Konodontová fauna spodního tournai v Lesním lomu (Brno-Líšeň)

Abstract

Early Tournaisian was a period of transition between devonian hot and carboniferous cold climate system and therefore crucial in terms of global reconstruction evolution. Early Tournaisian represents a period that follows a detailed studied Hangenberg crisis (late Famenian) and that is connected to glaciation. Based on the study of conodont fauna this article outlines the biostratigraphy of the Lower Tournaisian upper Křtiny limestones situated in the Lesní lom quarry. „Upper“ Křtiny limestones are pale grey mud calciturbidites containing abundant microfauna of conodonts, echinoderms, ostracods, brachiopods, bivalves, bryozoans, ichthyoliths, radiolarians, trilobites and foraminiferas. They are part of the Líšeň Formation which belongs to Paleozoic of Moravian Karst. 8 samples were taken and evaluated from 3 profiles. In total there were determined 22 conodont species belonging to conodont families of Bispathodus, Polygnathus, Pseudopolygnathus and Siphonodella. Following taxons were found: Siphonodella belkai DZIK 1997, Si. carinthiaca SCHÖNLAUB 1970, Si. cf Si. isosticha COOPER 1939, Si. duplicata-jii, Si. jii HASS 1959, Si. lobata BRANSON & MEHL 1934b, Si. obsoleta HASS 1959, Si. sandbergi (M1, M2) KLAPPER 1966, Polygnathus communis communis BRANSON & MEHL 1934b, Po. distortus BRANSON & MEHL 1934b, Po. inornatus BRANSON 1934, Po. purus purus VOGES 1959, Po. spicatus BRANSON 1934, Po. vogesi ZIEGLER 1962, Pseudopolygnathus fusiformis BRANSON & MEHL 1934b, Ps. primus BRANSON & MEHL 1934, Ps. triangulus inaequalis VOGES 1959 and Ps. triangulus triangulus VOGES 1959. Based on the conodont elements the Siphonodella jii and Siphonodella sandbergi zones were distinguished. All profiles but profile 2 belonged to the siphonodellid-polygnathid biofacies, profile 2 belonged to the polygnathid biofacies.