Manifestation of infiltration-metasomatic processes in the Kazanian stage sediments of the Lobach Mountain in Tatarstan

Abstract

© 2020 IOP Publishing Ltd. All rights reserved. For the first time in the Kazanian stage evaporate sediments of the Kama-Ustyinsky structure, metasomatites were identified confined to bituminous accumulations zones. metasomatites develops in microgranular sedimentary-diagenetic dolomites. The main dense core of metasotatic bodies is composed of marble-like calcite, along periphery of which there is ferriferous goethite-hydrogetite edge. Numerous calcite veins extend from carbonate core to sides, their thickness decreases with distance from metasotatic bodies. In the zone of metasomatites development, processes of gypsum lenses recrystallization and siliceous nodules dissolution, originally found in micrograin dolomites, are observed. The small size siliceous nodules are completely leached and replaced by calcite aggregates. Larger flints partially pass into translucent chalcedony and aggregates, consisting of large quartz crystals - clear rock crystal. The formation of metasomatites is due to aggressive hydrocarbon-containing fluids introduction into the rocks, as indicated by their spatial confinement to bituminous accumulations.