Facies and depositional environment of the Pridoli carbonate ramp in the Silurian Baltic Basin, Lithuania

The present study focuses on the Pridoli succession in the Lithuanian part of the Silurian Baltic Basin. Seven main microfacies are distinguished, based on the carbonate classification system of Dunham (1962): marly shale, mudstone, brachiopod-crinoid wackestone, crinoid-brachiopod packstone, crinoid grainstone, stromatoporoid-crinoid or coral-crinoid float-rudstone and dolomudstone. These microfacies are arranged in five major lateral depositional facies belts. From proximal to distal, the following facies can be distinguished: Sabkha, Inner-shallow ramp, Mid ramp, Outer ramp, Lower ramp slope - deep basin. There was no evidence found of reefs or reef belts in the system, and the central facies belt with abundant stromatoporoid rudstones and floatstones is interpreted as a biostrome. Based on the microfacies and lithofacies distribution, instead of the common platform interpretation, a ramp model is appropriate for the Pridoli succession in Lithuania.