Facies development across the Late Silurian Lau Event based on temperate carbonates of the Prague Basin (Czech Republic)

The facies development through the stratigraphical interval of the Silurian (late Ludlow) Lau Event and the associated major δ13C record excursion have been studied in the Prague Basin. The investigated sections consist of temperate-water carbonates (Kopanina Formation) that were deposited in shallow as well as deeper parts of the basin. In both areas, the facies evolution reflects a major shallowing of sea-level during the early part of the event, which resulted in weathering (karstification) and erosion in the shallower parts of the basin, leading to stratigraphic gaps there. Paleokarst features and dolomitization are associated with these strata in the vicinity of Prague, where the δ13C record displays a strong diagenetic overprint and palynomorphs are very poorly preserved. A transition from deep-water shale to subtidal, thick-bedded limestone facies in the deeper parts of the basin, close to Kosov, signals the same sea-level drop, indicating that it was basin-wide. Detailed lithologic descriptions for the studied sections are provided and the development in the Prague Basin is compared with the coeval succession on Gotland, Sweden, which was located in the tropical realm at this times