Moilanen, M., Hanski, E., Konnunaho, J. et al. Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia: application to mineral exploration. Miner Deposita (2020). https://doi.org/10.1007/s00126-020-00953-1
Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia : application to mineral exploration
|Author:||Moilanen, M.1; Hanski, E.1; Konnunaho, J.2;|
1Oulu Mining School, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland
2Geological Survey of Finland, P.O. Box 77, FI-96101, Rovaniemi, Finland
3Geological Survey of Finland, P.O. Box 96, FI-02151, Espoo, Finland
4Mawson Oy, Ahjotie 7, 96320, Rovaniemi, Finland
|Online Access:||PDF Full Text (PDF, 7.8 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2020052839536
|Publish Date:|| 2020-05-28
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 Cr-magnetite 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 Cr-magnetite 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.
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
Open access funding provided by University of Oulu including Oulu University Hospital. This research was supported by the Academy of Finland (grant #281859), K.H. Renlund Foundation and Tauno Tönning Foundation.
|Academy of Finland Grant Number:||
281859 (Academy of Finland Funding decision)
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00126-020-00953-1) contains supplementary material, which is available to authorized users.
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