COMPREHENSIVE SUBSTANTIATION OF JURASSIC PHYTOSTRATIGRAPHY AND CORRELATIONS IN THE KANSK COAL BASIN, SIBERIA

Abstract

Paleobotanical characteristics based on studied plant macrofossils and miospores from Jurassic sediments of the Kansk coal basin are discussed. The studied samples characterize the formation stratotypes and borehole sections. Plant macrofossils and palynologic samples have been collected from the same intervals of sections. The comparative analysis of distribution of miospores and plant macrofossils is used for the first time to distinguish independent phytostratigraphic units, i.e., the floral and palynologic beds, which are found to be of almost equal ranges. Remote correlations of spore-pollen assemblages with those from West Siberia and from marine sediments of northern Central Siberia enabled a more reliable dating of the distinguished phytostratigraphic units. Four spore-pollen assemblages are recognized: the Pereyaslovka assemblage of the Sinemurian-Pliensbachian age (from the lower part of eponymous formation), the Toarcian Ilan assemblage (characteristic of the uppermost Pereyaslovka and Ilan formations), the Aalenian Kamala and the Bajocian Borodino assemblages (from synonymous formations, respectively). Three assemblages of plant macrofossils termed as the Aban (Pereyaslovka and Ilan formations), Rybinskoe (Kamala Formation), and Quarry (Borodino Formation) floras have distribution ranges corresponding respectively to the Pliensbachian-Toarcian, Aalenian, and Bajocian interval.