Facies, scale and chronostratigraphic levels of carbonate episodes in the Salair Ordovician basins with volcanic-terrigenous sedimentation
N.V. Sennikov, O.T. Obut, E.V. Lykova, R.A. Khabibulina, A.V. Timokhin, T.A. Shcherbanenko, I.G. Zakiryanov
Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Ordovician, biostratigraphy, carbonates, terrigenous rocks, tuffs, Salair.
Abstract
Against the general predominance of terrigenous and, to a lesser extent, tuff-terrigenous sedimentation, carbonate formations occasionally occur in the Ordovician of Salair basins. They were found at five different stratigraphic levels: 1) Tremadocian, 2) middle Floian, 3) late Dapingian, 4) early-middle Darriwilian, 5) Katian. In Tremadocian, carbonates are known in the Medvedkovo and Yeltsovka teсtonic blocks, and at other levels – in the East-Berd’, Guryevsk and Yeltsovka tectonic blocks. By the nature and scale of the manifestation, carbonate formations in the Ordovician of Salair are represented by shell rocks, lenses of clastic limestones, bedded, sandy and clayey limestones, small thin bioherms, small mudmounds. Paleogeomorphological control of their confinedness to the slopes of Ordovician volcanic structures was observed.
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