A new formal subdivision of the Holocene Series/Epoch in Estonia

Abstract

Over the past 25 years since the ratification of the last official Holocene Stratigraphic Chart in Estonia, the stratigraphic framework of global Quaternary geology has significantly progressed. The Pleistocene/Holocene boundary is defined in the NGRIP2 ice core from Greenland, with an age of 11 700 calendar yr b2k (before AD 2000). The International Subcommission on Quaternary Stratigraphy developed a formal tripartite stratigraphical subdivision of the Holocene into the Greenlandian, Northgrippian and Meghalayan stages/ages, each supported by a Global Boundary Stratotype Section and Point (GSSP). All three GSSPs are defined on the basis of geochemical markers reflecting abrupt global climatic events dated with high accuracy and serving as a reliable foundation for cross correlation. In the light of this development we present a new formal subdivision for the Holocene in Estonia. The new chart is climatostratigraphic with tripartite subdivision. The chronological boundaries and corresponding names for the stages/ages are aligned with the International Holocene Stratigraphic Chart. The correlation is achieved using synchronous and significant global climatic oscillation events, preserved in Estonian Holocene sedimentary proxy archives. The correlation relies on the direct dating of these Holocene sedimentary successions, particularly AMS 14C dating, lake sediment varve counts, etc. The subdivision of the Baltic Sea sediments in the new Holocene stratigraphic chart is based on the internationally recognized stages in the Baltic Sea history and the chronology of their boundaries. Long-term traditions in geoarchaeological studies in Estonia require a common understanding of the chronological background. Therefore, the subdivision of the Estonian Prehistoric period was included in the new Holocene Stratigraphic Chart of Estonia which was approved by the Estonian Commission on Stratigraphy on 15 January 2020.

Keywords

• estonia
• holocene
• greenlandian
• meghalayan
• northgrippian
• stratigraphic subdivision.