Using the chemical analysis of magnetite to constrain various stages in the formation and genesis of the Kiruna-type chadormalu magnetite-apatite deposit, Bafq district, Central Iran

Heidarian, Hassan; Lentz, David R.; Alirezaei, Saeed; Peighambari, Sima; Hall, Douglas C.

doi:10.1007/s00710-016-0440-8

Cited by 35 publications

(15 citation statements)

References 40 publications

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“…Alteration and remobilization features comparable to those in apatite has recently been documented through SEM and EPMA studies on different magnetite types from the Chadormalu deposit [22]. Primary magnetite (Mag 1) formed initially from magmatic hydrothermal fluids was enriched in Si, Al, and Ca, whereas secondary magnetite (Mag 2) with higher Fe and lower Si, Al, and Ca contents were generated through interaction of the primary ore with infiltrating fluids of non-magmatic origin.…”

Section: Comparison With Magnetite Alterationmentioning

confidence: 87%

Multiple Stage Ore Formation in the Chadormalu Iron Deposit, Bafq Metallogenic Province, Central Iran: Evidence from BSE Imaging and Apatite EPMA and LA-ICP-MS U-Pb Geochronology

et al. 2018

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Abstract:The Chadormalu magnetite-apatite deposit in Bafq metallogenic province, Central Iran, is hosted in the late Precambrian-lower Cambrian volcano-sedimentary rocks with sodic, calcic, and potassic alterations characteristic of iron oxide copper-gold (IOCG) and iron oxide-apatite (IOA) ore systems. Apatite occurs as scattered irregular veinlets and disseminated grains, respectively, within and in the marginal parts of the main ore-body, as well as apatite-magnetite veins in altered wall rocks. Textural evidence (SEM-BSE images) of these apatites shows primary bright, and secondary dark areas with inclusions of monazite/xenotime. The primary, monazite-free fluorapatite contains higher concentrations of Na, Si, S, and light rare earth elements (LREE). The apatite was altered by hydrothermal events that led to leaching of Na, Si, and REE + Y, and development of the dark apatite. The bright apatite yielded two U-Pb age populations, an older dominant age of 490 ± 21 Ma, similar to other iron deposits in the Bafq district and associated intrusions, and a younger age of 246 ± 17 Ma. The dark apatite yielded a U-Pb age of 437 ± 12 Ma. Our data suggest that hydrothermal magmatic fluids contributed to formation of the primary fluorapatite, and sodic and calcic alterations. The primary apatite reequilibrated with basinal brines in at least two regional extensions and basin developments in Silurian and Triassic in Central Iran.

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Section: Comparison With Magnetite Alterationmentioning

confidence: 87%

Multiple Stage Ore Formation in the Chadormalu Iron Deposit, Bafq Metallogenic Province, Central Iran: Evidence from BSE Imaging and Apatite EPMA and LA-ICP-MS U-Pb Geochronology

et al. 2018

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“…The average compositions of "impure" elements in the two samples (C-4, S-2) are plotted in the discriminant diagrams of Al + Mn vs. Ti + V, Ca + Al + Mn vs. Ti + V, and Ni/(Cr + Mn) vs. Ti + V (Figure 7), published by Dupuis and Beaudoin [1], in order to compare with data of silician magnetite from other types of Fe deposits [17][18][19][20]. The mean value of the fairly homogeneous C-4 sample plots within the IOCG field; however, that of the zoned S-2 sample plots in the skarn field.…”

Section: Epmamentioning

confidence: 99%

“…This implies that the Copiapó Nordeste silician magnetite has a chemical characteristic between IOCG-and skarntypes. [4], El Laco (purple) [19], Chadormalu Si-rich magnetite (orange) [20], Chadormalu Si-poor magnetite (yellow) [20], and Chengchao (green) [17]. Modified from Dupuis and Beaudoin [1] and Nadoll et al [3].…”

Section: Epmamentioning

confidence: 99%

Silician Magnetite from the Copiapó Nordeste Prospect of Northern Chile and Its Implication for Ore-Forming Conditions of Iron Oxide–Copper–Gold Deposits

et al. 2018

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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.

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“…However, the presence of cations with variable valence states (e.g., FeO vs. Fe 2 O 3 vs. Fe 3 O 4 ; MnO vs. Mn 3 O 4 ) may complicate the determination of stoichiometric oxygen and significantly affect matrix corrections, as the above cations are assigned a fixed oxidation state (e.g., Fe 2+ for FeO, Fe 2 O 3 and Fe 3 O 4 , and Mn 2+ for both MnO and Mn 3 O 4 ), for example Fe oxides have been extensively described as FeO (e.g., Heidarian et al . , Ivanyuk et al . , Tan et al .…”

mentioning

confidence: 99%

“…In this method, the content of oxygen was calculated by defining the valences of cations in EPMA software, which is useful for analysing oxides where the identities and oxidation states of all cations and anions are known. However, the presence of cations with variable valence states (e.g., FeO vs. Fe 2 O 3 vs. Fe 3 O 4 ; MnO vs. Mn 3 O 4 ) may complicate the determination of stoichiometric oxygen and significantly affect matrix corrections, as the above cations are assigned a fixed oxidation state (e.g., Fe 2+ for FeO, Fe 2 O 3 and Fe 3 O 4 , and Mn 2+ for both MnO and Mn 3 O 4 ), for example Fe oxides have been extensively described as FeO (e.g., Heidarian et al 2016, Ivanyuk et al 2016, Tan et al 2016, Velasco et al 2016, Uenver-Thiele et al 2017, Yin et al 2017, and Mn oxides have been extensively described as MnO (e.g., Gnos andPeters 1995, Bosi et al 2010). Besides, the valence of Fe cation in some solid-solution series of haematite and magnetite is various and cannot be defined before analysis.…”

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confidence: 99%

Electron Probe Microanalysis of Variable Oxidation State Oxides: Protocol and Pitfalls

Yang

Zhang

Jiang

et al. 2017

Geostandard Geoanalytic Res

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Electron probe microanalysis of geological oxide materials relies on stoichiometric considerations to estimate the content of undetermined oxygen and thus calculate ZAF (atomic number, absorption, fluorescence) matrix correction factors, requiring the valences of cations in the corresponding software to be unambiguously defined. However, stoichiometric ZAF corrections may be problematic in the presence of other undetermined elements or variable valence state cations. Herein, we analyse several oxides containing such cations, that is magnetite (Fe3O4), haematite (Fe2O3), hausmannite (Mn3O4) and cuprite (Cu2O). We compare data re‐calculated for incorrect valence states (Method 1) with reference values, revealing incorrect results, due to an incorrect amount of oxygen used in the matrix correction. Some solid‐solution series of haematite and magnetite were also modelled in CalcZAF program to prove the relative errors when the incorrect oxygen is used. To resolve these issues, we describe two accurate methods. Method 2 uses the true valence states of analysed elements. In Method 3, all cations are analysed as metals, with the content of undetermined oxygen determined by difference. As EPMA software does not allow the use of non‐integer valences, Method 3 is applicable to cations with non‐integer or dubious valences in cases where these non‐integer valences cannot be defined.

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Using the chemical analysis of magnetite to constrain various stages in the formation and genesis of the Kiruna-type chadormalu magnetite-apatite deposit, Bafq district, Central Iran

Cited by 35 publications

References 40 publications

Multiple Stage Ore Formation in the Chadormalu Iron Deposit, Bafq Metallogenic Province, Central Iran: Evidence from BSE Imaging and Apatite EPMA and LA-ICP-MS U-Pb Geochronology

Multiple Stage Ore Formation in the Chadormalu Iron Deposit, Bafq Metallogenic Province, Central Iran: Evidence from BSE Imaging and Apatite EPMA and LA-ICP-MS U-Pb Geochronology

Silician Magnetite from the Copiapó Nordeste Prospect of Northern Chile and Its Implication for Ore-Forming Conditions of Iron Oxide–Copper–Gold Deposits

Electron Probe Microanalysis of Variable Oxidation State Oxides: Protocol and Pitfalls

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