Outline of the lithology and depositional features of the lower Paleozoic strata in the Polish part of the Baltic region

Abstract

Lower Paleozoic deposits have been noted in the western part of the Baltic Depression belonging to the Precambrian platform as well as in the Koszalin-Chojnice Zone that represents a hypothetical fragment of the Caledonian fold and thrust belt. Generally, the boundary between these regions is considered to run along faults belonging to the Teisseyre-Tornquist Zone. The deposits have been widely recognized in the East European Craton, and their entire lithological column has been drilled through in on- and offshore boreholes. New constructed lithofacies-thickness maps have updated the lithofacies diversity and thickness changes of the Ediacaran-lower Paleozoic deposits. The sedimentary infill of the Baltic Basin begins with deposits of the arnowiec Formation ascribed to the uppermost Ediacaran and lowermost Cambrian. The upper part of the Lower Cambrian comprises sandstones and mudstones and the Middle Cambrian is made of sandstones, mudstones and claystones. Upper Cambrian to Tremadocian strata are represented by dark bituminous shales. Arenigian to Ashgillian deposits are developed as thin calcareous-muddy deposits. Silurian strata represent a thick (over 3000 m) succession of siltstones and shales with subordinate calcareous intercalations in the upper part of the succession (Pridoli). In the Koszalin-Chojnice Zone only, fragments of tectonically disturbed Ordovician and Silurian shales and siltstones have been recognized.