Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)

The mantle tectonite of the Kraka ophiolite contains several chromite deposits. Two of them consisting of high-Cr podiform chromitite—the Bolshoi Bashart located within harzburgite of the upper mantle transition zone and Prospect 33 located in the deep lherzolitic mantle—have been investigated. Both...

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Autores principales:	Giorgio Garuti, Evgenii V. Pushkarev, Irina A. Gottman, Federica Zaccarini
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	chromitite platinum group minerals low depleted lherzolite Kraka ophiolite complex Southern Urals Russia Mineralogy QE351-399.2
Acceso en línea:	https://doaj.org/article/7f3e2bc14b024bf0989f6262a5f400cd
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spelling	oai:doaj.org-article:7f3e2bc14b024bf0989f6262a5f400cd2021-11-25T18:26:52ZChromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)10.3390/min111112872075-163Xhttps://doaj.org/article/7f3e2bc14b024bf0989f6262a5f400cd2021-11-01T00:00:00Zhttps://www.mdpi.com/2075-163X/11/11/1287https://doaj.org/toc/2075-163XThe mantle tectonite of the Kraka ophiolite contains several chromite deposits. Two of them consisting of high-Cr podiform chromitite—the Bolshoi Bashart located within harzburgite of the upper mantle transition zone and Prospect 33 located in the deep lherzolitic mantle—have been investigated. Both deposits are enveloped in dunite, and were formed by reaction between the mantle protolith and high-Mg, anhydrous magma, enriched in Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and Na<sub>2</sub>O compared with boninite. The PGE mineralization is very poor (<100 ppb) in both deposits. Laurite (RuS<sub>2</sub>) is the most common PGM inclusion in chromite, although it is accompanied by erlichmanite (OsS<sub>2</sub>) and (Ir,Ni) sulfides in Prospect 33. Precipitation of PGM occurred at sulfur fugacity and temperatures of logƒS<sub>2</sub> = (−3.0), 1300–1100 °C in Bolshoi Bashart, and logƒS2 = (−3.0/+1.0), 1100–800 °C in Prospect 33, respectively. The paucity of chromite-PGM mineralization compared with giant chromite deposits in the mantle tectonite in supra-subduction zones (SSZ) of the Urals (Ray-Iz, Kempirsai) is ascribed to the peculiar petrologic nature (low depleted lherzolite) and geodynamic setting (rifted continental margin?) of the Kraka ophiolite, which did not enable drainage of the upper mantle with a large volume of mafic magma.Giorgio GarutiEvgenii V. PushkarevIrina A. GottmanFederica ZaccariniMDPI AGarticlechromititeplatinum group mineralslow depleted lherzoliteKraka ophiolite complexSouthern UralsRussiaMineralogyQE351-399.2ENMinerals, Vol 11, Iss 1287, p 1287 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	chromitite platinum group minerals low depleted lherzolite Kraka ophiolite complex Southern Urals Russia Mineralogy QE351-399.2
spellingShingle	chromitite platinum group minerals low depleted lherzolite Kraka ophiolite complex Southern Urals Russia Mineralogy QE351-399.2 Giorgio Garuti Evgenii V. Pushkarev Irina A. Gottman Federica Zaccarini Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)
description	The mantle tectonite of the Kraka ophiolite contains several chromite deposits. Two of them consisting of high-Cr podiform chromitite—the Bolshoi Bashart located within harzburgite of the upper mantle transition zone and Prospect 33 located in the deep lherzolitic mantle—have been investigated. Both deposits are enveloped in dunite, and were formed by reaction between the mantle protolith and high-Mg, anhydrous magma, enriched in Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and Na<sub>2</sub>O compared with boninite. The PGE mineralization is very poor (<100 ppb) in both deposits. Laurite (RuS<sub>2</sub>) is the most common PGM inclusion in chromite, although it is accompanied by erlichmanite (OsS<sub>2</sub>) and (Ir,Ni) sulfides in Prospect 33. Precipitation of PGM occurred at sulfur fugacity and temperatures of logƒS<sub>2</sub> = (−3.0), 1300–1100 °C in Bolshoi Bashart, and logƒS2 = (−3.0/+1.0), 1100–800 °C in Prospect 33, respectively. The paucity of chromite-PGM mineralization compared with giant chromite deposits in the mantle tectonite in supra-subduction zones (SSZ) of the Urals (Ray-Iz, Kempirsai) is ascribed to the peculiar petrologic nature (low depleted lherzolite) and geodynamic setting (rifted continental margin?) of the Kraka ophiolite, which did not enable drainage of the upper mantle with a large volume of mafic magma.
format	article
author	Giorgio Garuti Evgenii V. Pushkarev Irina A. Gottman Federica Zaccarini
author_facet	Giorgio Garuti Evgenii V. Pushkarev Irina A. Gottman Federica Zaccarini
author_sort	Giorgio Garuti
title	Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)
title_short	Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)
title_full	Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)
title_fullStr	Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)
title_full_unstemmed	Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)
title_sort	chromite-pgm mineralization in the lherzolite mantle tectonite of the kraka ophiolite complex (southern urals, russia)
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/7f3e2bc14b024bf0989f6262a5f400cd
work_keys_str_mv	AT giorgiogaruti chromitepgmmineralizationinthelherzolitemantletectoniteofthekrakaophiolitecomplexsouthernuralsrussia AT evgeniivpushkarev chromitepgmmineralizationinthelherzolitemantletectoniteofthekrakaophiolitecomplexsouthernuralsrussia AT irinaagottman chromitepgmmineralizationinthelherzolitemantletectoniteofthekrakaophiolitecomplexsouthernuralsrussia AT federicazaccarini chromitepgmmineralizationinthelherzolitemantletectoniteofthekrakaophiolitecomplexsouthernuralsrussia
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Chromite-PGM Mineralization in the Lherzolite Mantle Tectonite of the Kraka Ophiolite Complex (Southern Urals, Russia)

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