UPPER VENDIAN AND LOWER CAMBRIAN STRATIGRAPHY OF THE BALTIC-LADOGA MONOCLINE OF THE EAST EUROPEAN PLATFORM: MULTIFACETED LITHOLOGICAL AND PALAEONTOLOGICAL APPROACH
GOLUBKOVA E.YU.1, SHISHLOV S.B.1, KUSHIM E.A.1, TITOVA A.V.1,DUBKOVA K.A.1,SILIVANOV M.O.1,2, GRAZHDANKIN D.V.3,4
1 Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg
2 Saint Petersburg Mining University, St. Petersburg
3 Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk
4 State Key Laboratory of Continental Evolution and Early Life, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an
Keywords: LITHOLOGY, FORMATION, REGIONAL STAGE, PALAEONTOLOGY, MICROFOSSILS, STRATIGRAPHY, EAST EUROPEAN PLATFORM, VENDIAN, EDIACARIAN, CAMBRIAN
Abstract
In order to revise the Upper Vendian and Lower Cambrian stratigraphy in the northwest of Russia, a lithological and paleontological study was conducted for the Geolkom, Taitsy-2, Utkina Zavod'-1 reference drill-core sections in central part of the Baltic-Ladoga monocline of the East European Platform. The strata have been subdivided into the Staraya Russa (Redkino Regional Stage), Vasilevskiy Ostrov (Kotlin Regional Stage), Lomonosov and Siverskaya (Kotlin – undivided Rivne-Lontova Interval) formations. The uppermost Upper Member of the Vasilevsky Ostrov Formation is missing in the Geolkom drill-core stratotype section, where the Kotlin Regional Stage is unconformably overlain by Quaternary deposits. A complete section in the Taitsy-2 drill-core section (depths 318-188 m) is here suggested as a hypostratotype of the Vasilevsky Ostrov Formation. Taking into account that the Lomonosov Formation was erected without a designated stratotype, the further suggest the Taitsy-2 drill-core section (depths 188-126 m) as its lectotype. The Vendian–Cambrian boundary is placed in the mid-section of the Lomonosov Formation Lower Member marked by the Kotlin Fossil Assemblage (strata with Aataenia reticularis - Bicuspidata fusiformis - Vanavarataenia insolita) being replaced by the Rivne-Lontova Fossil Assemblage (strata with Ceratophyton sp. - Teophipolia lacerata). The lowermost Redkino Fossil Assemblage (strata with Tynnia precambrica - Zinkovioides inclusus) hosts elements of the Ediacaran-type acanthomorphic biota (Tanarium aff. T. conoideum, Mengeosphaera sp.), which is not typical for central and western regions of the East European Platform.
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