Annulata event from a pit-quarry near Ochoz u Brna – remarks on conodont biostratigraphy (Famennian, Moravian Karst)

About two meters thick section of the Famennian Křtiny Limestones (Líšeň Formation) was studied in a small pit-quarry near the road leading from Brno-Líšeň 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.About two meters thick section of the Famennian Křtiny Limestones (Líšeň Formation) was studied in a small pit-quarry near the road leading from Brno-Líšeň 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

VARISKÉ DEFORMACE VE VYBRANÝCH VRTECH V PALEOZOIKU U HRANIC

Based on structural analysis of thin sections from V501-V503, V505, V506 and LV60 borehole cores, mylonitised limestones were identified. Different strain indicators were used to distinguishing tectonic limestones facies, which include weakly recrystalized protoliths, protoblastomylonites and blastomylonites. Mylonites are forming shear zones, which were localized in boreholes as well as in geological maps. Stratigraphic sequences are usually duplicated in association with the shear zones. Alpine-style structure model of Hranice Paleozoic area is the result of the ductile Variscan thrust tectonics

Petrophysical signature of the Devonian/Carboniferous boundary interval in the Moravian Karst

The first results of the petrophysical research (gamma-ray spectrometry, magnetic susceptibility, diffuse spectral reflectance) of the Devonian/Carboniferous boundary interval in the southern and middle part of the Moravian Karst demonstrate a good correlation potential of outcrop logging by gamma-ray spectrometry. This method allows us to correlate distinct petrophysical patterns through the different lithofacies developments (Horákov and Hostěnice facies), while magnetic susceptibility and diffuse spectral reflectance failed to show correlatable patterns. The most prominent petrophysical patterns at the sections can be correlated with the polyphase Hangenberg Event.The first results of the petrophysical research (gamma-ray spectrometry, magnetic susceptibility, diffuse spectral reflectance) of the Devonian/Carboniferous boundary interval in the southern and middle part of the Moravian Karst demonstrate a good correlation potential of outcrop logging by gamma-ray spectrometry. This method allows us to correlate distinct petrophysical patterns through the different lithofacies developments (Horákov and Hostěnice facies), while magnetic susceptibility and diffuse spectral reflectance failed to show correlatable patterns. The most prominent petrophysical patterns at the sections can be correlated with the polyphase Hangenberg Event

VÝVOJ MYLONITIZACE VÁPENCŮ A KONTRASTNÍ VARISKÁ DEFORMACE TEKTONICKÝCH DOMÉN JIHOZÁPADNÍHO BRUNOVISTULIKA

The calcite mylonites in the Brunovistulian sedimentary cover developed in frontal thrust area of Moravian nappe units were examined. The inhomogeneous composition of sedimentary protoliths allowed the analysis of the contrasting behavior of matrix and clasts and the interpretation of microfabric evolution during deformation under low temperature conditions. Several tectonofacies with microfabric characteristic for a given position within the progressive/retrogressive deformation path are distinguished. Generally, the progressive phase of mylonitization is characterized by grain growth in the matrix and the grain size reduction of the clasts leading to a stress-determined equillibration of grain size. With rising temperature during deformation, grain growth predominated after grain size homogenization was finished. Large-scale thrusting within the Brunovistulian basement is evidenced by the juxtaposition of calcite and quartz mylonites with contrasting microstructures. In terms of deformational styles of calcite and quartz the lower unit of the Svratka tectonic window differs distinctively from both the lower unit of the Thaya tectonic window and the western margin of the Brno Batholith. Although these differences include such pronounced contrast as the fully brittle vs. fully plastic deformation of quartz, paleothermometric data which are available to date, suggest that the variation in microstructures is not accompanied by major changes in paleotemperatures. This can be explained by an abrupt change of deformation mechanisms in both calcite and quartz at temperatures around 300°C

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 Říčka 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 Chlupáč, 1966 and ?Spinibole sp. The newly discovered fossiliferous beds belong to the Viséan (Lower to ?Upper Viséan, 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 Hády-Říčka limestone sequence of the Líšeň Formation.New fossiliferous layers of the Březina Formation were discovered in the valley of the Říčka 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 Chlupáč, 1966 and ?Spinibolesp. The newly discovered fossiliferous beds belong to the Viséan (Lower to ?Upper Viséan, 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 Hády-Říčka limestone sequence of the Líšeň Formation

Zpráva o výzkumu vápenců při východním okraji boskovické brázdy

A report on research of limestones at the eastern border of the Boskovice Grabe

Carboniferous limestone boulder from the Badenian clastics (Carpathian Foredeep, Czech Republic): A useful data source on the Palaeozoic of the Moravosilesian Basin

The lower Badenian basal and marginal clastics of the Carpathian Foredeep represent a useful source of information on the Palaeozoic units of the Moravosilesian Basin (Bohemian Massif). This study addresses in detail a Tournaisian limestone boulder from a locality near Kučerov village. Foraminifers indicate a narrow interval within the Mississippian Foraminifer Zone 8, characterized by the co-occurence of Darjella monilis Malakhova, 1964 and Eoparastaffella ex. gr. vdovenkoae Devuyst & Kalvoda, 2007. Fourteen recorded brachiopod taxa include: markedly predominant chonetidines, represented by Megachonetes zimmermanni (Paeckelmann, 1930) and other rugosochonetids; less frequent strophomenides (Leptagonia M’Coy, 1844) and orthotetides (Pulsiidae, Schuchertellidae); and rather rare spiriferides, athyrides?, orthides and productidines. The brachiopod fauna is generally close to associations known from other European areas. Trilobites are represented by the genus Cummingella Reed, 1942. The specimens recorded do not match the species previously known from the Czech Republic and the morphological features preserved suggest similarity with taxa from other European areas (e.g. Belgium, Poland). The microfacies correspond to floatstone with a packstone/grainstone matrix and contain crinoids, peloids, foraminifers, intraclasts, cortoids, moravamminids, algae and other allochems. Based on microfacies and foraminifer data, the boulder might originate in the limestone succession of the Líšeň Formation in the vicinity of Mokrá or in the limestone olistoliths in the siliciclastic Culm facies. Accordingly, at least some of the dark grey limestone clasts at the studied locality correspond to the Carboniferous and not only to the Devonian as previously assumed