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Nine major microfacies and eight transgressiveregressive cycles have been recognized in the middle Frasnian-Famennian microbial mound of the Shar'yu River section in the Chernyshev Swell, Timan-northern Ural region. Rocks including Palaeomicrocodium at the top of each cycle show signs of brecciation, freshwater leaching, and vadose cementation. Palaeomicrocodium, an enigmatic structure, being close in nature to Microcodium, is useful as a palaeoenvironmental indicator and can also be used in regional correlations. Seven levels of subaerial expose surfaces with Palaeomicrocodium correspond to seven breaks in growth of the microbial mound in the Upper Devonian reef-like formation. The high-amplitude sea-level changes recognized are in good correlation with those in the Moscow Syneclise and are also fixed on the global eustatic curve.

The continuous Upper Ashgill–Sheinwoodian carbonate succession in the most eastern Kozhym River area in the Subpolar Urals comprises the Yaptikshor (Rawtheyan), Kamennaya baba (Hirnantian), Ruchej and Manyuku (Llandovery–?Sheinwoodian) formations. The facies of the deep subtidal Yaptikshor Fm. mark an abrupt sea‐level rise following emergence of the Bad’ya reef (Rawtheyan). Carbonate breccias at the base of the Kamennaya baba Fm. correlate with the beginning of the Hirnantian glaciation and change upwards towards the Ordovician–Silurian boundary with the development of light‐grey massive boundstone/packstone shoal deposits. An abrupt change in facies to the Rhuddanian–Aeronian Ruchej Fm. continental slope environment marked the start of a long‐term sea‐level rise. The uppermost Aeronian–?Sheinwoodian is represented by submarine canyon carbonate conglobreccias of the Manyuku Fm. unconformably underlying the Balban’yu reef. The rapid facies changes at the base of the Hirnantian and at the Ordovician–Silurian boundary were of global eustatic origin. In contrast, the abrupt changes in the Rawtheyan and the formation of the Manyuku Fm. conglobreccias were of local or regional origin associated with tectonics. They were followed by the start of a regional transgression (Yaptikshor Fm.) and a global transgression marked by the initiation of the Balban’yu Reef in the Sheinwoodian.

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In the Palaeozoic history of the Timan-Pechora sedimentary basin three stages of organic structures are identified: Caradocian-Early Emsian, Middle Frasnian-Tournaisian and Late Visean-Early Permian. The distribution and dimensions of the various organogenic buildups in the Timan-Pechora basin show that Palaeozoic reef formation was regulated by the skeletal reef biota, by the physical and chemical parameters controlling the porostromate calcimicrobes and microbial carbonates, by global eustatic fluctuations of sea-level, and by the tectonic evolution of the Pechora Plate and the Palaeo-Urals Ocean. The development of petroleum systems in the Timan-Pechora Basin is largely controlled by primary (organic substance, its composition, quantity and maturity, continuous sinking of the basin's sedimentary cover) and secondary (stagnation period of sedimentation and the newest tectonic movements) factors. An integrated approach using the geochemical data enabled us to build a reliable model of petroleum genesis for the Timan-Pechora Basin with high probability of evaluating the petroleum potential and the composition of hydrocarbon systems.