Whole-rock and mineral compositional constraints on the magmatic evolution of the Ni-Cu-(PGE) sulfide ore-bearing Kevitsa intrusion, northern Finland

Luolavirta, Kirsi; Hanski, Eero; Maier, Wolfgang D.; Santaguida, Frank

doi:10.1016/j.lithos.2017.10.015

Cited by 17 publications

(15 citation statements)

References 40 publications

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“…3b), Ni-PGE Ore (Fig. 3c), and False Ore, with the last one being very low in base metals (Mutanen 1997;Luolavirta et al 2017). The Normal and False Ore samples contain euhedral-subhedral Cr-magnetite and some magnetite, and the Ni-PGE Ore sample contains mostly subhedral-anhedral magnetite.…”

Section: Samples and Iron Oxide Petrographymentioning

confidence: 94%

Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia: application to mineral exploration

et al. 2020

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Using electron probe microanalyzer (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), we analyzed major and trace element compositions of iron oxides from Ni-Cu-PGE sulfide deposits hosted by mafic-ultramafic rocks in northern Fennoscandia, mostly focusing on Finland. The main research targets were the Archean Ruossakero Ni-(Cu) deposit; Tulppio dunite and related Ni-PGE mineralization; Hietaharju, Vaara, and Tainiovaara Ni-(Cu-PGE) deposits; and Paleoproterozoic Lomalampi PGE-(Ni-Cu) deposit. In addition, some reference samples from the Pechenga (Russia), Jinchuan (China), and Kevitsa (Finland) Ni-Cu-PGE sulfide deposits, and a barren komatiite sequence in the Kovero area (Finland) were studied. Magnetite and Crmagnetite show a wide range of trace element compositions as a result of the variation of silicate and sulfide melt compositions and their post-magmatic modification history. Most importantly, the Ni content in oxide shows a positive correlation with the Ni tenor of the sulfide phase in equilibrium with magnetite, regardless of whether the sulfide assemblage is magmatic or post-magmatic in origin. The massive sulfide samples contain an oxide phase varying in composition from Cr-magnetite to magnetite, indicating that Crmagnetite can crystallize directly from sulfide liquid. The Mg concentration of magnetites in massive sulfide samples is lowest among the samples analyzed, and this can be regarded as a diagnostic feature of an oxide phase crystallized together with primitive Fe-rich MSS (monosulfide solid solution). Our results show that magnetite geochemistry, plotted in appropriate discrimination diagrams, together with petrographical observations could be used as an indicator of potential Ni-(Cu-PGE) mineralization.

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Section: Samples and Iron Oxide Petrographymentioning

confidence: 94%

Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia: application to mineral exploration

et al. 2020

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“…The metaperidotite masks the identification of the primary lithology, and thus, the problems of identifying traceable magmatic layers were initially attributed to inconsistent logging practices. However, as recent geological works by [26,27] do not anymore support the idea of continuous smaller-scale magmatic layering within the resource area, it now seems that the evidence for obvious layering is lacking altogether. Individual horizons are inconsistent between boreholes based on lithology, whole-rock compositions, and ore grades [27].…”

Section: Geological Backgroundmentioning

confidence: 96%

“…However, as recent geological works by [26,27] do not anymore support the idea of continuous smaller-scale magmatic layering within the resource area, it now seems that the evidence for obvious layering is lacking altogether. Individual horizons are inconsistent between boreholes based on lithology, whole-rock compositions, and ore grades [27]. This reopens the question about origin of the observed reflectivity within the Kevitsa intrusion ( Figure 2) for scrutiny.…”

Section: Geological Backgroundmentioning

confidence: 96%

Predicting Missing Seismic Velocity Values Using Self-Organizing Maps to Aid the Interpretation of Seismic Reflection Data from the Kevitsa Ni-Cu-PGE Deposit in Northern Finland

et al. 2019

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We use self-organizing map (SOM) analysis to predict missing seismic velocity values from other available borehole data. The site of this study is the Kevitsa Ni-Cu-PGE deposit within the mafic-ultramafic Kevitsa intrusion in northern Finland. The site has been the target of extensive seismic reflection surveys, which have revealed a series of reflections beneath the Kevitsa resource area. The interpretation of these reflections has been complicated by disparate borehole data, particularly because of the scarce amount of available sonic borehole logs and the varying practices in logging of borehole lithologies. SOM is an unsupervised data mining method based on vector quantization. In this study, SOM is used to predict missing seismic velocities from other geophysical, geochemical, geological, and geotechnical data. For test boreholes, for which measured seismic velocity logs are also available, the correlation between actual measured and predicted velocities is strong to moderate, depending on the parameters included in the SOM analysis. Predicted reflectivity logs, based on measured densities and predicted velocities, show that some contacts between olivine pyroxenite/olivine websterite-dominant host rocks of the Kevitsa disseminated sulfide mineralization-and metaperidotite-earlier extensively used "lithology" label that essentially describes various degrees of alteration of different olivine pyroxenite variants-are reflective, and thus, alteration can potentially cause reflectivity within the Kevitsa intrusion.Recently, data mining approaches, such as the self-organizing map (SOM; [1,2]) analysis employed in this study, have been increasingly used for analyses of the disparate and multivariate geoscientific datasets that are typical for mining and exploration environments (e.g., [3][4][5][6][7][8][9][10]). SOM is an artificial neural network that works on a vector quantization methodology allowing unsupervised analysis, i.e., no prior information is needed on the type or number of groupings within the data, to determine the underlying linear and non-linear relationships amongst different data. Typically 2D "maps" are used to visualize the underlying statistical relationships between the variables, which makes interpretation of the complex multidimensional data more effective (e.g., [11]). Major strengths of the methodology include the robust handling of sparse and disparate input data, labels, incomplete data, and the ability to predict missing data values for such data (e.g., [12][13][14]).Extensive seismic reflection data have been collected at the Kevitsa Ni-Cu-PGE deposit that is located in northern Finland (Figure 1). These data include four intersecting 2D seismic reflection profiles acquired in 2007 as a part of High-Resolution Reflection Seismics for Ore Exploration (HIRE) 2007-2010 project that aimed at testing the applicability of seismic exploration method in Kevitsa [16,17] and a 3D seismic reflection survey conducted in 2010 for mine planning and deep mineral exploration purposes [18,19]. Lateral...

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“…Frequent episodes of magma replenishment are essential to form mafic-ultramafic intrusive bodies, such as the Bushveld Complex (Cawthorn & Walraven, 1998;Mitchell, Eales, & Kruger, 1998;Nex, Cawthorn, & Kinnaird, 2002), Bjerkreim-Sokndal intrusion (Jensen, Wilson, Robins, & Chiodoni, 2003;Nielsen Frank, Campbell Ian, McCulloch, & Wilson, 1996), Kevitsa intrusion (Le Vaillant, Hill, & Barnes, 2017;Luolavirta, Hanski, Maier, & Santaguida, 2018), Jinchuan intrusion (Chai & Naldrett, 1992) and Panzhihua intrusion (Song, Qi, et al, 2013). Magma recharge events are recorded in whole-rock compositions, Sr-Nd isotopes and variations of mineral crystallization sequences and components (e.g., Eales et al, 1986;Nielsen Frank et al, 1996;Tanner, Mavrogenes, Arculus, & Jenner, 2014), and may be important in the generation of economic mineralization (e.g., Gregory, Journet, White, & Lappalainen, 2011;Kruger, 2005;Luolavirta et al, 2018;Mao et al, 2014). The composition of olivine is widely used to model fractional crystallization in the parental magma at different Ni-Cu-PGE deposits (e.g., Li, Xu, de Waal, Ripley, & Maier, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…The composition of olivine is widely used to model fractional crystallization in the parental magma at different Ni-Cu-PGE deposits (e.g., Li, Xu, de Waal, Ripley, & Maier, 2004). Recently, the mineral chemistry of other silicates and sulphides (orthopyroxene, clinopyroxene, hornblende, F I G U R E 1 Tectonic setting and distribution of major Cu-Ni sulphide deposits associated with mafic-ultramafic intrusive rocks in the eastern Tianshan orogenic belt (modified after Su et al, 2012) [Colour figure can be viewed at wileyonlinelibrary.com] plagioclase, pentlandite, pyrrhotite, and chalcopyrite) has been used to reveal the composition of the parental magma, multi-stage magmatism, fractional crystallization, and crustal contamination (e.g., Kang, Qin, Mao, Tang, & Yao, 2020;Luolavirta et al, 2018;Mansur, Barnes, & Duran, 2019;Tanner et al, 2014;Yang et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Two‐stage magmatism and mineralization of Tulaergen nickel‐copper deposit in eastern Tianshan, North‐west China: Evidence from bulk rock geochemistry and in situ mineral chemistry

et al. 2021

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Whole-rock and mineral compositional constraints on the magmatic evolution of the Ni-Cu-(PGE) sulfide ore-bearing Kevitsa intrusion, northern Finland

Cited by 17 publications

References 40 publications

Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia: application to mineral exploration

Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia: application to mineral exploration

Predicting Missing Seismic Velocity Values Using Self-Organizing Maps to Aid the Interpretation of Seismic Reflection Data from the Kevitsa Ni-Cu-PGE Deposit in Northern Finland

Two‐stage magmatism and mineralization of Tulaergen nickel‐copper deposit in eastern Tianshan, North‐west China: Evidence from bulk rock geochemistry and in situ mineral chemistry

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