首页|Genesis of the Ray-Iz chromitite, Polar Urals: Inferences to mantle conditions and recycling processes
Genesis of the Ray-Iz chromitite, Polar Urals: Inferences to mantle conditions and recycling processes
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NSTL
Elsevier
Ophiolitic chromitites in the eastern sector of the Alpine-Himalayan and Polar Ural orogenic belts preserve evidence of formation under ultra-high-pressure (UHP), deep mantle conditions. The textural and compositional characteristics of microscopic and submicroscopic inclusions in magnesiochromite from the Ray-lz ophiolites are considered as clues of their complex evolutionary history. Bulk-rock platinum-group-element (PGE) compositions of refractory and metallurgical chromitite ores (102-309 ppb) with generally IPGE>PPGE are consistent with supra-subduction zone (SSZ) metasomatism. The abundant unusual UHP phases (e.g., micro-diamonds, moissanite, coesite...etc.), together with clinopyroxene lamellae, and globular silicate inclusions in the Cr-spinel are seen as indications of deep mantle recycling of the mantle section of the Ray-lz ophiolites. The calculated fO(2) values for dunite and chromitite (+1.17 to +4.16, generally above the FMQ buffer) are in line with interaction of mid-ocean ridge (MOR) or back-arc ophiolites with oxidized, Mg-rich silicic (boninitic) melts in a SSZ environment. (C) 2020 Elsevier B.V. All rights reserved.
NSTL
Elsevier
