The Formation Conditions of the Evenki Formation in the Lower Reaches of the Podkamennaya Tunguska River, Siberian Platform

Abstract

The Evenki Formation of the Siberian Platform has been studied on the right bank of the Podkamennaya Tunguska River near the Sulomai settlement (Evenki municipal district of Krasnoyarsk krai). The structures and textures of the composing sediments are described. The main petrogenic oxides have been identified and the normative mineral composition has been determined following this identification. The increase of terrigenous components in the strata indicates periods of enhanced erosion in the provenance area (the Yenisei Ridge). In turn, the increased contribution of feldspars in the middle part of the section shows an intensification of physical weathering in arid conditions. The principal hypotheses of the origin of the Evenki Formation and other recent and ancient tidal flat and sabkha facies are outlined. We suggest that the studied facies of the Evenki Formation accumulated mostly under intertidal and, possibly in part, under lower supratidal conditions, which alternated depending on eustatic fluctuations in the basin. A conceptual model of the genesis of the Evenki Formation on the Siberian Platform has been developed.