In situ LA–ICP-MS and EPMA trace element characterization of Fe–Ti oxides from the phoscorite–carbonatite association at Phalaborwa, South Africa

Milani, Lorenzo; Bolhar, Robert; Cawthorn, R. Grant; Frei, Dirk

doi:10.1007/s00126-016-0696-2

Cited by 27 publications

(9 citation statements)

References 80 publications

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“…These ages suggest a synchronous emplacement of the main geological units. Compositions of banded carbonatite and phoscorite indicate a cogenetic origin of these two rocks, which support the concept of a rapid emplacement of the Loolekop carbonatite–phoscorite complex (Wu et al , 2011; Milani et al , 2017a, b).…”

Section: Geological Settingsupporting

confidence: 64%

“…In the Loolekop Pipe, immiscibility combined with density difference and magmatic flow leads to the preferential emplacement of phoscorite along the edges of the intrusion (Basson et al , 2017; Giebel et al , 2019). Another possibility for the genesis of the carbonatite and phoscorite involves fractional crystallisation (Skulski et al , 1994; Veksler et al , 1998; Chakhmouradian, 2006; Milani et al , 2017a, b). Mineralogical zoning was also observed in both the Kovdor and Salmagorskii intrusions and ascribed to fractional crystallisation (Korobeinikov et al , 1998; Ivanyuk et al , 2016).…”

Section: Discussionmentioning

confidence: 99%

“…3). It is particularly the case between chalcopyrite and magnetite in the Loolekop Pipe due to the high Ti content of magnetite (Milani et al , 2017a), which significantly lowers its attenuation coefficient (Fig. 3).…”

Section: Samples and Methodsmentioning

confidence: 99%

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Three-dimensional textural investigation of sulfide mineralisation from the Loolekop carbonatite–phoscorite polyphase intrusion in the Phalaborwa Igneous Complex (South Africa), with implications for ore-forming processes

Bras

Bolhar

Bam

et al. 2021

MinMag

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Section: Geological Settingsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

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Three-dimensional textural investigation of sulfide mineralisation from the Loolekop carbonatite–phoscorite polyphase intrusion in the Phalaborwa Igneous Complex (South Africa), with implications for ore-forming processes

Bras

Bolhar

Bam

et al. 2021

MinMag

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“…Before starting an analysis, the system was calibrated to a NIST 612 reference glass measuring 139 27 Al, 29 Si, 43 Ca, 4 5Sc, 49 Ti, 51 V, 53 Cr, 55 Mn, 59 Co, 60 Ni, 63 Cu, 66 Zn, 69 Ga, 85 were quantitatively analyzed using the NIST 612 glass as an external standard while stoichiometric Fe (97% wt.% FeO) was the internal standard, since total concentration of minor elements is <3 wt.% (cf. Milani et al [60]). Run time of the single ablation pattern was 60 s (20 s for background and 40 s for peak after switching the laser on).…”

Section: Methodsmentioning

confidence: 99%

Trace Elements in Magnetite from the Pagoni Rachi Porphyry Prospect, NE Greece: Implications for Ore Genesis and Exploration

et al. 2019

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Magnetite is a common accessory phase in various types of ore deposits. Its trace element content has proven to have critical implications regarding petrogenesis and as guides in the exploration for ore deposits in general. In this study we use LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) analyses of trace elements to chemically characterize magnetite from the Pagoni Rachi Cu–Mo–Re–Au porphyry-style prospect, Thrace, northern Greece. Igneous magnetite mostly occurs as euhedral grains, which are commonly replaced by hematite in fresh to propylitic-altered granodiorite porphyry, whereas, hydrothermal magnetite forms narrow veinlets or is disseminated in sodic/potassic-calcic altered (albite + K-feldspar + actinolite + biotite + chlorite) granodiorite porphyry. Magnetite is commonly associated with chalcopyrite and pyrite and locally exhibits martitization. Laser ablation ICP-MS analyses of hydrothermal magnetite yielded elevated concentrations in several trace elements (e.g., V, Pb, W, Mo, Ta, Zn, Cu, and Nb) whereas Ti, Cr, Ni, and Sn display higher concentration in its magmatic counterpart. A noteworthy enrichment in Mo, Pb, and Zn is an unusual feature of hydrothermal magnetite from Pagoni Rachi. High Si, Al, and Ca values in a few analyses of hydrothermal magnetite imply the presence of submicroscopic or nano-inclusions (e.g., chlorite, and titanite). The trace element patterns of the hydrothermal magnetite and especially the decrease in its Ti content reflect an evolution from the magmatic towards the hydrothermal conditions under decreasing temperatures, which is consistent with findings from analogous porphyry-style deposits elsewhere.

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“…Corresponding low 18 OH2O values (-0.45 to 1.01 ‰) for these fluids suggest interaction with Archean seawater or meteoric waters. Oxide-Apatite (Dupuis and Beaudoin, 2011), VMS deposits (Singoyi et al, 2006;Makvandi et al, 2016), carbonatite in Phalaborwa (Milani et al, 2016), as well as porphyry Cu-Mo, skarn, Ag-Pb-Zn veins, and BIF (Dupuis and Beaudoin, 2011;Nadoll, 2011;Nadoll et al, 2014). Recently, magnetite and hematite compositions have been used to identify the involvement of metamorphic and hydrothermal fluids in the genesis of high-grade iron orebodies hosted by BIF in the Quadrilátero Ferrífero, Brazil (Cabral and Rosière, 2013;Hensler et al, 2015), and the Koolyanobbing and Marda greenstone belts, Western Australia (Angerer et al, 2012;Angerer et al, 2013).…”

Section: Carbon and Oxygen Isotope Data: Fluid Sourcesmentioning

confidence: 99%

A synvolcanic origin for magnetite-rich orebodies hosted by BIF in the Weld Range District, Western Australia

Duuring

Hagemann

Banks

et al. 2018

Ore Geology Reviews

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Iron ore deposits hosted by Archean banded iron-formation (BIF) in the Weld Range greenstone belt are representative of most of the documented iron ore deposits in the Yilgarn Craton. They include nearsurface, supergene goethite-hematite orebodies that overlie and partly modify deeper occurrences of hypogene magnetite and specular hematite ores. The Cenozoic goethite-hematite-rich orebodies in these deposits are unequivocally the product of meteoric fluid alteration affecting BIF in the near-surface supergene environment; however, the deeper and likely older magnetite-and specular hematite-rich orebodies have a more contentious origin. This study is the first to present a fluid-alteration model for hypogene iron mineralization in the Yilgarn Craton that uses fluid inclusion and mineral chemistry data to constrain the physical-chemical characteristics and source of hypogene fluids responsible for mineralization. High-grade (>57 wt% Fe), magnetite-rich iron ore at the Beebyn deposit defines a discontinuous series of <80 m-thick by <1 km-long lenses that extend 3 km along strike in the BIF. These magnetite-rich lenses are surrounded by a broad carbonate alteration halo in the BIF and intense ferroan chlorite and talc alteration in nearby basalt, dolerite, and gabbro country rocks. Magnetite-rich lenses at Beebyn are the product of the replacement of primary quartz bands in the BIF by Stages 1 and 2 hypogene carbonate minerals, followed by their replacement by magnetite and minor ferroan dolomite. Fluid inclusion studies demonstrate that Stage 1 fluids were high-temperature (>440 °C) and CO2-rich. Paired O and C stable isotope data for Stage 1 ferroan dolomite suggest that these fluids had a magmatic source, while Stage 1 magnetite chemistry (e.g. enrichments in Mg, Mn, Ca, and Na) indicates chemical exchange took place between the fluids and mafic igneous rocks prior to crystallization of magnetite. The presence of monophase carbonic fluid inclusions in Stage 1 ferroan dolomite suggest that phase separation of a bicarbonate-rich aqueous fluid took place in deeper parts of the hydrothermal system, which led to the separation of the resultant volatile-rich and brine phases during transport of the Stage 1 fluid to shallower crustal levels. Cooling of the hydrothermal system during the Stage 2 fluid event involved (i) an early brine (>275 to 327 ºC; 36 to 40 equiv. wt% NaCl) with Cl/Br and C and O isotopes values that overlap the ranges 2 for magmatic fluids, with minor involvement of Archean seawater, and extensive chemical exchange with country rocks; followed by (ii) pulses of moderate-and lower-temperature Stage 2 brines (>125 to 260 ºC; 2 to 24 equiv. wt% CaCl2) with Cl/Br, O and C isotope, Na/Br, and Ca/Ca+Na signatures that suggest cooling of magmatic-derived fluids that mixed with Archean seawater and reacted with mafic igneous country rocks in areas more distal to fluid pathways. The last stage of formation of magnetite-rich ore at the Beebyn deposit involved the flow of Stage 3 fluids through the existing faul...

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In situ LA–ICP-MS and EPMA trace element characterization of Fe–Ti oxides from the phoscorite–carbonatite association at Phalaborwa, South Africa

Cited by 27 publications

References 80 publications

Three-dimensional textural investigation of sulfide mineralisation from the Loolekop carbonatite–phoscorite polyphase intrusion in the Phalaborwa Igneous Complex (South Africa), with implications for ore-forming processes

Three-dimensional textural investigation of sulfide mineralisation from the Loolekop carbonatite–phoscorite polyphase intrusion in the Phalaborwa Igneous Complex (South Africa), with implications for ore-forming processes

Trace Elements in Magnetite from the Pagoni Rachi Porphyry Prospect, NE Greece: Implications for Ore Genesis and Exploration

A synvolcanic origin for magnetite-rich orebodies hosted by BIF in the Weld Range District, Western Australia

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