Lithofacies Characteristics of the Fedorovka Chromite Placer Cluster in the Southwestern Cis-Urals (Bashkiria)

The structure of the Fedorovka chromite-bearing placer cluster, located in the East European Platform adjacent to the Southern Urals, is divided into two facies-stratigraphic complexes of the Middle Permian Biarmian stage: the lower complex, represented by beach and shallow-water sediments of a marine or lacustrine basin, belongs to the Kazanian stage; and the upper alluvial complex, to the late Kazanian (according to other sources, early Urzhumian) stage. The main placer chromite deposits are confined to the beach and shallow water complex (Sabantui placer occurrence), where sedimentation conditions were most favorable for the concentration of heavy minerals. The low-chromite alluvial deposits can serve as a transition zone or intermediate host for basin sediments located to the west. Chemically, Cr-spinels are typical for ophiolite massifs. The nearest massifs (Kraka group) are approximately 200 km away from the Fedorovka cluster. Placer occurrences exhibit features of proximal transport, which can be explained by the overthrust nature of ultramafic massifs and the possibility of more westward ophiolite allochthon migration from the ophiolite suture zone toward the East European Platform during the Permian orogeny. The industrial potential of the Fedorovka placer cluster requires further study. Similar deposits can be discovered within the coastal zone of the Biarmian Basin, located west of folded structures of the Southern Urals.