Ordovician of Baltoscandia: facies, sequences and sea-level changes

Sea level changes are the main mechanism controlling facies dynamics, stratal geometry and temporal variations in fossil assemblages in marine sedimentary basins. Besides having direct influence on the water depth sea-level changes could serve as a trigger for various oceanographic, climatic, sedimentary, chemical, and biotic events. Patterns of large-scale evolutionary radiation and mass extinction may be related in complex ways to large-scale fluctuations of the sea level. In recent years a number of new sea-level reconstructions for specific Ordovician basins around the world (Munnecke et al., 2010) as well as the refinement of the global chronology of the Ordovician depositional sequences (Haq and Schutter, 2008) have been suggested. Bathymetry of the Ordovician basin of Baltoscandia is considered in numerous papers and has been summarized in regional sea-level curves (Nestor and Einasto, 1997; Dronov and Holmer, 2002; Nielsen, 2004) which differ in several stratigraphic levels. The purpose of this article is to present a refined review of sequence stratigraphy and sea-level changes for the relatively shallow-water Estonian part of the basin.