HYDROCARBON-BIOMARKERS IN JURASSIC PLANTS OF THE ULUGH-KHEM BASIN (REPUBLIC OF TYVA, RUSSIA) AND THE ANGREN COAL BASIN (UZBEKISTAN)
D.A. Bushnev1, N.V. Nosova2, N.S. Burdelnaya1, S.A. Ondar3
1 Institute of Geology of Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences, Syktyvkar, Russia
2 Komarov Botanical Institute of the Russian Academy of Sciences, Saint Petersburg, Russia
3 Tuvinian Institute for Exploration of Natural Resources of the Siberian Branch of the Russian Academy of Sciences, Kyzyl, Russia
Keywords: Jurassic plants, Leptostrobales, chemotaxonomy, diaromatic secobicadinane, n-C33 n-C35 alkanes, plant biomarkers
Abstract
Samples of Jurassic coal-bearing rocks from the Ulug-Khem Coal Basin (Republic of Tyva, Russia) and from the Angren coal mine (Uzbekistan) were investigated. These rocks contain numerous leaf remains of leptostrobaleans. The material from Angren is represented by a mass of numerous leaf fragments of Phoenicopsis taschkessiensis and Czekanowskia eugeniae (Leptostrobales) forming the leaf litter. The hydrocarbon composition of the rock extracts was studied. All the samples showed high concentrations of C33 and C35 n‑alkanes. The rock extract contains high concentrations of abietic acid derivatives such as dehydroabietanes, simonellite, retene, and norisopimarane indicating a relationship between leptostrobaleans and conifers by their biochemistry. Retene was found in a more mature sample from Tyva, containing abundant leaf remains of Czekanowskia tuvensis. The extract of a rock sample from Tyva contains aromatic secobicadinans, which are the major components of the aromatic fraction. Their connection with leptostrobaleans was excluded based on comparison with samples from Angren; however, their botanical affiliation is not obvious. The discovery of polycadinene resin derivatives in the Middle Jurassic material from Tyva indicates that they were probably produced by some groups of Jurassic plants.
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