Insufficient knowledge of carbon isotope cycling in the latest Silurian initiated the study of two regions at the western and southwestern margins of Baltica in order to obtain a more complete picture about the carbon isotope trend through the Přídolí. Shallow and open shelf carbonate rocks of the Dniester River outcrops and Kotuzhiny core in Podolia and deep shelf rocks of the East Baltic area, especially the Lithuanian cores, were studied for bulk-rock isotope analysis. The data sets of both regions begin with the mid-Ludfordian excursion and include also some part of the lowermost Devonian. The data show a new minor twin positive δ13C excursion (peak values 0.8–1.7‰) in the upper Ludfordian. The Přídolí carbon isotope trend begins with a low of negative δ13C values, succeeded by the lower to middle Přídolí ‘stability’ interval (variable values below or close to 0‰ with a slight rising trend). The upper Přídolí begins with a medium to major excursion (peak values 2.3–4.5‰), which reflects the pattern of the carbon isotope trend on the west of the Baltica palaeocontinent. Its wider significance awaits confirmation from observations elsewhere. The carbon isotope excursion at the Silurian–Devonian boundary, named here the SIDE excursion (its δ13C values range from 1.6‰ in deep shelf settings to 3.8‰ in shallower ones and 4.5‰ in brachiopod shells), has been traced on several continents, and now also in Baltica. This excursion can serve as a well-dated global chemostratigraphic correlation tool. The shape of the excursion indicates the completeness of the studied section. We conclude that carbon isotope chemostratigraphy may contribute to subdividing the Přídolí Series into stages and that Baltica sensu lato seems to be the right place for such a development

No abstract

No abstract

No abstract

Reefs and a barrier reef have been newly identified and mapped by three-dimensional (3D) seismic survey in Lithuania. Seismic data analysis has allowed the size and geometry of these reefs to be determined. The largest reefs occur at Pavasaris and South Bliudziai. They have a similar shape and are about 1.5 km long and 1 km wide. A circle-shaped smaller patch reef at North Bliudziai is 1 km in diameter. The overall heights of the studied structures do not exceed 30-40 m. The reefs consist of coarse-grained bioclastic stromatoporoid limestone. A barrier reef rising structurally from SW to NE was established in the west of the mapped area. The stratigraphic position (early Minija Regional Stage) and lateral distribution of the barrier reef suggest it started to form earlier than the group of patch reefs. The development of patch reefs was related to the transgression of the Silurian Baltic basin.