Stable carbon isotope stratigraphy of the Silurian in the Jočionys-299 borehole (eastern Lithuania).

In recent years it has become commonplace to formalize chemostratigraphic units and identify isotopic zones (chemo - stratigraphic units) from excursions. Stable carbon isotopes have been used in solving stratigraphic problems in the Silurian for more than 30 years. d13C data supplement other stratigraphic proxies, allowing the subdivision of geological sections and more precise correlation. In this paper we give new d13C data from the Silurian section of the Jočionys-299 borehole, which is located in eastern Lithuania, crossing shallow marine and lagunal deposits. Based on d13C variability, the Ireviken carbon isotope excursion (CIE), the Šlilalė CIE, and probably the Valgu CIE have been identified in the investigated section. The Valgu CIE is linked to the lower part of the Švenčionys Formation. The Ireviken CIE is linked to the upper parts of the Švenčionys Formation and the Paprieniai Formation (rise in d13C values), the Jočionys Formation (moderately stable d13Ccarb values) and the Verknė Formation (fall in d13C values). A small negative d13C shift is documented in the Pabradė Formation. Chemostratigraphy together with biostratigraphic data allow us to correlate eastern Lithuanian lithostratigraphic units (shallow marine environment) with the global Silurian Geochronological Scale more accurately. [ABSTRACT FROM AUTHOR]

Viimase 30 aasta jooksul on stabiilsete süsiniku isotoopide (d13Ccarb) uuringud leidnud üha laiemat kasutamist Siluri ajastu stratigraafias. Stratigraafilisi skeeme on täiendatud kemostratigraafiliste ühikutega - isotooptsoonidega. d13Ccarb andmestiku kasutamine koos teiste stratigraafiliste meetoditega võimaldab läbilõigete detailsemat liigestamist ja usaldusväärsemat korrelatsiooni. Artiklis on esitatud Jočionys-299 puurläbilõike d13Ccarb uuringute tulemused, mis võimaldavad läbilõikes fikseerida Irevikeni (vastab Paprieniai ja Jočionyse kihistutele ning Verknė kihistu basaalsele osale) ja tõenäoliselt ka Valgu (Švenčionyse kihistu alumises osas) ning Šlilalė (Pabredė kihistu alumine osa) isotoopsündmuste (CIE) intervallid. Kemostratigraafilise andmestiku integreerimine biostratigraafilisega võimaldab ida-Leedu siluriaegsete madalveeliste setete usaldusväärset korrelatsiooni globaalse Siluri geokronoloogilise skaalaga. [ABSTRACT FROM AUTHOR]

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