Plagioclasites from chromite-bearing ultramafic rocks of the Rai-Iz massif

• Main Authors: N. V. Vakhrusheva, K. S. Ivanov, A. E. Stepanov, S. P. Shokalsky, A. N. Azanov, V. V. Hiller, P. B. Shiryayev
• Format: Article in Journal/Newspaper
• Language: English; Russian
• Published: A.N. Zavaritsky Institute of Geology and Geochemistry 2016
• Subjects: ультрамафиты; плагиоклазиты; Полярный Урал; цирконы; U-Pb датирование; возраст; палеозой; ultramafic rocks; plagioclasites; Polar Urals; zircons; U-Pb dating; age; Paleozoic; Engineering geology. Rock mechanics. Soil mechanics. Underground construction; TA703-712
• Online Access: https://doaj.org/article/bcd2cc173f244d6fae59b1dfa20178b1

The corundum-bearing and without-corundum plagioclasites from chromite-bearing ultramafic rocks of Rai-Iz massif were studied. Chemical composition of the rock-forming minerals and rock geochemical characteristics was determined. The U-Pb zircon dating (using SHRIMP-II microprobe) of plagioclasites yielded an age of 398 ± 3 and 404.4 ± 2.8 Ma - Lower-Middle Devonian boundary. At that time on the background of powerful collision it occurred a deep metamorphic processing of Rai-Iz ultramafic rocks resulting in forming of high-chromium chromite ore and separation of vein-series represented by substantially plagioclase rocks with corundum (ruby) mineralization.