Volume 27, Issue 1 (4-2019)                   www.ijcm.ir 2019, 27(1): 109-122 | Back to browse issues page

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Mazhari S A. Distribution of platinum-group elements (PGE) in chromitites of Sabzevar, NE of Iran. www.ijcm.ir. 2019; 27 (1) :109-122
URL: http://ijcm.ir/article-1-1229-en.html
Abstract:   (13 Views)
The chromitite ores of Sabzevar ophiolitic zone could be divided into two groups of high Cr and high Al. The concentration of Cr2O3, As, S and some heavy metals (Cu, Ni, Ag, Co, Zn) is higher in high Cr samples; while high Al chromitites show higher concentration of Al2O3, SiO2, TiO2 and other trace elements. The high Cr chromitites have higher PGE than Al-rich samples and PGE concentration increases with Cr2O3. The high Cr chromitites have fractionated PGE chondrite- normalized patterns with negative slope (Pd/Ir = 0.25) and high IPGE/PPGE (average 6.22); while high Al chromitites show unfractionated and relatively flat patterns
(Pd/Ir = 1.9, IPGE/PPGE = 2.88). The PGE composition of high Cr chromitites indicates they are formed by high degrees of partial melting (boninitic melt) in arc setting. In contrast, Al- enriched samples have been produced by low degrees of partial melting (toleiitic melt) beneath spreading centers (i.e., mid-ocean ridges or back-arc basins). The results of PGE composition of Sabzevar chromitites are coincident with chemical composition data of chromite crystals in these samples.
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Type of Study: Research | Subject: Special
Received: 2019/03/16 | Accepted: 2019/03/16 | Published: 2019/03/16

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