Middle Jurassic Flora and palaeoenvironmental reconstruction of the Kamala Formation in Rybinsk Formational Zone, the Kansk Coal Basin, Siberia

Abstract

The Kansk Basin is one of the biggest reserves of brown coal in Russia. Jurassic coal-containing terrestrial deposits bearing plant remains crop out in several localities. This work is focused on five fossil-plant-containing localities in the Middle Jurassic Kamala Formation of the Kansk Basin within the Rybinsk Formational Zone. The studied material comprises 29 plant morphospecies. They are assigned to: Pteridophytes (Equisetites, Coniopteris, Cladophlebis and Raphaelia), Bennettitales (cf. Pterophyllum), Ginkgoales (Ginkgoites, Sphenobaiera and Eretmophyllum), Leptostrobales (Czekanowskia and Phoenicopsis) and Coniferales (Pityophyllum). There are several plants remains of uncertain systematic position, such as roots (Radicites sp.), cones and fossil wood. As a result, palaeoenvironmental interpretation was implemented; three taphonomic units were distinguished utilising complex palaeobotanical, lithofacial analyses, and literature-based data. Palaeoecological analysis identified three depositional environments with corresponding type of vegetation: a) periodically flooded alluvial plain dominated by Czekanowskia-Phoenicopsis; b) swamp-semiaquatic dominated by Equisetites, Coniopteris, Cladophlebis and Phoenicopsis; c) slope and upland vegetation dominated by Sphenobaiera, Ginkgoites, Eretmophyllum and Pityophyllum.