An exotic platinum-group-mineral-rich and Mg-poor chromitite in the Kevitsa Ni-Cu-platinum-group-elements deposit

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Marco E. Ciriotti
Messaggi: 31675
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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An exotic platinum-group-mineral-rich and Mg-poor chromitite in the Kevitsa Ni-Cu-platinum-group-elements deposit

Messaggio da Marco E. Ciriotti » gio 20 mag, 2021 18:33

Prossima pubblicazione.

Referenza:
▪ González-Pérez, I., Gervilla, F., González-Jiménez, J.M., Kojonen, K. (2021): Genesis of an exotic platinum-group-mineral-rich and Mg-poor chromitite in the Kevitsa Ni-Cu-platinum-group-elements deposit. Mineralogy and Petrology, 115, (in press).

Abstract:
This paper offers the first-ever study of a local chromitite stringer (~ 2 cm wide) enriched in platinum-group elements (PGE) from the Kevitsa Ni-Cu-PGE deposit. Chromite forming this chromitite is rich in Cr2O3 (29.06 ̶ 37.17 wt%) and FeO (FeOtotal = 45.88 ̶ 56.06 wt%) and low in MgO (0.04 ̶ 0.91 wt%). The chromitite host an unusual set of mineral inclusions including: (1) platinum-group minerals of the laurite-erlichmanite (RuS2-OsS2) solid solution series, irarsite (IrAsS), sperrylite (PtAs2), hollingworthite (RhAsS), anduoite [(Ru, Os)As2], kotulskite (PdTe) and As-, Te-, Os-, and Ru- bearing unidentified phases; (2) exsolution-lamellae of ilmenite and ulvöspinel along with chromite (111) and (100) planes, respectively; (3) silicates including crystallographically-oriented biotite, euhedral pyroxene and irregular-shaped amphiboles which tend to follow chromite growth planes, and (4) Fe-oxides, pyrrhotite, pentlandite, galena, barite, apatite, and native gold. Intercumulus minerals are microcrystalline Mg-rich biotite and minor amphibole. Pyroxenes (diopside) located immediately above the chromitite stringer exhibit higher CaO (23.02 ̶ 25.42 wt%) and Na2O (0.16 ̶ 0.55 wt%) than pyroxenes (augite) located below. We suggest that chromite saturation in the mafic melt was caused by local assimilation of a small pelitic xenolith. The xenolith also provided K and H2O explaining the occurrence of K-and volatile-rich intercumulus phases. Crystallization of chromite in this environment promoted preferential sequestering of Ir and Ru, and to a lesser extent Os, from the parental magma giving rise to an anomalous iridium-group-PGE (IPGE: Ir, Ru, and Os) enrichment.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 31675
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: An exotic platinum-group-mineral-rich and Mg-poor chromitite in the Kevitsa Ni-Cu-platinum-group-elements deposit

Messaggio da Marco E. Ciriotti » ven 17 set, 2021 14:24

Pubblicazione effettuata.

Referenza:
▪ González-Pérez, I., Gervilla, F., González-Jiménez, J.M., Kojonen, K. (2021): Genesis of an exotic platinum-group-mineral-rich and Mg-poor chromitite in the Kevitsa Ni-Cu-platinum-group-elements deposit. Mineralogy and Petrology, 115, 535–555.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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