“Volkhovian” as a name for the third global stage of the Ordovician System

• Andrei V. Dronov ^[1] ; Tatiana N. Koren ^[2] ; Tatiana Ju Tolmacheva ^[3] ; Lars Holmer ^[3] ; Tõnu Meidla ^[4]
  1. [1] Saint Petersburg State University

     Saint Petersburg State University

     Rusia

     
  2. [2] A.P. Karpinsky Russian Geological Research Institute

     A.P. Karpinsky Russian Geological Research Institute

     Rusia

     
  3. [3] Uppsala University

     Uppsala University

     Uppsala domkyrkoförs., Suecia

     
  4. [4] University of Tartu

     University of Tartu

     Tartu linn, Estonia

     

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• Localización: Serie correlación geológica, ISSN-e 1666-9479, ISSN 1514-4186, Vol. 17, Nº. 1, 2003
• Idioma: inglés
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• Resumen

  • In 1996 the International Subcomission on Ordovician Stratigraphy voted in favor of a subdivision of the Ordovician System into three series and six global stages (Mitchell et al., 1997). Four of the six stages have yet to be formally defined and named, and the Volkhovian (based on a section on the Volkhov River, near St. Petersburg, Russia) is, perhaps, the most appropriate name for the global third stage of the Ordovician System (Webby, 1998). The Volkhovian is one of the best defined and well known of the Ordovician regional stages in Baltoscandia. Deposits of this age are widespread all over the Russian Platform, and they possess very distinctive lithological and palaeontological characteristics, which make them easily recognizable both in outcrops and drill cores. The most biostratigraphically significant groups in the Volkhovian fauna have traditionally been trilobites, brachiopods, conodonts, and graptolites. However, echinoderms, bryozoans, ostracodes, and acritarchs as well as trace fossils are also important components of the fauna.

    The Ordovician succession in St. Petersburg Region has had a long history of investigations. The deposits now recognized as the Volkhovian were first established by Schmidt (1858) as the "Chlorite limestone" and after renamed the "Glauconite Limestone" and indexed as the BII Stage (Schmidt, 1881). At the beginning of the 20th century, a very detailed stratigraphy for the Volkhovian deposits of the St. Petersburg region and Estonia was established by Lamansky (1905), who introduced the a, b and g indexes for the existing BII subdivision of Schmidt (1881). The name Volkhov (or Walkhov Formation) was introduced by Raymond in 1916. Later it was converted into the Volkhov Stage by Balashova and Balashov (1959), and a slightly emended and reduced definition was introduced by Männil (1966). Since that time it has been widely used all over the Baltoscandian basin. During the last decade, the classical Volkhovian sections in the St. Petersburg region have been the subject of intensive multidisciplinary study (Dronov et al., 2000, and references therein).