Original paper

Tectolinear interpretation of the Copiapo Region, Chile

Rojas, Gabriel Pérez

Global Tectonics and Metallogeny Volume 1 Number 3 (1981), p. 246 - 253

16 references

published: Jan 1, 1981

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ArtNo. ESP136000103003, Price: 19.00 €

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Abstract

The Copiapo region is an intensely mineralized part of the Andean Cordillera. One of its principal characteristics is the scarce distribution of cover by Cenozoic volcanic rocks which cover a major part of northern Chile. In this region there has developed an important tradition of mining in which gold, copper and silver are the most important. Tectolinear interpretation of Landsat images has contributed significantly to the study of the distribution of the metal mining districts of the region. Two principal tectolinear elements are described: 1) rectilinear features that are associated to faults, fractures, folds and similar structures; and 2) curvilinear features, generally circular in shape, that are related to intrusive or sub-volcanic bodies. The lineaments vary in strike from N-S, N1O°E, N20°E, N35°E, N55°E, N70°E, E-W, and N1O°W, N30-40°W, and N50°W. The Atacama Fault (AF) is the principal megalineament of the region, having more than 1000 km in length, and which can be subdivided into North, Central and South parts. The last two of these are related closely to a dynamic zone of schistosity, that is 15 km wide and controls the location of some of the deposits of iron, copper and gold that are found in the Coastal Cordillera (e.g., Algarrobo, Tofo, Boqueron Chanar, Carrizal Alto, Pajonales, and others). There are also lineaments that are transversal to the Atacama Fault with strikes bearing NW, NNW and WNW that also control the distribution of deposits in mining districts such as Las Animas as well as the emplacement of some intrusive bodies. The curvilinear features correspond to structures that control El Salvador, Cerro Pingo and Cerro La Peineta of 18, 20 and 50 km in diameter, respectively, and which are confined to the Central Valley. The majority of these correspond to a species of ring dike in the perifery of which are circular structures controlling the distribution of mineralized chimneys of tourmaline breccia as found in the Cabeza de Vaca mining district.

Abstract

La región de Copiapó es un área intensamente mineralizada de la Cordillera de Los Andes, siendo una de sus principales caracteristicas las escasa distribución de la cubierta de rocas cenozoicas volcanicas que cubre la mayor parte del norte de Chile. En esta región se ha desarrollado una tradición minera importante en ore, cobre y plata. La interpretacion tectolinear de imagenes Landsat ha contribuido al estudio de la distribucion de los distritos mineros metálicos de la región. Se describen dos elementos tectolineares: los rectilineos asociados a fallas, fracturas, pligues, etc y los curvilineos definidos como estructuras aproximadamente circulares relacionadas a cuerpos intrusivos o sub-volcánicos. Los lineamientos presentan rumbos que varian entre NS, N10° E, N20° E, N35° E, N55° E, N70° E, EW, N10° W, N30-40° W y N50° W. La falla Atacama (FA) es el principal megalineamiento de la región, tiene mas de 1000 km de longitud y se subdivide en las partes Norte, Central y Sur. Las dos últimas se presentan relacionadas a una zona de esquistos dinamico. Tiene 15 km de ancho y controla algunos de los yacimientos de hierro, cobre y oro de la Cordillera de la Costa. (Algarrobo, Tofo, Boquerón Chanar, Carrizal Alto, Pajonales, etc.). Hay lineamientos transversales a la Falla Atacama de rumbo NW, NNW y WNW que tambien controlan la distribución de yacimientos de distritos mineros como Las Animas y el emplazamiento de cuerpos intrusivos. Los curvilineam ientos corresponden a la estructuras El Salvador, Cerro Pingo, y Cerro La Peineta de 18, 20 y 50 km de diámetro que se presentan restringidas al Valle Central. La mayor de ellas corresponde a una especie de ring dike en cuya periferia contiene una estructura circular menor que controla la distribución de las chimeneas mineralizadas de brecha de turmalina del distrito Cabeza de Vaca.

Keywords

Copiapo RegionChilegoldcoppersilverLas AnimasCoastal Cordilleratourmaline