Аннотации:
© SGEM2019. Marble onyx is a banded aggregate consisting of calcite and aragonite of the most diverse colors. Due to its decorative properties, onyx is valued in the jewelry and construction industry. In nature, marble onyx is formed by layer-by-layer deposition of carbonate substance from carbon-calcium dioxide water. It occurs mainly in the areas of young volcanism, rich in thermal springs. In recent years, information has appeared platform manifestations of onyx mineralization. One of these manifestations was found on the territory of the Tatarstan Republic located within the Syukeev anticlinal structure. Within the framework of the structure under consideration, three types of onyx mineralization manifestations were established: Subjacent intrusive bodies, veins and block masses. Subjacent intrusive bodies are found in the apical parts of the Syukeev anticline. In the outcrops, the intrusions are represented in the form of cylindrical pillars with a diameter of 2.0–3.0 m, consisting of pieces of crushed carbonate rocks cemented by dripping aggregates of marble honey onyx. The veins of marble onyx are confined to the wings of the Syukeev anticline, where there is an increased amount of fracture into sedimentary rocks. Veins develop on the contacts of marl layers with dolomites. Throughout the periphery they are enriched with chalcedony, which gives them increased strength. Block masses of marble onyx are found on separate parts of the Volga River terrace. They are fragments of subjacent intrusive bodies and veins destroyed by waves, composed of marble onyx. The prevalence of onyx mineralization in area of the Syukeev anticline is due to the localization of the bituminous deposit here. During the oxidation of hydrocarbons cap-rocks periodically were broke by fluids. On the migration ways of gas-water carbonated fluids, sedimentary rocks partially dissolved, forming cavities, which were subsequently filled with banded marble onyx. The peculiar honey-yellow color of onyx caused by the capture of organic matter in the process of calcite aggregates growth.
