Formation of the Mantoverde iron oxide-copper-gold (IOCG) deposit, Chile: insights from Fe and O stable isotopes and com
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ARTICLE
Formation of the Mantoverde iron oxide-copper-gold (IOCG) deposit, Chile: insights from Fe and O stable isotopes and comparisons with iron oxide-apatite (IOA) deposits Tristan M. Childress 1 Ilya N. Bindeman 5
&
Adam C. Simon 1 & Martin Reich 2 & Fernando Barra 2 & Mauricio Arce 3 & Craig C. Lundstrom 4 &
Received: 1 February 2018 / Accepted: 8 November 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The Mantoverde iron oxide-copper-gold (IOCG) deposit, Chile, contains hundreds of millions of tonnes (Mt) of mineable iron oxide and copper sulfide ore. While there is an agreement that mineralization at Mantoverde was caused by hydrothermal fluid(s), there is a lack of consensus for the role(s) that non-magmatic vs. magmatic fluid(s) played during the evolution of the mineralized system. In order to overcome the hydrothermal overprint at Mantoverde, which is known to disturb most conventional stable isotope systems (e.g., oxygen), we report the first δ56Fe and δ18O pairs for early-stage magnetite and late-stage hematite that provide information on the source reservoir of the hydrothermal fluids. Magnetite δ56Fe values range from 0.46 ± 0.04 to 0.58 ± 0.02‰ and average 0.51 ± 0.16‰ (n = 10; 2σ). Three hematite δ56Fe values were measured to be 0.34 ± 0.10, 0.42 ± 0.09, and 0.46 ± 0.06. Magnetite δ18O values range from 0.69 ± 0.04 to 4.61 ± 0.05‰ and average 2.99 ± 2.70‰ (n = 9; 2σ). Hematite δ18O values range from − 1.36 ± 0.05 to 5.57 ± 0.05‰ and average 0.10 ± 5.38‰ (n = 6; 2σ). These new δ56Fe and δ18O values fingerprint a magmatic-hydrothermal fluid as the predominant ore-forming fluid responsible for mineralization in the Mantoverde system. Keywords Kiruna . Chilean Iron Belt . Magnetite . Hematite . Iron oxide-copper-gold . IOCG . Iron oxide-apatite . IOA
Introduction Iron oxide-copper-gold (IOCG) deposits contain variable quantities of their namesake metals, and some deposits contain mineable grades of rare earth elements (REE), P, U, Ag, Co, Ba, and F (Sillitoe 2003; Williams et al. 2005; Groves
et al. 2010; Barton 2014). Since the discovery in the 1970s of the giant Precambrian Olympic Dam deposit in Australia, investigations of IOCG deposits have focused on determining the source reservoir(s) hydrothermal fluids in order to develop a genetic model that explains mineralization and can be used to guide exploration strategies (Roberts and Hudson 1983;
Editorial handling: M. Fayek Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00126-019-00936-x) contains supplementary material, which is available to authorized users. * Tristan M. Childress [email protected] Adam C. Simon [email protected] Martin Reich [email protected] Fernando Barra [email protected]
Mauricio Arce [email protected] Craig C. Lundstrom [email protected] Ilya N. Bindeman [email protected] Extended author information available on the last page of the article
Miner Deposita
Hitzman et al. 1992; Porter 2000; Williams et al. 2
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