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A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: the case of the El Tesoro Central copper deposit, Atacama Desert, Chile

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Fernández-Mort, A. and Riquelme, R. and Alonso-Zarza, Ana María and Campos, E. and Bissig, T. and Mpodozis, C. and Carretier, S. and Herrera, C. and Tapia, M. and Pizarro, H. and Muñoz, S. (2018) A genetic model based on evapoconcentration for sediment-hosted exotic-Cu mineralization in arid environments: the case of the El Tesoro Central copper deposit, Atacama Desert, Chile. Mineralium Deposita, 53 (6). pp. 775-795. ISSN 0026-4598, ESSN: 1432-1866

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Official URL: https://link.springer.com/article/10.1007/s00126-017-0780-2


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Abstract

lthough the formation of exotic-Cu deposits is controlled by multiple factors, the role of the sedimentary environment has not been well defined. We present a case study of the El Tesoro Central exotic-Cu deposit located in the Atacama Desert of northern Chile. This deposit consists of two mineralized bodies hosted within Late Cenozoic gravels deposited in an arid continental environment dominated by alluvial fans with sub-surficial ponded water bodies formed at the foot of these fans or within the interfan areas. Both exotic-Cu orebodies mostly consist of chrysocolla, copper wad, atacamite, paratacamite, quartz, opal, and calcite. The most commonly observed paragenesis comprises chrysocolla, silica minerals, and calcite and records a progressive increase in pH, which is notably influenced by evaporation. The results of stable isotope analyses (δ13C and δ18O) and hydrogeochemical simulations confirm that evapoconcentration is the main controlling factor in the exotic-Cu mineralization at El Tesoro Central. This conclusion complements the traditional genetic model based on the gradual neutralization of highly oversaturated Cu-bearing solutions that progressively cement the gravels and underlying bedrock regardless of the depositional environment. This study concludes that in exotic-Cu deposits formed relatively far from the source, a favorable sedimentary environment and particular hydrologic and climatic conditions are essential to trap, accumulate, evapoconcentrate, neutralize and saturate Cu-bearing solutions to trigger mineralization. Thus, detailed sedimentological studies should be incorporated when devising exploration strategies in order to discover new exotic-Cu resources, particularly if they are expected to have formed relatively far from the metal sources.


Item Type:Article
Uncontrolled Keywords:Exotic-Cu deposit, Atacama Desert, Chrysocolla, Sediment-hosted ore deposit, Supergene mineralization, Stable isotopes
Subjects:Sciences > Geology > Stratigraphic geology
Sciences > Geology > Mineralogy
Sciences > Geology > Petrology
ID Code:50441
Deposited On:13 Dec 2018 18:23
Last Modified:14 Dec 2018 08:23

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