LITHOLOGY AND STRATIGRAPHY OF THE DEVONIAN DEPOSITS AT THE NORTH-WESTERN MARGIN OF THE TUNGUSKA SYNECLISE (NORILSK REGION)

I. V. Varaksina, N. G. Izokh, I. V. Tumashov

Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia

The paper contains the results of lithological and stratigraphic studies of the Devonian deposits uncovered in the Norilsk region at the north-western margin of the Tunguska syneclise. The composition, structure, and depositional environments have been determined. There is the alternation of carbonaceous, argillaceous-carbonaceous, and sulphide rocks in the Lower and Middle Devonian interval in the southern cross-section (Fokinskaya area). The Upper Devonian in the south is characterised by entirely calcareousdolomitic composition, and in the central part of the region (Severo-Vologochanskaya area), together with carbonaceous rocks, there are abundant anhydrites. The analysis of conditions under which different types of rocks had formed, and their distribution patterns, has revealed that deposition in the area under study occurred within a shallow basin with a limited circulation of water and increased salinity, with a normal marine regime recovered in the periods of large transgressions. New Middle and Upper Devonian conodont associations have been discovered, represented by cosmopolite taxons, which indicates open palaeoaquatories.

Keywords: Tunguska syneclise, Norilsk region, Devonian, lithology, stratigraphy.

DOI 10.20403/2078-0575-2017-4-23-33

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