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The Cupriferous Province of the Coastal Range, Northern Chile

By
Sergio Espinoza R.
Sergio Espinoza R.
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HÉCtor Veliz G.
HÉCtor Veliz G.
Departamento de Ciencias Geológicas, Universidad Católica del Norte. Box 1280, Antofagasta, Chile
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Justo Esquivel L.
Justo Esquivel L.
Minera Logrono, Monte Grande 371, Antofagasta, Chile
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Jaime Arias F.
Jaime Arias F.
Minera Oregon Ltda. Box 1155, Antofagasta, Chile
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Aldo Moraga B.
Aldo Moraga B.
Eulogio Gordo y Compañía. Box 940, Antofagasta, Chile
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Published:
January 01, 1998

Abstract

The Coastal Range of northern Chile is formed mainly by andesitic-basaltic lavas intruded by granitoids of intermediate composition. These rocks originated as a result of the development of a Jurassic-lower Cretaceous magmatic arc, which marks the beginning of the evolution of the Andean Tectonic Cycle. Copper deposits emplaced in these rocks constitute a polytypical, homochronic, and practically monometallic metallogenetic province.

The distinctive characteristics of these mineral deposits are strongly controlled by the nature of the rocks in which they are hosted. These deposits can be grouped in:

Volcanic-hosted deposits

Buena Esperanza Type

Buena Esperanza Sub-Type (“manto type”): Pseudostratiform deposits with chalcocite, bornite and minor chal-copyrite mineralization which occur as: stratiform disseminated mineralization located in the tops of successive vesicular lava flows; hydrothermal breccias, and fracture filling. 
Carolina Sub-Type: Veins emplaced in volcanics which present an important oxidation zone with atacamite. 
Mantos Blancos Sub-Type: with similar characteristics to the Buena Esperanza type but hosted in more acid older rocks. 
Intrusive-hosted deposits.   
Montecristo Type veins: Vein filling includes abundant iron oxides, actinolite, pyrite, chal-copyrite, bornite; ocassionally with minor quantities of apatite, tourmaline, quartz and calcite. Antlerite and atacamite occur in their deep oxidation zones. Some veins contain gold 
Sedim entary-hosted deposits.   
Caleta Coloso ore deposits: Atacamite and djurleite mineralization in Neocomian alluvial fan, conglomerates and sandstones of Caleta Coloso Formation. 
Buena Esperanza Sub-Type (“manto type”): Pseudostratiform deposits with chalcocite, bornite and minor chal-copyrite mineralization which occur as: stratiform disseminated mineralization located in the tops of successive vesicular lava flows; hydrothermal breccias, and fracture filling. 
Carolina Sub-Type: Veins emplaced in volcanics which present an important oxidation zone with atacamite. 
Mantos Blancos Sub-Type: with similar characteristics to the Buena Esperanza type but hosted in more acid older rocks. 
Intrusive-hosted deposits.   
Montecristo Type veins: Vein filling includes abundant iron oxides, actinolite, pyrite, chal-copyrite, bornite; ocassionally with minor quantities of apatite, tourmaline, quartz and calcite. Antlerite and atacamite occur in their deep oxidation zones. Some veins contain gold 
Sedim entary-hosted deposits.   
Caleta Coloso ore deposits: Atacamite and djurleite mineralization in Neocomian alluvial fan, conglomerates and sandstones of Caleta Coloso Formation. 

Other deposits and prospects, still little studied, occur as breccia pipes and stockworks related to intrusive rocks.

The Buena Esperanza Type is the most studied and important deposit from an economical point of view. Several mechanisms have been proposed for the Buena Esperanza genesis including syngenetic volcanic, epigenetic post-volcanic, epigenetic and hydrothermal metamorphic. An important characteristic of this type of deposits is their invariable association with hypabyssal intrusive bodies initially interpreted as volcanic feeder conduits, but radiometric dating indicates they are 20 to 30 Ma younger. If, however, an early mineralization related to the volcanism is not discarded, new evidence indicates that there could have been mineralization related to later hydrothermal phenomena during the Jurassic and part of the lower Cretaceous.

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Contents

Special Publications of the Society of Economic Geologists

Andean Copper Deposits: New Discoveries, Mineralization, Styles and Metallogeny

Francisco Camus
Francisco Camus
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Richard M. Sillitoe
Richard M. Sillitoe
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Richard Petersen
Richard Petersen
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Society of Economic Geologists
Volume
5
ISBN electronic:
9781629490298
Publication date:
January 01, 1998

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