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Original article

High-resolution biostratigraphy of the Tournaisian-Visean (Carboniferous)boundary interval, Mokrá quarry, Czech Republic§

Biostratigraphie haute-résolution de la limite Tournaisien-Viséen (Carbonifère),carrière de Mokrá, République Tchèque

Jirí Kalvoda a,*, François-Xavier Devuyst a,b, Ondrej Bábek a,Ladislav Dvorák a, Stepán Rak c, Jirí Rez a

a Institute of Geological Sciences, Masaryk University, 2 Kotlarska, 61137 Brno, Czech Republicb Carmeuse Lime and Stone, Technology Center, 3600 Neville Road, Pittsburgh PA 15225, USA

c Institute of Geology and Palaeontology, Faculty of Sciences, Charles University,6 Albertov, Praha 2, Czech Republic

Received 9 June 2009; accepted 19 October 2009

Available online 8 April 2010

Abstract

This paper summarizes the results of investigations carried out in the Mokrá quarry since 2006 on the biostratigraphy of the Tournaisian-Visean(T-V) boundary interval. It also integrates previous results obtained by J. Kalvoda and collaborators. The main focus is on the boundary itself, butstratigraphically lower and higher levels have been investigated as well to provide a biostratigraphical context spanning the late Tournaisian to earlyVisean. This stratigraphical level has been the focus of intense international research in the recent years under the auspices of the Subcommissionon Carboniferous Stratigraphy (SCCS) in order to find a new criterion and reference section (Global Stratotype Section and Point, GSSP) for thebase of the Visean Stage. The appearance of Eoparastaffella simplex from its ancestor E. ‘‘ovalis’’ and the Pengchong section (Guangxi, southernChina) have recently been proposed by the Task Group on the Tournaisian-Visean Boundary and ratified by the SCCS as the new biostratigraphiccriterion and GSSP for the base of the Visean, respectively. The sequence exposed in Mokrá is not suitable as a GSSP, notably because it is an activequarry, but it contains most of the foraminifer and conodont guides allowing a high-resolution biostratigraphy of the boundary interval. In addition,it contains abundant trilobites. For these reasons, it constitutes one of the best sections across the T-V boundary in Europe and can serve as a usefuladditional reference.# 2010 Elsevier Masson SAS. All rights reserved.

Keywords: Biostratigraphy; Foraminifers; Conodonts; Tournaisian; Visean; Carboniferous

Résumé

Cet article fait la synthèse des études biostratigraphiques menées depuis 2006 sur la limite Tournaisien-Viséen (T-V) dans la carrière de Mokrá.Les résultats obtenus précédemment par J. Kalvoda et ses collaborateurs ont été inclus. L’objet principal de l’article est la limite elle-même, maisl’intervalle stratigraphique étudié couvre le Tournaisien supérieur et le Viséen inférieur afin que la limite puisse être comprise dans son contexte.Ces dernières années, cet intervalle stratigraphique a été l’objet d’intenses recherches internationales sous les auspices de la Sous-commission deStratigraphie du Carbonifère (SCCS) dans le but de trouver le meilleur critère biostratigraphique possible pour la base de l’étage Viséen ainsi qu’unstratotype global (Global Stratotype Section and Point, GSSP). L’apparition d’Eoparastaffella simplex dans la lignée évolutive E. « ovalis » à E.simplex et la coupe de Pengchong (Guangxi, Chine du sud) ont récemment été proposés par le Groupe de Travail sur la Limite Tournaisien-Viséenet ratifiés par la SCCS comme nouveau critère biostratigraphique et GSSP pour la base du Viséen, respectivement. La séquence stratigraphiquevisible à Mokrá ne remplit pas les critères d’un GSSP, notamment car il s’agit d’une carrière active, mais elle contient la plupart des espèces deforaminifères et conodontes qui permettent de définir une biostratigraphie haute-résolution de la limite Tournaisien-Viséen. La coupe de Mokrá

Geobios 43 (2010) 317–331

§ Corresponding editor: Frédéric Quillévéré.* Corresponding author.

E-mail address: [email protected] (J. Kalvoda).

0016-6995/$ – see front matter # 2010 Elsevier Masson SAS. All rights reserved.doi:10.1016/j.geobios.2009.10.008


contient par ailleurs une riche faune de trilobites. Ces qualités en font une des meilleures coupes de la limite T-V en Europe et une coupe deréférence complémentaire au stratotype.# 2010 Elsevier Masson SAS. Tous droits réservés.

Mots clés : Biostratigraphie ; Foraminifères ; Conodontes ; Tournaisien ; Viséen ; Carbonifère

1. Introduction

Active research on the Tournaisian-Visean (T-V) boundaryinterval has been carried out in the past 10 years as a result of thedecision of the International Commission on Stratigraphy (ICS)to revise and standardize the Phanerozoic chronostratigraphicscale. A Task Group on the T-V boundary was set up in 1995 bythe Subcommission on Carboniferous stratigraphy in order tofind a better section to replace the historical stratotype for thebase of the Visean (Bastion section, Namur-Dinant Basin,southern Belgium) and to evaluate critically the applicability ofthe existing criterion (appearance of the foraminifer Eopar-astaffella simplex Vdovenko; Devuyst et al., 2003 and referencestherein). The sequence stratigraphy context (Hance et al., 2001)and biostratigraphy (Poty et al., 2006) of the Namur-Dinant

region were revised and potential new reference sections wereinvestigated worldwide (see summary and references in Devuyst,2006). Results showed that:

� Eoparastaffella, used in conjunction with other foraminiferand conodont taxa, allows a high-resolution biostratigraphyin the latest Tournaisian and early Visean at the scale ofEurasia (Devuyst, 2006; Devuyst and Kalvoda, 2007;Devuyst and Hance in Poty et al., 2007);� The historical criterion for the base of the Visean can be

retained as E. simplex is part of an evolutionary lineagestarting in the latest Tournaisian (Hance and Muchez, 1995;Hance, 1997; Devuyst, 2006);� The Pengchong section of Guangxi, southern China,

constitutes the best-known section to replace Bastion as a

Fig. 1. Satellite photograph (A) and sketch (B) showing the location of the profiles studied in Mokrá quarry (based on http://earth.google.com/). Dotted lines indicatethe floors in each sub-quarry; the floors of the main quarry are numbered from B1 to B4 for reference; profiles studied are numbered from 1 to 6.

J. Kalvoda et al. / Geobios 43 (2010) 317–331318


new stratotype for the base of the Visean (Hance, 1997;Devuyst et al., 2003).

Both the criterion for the base of the Visean and the newstratotype section have now been ratified by the SCCS and theInternational Union of Geological Sciences (IUGS; Work,2002, 2008). Although Mokrá quarry cannot serve as astratotype because of its sedimentary context (relativelydiscontinuous sedimentation), tectonic setting (see below andDvorák et al., 1987) and because it is an active quarry, itexposes one of the best successions known for the biostrati-graphy of the T-V boundary interval with abundant and diverseforaminifers, conodonts and trilobites. Such sections areespecially rare in Europe. The goal of the present work istherefore to describe the distribution of the main foraminiferand conodont guides together with trilobite occurrences in thelatest Tournaisian and early Visean of Mokrá and to provide areference T-V boundary succession in Europe.

2. Material and methods

Different profiles were studied and sampled over the years,following the advance of the quarry faces. A first series of thinsections was typically made and examined to identify therichest levels. Additional numerous thin sections (over 700)were cut in the best beds. Foraminifers were studied with ahigh-magnification binocular microscope Nikon 80i. About 40samples, 3 to 4 kg each, were collected, processed (standardtechnique with acetic acid and bromoform) and examined forconodonts in profiles 1, 2 and 3; not all were productive.Between 1500 and 2000 specimens of trilobites were collectedin the late Tournaisian to early Visean part of the Brezina Fm.Two main levels were especially productive, one in the latestTournaisian and one in the early Visean. Trilobite specimensare currently being studied by S. Rak for a Ph.D. thesis.

3. Mokrá quarry

3.1. Location, general stratigraphy and sections studied

Mokrá quarry is a vast active quarry composed of three sub-quarries (Fig. 1) located 15 km east-northeast of Brno in thesouthernmost Moravian Karst. It exposes rocks of Frasnian tolate Visean age. The Frasnian is represented by reefoidlimestones (Macocha Fm) whereas the Famennian to Viseaninterval is composed of mass flow deposits, basinal shales(Hády-Rícka Mbr of the Lísen, and Brezina Fms) and rarerhemipelagites (Krtiny Mbr of the Lísen Fm). The Tournaisian-Visean boundary occurs in the lower part of the Brezina Fm(Fig. 2). The middle to upper Visean is represented by typicalflysch facies of the Rozstání and Myslejovice Fms (Dvoráket al., 1987).

The late Tournaisian to early Visean succession was studiedin six main subsections referred to as ‘‘profiles’’ (Figs. 1, 3 and4). The numbering of the profiles was made as researchprogressed. Profiles 1 and 3 to 6 are/were located in thenortheastern corner of the middle quarry whereas Profile 2 is

located at the entrance of the eastern quarry (Fig. 1). Thestratigraphically oldest profile studied (Fig. 5) exposes theupper part of the Hády-Rícka Mbr (Fig. 2), characterized hereby medium to dark, fine-grained, sandy and cherty limestonesoverlain by dark, very sandy, medium-grained limestones andmassive sandy limestone sedimentary breccias passing to thelowermost part of the Brezina Fm. The lower part of the section(Hády-Rícka Lm) is not folded but becomes strongly folded inthe Brezina Fm (alternating medium- to thin-bedded bioclastic-lithoclastic calcarenites, bioclastic calcilutites and greenish toreddish calcareous shales, locally with abundant trilobites).Profile 4 (quarried out; Fig. 4) used to expose the upper part ofthe same massive sandy limestone breccias and the lowermostpart of the overlying Brezina Fm directly N-Westwards ofProfile 3. Profile 1 (quarried out; Fig. 6) used to expose amoderately folded (small scale) sequence in the lowermost partof the Brezina Fm with alternating thin- to medium-beddedbioclastic and often sandy calcarenites and calcilutites andbrownish calcareous shales (�1/1 ratio). The limestone beds

Fig. 2. General lithostratigraphical column for the late Devonian and earlyCarboniferous of southern Moravia. Lithological symbols are of standard use.See text for detail.

J. Kalvoda et al. / Geobios 43 (2010) 317–331 319


were finer-grained and more micritic up-section. Outcropconditions were not suitable to produce a detailed log of Profile1 and the thickness shown in Fig. 7 is probably significantlyincreased by folding. Profile 3b (quarried out) used to display apart of the lower Brezina Fm laterally equivalent to the top ofprofile 3a and beds slightly higher stratigraphically (Figs. 4, 8and 9). It was characterized by alternating medium- to thin-bedded bioclastic calcarenites and calcilutites and brownishcalcareous shales (limestones were dominant, maybe becauseof tectonic reduction of shales). The succession was highlyfolded and beds were slightly displaced by creep. Anapproximate doubling of the thickness is inferred. Profile 3c(bench 3; Fig. 3) outcrops at present on the quarry wall locateddirectly S-Eastwards of former Profile 3b. It exposes a highlyfolded part of the Brezina Fm overlying the succession ofProfile 3b. Profile 6 (Fig. 6) exposes a highly folded sequence ofalternating reddish-grey, fine- to coarse, bioclastic calcarenitesand reddish-green, calcareous shales (the shales largelydominate). There is again probably an approximate doublingof thicknesses due to folding. Profile 2 (eastern quarry; Fig. 6)displays an overturned and highly condensed sequence of thelower Brezina Fm resting tectonically on lower Tournaisiannodular calcilutites (Krtiny Mbr of the Lísen Fm). Here, thelower Brezina Fm is composed of alternating medium- tocoarse-grained bioclastic calcarenites (some very rich inforaminifers) and calcareous shales. In the upper part of theprofile, limestone beds become finer-grained and more micritic.Outcrop conditions do not allow detailed logging but there is noapparent major folding. The structural context of Mokrá quarry

is complicated (see below) and some of the profiles studiedundoubtedly belong to separate thrust sheets with distinctlateral variations of facies in a N-S direction (Fig. 2). Suchvariations are observed, for instance, in the thickness of themassive limestone breccias and in the grain size of thecalcarenite beds of the Brezina Fm at equivalent stratigraphicallevels. The correlation between profiles shown in Figs. 4 and 6is interpretative and based both on biostratigraphic (forami-nifers, conodonts) and lithostratigraphic (massive breccias)evidences.

3.2. Paleogeographical, geological and sedimentarysetting

In southern Moravia upper Devonian and lower Carbonifer-ous rocks represent the sedimentary cover of the Brunovistulianterrane, which is generally regarded as an eastern continuationof the Rhenohercynian Zone (e.g., Franke, 1989; Kalvoda,1998; Chadima and Melichar, 1999; Hartley and Otava, 2001;Kalvoda et al., 2002, 2003, 2008). Fig. 10 shows the generalgeological context of the eastern Czech Republic. During theVariscan orogeny the Brunovistulian terrane was located on thesouthern tip of Laurussia and was involved in the collision withthe Lugodanubian terranes (Armorican Terrane Assemblage ofTait et al., 1997; Kalvoda et al., 2003).

In the early Famennian, extension and block tiltingtransformed the carbonate platform, which occupied the Mokráarea into a graben basin. The structure of this basin wasmaintained up to the start of flysch sedimentation in the middle

Fig. 3. Photo-panoramas of the N-NE wall of the main quarry showing the location of all profiles studied. Profile 2 is in the east quarry. B is an enlargement of A and C isan enlargement of B. The locations of outcrops of the massive breccias are shown in C. Note large quarry truck in A, drill on second bench in B and car in C for scale.



Visean. Famennian limestones were deposited in the grabeneither as upper slope hemipelagic carbonate oozes (Krtiny Mbr)or as lower slope skeletal calciturbidites (lower Hády-RíckaMbr; Kalvoda et al., 1996a,b). The source area for thecalciturbidites was situated on another carbonate platformlocated north of Mokrá. This platform is now covered by nappesof flysch sediments. At the Devonian-Carboniferous boundaryan important sea-level fall occurred and resulted in theemergence of the platform. The lower Tournaisian wascharacterized by deposition of hemipelagites, mud calciturbi-dites and rare skeletal calciturbidites. A transgression at thebase of the crenulata Zone (Kalvoda, 1989, 1992) is evidencedby the change from nodular limestones (Krtiny Mbr) to planar-bedded, fine-grained limestones with frequent chert nodulesand rare thin radiolarite layers (upper Hády-Rícka Mbr).

The onset of Variscan compression is recorded at the base ofthe late Tournaisian by the deposition of sandy lithoclasticcalciturbidites, sandstones and massive sandy limestonebreccias (top of the Hády-Rícka Mbr; Fig. 2). The presence

of feldspar grains in some beds at that stratigraphic levelsuggests a more arid climate. Higher in the late Tournaisian andin the early Visean, thicker-bedded and coarser-grainedcalciturbidites and other mass-flow deposits were depositedin the upper slope to the north whereas thinner-bedded andfiner-grained calciturbidites and reddish to greenish shales(Brezina Fm) were deposited in the deeper part of the basin tothe south. A general fining upwards trend is observed in theBrezina Fm. The calciturbidites contain, among other graintypes (dominated by crinoids and moravamminids), abundantforaminifers, locally rugose corals, trilobites and variableamount of conodonts whereas the shales contain trilobites andbrachiopods, but also some bivalves and rare unidentifiedammonoids.

3.3. Tectonic setting

The sedimentary sequence exposed in the Mokrá areaunderwent polyphased deformation in a tectonically convergent

Fig. 4. Stratigraphical logs of selected profiles studied. Profile 3b (after Rak, 2004) is not as detailed as other profiles; profiles 3c and 5 were not logged. Forinterpretation of colours, see the web version of this article.



context characterized by complex overthrusting (Rez, 2004a,b).The most obvious deformation features are folds. Two mainphases of folding can be distinguished. Older folds are mostlyasymmetric and recumbent with axes dipping to the SE.Stretching lineations indicate a NNE-SSW compression, andthe asymmetry suggests a NNE movement. Younger folds arealmost perpendicular to the previous ones, gently refoldingthem. Stretching lineations indicate NW-SE shortening. Thesestructures are further complicated by brittle tectonics. Inaddition to minor faults, there are two main faulting systems,which cross-cut the folds. The first system is represented byNNE-SSW normal faults and the second by WNW-ESE strike-slip faults (Figs. 10 and 11). The orientation of these faults andtheir relationship to other structures suggest an alpine origin.The most important tectonic features of the Mokrá area,however, are thrust faults separating sedimentary sequences ofdifferent facies (and paleo-positions in the sedimentary basin)in normal and reversed position (Fig. 11). These faults appear inthe field as decimetric to metric-thick black mylonitic zoneswith graphitic organic material. Stretching lineations and theasymmetry of duplexes developed during thrusting indicateNNE directed movement. Equal area plots of fault planes andbedding planes show the same pattern. Moreover, someduplexes present in the thrust sheets have anticlinal or synclinalgeometries. This suggests that the thrusting took place duringthe older phase of folding, when the shortening could not beaccommodated by folding only. During the same compressionphase the newly formed thrusts were progressively folded (NW-SE folds) and the resulting complex thrust/fold structure wassubsequently refolded by younger folds. The general structurein the Mokrá area can therefore be interpreted as a part of foldthrust belt, refolded during the Variscan Orogeny and affectedby later faulting resulting from thrusting in the westernCarpathians.

3.4. Fauna

3.4.1. ConodontsConodonts are abundant in the late Tournaisian and early

Visean of the Mokrá sequence; their study is still in progress (L.Dvorák). They will be the subject of a forthcoming publicationbut stratigraphically important taxa are mentioned here tocomplement the foraminiferal biostratigraphy. Scaliognathusanchoralis Branson and Mehl (mainly S. anchoralis europensisLane and Ziegler but also S. anchoralis fairchildi Lane andZiegler and probably S. anchoralis anchoralis) and Gnathoduspseudosemiglaber Thompson and Fellows are particularlyabundant, but Pseudopolygnathus pinnatus Voges, Proto-gnathodus cordiformis Lane, Sandberg and Ziegler, Poly-gnathus bischoffi Rhodes, Austin, and Druce andSpathognathodus sp. are common as well. The Visean guideGnathodus homopunctatus Ziegler was found only in profile 2.The distribution of the main guides is discussed in theBiostratigraphy section.

3.4.2. ForaminifersForaminifers of the late Tournaisian and early Visean are

remarkably abundant and diverse in Mokrá. In particular thefauna comprises the following guides: Eotextularia diversa(Chernysheva), Tetrataxis sp., Brunsia sp., Endospiroplecta-minna sp. (E. conili Lipina and E. venusta (Vdovenko)),Laxoendothyra ex. gr. laxa (Conil and Lys) (various forms),Pseudolituotubella sp., Dainella sp., Florenella sp., Bessiellasp., Darjella monilis Malakhova, Elevenella parvula Bozorg-nia, Biseriella bristolensis (Reichel), Lysella gadukensisBozorgnia and Eoparastaffella sp. The last genus is representedby an exceptional number of species for Europe with: E. ex. gr.rotunda Vdovenko, E. vdovenkoae Devuyst and Kalvoda, E.interiecta Vdovenko, E. macdermoti Devuyst and Kalvoda, E.

Fig. 5. Photograph of Profile 5 showing the uppermost part of the Lísen Fm (Hády-Rícka Mbr) and the lower part of the Brezina Fm with the location of samples.



tumida subsp. 1 (Devuyst and Kalvoda, 2007), E. ex. gr.florigena (Pronina), E. ex. gr. asymmetrica Vdovenko, E.‘‘ovalis’’ M2, E. ‘‘ovalis’’ M3, E. simplex and E. simplexsimplex. The common presence of these taxa in a single section

makes Mokrá a unique locality in Europe and allows a veryfinely resolved biostratigraphy of the late Tournaisian and earlyVisean. The only section known to date, which rivals Mokrá inabundance and diversity of foraminifers of that age is

Fig. 6. Stratigraphical logs of selected profiles studied. Profiles 1 and 2 are after Ondrácková (2001) and are not as detailed as other profiles. For interpretation ofcolours, see the web version of this article.



Pengchong (Guangxi, southern China), which has been ratifiedas a the new stratotype for the base of the Visean (Devuyst et al.,2003; Work, 2008).

Remark on the taxonomy of Eoparastaffella: Recent workon the genus Eoparastaffella in the late Tournaisian and earlyVisean has revealed a much larger diversity of forms thanpreviously known (e.g., Hance, 1997; Ondrácková, 2001;Kalvoda, 2003; Devuyst, 2006; Devuyst and Kalvoda, 2007 andreferences herein). This is not surprising given the low numberof publications dealing with the taxonomy of that genusbetween the pioneering work of Russian and Ukrainianmicropalaeontologists in the late 1950s to early 1970s andthe recent renewal of interest (late 1990s) triggered by theresearch on the T-V boundary (see reviews in Devuyst, 2006;Devuyst and Kalvoda, 2007). That large diversity presents anopportunity for much higher resolution biostratigraphy but also

a challenge to refine the taxonomy of the genus. The revision ofthe genus Eoparastaffella is in progress (Devuyst and Kalvoda,2007) but a great deal of work remains to be done and thisexplains the number of provisional informal taxon names usedin recent publications, including this one. The reader is referredto Devuyst (2006) and Devuyst and Kalvoda (2007) for adiscussion of the various new species, subspecies andmorphotypes recognized to date.

3.4.3. TrilobitesTrilobites are common in beds 2R to 10R of section 3a

(Fig. 4) but they are commonly deformed, which renders theiridentification difficult in some cases. Their study is in progress(S. Rak) but the following taxa have already been identified:Archegonus (Archegonus) aequalis philliboloides R. Hahn,Bollandia megaira (Hahn and Hahn) and three currently

Fig. 7. Correlation of the profiles based on ranges of important foraminiferal and conodont taxons.



unnamed species of Bollandia (sp. 1 to 3), ?Carbonocoryphe(Winterbergia) sp., C. (Carbonocoryphe) bindemanni Richterand Richter, Liobole (Panibole) sp., L. (Panibole) jugovensis(Osmólska), L. (Sulcubole) glabroides (Richter and Richter),Linguaphillipsia sp., Proliobole vigilax and Waribole (Lati-bole) granifera Chlupác. The association is similar to the faunadescribed from the Erdbach limestone (latest Tournaisian toearly Visean) in Germany (Richter and Richter, 1949; Hahn,1967; Hahn et al., 1998).

4. Biostratigraphy

4.1. Previous work

The position of the T-V boundary in Moravia has been amatter of discussion for decades. In two pioneering papersDvorák and Conil (1969) and Conil (1977) applied the Belgianforaminifer zonation of Conil et al. (1977) to Moravia and, in

accordance with the data of the Namur-Dinant Basin, identifieda fauna with ‘‘Visean elements’’ as V1a (earliest Visean of the1977 zonation) in the upper part of the Hády-Rícka Mbr and inthe Brezina Fm. Based on the study of conodonts andforaminifers, Kalvoda (1982) showed that some of the taxaconsidered as ‘‘typical Visean’’ in the Belgian zonation actuallyoccur at least one or two conodont zones (i.e. �1 to 2 millionsyears) earlier in Avalonian (including Moravia) and easternEuropean terranes. Kalvoda (1982) argued that this resultedfrom the deeper sedimentary facies that characterized most ofthe Dinant area in the late Tournaisian. These conclusions wereconfirmed by subsequent researches (Hance, 1988; Conil et al.,1989; Lees, 1997; Hance et al., 2001; Devuyst, 2006) andincluded in a regional foraminiferal zonation for Moraviaproposed by Kalvoda (1983, 1990). Other studies by Kalvodaand Ondrácková (1999), Kalvoda and Ondrácková (2001),Kalvoda (2003) and Kalvoda et al. (2005) have shown therichness of the foraminifer (and in particular of Eoparastaf-fella), conodont and trilobite associations in the T-V boundaryinterval of the Mokrá sequence.

In this work the recently revised zonation of the lowerCarboniferous of the Franco-Belgian Basin by Devuyst andHance in Poty et al. (2006) is used (Fig. 12). This new zonationbrings improvements to the previous zonation of Conil et al.(1991), notably in the T-V boundary interval. Eight zones (MFZ1 to 8) are distinguished in the Tournaisian and seven in theVisean (MFZ 9 to 15). Devuyst (2006) and Devuyst andKalvoda (2007) have recently shown that evolutionary lineagesin the genus Eoparastaffella can be used to refine thebiostratigraphic resolution of MFZ 7 to 9 at the scale of Eurasia.

4.2. New data

A test sample taken in the dark, very sandy limestone unitdirectly underlying the massive limestone breccias in Profile 5

Fig. 8. Photographs of Profile 3a. Note the intense folding of the shale-richlower part of the Brezina Fm and the massive breccias at the top of the Hády-Ricka Mbr (Lísen Fm). A few sample horizons are indicated. The top of theprofile corresponds with the hinge of a syncline (a). Rectangles in a correspondto b and c. T = Tournaisian; V = Visean.

Fig. 9. Photo-montage of Profile 3b.



Fig. 10. Geology and general tectonic context of the eastern Czech Republic (modified after Kodym et al., 1967).

Fig. 11. Geology of the Mokrá quarries based on field and borehole data.



has yielded Brunsia sp., Endothyra sp., Granuliferella sp.,Tournayellina sp., cf. Palaeospiroplectamina sp. and Eotextu-laria diversa. This association and especially the last taxonindicate MFZ 6 (late Tournaisian). The upper part ofthe breccias in Profile 4 has the same microfauna withthe addition of Septabrunsiina sp., cf. Globoendothyra sp. andQuasiendothyra sp. reworked in limestone clasts. In thesame profile, the limestones directly overlying the brecciashave the first Laxoendothyra ex gr. laxa, Dainella sp.,Pseudolituotubella sp., Tetrataxis sp., Globoendothyra sp.,Endospiroplectammina sp., Urbanella sp. and commonDarjella monilis (Fig. 13). This association, and especiallythe guide D. monilis, characterizes MFZ 7. Darjella monilis isstill present in the upper part of Profile 1 with the firstEoparastaffella, which indicate MFZ 8 and the very latestTournaisian.

More detailed sampling (foraminifers and conodonts) in theupper part of Profile 1 and in Profiles 2, 3a and 3b allows a high-

resolution biostratigraphy of the T-V boundary intervalitself (Fig. 7). Correlations between Profiles 1, 2 and 3 arehypothetical due to tectonic complications. Granulometricsorting certainly played an important role in the distribution offoraminifers. In a general way, calciturbidites are coarsergrained in Profiles 1 and 3b than in Profile 3a. The lower part ofProfile 3a, in particular, is poor in suitable levels forforaminifers. Despite these difficulties some interestingobservations can be made:

� The lowest samples of Profile 1 and 7 already contain a MFZ7 foraminifer assemblage with notably: Palaeospiroplecta-mina mellina (Malakhova), Pseudolituotubella sp., Laxoen-dothyra ex gr. laxa, Globoendothyra sp., Latiendothyranopsissp., Dainella sp., cf. Bessiella sp. and Florennella sp.;� The first Eoparastaffella (MFZ 8) are observed in the range of

Darjella monilis, in the Scaliognathus anchoralis Zone, andbelong to the group rotunda;

Fig. 12. Foraminiferal (Devuyst and Hance) and coral (Poty) zonation of Poty et al. (2006) with chronostratigraphical divisions and correlation with conodontoccurrences (after Groessens in Conil et al., 1991) and previous zonations of Mamet (1974) and Conil et al. (1991). Liv = Livian; N = Namurian; carina = Po-lygnathus communis carina; S = Scaliognathus; P = Protognathodus; homo = Gnathodus homopunctatus; T = Taphrognathus; bilineatus = Gnathodus bilineatusbilineatus; boll = Gnathodus bilineatus bollandensis. Slightly modified after Poty et al. (2006).



� The last occurrence of tuberculate tournayellids (Costayella/Carbonella) is in the lower part of MFZ 8;� Eoparastaffella vdovenkoae (juveniles) first appears higher,

at the top of the range of Darjella monilis, together withBiseriella bristolensis in Profile 1;� Elevenella parvula first appears together with the oldest

Eoparastaffella and extends up to the entry of Eoparastaffella‘‘ovalis’’ M2 at the very base of the Visean (this constitutesthe youngest LAD of E. parvula to date), but is rarer in theuppermost part of the Scaliognathus anchoralis Zone and inthe Gnathodus Interzone;� In Profile 3a, Lysella gadukensis, Eoparastaffella vdoven-

koae, E. interiecta and E. macdermoti appear late, at the samelevel as E. ‘‘ovalis’’ M2 (earliest Visean). They are, however,remarkably abundant in the upper part of Profile 3a and inProfile 3b;

� As in northern Iran (Gaduk section; Devuyst, 2006), typicalLysella gadukensis are preceded by narrow forms, which weattribute to Bessiella legrandi (Conil and Hance), but whichhave affinities with L. gadukensis;� Eoparastaffella tumida subsp. 1 and a particular type of

Eoparastaffella (E. sp. 1 of Devuyst, 2006), which have beenobserved only in Oughterard (western Ireland; Devuyst,2006) previously, are present in Mokrá at a similarstratigraphic level (very latest Tournaisian to earliestVisean);� In Mokrá, Eoparastaffella ex gr. florigena have currently only

been found in the Visean but they are common in the latestTournaisian of the Pengchong GSSP (Devuyst, 2006);� Eoparastaffella simplex simplex is well represented at one

level of Profile 2 with specimens that exactly match the typematerial;

Fig. 13. Illustration of foraminifers from the T-V boundary interval in the Mokrá quarry. 1. Costayella costata (Lipina), Profile 7 (M7/1). 2. Darjella monilis, Profile7 (M7/2). 3. Forschiella prisca Mikhailov, Profile 2 (98/7). 4. Bessiella legrandi, Profile 3a (R2-I). 5. Lysella gadukensis, Profile 6b (06/27). 6. Omphalotis ex gr.chariessa (Conil and Lys), Profile 6 (06/21). 7. Lysella gadukensis, Profile 3b (02/12). 8, 9. Lysella gadukensis, Profile 3b (R2E). 10. Elevenella parvula, Profile 1 (98/32). 11. Paraendothyra cummingsi (Conil and Lys), Profile 3a (R2-VI). Scale bar: 0.2 mm.



Fig. 14. Illustration of Eoparastaffella from the T-V boundary interval in Mokrá quarry. Most specimens come from the entirely early Visean Profile 6. 1.Eoparastaffella simplex, Profile 6 (06/21). 2. Eoparastaffella ex gr. florigena, Profile 6 (06/21). 3. Eoparastaffella simplex, Profile 6 (06/21). 4. Eoparastaffella ex gr.tumida (Pronina), Profile 6 (06/21). 5. Eoparastaffella simplex, Profile 6 (06/21). 6. Eoparastaffella ex gr. florigena, Profile 6 (06/26). 7. Eoparastaffella ovalis, M2,Profile 6 (06/27). 8. Eoparastaffella macdermoti, Profile 6 (06/21). 9. Eoparastaffella simplex, Profile 6 (06/21). 10. Eoparastaffella ex gr. florigena, Profile 6 (06/21).11. Eoparastaffella simplex, Profile 6 (06/21). 12. Eoparastaffella simplex, Profile 6 (06/21). 13. Eoparastaffella macdermoti, Profile 6 (06/22b). 14. Eoparastaffellainteriecta, Profile 3a (13R). 15. Eoparastaffella ex gr. florigena, Profile 6 (06/21). 16. Eoparastaffella simplex, Profile 2 (98/7). 17. Eoparastaffella ex gr. florigena,Profile 2 (98/7). 18. Eoparastaffella simplex, Profile 2 (98/7). 19. Eoparastaffella simplex, Profile 6 (06/21). 20. Eoparastaffella ovalis, M2, Profile 6 (06/27).Specimen 5 shows similarities with a specimen illustrated as E. simplex by Fewtrell et al. (1989: pl. 3-3, Fig. 12). Scale bar: 0.2 mm.



� Gnathodus homopunctatus, the conodont guide for the baseof the Visean was only found higher in Profile 2, together withEoparastaffella simplex simplex.

A selection of representative specimens of the T-V boundaryinterval is illustrated in Figs. 13 and 14.

The basal beds of the recently investigated Profile 6 (Fig. 6)already contain relatively evolved E. simplex together witha diverse Visean microfauna. This association remainsunchanged throughout the profile (which is intensely folded).Its most significant characteristic is the common presence ofrelatively advanced E. simplex (but not E. simplex simplex,which is present in the upper part of Profile 2), wide E. simplexin axial section and common representatives of E. ex gr.florigena (Fig. 14). This association belongs to MFZ 9. Evenwhen structural thickening of Profile 6 (folding) is taken intoaccount, there is no doubt that Profile 2 represents a verycondensed sequence compared to other profiles.

Archaediscids (MFZ 10 and above) were not observed in thecourse of this study but they are known from the uppermost partof the Brezina Fm from boreholes drilled in the late seventies inthe northwestern part of the present main quarry (Dvorák et al.,1984).

5. Conclusions

The richness and diversity of the foraminifer and conodontfaunas of the late Tournaisian and early Visean of the Mokráquarry allow precise dating of the deposits. The uppermost partof Hády-Rícka Mbr of the Lísen Fm, including the prominentmassive breccias of its top, is of late Tournaisian (MFZ 6) age.The lowermost part of the overlying Brezina Fm is stillTournaisian (MFZ 7 to 8, S. anchoralis europensis conodontZone and Gnathodus interzone) and the base of the Viseanoccurs about 9.6 m above the base of the formation (bed 13;Fig. 4). The remaining part of the Brezina Fm covers astratigraphic interval ranging from MFZ 9 to MFZ 10 (Dvoráket al., 1984). The presence of diverse Eoparastaffella and otherforaminifer guides further allows increasing the resolution inMFZ 8 and MFZ 9. In particular, the near-synchronous entry ofrepresentatives of the group E. interiecta (Devuyst andKalvoda, 2007) above the first Eoparastaffella is useful. Theuppermost part of MFZ 8 is, however, less well defined than inthe Pengchong section (Devuyst, 2006), as the first Eopar-astaffella ex. gr. florigena and Lysella gadukensis occurtogether with the first E. simplex (rare in the early Visean ofMokrá), shortly above the first E. ‘‘ovalis’’ M2, which is also aguide for the base of the Visean (MFZ 9; Devuyst, 2006). Thesuccessive appearances of E. tumida subsp. 1 and of E. simplexsimplex allow refining the biostratigraphy of MFZ 9. It is notknown yet if these levels can be used widely but they appear tobe equally useful in western Ireland at least (Oughterardsection; Devuyst, 2006). The conodont guide Gnathodushomopunctatus was only found with E. simplex simplex. Thedistribution of foraminifers and conodonts in the lateTournaisian and early Visean of Mokrá is in general agreementwith data from other regions of Eurasia and contributes to the

refinement of the zonation of that stratigraphical interval. Thedata on trilobites will be of particular importance in thiscontext. Mokrá is therefore undoubtedly a critical referencesection for the western part of Eurasia.

Acknowledgements

This research was supported by grant project GACR 205/08/0182 and 205/08/J015 and by Ceskomoravsky Cement a.s. JiríPovolny is thanked for preparing numerous high-quality thinsections.

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