The first lower Viséan trilobite association from limestone facies of the Moravian Karst and its relation to the sedimentary environment (Líšeň Formation, Czech Republic)

Abstract

A lower Visean trilobite association from limestones of the Liseň Formation in the Moravian Karst (Czech Republic) was studied in detail for the first time. The trilobites were obtained from a thin interval in the succession of the HadyŘicka Limestone exposed in the Zetor section situated on the southern margin of the Moravian Karst near Brno. The limestone succession of the Zetor section with prevalently distal calciturbidites was deposited on the lower part of the carbonate ramp. Biostratigraphic data suggest the span of the lower Visean MFZ11 (foraminiferal zone) for the interval rich in trilobites. The trilobites are preserved in at least a partly silicified state. Around twenty trilobite species or subspecies were recorded including one new taxon Bollandia megaira brunensis subsp. nov., various species of ?Namuropyge R. Richter & E. Richter, Liobole R. Richter & E. Richter, Angustibole G. Hahn, ?Cyrtoproetus Reed, Gitarra Gandl, Pseudowaribole (Geigibole) Gandl, Winterbergia G. Hahn & Brauckmann, Bollandia Reed and several taxa of problematic affinity, which are discussed. The recorded taxa show an affinity with associations from the Erdbach Limestone facies in Germany but also with other areas (e.g. Cantabrian Mountains, Spain). The trilobite association shows similarities to the “Shelf Slope” and “Erdbacher Kalke” communities recorded in Germany. In contrast, the previously described lower Visean trilobite associations from the Moravian Karst were restricted to the aleuropelitic facies of the Březina Formation and correspond rather to the “Culm facies” community known from Germany. These associations might represent more distal and deeper basinal settings than the Zetor section or an environment of generally similar depths with a different source area and bottom topography.