Tomáš Weiner

Biostratigraphic and sedimentary record of the Annulata Events in the Moravian Karst (Famennian, Czech Republic)

The biostratigraphy and facies of halfgraben limestones in the southern part of the Moravian Karst (Czech Republic) have been studied from Uppermost Palmatolepiscrepida to Upper Palmatolepisgracilisexpansa conodont Zones. Only one Annulata Event horizon was detected, reflecting condensed sedimentation with the possible influence of erosion on the bypass slope. The “Wagnerbank” equivalent above the Annulata Events in the uppermost part of the Upper Palmatolepis rugosa trachytera Zone was not clearly recognized. The conodont data suggest the event beds in the Ochoz, Hostěnice 2, and Mokrá sections represent the Lower Annulata Event. Correlation of the Annulata Event bed in the Hostěnice 1 section with the Upper Event remains tentative. Recorded microfacies were deposited slightly below or above the storm wave base. The Annulata Event beds correspond to mudstones/wackestones to floatstones/rudstones with cephalopods and other fauna. Other microfacies include mostly various wackestones to packstones up to floatstones/rudstones. Conodont biofacies show the increase in both epipelagic taxa in the Annulata Event beds and “granulated” polygnathids above the Annulata Event beds. The cause of the increase in alternognathids in the Annulata Event beds remains questionable. Both the microfacies and conodont biofacies are generally similar to those seen widely distributed in other European and Moroccan sections, thus documenting the global nature of the Events.

PRELIMINARY REPORT ON THE NEW FINDINGS OF MISSISSIPPIAN TRILOBITES IN THE BŘEZINA FORMATION (MORAVIAN KARST, CZECH REPUBLIC)

New fossiliferous layers of the Březina Formation were discovered in the valley of the Řicka Brook SSW of the village of Ochoz u Brna in 2011. Four taxa of trilobites were preliminary determined: Archegonus (Phillibole) cf. polleni (Woodward, 1894), Archegonus (Phillibole) cf. cauliquercus Brauckmann 1981, Liobole (Liobole) glabra proxima Chlupac, 1966 and ?Spinibole sp. The newly discovered fossiliferous beds belong to the Visean (Lower to ?Upper Visean, approximately cu IIγ–cu IIδ). The occurrence of limestone pebbles and limestone cobbles in aleuropelitic shales was also recorded. The Late Tournaisian foraminifer Darjella monilis Malakhova, 1964 was discovered in a dark grey limestone cobble derived from the Hady-Řicka limestone sequence of the Liseň Formation.

Microproblematica, calcareous algae, and microbialites at the Frasnian-Famennian boundary interval in the Šumbera section (Moravian Karst, Czech Republic) and their significance in the context of the Kellwasser Crisis

The Kellwasser Crisis represents one of the most severe extinction events in the Phanerozoic. The Šumbera section (Moravo-Silesian Basin, Moravian Karst) spans the Upper rhenana to Palmatolepis minuta minuta (or younger) conodont zones and corresponds to the upper part of a carbonate ramp with material derived from shallower areas. A rich association of calcareous algae, cyanobacteria, and microproblematica, comprising renalcids (Izhella), Girvanella, Rectangulina cf. tortuosa, Rothpletzella, “solenoporaceans”, “Keega”-like microfossils, udoteacean alga Paralitanaia, volvocean and radiospherid calcispheres, palaeoberesellids, Umbellina bella, and Wetheredella, is similar in diversity to associations known from China, Australia, Canada, and Belgium. The Šumbera section represents a unique locality where changes in shallow-water biota at the Frasnian-Famennian boundary are well calibrated by detailed conodont biostratigraphy. We track in detail the evolution of shallow-water biota and the features that are often discussed in the context of “anachronistic” facies, such as flourishing microbial structures, enhanced early marine cementation, and flat-pebble conglomerates. Some features which could be indicative of environmental stress such as flat-pebble conglomerates developed during the Frasnian part of the Kellwasser Crisis (Upper rhenana to linguiformis Zones), whereas a renalcid boom started at the Frasnian-Famennian boundary.

Annulata event z profilu v jámovém lůmku u Ochozi u Brna -poznámky ke konodontové biostratigrafii (famen, Moravský kras)

About two meters thick section of the Famennian Křtiny Limestones (Liseň Formation) was studied in a small pit-quarry near the road leading from Brno-Liseň to Ochoz u Brna. Conodont samples were taken from seven diff erent stratigraphical levels. A richly fossiliferous interval (about 40 cm thick) can be distinguished in the higher part of the section. This interval is characterized by abundant occurence of clymenids, bivalves, orthocone nautiloids, trilobites and other groups. Black limestone lenses (maximal thickness about 10 cm) are developed in the lowermost part of the richly fossiliferous interval. A presence of Palmatolepis glabra lepta (late morphotype), Palmatolepis minuta minuta and Palmatolepis rugosa trachytera suggests these black limestones probably represent the Lower Annulata event (Upper Palmatolepis rugosa trachytera zone). Polygnathus styriacus indicating the base of the Palmatolepis perlobata postera zone enters within about 10 centimeters thick interval of dark grey biodetritic limestones which occur closely above the black limestone lenses. The Upper Annulata event and equivalents of „Wagnerbank“ or „Annulata limestone“ were not distinguished in the studied section. This might be caused by condensed sedimentation. Grey limestones and marly limestones belonging to the higher part of the richly fossiliferous interval are placed above the base of the Palmatolepis perlobata postera zone. The studied locality might correspond to the original fossil site described by Rzehak in 1910.