The Lower and Middle Devonian of the south-eastern Baltic Sea

In the Baltic region, Devonian sedimentary bedrock is exposed in a wide are a extending From north-eastern Estonia through Latvia to the south-eastern Baltic Sea. Westwards in the Baltic Sea, the outcrop terminates against a p resumably Permian fault, which extends southwards from Gotland. In the sout hernmost part of the Baltic Sea, the Devonian sedimentary bedrock was erode d during the Permian-Carboniferous uplift event. The Devonian sedimentary b edrock of the investigated area southeast of Gotland, consists of near-shor e marine deposits, namely sandstone, siltstone, clay, dolomite, dolomitic m arl, and limestone. Gypsum and anhydrite deposits occur frequently in the l ower parts. The Silurian-Devonian boundary is marked by a stratigraphic bre ak across the presently investigated offshore area. All regional stages of the Lower and Middle Devonian are present in exposures in the area. In the north-eastern part, offshore Latvia, the basal Devonian Gargzdai deposits f ollow ontop of the Silurian sedimentary bedrock. Further to the south-west, the Gargzdai beds are missing, and deposits of the next younger Kemeri Sta ge rest directly on the Silurian. In the Middle Devonian, the Parnu Stage c ontains widespread sandbars, which are locally deeply truncated. This may i ndicate a shallow nearshore environment. Within the Old Red Sandstone facie s of the late Middle Devonian Arukula-Burtnieki complex, several discontinu ity surfaces are present. The reflectors exhibit a mound-like pattern, whic h again may indicate a shallow nearshore environment with rapid deposition, erosion, and redeposition.