, Chile, San Felipe