Discriminant diagrams for iron oxide trace element fingerprinting of mineral deposit types

Mineralium Deposita (Impact Factor: 2.56). 04/2011; 46(4):319-335. DOI: 10.1007/s00126-011-0334-y

ABSTRACT Magnetite and hematite are common minerals in a range of mineral deposit types. These minerals form partial to complete solid
solutions with magnetite, chromite, and spinel series, and ulvospinel as a result of divalent, trivalent, and tetravalent
cation substitutions. Electron microprobe analyses of minor and trace elements in magnetite and hematite from a range of mineral
deposit types (iron oxide-copper-gold (IOCG), Kiruna apatite–magnetite, banded iron formation (BIF), porphyry Cu, Fe-Cu skarn,
Fe-Ti, V, Cr, Ni-Cu-PGE, Cu-Zn-Pb volcanogenic massive sulfide (VMS) and Archean Au-Cu porphyry and Opemiska Cu veins) show
compositional differences that can be related to deposit types, and are used to construct discriminant diagrams that separate
different styles of mineralization. The Ni + Cr vs. Si + Mg diagram can be used to isolate Ni-Cu-PGE, and Cr deposits from
other deposit types. Similarly, the Al/(Zn + Ca) vs. Cu/(Si + Ca) diagram can be used to separate Cu-Zn-Pb VMS deposits from
other deposit types. Samples plotting outside the Ni-Cu-PGE and Cu-Zn-Pb VMS fields are discriminated using the Ni/(Cr + Mn)
vs. Ti + V or Ca + Al + Mn vs. Ti + V diagrams that discriminate for IOCG, Kiruna, porphyry Cu, BIF, skarn, Fe-Ti, and V deposits.

KeywordsMagnetite–Hematite–Mineral deposit–Electron microprobe–Mineral chemistry–Discriminant diagram

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Available from: Georges Beaudoin, Sep 27, 2015
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    • "Magnetite composition from a wide variety of iron deposit types has been the focus of many recent studies (e.g., Dupuis and Beaudoin, 2011; Huang et al., 2013; McQueen and Cross, 1998). Those studies have demonstrated that trace elemental compositions of iron oxides are important for the understanding of the origin of different mineralization styles (Müller et al., 2003; Carew, 2004; Singoyi et al., 2006; Anderson et al., 2008; Dupuis and Beaudoin, 2011; Dare et al., 2012; Nadoll et al., 2014; Chen et al., 2015; Huang et al., 2015; Liu et al., 2015; Zhao Ore Geology Reviews 65 (2015) 917–928 ⁎ Corresponding author. "
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    ABSTRACT: Keywords: Magnetite Trace elements LA–ICP-MS Late Palaeoproterozoic Iron formation Labrador Trough Sokoman Formation Canada The Sokoman Iron Formation in the Labrador Trough, Canada, a typical granular iron formation (GIF), is coeval with the ~1.88 Ga Nimish volcanic suites in the same region. It is composed of the Lower, Middle and Upper Iron Formations. In addition to primary and altered magnetite in iron formations of the Hayot Lake, Rainy Lake and Wishart Lake areas, magnetite in volcanic breccia associated with the iron formation is identified for the first time in the stratigraphy. Trace elemental compositions of the most primary, altered and volcanic brecciated magnetite of the Sokoman Iron Formation were obtained by LA–ICP-MS. Commonly detected trace elements of magnetite include Ti, Al, Mg, Mn, V, Cr, Co and Zn. These three types of magnetite have different trace elemental compositions. Primary magnetite in the iron formation has a relatively narrow range of compositions with the depletion of Ti, Pb, Mg and Al. Magnetite from volcanic breccia is rich in Ti, Al, V, Mn, Mg, Zn, Cu and Pb, indicative of crystallization from mantle-derived magmas. Altered magnetite in the iron formation shows a relatively wide range of trace elemental compositions. Mineralizing fluids associated with magmas that generated the ~1.88 Ga Nimish volcanic suites circulated through the sedimentary piles to further enrich the iron formations and to form magnetite with variable compositions. The comparisons of different types of primary and altered magnetite in the iron formation in the region show distinct provenance discrimination. Our findings also support the origin of iron formations in association with multiple stages of exhalative volcanic and hydrothermal processes.
    Ore Geology Reviews 11/2015; 65. DOI:10.1016/j.oregeorev.2014.09.030 · 3.56 Impact Factor
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    • "Magnetite contains numerous trace elements, such as Al, Ti, Mg, Mn, Zn, Cr, V, Ni, Co and Ga, and can form in a variety of physico-chemical environments. Chemical composition of magnetite thus can be used to fingerprint the types of mineral deposits and to distinguish different ore forming processes (Beaudoin and Dupuis, 2009; Carew, 2004; Chen et al., 2015-in this issue; Dare et al., 2012; Dupuis and Beaudoin, 2011; Hu et al., 2013; Huang et al., 2013, 2014, 2015-in this issue; Müller et al., 2003; Nadoll et al., 2012, 2014; Rusk et al., 2009; Singoyi et al., 2006). Previous studies of Fe oxides in Bayan Obo have dealt with the paragenesis and chemical compositions of magnetite (IGCAS (Institute of Geochemistry, Chinese Academy of Sciences), 1988; Wei and Shangguan, 1983; Zeng et al., 1981) . "
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    ABSTRACT: Keywords: Trace element LA-ICP-MS Magnetite Hematite Bayan Obo North China The Bayan Obo Fe-REE-Nb deposit in northern China is the world's largest light REE deposit, and also contains considerable amounts of iron and niobium metals. Although there are numerous studies on the REE mineraliza-tion, the origin of the Fe mineralization is not well known. Laser ablation (LA) ICP-MS is used to obtain trace elements of Fe oxides in order to better understand the process involved in the formation of magnetite and hematite associated with the formation of the giant REE deposit. There are banded, disseminated and massive Fe ores with variable amounts of magnetite and hematite at Bayan Obo. Magnetite and hematite from the same ores show similar REE patterns and have similar Mg, Ti, V, Mn, Co, Ni, Zn, Ga, Sn, and Ba contents, indicating a similar origin. Magnetite grains from the banded ores have Al + Mn and Ti + V contents similar to those of banded iron formations (BIF), whereas those from the disseminated and massive ores have Al + Mn and Ti + V contents similar to those of skarn deposits and other types of magmatic-hydrothermal deposits. Magnetite grains from the banded ores with a major gangue mineral of barite have the highest REE contents and show slight moderate REE enrichment, whereas those from other types of ores show light REE enrichment, indicating two stages of REE mineralization associated with Fe mineralization. The Bayan Obo deposit had multiple sources for Fe and REEs. It is likely that sedimentary carbonates provided original REEs and were metasomatized by REE-rich hydrothermal fluids to form the giant REE deposit.
    Ore Geology Reviews 10/2015; 65. DOI:10.1016/j.oregeorev.2014.09.010 · 3.56 Impact Factor
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    • "These concentrations and distributions are useful for discriminating types of mineralization, tracing the provenance of detrital/alluvial oxide resources and understanding the genesis of an ore deposit (e.g. Dupuis and Beaudoin 2011; Nadoll et al. 2014; Boutroy et al. 2014). Moreover, the recent discovery of U and Pb in hematite shows the potential application of Fe-oxides as geochronometers to provide direct ages and estimate the lifespan for mineralization (Ciobanu et al. 2013). "
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    ABSTRACT: Iron oxides, the dominant minerals in the giant Olympic Dam IOCG deposit, contain concentrations of more than 25 trace elements at concentrations measurable by LA-ICP-MS, including several elements not commonly reported (or analyzed for). Mineral geochemical signatures based on W, U, Sn and Mo (named 'granito-phile' elements), and chondrite-normalized REY fractionation trends for hematite and magnetite show promise to distinguish discrete generations of Fe-oxides when interpreted in their petrographic context. Fe-oxides are possibly the main mineral repositories of elements such as W, Mo and Sn, and may play significant roles in the overall mineralogical balance of several others, notably U and REY.
    SGA Biennial Meeting 2015, Nancy, France; 08/2015
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