Chromite Paleoplacer in the Permian Sediments at the East Edge of the East European Platform: Composition and Potential Sources

A chromite occurrence called the Sabantuy paleoplacer was discovered in Southern Pre-Ural region, at east edge of East-European Platform transitional zone to Ural Foredeep. ca. 1 m-thick chromite-bearing horizon is traced a depth 0.7–1.5 m from earth’s surface for area 15,000 m2. The chromspinel content sandstones reaches 30–35%, maximum values Cr2O3 are 16–17 wt.%. grain size detrital ranges 0.15 0.25 mm. Subangular octahedral crystals dominate; rounded grains and debris rare. composition varies widely constrained by substitution Al3+ Cr3+, Fe2+ Mg2+ cations. Chemically, low-Al (Al2O3 = 12 wt.%) high-Cr (Cr2O3 52–56 prevail. compositional analysis using discrimination diagrams showed that most chromites correspond mantle peridotites subduction settings. Volcanic rocks could be an additional source chromites. It confirmed compositions monomineralic, polymineralic melt inclusions chromspinels. presented data indicates ophiolite related ore associated with oceanic island-arc volcanic rocks, widespread orogen, main sources paleoplacer.