Metamorphic amphiboles in the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin: Implications for potential resource development

Green, Carlin J.; Seal, Robert R.; Piatak, Nadine M.; Cannon, William F.; McAleer, Ryan J.; Nord, Julia Ann

doi:10.2138/am-2020-7211

Cited by 3 publications

(5 citation statements)

References 27 publications

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“…Previous research has associated lower Fe# to higher temperature formation in amphiboles 26 , 27 suggesting that cluster-1 formed at a higher temperature than cluster-2. The composition of actinolite, can be sensitive to prograde and retrograde metamorphic reactions 33 , the amphibole morphology 34 , large changes in pressure conditions 35 , and the presence of coexisting minerals that can incorporate or buffer Fe and Mg 33 . In the Candelaria deposit, the composition of the host rocks is relatively uniform 6 , actinolite composition is independent of grain morphology or texture (Fig.…”

Section: Discussionmentioning

confidence: 99%

Formation of giant iron oxide-copper-gold deposits by superimposed episodic hydrothermal pulses

Real¹,

Reich²,

Simon³

et al. 2023

Sci Rep

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Iron oxide-copper-gold (IOCG) deposits are a globally important source of copper, gold and critical commodities. Despite their relevance, IOCG deposits remain an ill-defined clan, with a range of characteristics that has complicated development of the general genetic model. Here we focus on the Candelaria IOCG deposit in Chile and reveal that by using micro-textural and compositional variations in actinolite, a common alteration mineral found in many IOCG deposits, we can constrain the evolution of these systems. We demonstrate that Candelaria formed by the superposition of at least two pulses of mineralization with a late Cu-rich event overprinting and superimposed over an early, and probably higher temperature, iron oxide-apatite (IOA) mineralization event. These distinct pulses were likely caused by episodic injections of magmatic-hydrothermal fluids from crystallizing magmas at depth. Our data provide empirical evidence of grain-to-deposit scale compositional and potentially temperature changes in an IOCG system. The results support the use of actinolite chemistry as a novel approach to understand the formation of IOCG deposits and a potential tool for vectoring in exploration.

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Section: Discussionmentioning

confidence: 99%

Formation of giant iron oxide-copper-gold deposits by superimposed episodic hydrothermal pulses

Real¹,

Reich²,

Simon³

et al. 2023

Sci Rep

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“…Most of them are high-grade hematite deposits, with multistage fluids moved downward and leached the BIFs along deformation structures, including the Hamersley Province in Australia and the Quadrilátero Ferrífero region in Brazil (Hagemann et al, 2016;Sheppard et al 2017aSheppard et al , 2017bRasmussen and Muhling 2018;Li et al 2019). However, the highgrade Fe ores in China are related to magnetite deposits hosted by BIFs and have undergone retrograde metamorphism with fluid metasomatism (Li and Zhang 2013;Lan et al 2019aLan et al , 2019bGreen et al 2020). High-grade magnetite deposits hosted by BIFs have been mined mainly in the Anshan-Benxi area and eastern Hebei province-Miyun Terrane of the North China (Wan et al 2018;Wang et al 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Compositions of these minerals have been successfully used for tracing the genesis of BIFs and enrichment mechanism of the BIFs-related high-grade Fe ores (e.g., James 1954;Gross 1980Gross , 1983Clout and Simonson 2005;Dai et al 2014Dai et al , 2017Li et al 2019;Aftabi et al 2021;Pirajno and Yu 2021). Most BIFs have undergone retrograde metamorphism at various grades after diagenesis (Klein 1978;Klein and Beukes 1993;Mücke et al 1996;Konhauser et al 2009;Li and Zhang 2013;Lan et al 2019aLan et al , 2019bGreen et al 2020). Magnetite (an abundant and widespread oxide mineral) and apatite (a common tracer mineral) in BIFs are ideal minerals to study the hydrothermal and metamorphic processes, and the genesis of high-grade iron ores of BIFs (Cook et al 2016;Andersson et al 2019;Xing et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…The hydrothermal alteration and metamorphism can modify the structure of magnetite and alter the apatite in BIFs. Some trace elements (e.g., Mg, Mn, Al, Cr, V, and Ti) could partially exchange with Fe in magnetite (Skublov and Drugova 2003;Klein 2005;Zhang et al 2011;Angerer et al 2013Angerer et al , 2016Deng et al 2017;Lan et al 2019aLan et al , 2019bGreen et al 2020), and compositions of the apatite intergrowing or coexisting with magnetite would be partly or completely changed (Piccoli and Candela 2002;Andersson et al 2019;Xing et al 2020;Gillespie et al 2021). Previous studies have found that the hydrothermally altered apatite has been relatively depleted in Sr from the BIFs in Pääkkö of Finland and Hamersley Basin of Australia (Alibert 2016;Azadbakht et al 2018;Andersson et al 2019;Wudarska et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Modified magnetite and hydrothermal apatite might offer insights into the intensity of chemical exchanges during the metamorphism of BIFs, and the metallogenic process of high-grade Fe ores (Urban et al 1992;Duuring et al 2012Duuring et al , 2018Bouzari et al 2016;Adomako-Ansah et al 2017;Soares et al 2017;Kumar et al 2018;Chen et al 2019;Lan et al 2019aLan et al , 2019bGreen et al 2020;Xing et al 2020). However, how the original compositions in magnetite and apatite from BIFs have been modified in such process and its genetic link to high-grade Fe mineralisation remain unclear.…”

Section: Introductionmentioning

confidence: 99%

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Modified magnetite and hydrothermal apatite in banded iron-formations and implications for high-grade Fe mineralization during retrogressive metamorphism

Shi,

Wang,

Bagas

et al. 2024

American Mineralogist

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Modified magnetite and hydrothermal apatite in banded iron-formations (BIFs) are ideal minerals for studying hydrothermal and metamorphic processes, and are applied to linking with high-grade Fe mineralisation and metamorphism in iron deposits hosted by BIFs. This study investigates the geochemical composition of modified magnetite and hydrothermal apatite, and in situ U-Pb geochronology on apatite from the Huogezhuang BIF-hosted Fe deposit in the northeastern China. The magnetite in metamorphosed BIF is modified, locally fragmented and forms mm-to μm-scale bands. The apatite is present surrounding or intergrowing with magnetite, and has corroded surfaces and contains irregularly impurities and fluid inclusions, indicating that it has been partly hydrothermal altered. Original element compositions (e.g., Fe, Al, Ti, K, Mg and Mn) of magnetite in BIFs have been modified during high-grade Fe mineralisation and retrogressive metamorphism with the temperature reduction and acids. The hydrothermally altered apatite has been relatively reduced in Ca, P, F, La, Ce, Nd, δCe, δEu, and total REEs contents compared to non-altered apatite. The magnetite and apatite in low-grade BIFs are poorer in FeO T than those of from the high-grade Fe ores, indicating that Fe is remobilised during the transition from BIFs to high-grade Fe ores. The magnetite and apatite in high-grade Fe ores are overgrown by greenschistfacies minerals formed during retrograde metamorphism, suggesting that the high-grade Fe mineralisation may be related to retrogressive metamorphism.In situ U-Pb geochronology of apatite intergrown with magnetite and zircon LA-ICP-MS U-Pb dating at Huogezhuang deposit reveal that the BIF-hosted magnetite was altered and remobilised at ca. 1950-1900 Ma, and deposition This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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RETRACTED ARTICLE: Formation of giant iron oxide-copper-gold deposits by superimposed, episodic hydrothermal pulses

Real

Reich

Simon

et al. 2021

Commun Earth Environ

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Iron oxide-copper-gold deposits are a globally important source of copper, gold and critical commodities. However, they possess a range of characteristics related to a variety of tectono-magmatic settings that make development of a general genetic model challenging. Here we investigate micro-textural and compositional variations in actinolite, to constrain the thermal evolution of the Candelaria iron oxide-copper-gold deposit in Chile. We identify at least two mineralization stages comprising an early 675–800 °C iron oxide-apatite type mineralization overprinted by a later copper-rich fluid at around 550–700 °C. We propose that these distinct stages were caused by episodic pulses of injection of magmatic-hydrothermal fluids from crystallizing magmas at depth. We suggest that the mineralisation stages we identify were the result of temperature gradients attributable to changes in the magmatic source, rather than variations in formation depth, and that actinolite chemistry can be used as a proxy for formation temperature in iron oxide-copper-gold systems.

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Metamorphic amphiboles in the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin: Implications for potential resource development

Cited by 3 publications

References 27 publications

Formation of giant iron oxide-copper-gold deposits by superimposed episodic hydrothermal pulses

Formation of giant iron oxide-copper-gold deposits by superimposed episodic hydrothermal pulses

Modified magnetite and hydrothermal apatite in banded iron-formations and implications for high-grade Fe mineralization during retrogressive metamorphism

RETRACTED ARTICLE: Formation of giant iron oxide-copper-gold deposits by superimposed, episodic hydrothermal pulses

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