Iron Oxide-Copper-gold (IOCG) Deposits

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (20 April 2019) | Viewed by 26428

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Guest Editor
Departamento de Ingeniería en Minas, Facultad de Ingeniería, Universidad de Santiago de Chile, Santiago, Chile
Interests: economic geology; mineralogy, geochemestry; volcanology; metalogenesis; ore petrology; ore deposits exploration; iron ore magma; IOA and IOCG deposits

Special Issue Information

Dear Colleagues,

The discovery of the Olympic Dam, and its definition as a new type of copper deposit with important resources and other commodities (Fe, Au, U) and Iron Oxide-Copper-Gold (IOCG) deposits, has caused great interest in formation processes and characteristic guidelines that are useful for their exploration. New discoveries have emphasized a hydrothermal origin of these deposits but the metal source, and especially the relationship with IOA (Iron oxide-apatite, or Kiruna type) deposits, are still discussed. This Special Issue aims to bring together new discoveries, studies in the areas of mineralogy, alteration, genesis, classification and structural control, and to review the current state-of-the-art in terms of knowledge. We welcome studies from all these areas, including new geological models and exploration guides.

Prof. Fernando Henriquez
Guest Editor

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Keywords

  • IOCG
  • IOA
  • Kiruna
  • genesis
  • classification
  • characteristics
  • alteration
  • magnetite
  • hematite
  • sulfides
  • breccias

Published Papers (3 papers)

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Research

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17 pages, 4933 KiB  
Article
Geology and Genesis of Xianglushan Fe-Cu Orefield in Sichuan (SW China): Evidence from C-O-S-Pb Isotopes
by Tianguo Wang, Chunkit Lai and Huan Li
Minerals 2019, 9(6), 338; https://doi.org/10.3390/min9060338 - 01 Jun 2019
Cited by 1 | Viewed by 2946
Abstract
The Proterozoic Xianglushan Fe-Cu orefield (western Sichuan) is located in the Huili–Dongchuan ore belt on the southwestern margin of the Yangtze Block in SW China. The orefield has experienced complex magmatotectonic activities, and hosts a wide variety of Fe oxide-(Cu-Au) deposits. At Xianglushan, [...] Read more.
The Proterozoic Xianglushan Fe-Cu orefield (western Sichuan) is located in the Huili–Dongchuan ore belt on the southwestern margin of the Yangtze Block in SW China. The orefield has experienced complex magmatotectonic activities, and hosts a wide variety of Fe oxide-(Cu-Au) deposits. At Xianglushan, the orebodies are made of stratabound magnetite–hematite orebodies superimposed by vein-type chalcopyrite mineralization. The stratabound Fe orebodies are hosted mainly in the Proterozoic volcanic-sedimentary rocks of the lower Yinmin Formation, whilst the Cu vein or stockwork ores were mainly emplaced into the upper part of the footwall volcanic rocks and the lower part of the Fe orebodies. We divided the alteration/mineralization and their fluid inclusions (FIs) into the (I) sodic-calcic alteration, (II) potassic-silicic-sericite alteration and Fe-(Cu) mineralization, and (III) carbonate alteration and Cu mineralization stages. Stage II FIs are mainly two-phase (vapor-liquid), and are featured by medium temperature (348 to 379 °C) and high salinity (21.8 to 22.9 wt % NaCl eqv). Their generally negative calcite δ13C (−4.1‰ to −3.1‰) and δ18OH2O (12.2‰ to 15.3‰) values reveal that the Stage II ore fluids have had a seawater-magmatic fluid mixed source. Late Stage II pyrite has δ34S (−3.3‰ to 13.7‰), 206Pb/204Pb (17.663 to 18.982), 207Pb/204Pb (15.498 to 15.824) and 208Pb/204Pb (37.784 to 38.985), suggesting that the ore-forming materials were derived from dominantly upper crustal source. Stage III FIs are also mainly two-phase (vapor-liquid), and are featured by lower temperature (206 to 267 °C) and salinity (19.0 to 22.5 wt % NaCl eqv) than their Stage II counterparts. The Stage III ore fluids were also likely derived from a meteoric–magmatic mixed source with greater magmatic influence, as indicated by the generally negative calcite δ13C (−6.9‰ to −4.6‰) and δ18OH2O (6.3‰ to 9.2‰) values. Similar to the late Stage II pyrite, the Stage III chalcopyrite δ34S (−4.6‰ to 5.2‰) and Pb isotopes (206Pb/204Pb = 18.198 to 18.987; 207Pb/204Pb = 15.534 to 15.876; and 208Pb/204Pb = 37.685 to 39.476) also suggest a crustal ore-forming material source. Therefore, we suggest that the Fe-(Cu) and Cu mineralization at Xianglushan had similar ore fluid and material sources, although the magmatic influence increased in the later stage. This resembles many Fe-(Cu) deposits in the Huili–Dongchuan ore belt. We conclude that the Xianglushan Fe-Cu deposits are both similar to and different from typical iron-oxide copper gold (IOCG) deposits in terms of alteration styles and hydrothermal mineral assemblages, and are thus best classified as IOCG-like deposits hosted in submarine volcanic-sedimentary rocks. Considering the Mesoproterozoic regional tectonics in the southwestern Yangtze Block, we propose that the Xianglushan ore formation occurred in an intra-/back-arc inversion setting, possibly related to the closure of the Anning ocean basin. Full article
(This article belongs to the Special Issue Iron Oxide-Copper-gold (IOCG) Deposits)
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12 pages, 2728 KiB  
Article
Silician Magnetite from the Copiapó Nordeste Prospect of Northern Chile and Its Implication for Ore-Forming Conditions of Iron Oxide–Copper–Gold Deposits
by Elías González, Shoji Kojima, Yoshihiko Ichii, Takayuki Tanaka, Yoshikazu Fujimoto and Takeyuki Ogata
Minerals 2018, 8(11), 529; https://doi.org/10.3390/min8110529 - 14 Nov 2018
Cited by 7 | Viewed by 4851
Abstract
Silica-bearing magnetite was recognized in the Copiapó Nordeste prospect as the first documented occurrence in Chilean iron oxide–copper–gold (IOCG) deposits. The SiO2-rich magnetite termed silician magnetite occurs in early calcic to potassic alteration zones as orderly oscillatory layers in polyhedral magnetite [...] Read more.
Silica-bearing magnetite was recognized in the Copiapó Nordeste prospect as the first documented occurrence in Chilean iron oxide–copper–gold (IOCG) deposits. The SiO2-rich magnetite termed silician magnetite occurs in early calcic to potassic alteration zones as orderly oscillatory layers in polyhedral magnetite and as isolated discrete grains, displaying perceptible optical differences in color and reflectance compared to normal magnetite. Micro-X-ray fluorescence and electron microprobe analyses reveal that silician magnetite has a significant SiO2 content with small amounts of other “impure” components, such as Al2O3, CaO, MgO, TiO2, and MnO. The oscillatory-zoned magnetite is generally enriched in SiO2 (up to 7.5 wt %) compared to the discrete grains. The formation of silician magnetite is explained by the exchange reactions between 2Fe (III) and Si (IV) + Fe (II), with the subordinate reactions between Fe (III) and Al (III) and between 2Fe (II) and Ca (II) + Mg (II). Silician magnetite with high concentrations of SiO2 (3.8–8.9 wt %) was similarly noted in intrusion-related magmatic–hydrothermal deposits including porphyry- and skarn-type deposits. This characteristic suggests that a hydrothermal system of relatively high-temperature and hypersaline fluids could be a substantial factor in the formation of silician magnetite with high SiO2 contents. Full article
(This article belongs to the Special Issue Iron Oxide-Copper-gold (IOCG) Deposits)
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Review

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37 pages, 17976 KiB  
Review
The Olympic Cu-Au Province, Gawler Craton: A Review of the Lithospheric Architecture, Geodynamic Setting, Alteration Systems, Cover Successions and Prospectivity
by Anthony Reid
Minerals 2019, 9(6), 371; https://doi.org/10.3390/min9060371 - 20 Jun 2019
Cited by 44 | Viewed by 15805
Abstract
The Olympic Cu-Au Province is a metallogenic province in South Australia that contains one of the world’s most significant Cu-Au-U resources in the Olympic Dam deposit. The Olympic Cu-Au Province also hosts a range of other iron oxide-copper-gold (IOCG) deposits including Prominent Hill [...] Read more.
The Olympic Cu-Au Province is a metallogenic province in South Australia that contains one of the world’s most significant Cu-Au-U resources in the Olympic Dam deposit. The Olympic Cu-Au Province also hosts a range of other iron oxide-copper-gold (IOCG) deposits including Prominent Hill and Carrapateena. This paper reviews the geology of the Olympic Cu-Au Province by investigating the lithospheric architecture, geodynamic setting and alteration systematics. In addition, since the province is almost entirely buried by post-mineral cover, the sedimentary cover sequences are also reviewed. The Olympic Cu-Au Province formed during the early Mesoproterozoic, ca. 1.6 Ga and is co-located with a fundamental lithospheric boundary in the eastern Gawler Craton. This metallogenic event was driven in part by melting of a fertile, metasomatized sub-continental lithospheric mantle during a major regional tectonothermal event. Fluid evolution and multiple fluid mixing resulted in alteration assemblages that range from albite, magnetite and other higher temperature minerals to lower temperature assemblages such as hematite, sericite and chlorite. IOCG mineralisation is associated with both high and low temperature assemblages, however, hematite-rich IOCGs are the most economically significant. Burial by Mesoproterzoic and Neoproterozoic-Cambrian sedimentary successions preserved the Olympic Cu-Au Province from erosion, while also providing a challenge for mineral exploration in the region. Mineral potential modelling identifies regions within the Olympic Cu-Au Province and adjacent Curnamona Province that have high prospects for future IOCG discoveries. Exploration success will rely on improvements in existing potential field and geochemical data, and be bolstered by new 3D magnetotelluric surveys. However, drilling remains the final method for discovery of new mineral resources. Full article
(This article belongs to the Special Issue Iron Oxide-Copper-gold (IOCG) Deposits)
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