TURGA LAGERSTATTE (Middendorf’s Outcrop, Eastern Transbaikalia, Barremian-Aptian): STRATIGRAPHIC RANGE AND PALAEOENVIRONMENTS
I.N. Kosenko1,2, E.B. Pestchevitskaya1, V.D. Efremenko1,2, E.K. Metelkin1,2, P.A. Yan1,2, A.P. Rodchenko1, B.L. Nikitenko1,2, D.A. Mirzabaev3
1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
3Tyumen State University, Tyumen, Russia
Keywords: Barremian, Aptian, Turga Formation, Turga biocenosis, Jehol Biota, Transbaikalia
Abstract
The age of the Turga Formation in the Middendorf’s outcrop is determined as latest Barremian-earliest Aptian based on fauna and microfossil assemblages. The composition of the fauna and palynomorph assemblages allows correlations between the Turga Formation and the Yixian Formation and lower part of the Jiufotang Formation of Northeast China. Results of the petrographic and geochemical analysis as well as microfossil studies showed that sediments accumulated in a shallow lake with low-energy hydrodynamics, sometimes under low-oxygen conditions. Climate features (warm temperate climate transitional to subtropical) and type of vegetation (coniferous forests with admixture of hardwoods) are reconstructed taking into consideration the composition of spore-pollen assemblages.
|
