The Wenlock/ludlow Boundary inthe Prague Basin (Bohemia) · PDF fileälteren Ludlows. Für biostratigraphische Zwecke wurde die vertikale Verbreitung von Graptolithen, Conodonten,

~

Gedenkband zum 100. Todestag von Dionys Stur Redaktion: Harald Lobitzer & Albert Daurer

Jb. Geo!. B.-A. I ISSN 0016-7800 I Band 136 I Heft4 S.809-839 I Wien, Dezember 1993

The Wenlock/ludlow Boundaryin the Prague Basin

(Bohemia)

By JIRI KRlt, PAVEL DUFKA, HERMANN JAEGER t & HANS PETER SCHÖNLAUB*)

With 18 Text-Figures, 1 Table and 3 Plates

Tschechische RepublikÖsterreich

Prager BeckenKarnische Alpen

BarrandiumSilur

StratigraphieKorretation

Wenlock/L udlow-GrenzeBenthos

GraptolithenConodontenChitinozoen

Sporomorpha

Contents

Zusammenfassung 810Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 810

1. Introduction 8102. HistoryofStratigraphicaIStudies 8103. Facies Development ofthe Wenlock/Ludlow Boundary in the Prague Basin 8114. Principal Localities ofthe Wenlock/Ludlow Boundary Beds in the Prague Basin 811

4. 1. TheSouthern Segmentofthe Basin, VseradiceSection-No. 717 8124. 2. The Western Segment ofthe Prague Basin, Koneprusy Section - No. 781 8134. 3. The Pankrac Segment ofthe Prague Basin, Mladeznicka Section, Motokov Section and Kavci Hory Section 8144. 4. ThePankracSegmentofthePragueBasin, BranikSection-No. 764 8154. 5. TheCentralSegmentofthePragueBasin, KonvarkaSection-No. 785 8164. 6. The Central Segment ofthe Prague Basin, Nova Ves Volcanic Centre, Butovice Section - No. 584 8164. 7. The Central Segment of the Prague Basin, Nova Ves Volcanic Centre, Praha- Reporyje, Arethusina Gorge - No. 687 8174. 8. The Northern Segment ofthe Prague Basin, Listice Section - No. 770 and the Listice Pipeline Section - No. 579 8184. 9. The Northern Segment ofthe Prague Basin, Hacka Section, No. 758, Vysoky Ujezd Section, No. 567 8194.10. The Central Segment ofthe Prague Basin, Svaty Jan Volcanic Centre, Listice - No. 759 820

4.10.1. U Drdu Section - No. 760 8204.10.2. U Vitacku Section - No. 581 822

4.11. The Central Segment ofthe Prague Basin, the Svaty Jan Volcanic Centre, Pod Tetinem Section - No. 573 8224.12. The Central Segment of the Prague Basin, Kozolupy, Smoking Quarry Section-Trench 8234.13. The Central Segment of the Prague Basin, Tachlovice, Prosti'edni Mill Section No. 713 8244.14. The Western Segment ofthe Prague Basin, Kosov Volcanic Centre, Kosov Quarry Section - No. 767 and No. 776 824

5. Correlation of the Wenlock/Ludlow Boundary in the Prague Basin 8256. International Correlation 8277. Significance of Stratigraphically Important Animal and Plant Groups in Defining the Wenlock/Ludlow Boundary

in the Prague Basin 8277.1. Graptolithina 8277.2. Conodonta 8287.3. Chitinozoa 829

7.3.1. Biostratigraphy 8317.3.2. Description of New Species 831

7.4. Sporomorphs 8328. Conclusions 832

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 838

') Authors' addresses: JIRi KRiZ, PAVELDUFKA, Czech Geological Survey, P.O. Box 85, CZ-118 21 Praha 011; Dr. HERMANNJAEGER t,Bereich Paläontologisches Museum im Museum für Naturkunde der Humboldt-Universität, Berlin; Univ.-Prof. Dr. HANS PETERSCHÖNLAUB,Geologische Bundesanstalt, Rasumofskygasse 23, A-1 031 Wien.

809

©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at

Die Wenlock/Ludlow-Grenze im Prager Becken (Böhmen)

ZusammenfassungIn dieser Arbeit werden die Ergebnisse einer interdisziplinären Zusammenarbeit über die Wenlock/Ludlow-Grenze im Silur des Barrandiums der

Tschechischen Republik mitgeteilt. Der Report enthält lithologische und faunistische Neuergebnisse von 22 neu untersuchten Profilen in der Umge-bung Prags (Prager Mulde), die geeignet sind, die entsprechenden Grenzschichten exakt mit der international festgelegten Grenze zwischen denWenlock- und Ludlow-Serien im Stratotyp des Welsh Borderland (Steinbruch Pitch Coppice, Ludlow District) zu parallelisieren.

Die tieferen Teile des Prager Beckens werden durch eine kontinuierliche Graptolithenschiefer-Entwicklung gekennzeichnet. Darin manifestiert sichinnerhalb der Cyrtograptus /undgreni Biozone (T. testis Subzone) die gleiche Krise in der Evolution der Graptolithen, wie von H. JAEGER (1991) ausThüringen, Südspanien, Gotland und Litauen beschrieben. In der Flachwasserfazies des westlichen, zentralen und nördlichen Segments des PragerBeckens (J. KAlt, 1991) war hingegen die Sedimentation an der Wenlock/Ludlow-Grenze von vulkanischer Aktivität beeinflußt. Hierbei wurden lokal imjüngeren Wenlock Crinoidenkalke gebildet. Cephalopodenkalke dominieren aber und reichen von der T. testis Subzone in die C. c%nus Biozone desälteren Ludlows.

Für biostratigraphische Zwecke wurde die vertikale Verbreitung von Graptolithen, Conodonten, Chitinozoen und Sporomorpha untersucht unddokumentiert und der Leitwert von Vertretern der verschiedenen Gruppen erörtert. Danach eignen sich neben Graptolithen vor allem Conodonten fürdie Grenzziehung zwischen Wenlock und Ludlow. Zwei neue Arten von Chitinozoen werden beschrieben. Die "Graptolithen-Krise" des jüngerenWenlock und damit zusammenhängende Fragen und Schlußfolgerungen werden kurz diskutiert.

AbstractThe Wenlock/Ludlow boundary beds in the Prague Basin (Barrandian area, Czech Republic) were studied in great detail to provide all information

necessary for international correlations within the IGCP project 216 - Bioevents, subproject Wenlock/Ludlow boundary event. In deeper parts of thePrague Basin a continuous sequence in shale facies development was discovered in which the same graptolite crisis was observed at the end of theCyrtograptus /undgreni Biozone (T. testis Subzone) described by JAEGER (1991) from Thuringia, South Spain, Gotland and Latvia. In shallow parts of theWestern Segment, Central Segment and Northern Segment of the Prague Basin (KAlt, 1991) the sedimentation was influenced by volcanic activity atthe Wenlock/Ludlow boundary. Locally crinoidallimestones were deposited in the uppermost Wenlock. A cephalopod limestone biofacies was deve-loped in the upper Wenlock (T. testis Biozone) and in the lowermost Ludlow (C. c%nus Biozone). Changes in all segments of the Prague Basin aredocumented by 22 measured sections. The vertical distribution of graptolites, conodonts, chitinozoa and sporomorphs was studied and is describedto discuss its influence during the "big graptolite crisis" and during the Wenlock/Ludlow boundary.

1. Introduction

The study of the Wenlock/Ludlow boundary was in-cluded into the research programme of the Czech Geolo-gical Survey in 1988 in connection with the IGCP project216 - Bioevents, subproject Wenlock/Ludlow boundaryevent, to provide necessary data for international correla-tion.

The work was realized in terms of the internationalcooperation of the Czech Geological Survey with Geolo-gische Bundesanstalt, Vienna, and Museum für Natur-kunde, Berlin. Field investigations of the sections, cono-dont sampling, the study of bivalves and general biostrati-graphy were carried out by J. KRlt (Czech GeologicalSurvey, Prague), studies of conodonts were carried out byH.P. SCHÖNLAUB (Geologische Bundesanstalt, Wien), chi-tinozoa and sporomorphs sampling and studies weremade by P. DUFKA (Czech Geological Survey, Prague). J.FRYDA (Czech Geological Survey) identified gastropodsand A. GALLE (Czech Academy of Sciences) identifiedcorals. JAEGER (Museum für Naturkunde, Berlin) collectedand identified all graptolites from the Vseradice Sectionand Butovice Section during his visits of the Prague Basinbetween 1961 and 1991. He died in 1992 and was not ableto complete the work for a monograph.

2. History of Stratigraphical Studies

The first biostratigraphic subdivision of the Silurianbased on graptolite zones was introduced in Bohemia byMARR (1880) who first recognized the zone with Monograptuspriodon and the zone with Monograptus c%nus and mentionedthat he saw Monograptus testis only below the level with lime-stones and with Monograptus c%nus. According to this ob-servation PERNER & KODYM (1919) subdivided the lower

810

Silurian into three parts, i.e. beds with Dip/ograptus whichthey named the Zelkovice Beds, beds with Monograptus prio-donwhich they named the Motol Beds and beds with Mono-graptus dubius which they named the Butovice Beds. In theButovice Beds they recognized two zones - the zone withMonograptus testis and the higher zone with Monograptus co/-onus.

The upper zone with Monograptus c%nus was renamed byBOUCEK (1937) Monograptus nilssani Zone and assigned tothe Ludlow. In the same paper BOUCEK mentioned that it isvery difficult to distinguish the Monograptus ni/ssoni Zonefrom the higher Monograptus scanicus Zone.

In 1948 PRANTL & PRIBYL described the Kopanina Forma-tion and defined its lower boundary at the base of the Mo-nograptus scanicus-Pristiograptus ni/ssoni Zone.

HORNY (1955) accepted BOUCEK'S opinion (1937) that itis not possible to recognize the Pristiograptus nilssani Zone inthe field and proposed to use the M. scanicus Zone instead.In the volcanic facies, where graptolites are extremely rarein carbonate sediments, he recognized the limestonecomplex "Kozel" as lower Ludlow.

HORNY (in HORNY, PRANTL & VAN~ K, 1958) contributed tothe question of the Wenlock/Ludlow boundary in Bohemiaby the discovery of a graptolite association with Pristiograp-tus vulgaris in the boreholes between the zones of M. testisand M. scanicus where they occur in the level of 5-10 m ofshales. He recognized this association as the P vulgarisZone and distinguished at its base the level with mono-tonous association formed by Gothograptus nassa and Pristio-graptus eX.gr. dubius. HORNY (in HORNY, PRANTL & VAN~K,1958) correlated this association of graptolites with a simi-lar association described from the Holy Cross Mountainsby TOMCZYK (1956). Above the Pristiograptus vulgaris ZoneHORNY rediscovered the Pristiograptus ni/ssoni Zone with acharacteristic association of graptolites with a thicknessof 5-15 m.ln the volcanic facies he recognized the "Kozel"


limestone complex as the equivalent of the zone of P nilsso-ni and lower portions of the M. scanicus zone, Ludlow.HORNY retained in his monograph (1962) a similar opin-

ion. He recognized the "Kozel" limestone complex as anequivalent of the P vulgaris Zone and of the P nilssoni Zone.In 1971 HORNY found in the shale facies the subzone Pdeubeli (identified by H. JAEGER)above the "interregnum"with Pristiograptus dubius-Gothograptus nassa and below thecharacteristic P vulgaris Zone. He correlated, in agreementwith the results of new research of his colleagues A. GAL-LE, V. HAVLICEK,J. KRlt & J. VANEK, the "Kozel" limestonecomplex in the tuffitic facies with the upper parts of thezone of T. testis and with the P dubius-G. nassa Interregnum(upper Wenlock).In 1981 the definition and ratification of the interna-

tionally accepted Wenlock and Ludlow Series (MARTINS-SONet aI., 1981) was accomplished. The base of the Lud-low was defined at the base of the Neodiversograptus nilssonis.1. Zone.KRlt (1991) followed PRIBYL'S (1983) zonal subdivision of

the Silurian in Bohemia and the base of the Ludlow ac-cording to the international subdivision at the base of theN. nilssoni Zone.An important paper concerning the Wenlock/Ludlow

boundary was published by JAEGER(1991). He proposedthe new Wenlock/Ludlow boundary at the base of the newzone Monograptus dubius parvus. This level represents thecontemporary crisis ("Große Krise") in the graptoliteevolution when almost all graptolites of the older zone ofM. testis were extinct except the species Monograptus dubiusparvus and Gothograptus nassa. In Thuringia JAEGER recogn-ized above this zone the Interregnum with M. dubius frequens

and G. nassa, the M. praedeubeli Zone, the M. deubeli Zone andthe M. gerhardi/ M. vulgaris Zone.

3. Facies Developmentof the Wenlock/ludlow Boundary

in the Prague Basin

The Wenlock/Ludlow boundary in the Prague Basin isdeveloped in three principal facies:1) Shale facies, with rare levels of tuffites, developed

mainly in the Western Segment and the Southern Seg-ment of the Prague Basin (KR ft, 1991).

2) Shale and cephalopod limestone facies, developed inthe Nova Ves Volcanic Centre (KR ft, 1991).

3) Volcanic facies, represented by the effusive basaltsand volcaniclastics, brachiopod limestones and shal-low water crinoidallimestones developed mainly in theNorthern Segment, in the northern part of the CentralSegment, in the eastern part of the Western Segmentand in the western part of the Pankrac Segment (KR ft,1991).

4. Principal localitiesof the Wenlock/ludlow Boundary Beds

in the Prague Basin

For each facies development several sections werechosen. The selected sections were measured and

•N•

Lodeniceo

10kmI

Pankrcic

o

5I

PRAHA

I<osoi'o

Solopysky

)

oI

o Oi'ech

Tachlovice

/--"

o LUZce

Buboviceo 0 0 KozolupySvaty Jan p.Skalou

o Hostim ~M _."J\ I orlnao

BEROUN

Text-Fig. 1.Distribution of the Wenlock/Ludlow boundary in the Prague Basin (Barrandian area, Central Bohemia) and principallocalities.

811


VSERADICE SECTION717

- C.colonus

5m

V)

::>

:z3112 - C.colonus

0

..J a0 2881 - C.colonus

w

w 2650 - c.roemeri, M.dubius frequensB.bohemicus

21.80 - N.nil ssoni, C.cf.roemeri

2306C.colonus, M.dubius frequens

2273- B. bohemicus s.l.

V) M.vulgarisCl:~l!J 2115 - M. vulgaris..J::> 2040> - M. vulgaris

L1941 - M. vulgaris1885 - M. vulgaris

Gi.0 1775 - M. deubeli::JCU"0

L M. proedeubeli

ci.1605 - M. deubeli

:i 1531 M. proedeubel i

'" 1 516 = M. dubius frequens, G.nossoc:..=>er..J::

Cl'" 1352",=> - M. dubius frequens, G.nossoVl:ECl=>c::-q"''"' 1240 - M. dubius frequens,G.nosso.",.Q=> 1189 - M. dUbius porvus::J>'O~'ClL:_~ 1120

990 _- C.lundgreni, M.pseudodubius980:z

w - C.lundgreni, M.dubius, (.homotus

0::820 - M. priodon fleming;i

C. lundgreni, M. pseudodubiusl!J

Cl

:z::>

..J 437 - M. priodon flemingii, M.pseudodubius,cm C.lundgreni, C.homo tus

w

studied bed by bed in an interval comprising mostly thewhole outcrop. Beds were numbered and the faunalcontent collected and analyzed.

All sections of the Wenlock/Ludlow boundary aresituated in the broader vicinity of Prague (Text-Fig. 1),the most distant locality is about 32 km from the city. Alllocalities are easily accessible by public transportationsystem (train, bus, tram, underground) but protected byState Law. When sampling for serious scientific re-search is necessary, permission is given by the Pro-tected Landscape of Bohemian Karst Area Agency,Karlstejn 85, 267 18 or by the Czech Ministry of the En-vironment, Kodanska 10, Praha 10, 101 00. It is advis-able to realize the research in cooperation with theCzech Geological Survey, Prague.

4.1. The Southern Segment of the Basin:Vseradice Section - No. 717

The Vseradice Section represents the shale faciesdevelopment at the Wenlock/Ludlow boundary. Thesection is exposed along the field truck running north-north-west from the road Vseradice-Bykos, north-westof the Vseradice Village (Text-Figs. 1,2).

A generalized draft of the Vseradice section was pub-lished by HORNY (1960). The section was studied in de-tail by J. KR it, P. DUFKA & H. JAEGER in summer 1991.

The section starts close to the road in the M. belophorusBiozone. The following section is not continuously ex-posed up to the upper portions of the C. lundgreni Bio-zone which is exposed on the left side of the truck120 m from the milestone no. 2 on the main road. Fromthis point the whole section is exposed up to the C. col-onus Biozone.The upper parts of the C. lundgreni Biozone are

characterized by dark calcareous shales. They containthe graptolites M. priodon flemingii, C. hamatus, M. dubius, M.pseudodubius, C. lundgreni and retiolitids. The uppermostparts are developed as dark brown tuffaceous shalesand terminated by 130 cm thick grey tuffites with thinintercalation of grey micritic limestones.Above the tuffite, 133.8 metres from the milestone on

the main road, the base of the M. dubius parvus Biozone,developed as brownish grey shales is exposed. The bio-zone is characterized by the occurrence of only twograptolites: M. dubius parvus and Gothograptus nassa. Itsthickness is 120 cm. The basal15 cm contain a rich bra-chiopod and trilobite fauna: Mezounia bicuspis, Craniopsnana, Bracteoleptaena bracteola, Strophochonetes zephyrus, Ra-vozetina quaziprokopia, Borkopleura gorella, Decoroproetus misermiser, Delops? orbus, Raphiophorus roualti, Rabuloproetusborekensis, Radnoria sp., "Ortotheca" pulchra, "Plumulites" mi-nimus and Kolihaia eremita.The section continues by 290 cm thick brown calcar-

eous shales of the M. dubius frequens - Gothograptus nassaInterregnum with characteristic graptolites and the ce-phalopod Aptychopsis sp.

Brownish calcareous shales correspond to the M.praedeubeli Biozone (90 cm thick) and to the M. deubeliBiozone (280 cm thick). The M. vulgaris Biozone follows,developed again as light brownish calcareous shales

Text-Fig. 2.Vseradice Section (no. 717) near Vseradice with fossil ranges.

_calcareous

sholes tuffites ~micritic-=- limestones

812


KONEPRUSY SECTION781

Further up the section continues by 160 cm of dark thin-bedded shales with common M. dubius frequens and Gothograp-tus nassa. They are overlain by 50 cm of yellowish grey tuftite.The section is terminated by about 70 cm of dark thin-bed-ded shales of the M. dubius frequens and G. nassa Interregnum.

The Koneprusy Section is very similar to the VseradiceSection. Interesting is the change in the chitinozoan associ-ations at the boundary between the T. testis Subzone and theM. dubius parvus Biozone. In the uppermost levels of the T. testisSubzone Margachilina margaritana and? Urnochitina sp. B disap-pear. Eisenackitina branikensis sp.n. occurs at the base of M. du-bius parvus Biozone. Higher up, in the M. dubius frequens- Gotho-graptus nassa Interregnum, the association with Eisenackilinabranikensis, Conochitina tuba and Conochilina pachycepha/a occurs.Close to the boundary between the T. testis Subzone and M.dubius parvus Biozone a similar crisis or change in the chitino-zoan evolution may be seen as in the graptolites evolutionregistered by JAEGER(1991).

(420 cm thick). Besides the index species which is themost common, a few indeterminable cephalopods, re-tiolitids and M. cf. dubius frequens occur.

Higher in the sequence is the level of relatively largenodules of grey micritic limestone above a few centi-metres of brownish shales which contain C%nograptusc%nus, M. dubius frequens, Bohemograptus bohemicus s.1. andcorrespond to the C, c%nus (Neodiversograptus ni/ssom)Biozone. The level with nodules is overlain by 135 cmrusty yellow tuftites without fossils. Above the tuftitelevel another level of relatively large nodules of dark mi-critic limestone is developed. The C, c%nus Biozone fol-lows at least to 13 m above its base and contains acharacteristic association of the graptolites C, c%nus, C,roemeri, M. dubius frequens, Bohemograptus bohemicus, P/ecto-graptus maci/entus, Neodiversograptus ni/ssoni a.o. 50 cmabove the tuftite level the only determinable palyno-morphs in the micritic limestone nodule were dis-covered. Most common are phosphate mazulleoids, on-ly three species of chitinozoans were found. Of them on-ly Linochitina erratica described from the Wenlock/Ludlowboundary rocks in England and Baltoscandinavia is bio-stratigraphically important.

The section continues higher up by brownish calcar-eous shales of the M. fritschi /inearis Biozone which con-tinue with few nodules or thin limestone lenses 23.40 mup to the limestone level with the trilobite Ananaspis fecundaand characteristic brachiopods of the Ananaspis fecunda-Cyrtia postera Community (HAVLiCEK& STORCH,1990). It isequivalent to the basal parts of the horizon with Ananaspisfecunda in the Kosov Quarry.

Conodont samples from below and above the tuftite atthe base of the C, c%nus Zone did not provide any strati-graphically important taxa.

4.2. The Western Segment of the Prague Basin:Koneprusy Section - No. 781

The section lies along the road cut east of the Kone-prusy Village near the road from Kolednik Hamlet to Su-chomasty Village on the western slope of the Maly VrchHill (Text-Fig. 1,3).

The outcrop was discovered and studied in 1991 byKlilt (1992). The section is in the shale facies. It starts by200 cm of dark graptolitic shales of the T. testis Subzone.Then about 60 cm of shales follow in which graptoliteswere not found. They are overlain by 170 cm of mostlydark, thin bedded shales with M. dubius parvus and G, nassawhich have a thin layer of tuftite on the base. In the upper44 cm a common trilobite and brachiopod fauna occursunderlying another thin bed of tuftite: Raphiophorus roua/li,Rabu/oproetus borekensis, Miraspis simara babaricha, Odontop/euraaft. sa/ma, Strophochenetes zephyrus, Bracteo/eptaena bracteo/a,"Lingu/a" unguis, Ravozetina quaziprokopia, Lissatrypa sp., Mezou-nia bicuspis, "Chonetes" sp. and "Rhynchonella" indet., "P/umu-lites" minimus, "Ortotheca" pu/chra and the graptolites M. du-bius parvus and Gothograptus nassa.

V"lz:l.Ll:::ldl.Ll0::u..V"l:::l

oJ:::loL

1«V"lV"l«z:l:J

V"l:::l>0::«a..VI:::l

oJ:::loL

VI

I-V"ll.Lll-

r:

13 M,dubius frequens, G.nosso

M.dubius frequens, G,nosso

M.dubius porvus, G,nossa. Raphiophorus

]M.dubius parvus, G.nasso, RabuloproelusRovozetina, ßroeteoleptoeno

M.dubius porvus

100em

- T.testis, M priodon fleming" 50- T.testis, M.priodon flemingii

o

Text-Fig.3.Kon~prusy Section (no. 781) near Koneprusy with fossil ranges.

.sholes_micritic..... limestones

813


MLADEZNICKASECTION

A similar situation was in the exposure of the undergroundstation Mlädeznicka (Text-Fig. 4). Above the breccia is a se-quence of tuffaceous grey calcareous shales alternating withgrey laminated limestone and with cephalopod limestonein the upper part in which Nutricula gravida occurs. Thesection is terminated here too by a 800 cm thick sequence ofdark grey calcareous shales with few levels of light grey mi-critic limestone without fossils. Between the levels no. 46

o

5m

M. priodon f1emingii

1siola lyra

52

:z

T. testis

51M. priodon flemingii

«50

- T. testis, Isiola lyra,Cardiola ugno

47

- Jovenile cephalopods46" Cardiola agna, Isiola lyra45" M. priodon f1emingii

0:: 44"43" C.hamatus, C.lundgreni

t~~ -- Nutricula gravida391&;

3837"

W36"

"35" .. '"34 33:32-

31 "30 291

:E 271

:r:

53

o

4.3. The Pankrac Segmentof the Prague Basin:

Mladeznicka Section, Motokov Sectionand Kavc! Hory Section

In most sections at the C. lundgrenilM. dubius parvus Bio-zone boundary intrusive basalt is developed in thePankrac Segment. For this reason the sections belowthe boundary are described separately from the sec-tion above the boundary (Branik Section).

All three sections (Mladeznicka Section - Text-Fig. 4, Motokov Section - Text-Fig. 5, and KavCl HorySection - Text-Fig. 6) were exposed only temporarily(1971, 1976 and 1970) and a more detailed collectionwas impossible. Here only the upper parts of the sec-tions which correspond to the upper M. testis Subzone ofthe C. lundgreni Biozone are described.

In the middle parts of this biozone levels of grey mi-critic to bioclastic shallow water limestones are deve-loped in all sections, locally with cross-bedding. Com-mon to all sections is an endostratic breccia which canbe of the same age. In the Motokov Section a level ofeffusive granulated basalt is developed above thisbreccia followed by synsedimentary slides of largeparts of the limestone sequence. The endostratic brec-cia documents the development of irregularities andtremors of the bottom connected with volcanic activityprior to local effusion. In the Kavcf Hory Section (Text-Fig. 6) - above the endostratic breccia - a sequence oftuffaceous shales occurs with thin levels of tuffite andmicritic limestone which is overlain by a level of cepha-lopod limestone with common nektobenthic cephalo-pOds and the bivalve Nutricula gravida. Above it there is alevel with nodules, containing abundant indetermin-able cephalopods and bivalves. Grey granular lime-stone with Aulacopleura konincki follows containing frag-ments of tuffite and filling the spaces between thenodules with cephalopods. In the upper part of thelimestone complex a lenticular level of fining-up granu-lar limestone developed with common M. priodon flemingiiin the lower part of the level. The sequence continues by600 cm of grey brownish tuffaceous shales altered atthe contact with the basalt intrusion in the upper part.

In the Motokov Section (Text-Fig. 5) about 250 cmthick shales with lenses and concretions of grey micrit-ic limestone are developed above the breccia. Then tuf-faceous limestones follow, altered in the upper part atthe contact with the granulated basalt which overliesthe sequence. Above the granulate are shales about200 cm thick with large fragments of tuffaceous lime-stone identical in lithology with that below the granu-late. Fragments of the same limestone are also enve-loped by the granulate. The sequence continues by tuf-faceous shales with tuffaceous limestone, tuffite andlimestone with cephalopods and M. priodon flemingii,about 250 cm thick.

The section is terminated by a 700 cm thick se-quence of dark calcareous shales with severallevels ofmicritic limestones and common nodules of micriticlimestone in the upper part, where also tuffite bedsoccur. The upper part of the sequence is overprinted bythe intrusive basalt.

Text-Fig.4.Mlädeinicka Section in Praha-Pankrac with fossil ranges.

DllJ intrusivebasalt

~(ontod me-UIIUII tamorphism

.shales== limestones

~ endostralic~bre((ia

~ limestone with-...... cephalopods

and

814


MOTOKOVSECTION

Text-Fig.5.Motokov Section in Praha-Pankrac with fossil ranges.

- M. priodon flemingii

4.4. The Pankrck Segment of the Prague Basin:Branrk Section - no. 764

The Branfk Section is situated north of the church ofSt. Prokop in Praha-Branik, south of the Branfk Quarry(Text-Fig. 1, 7). The section was studied by J. KRlt in1991.The sequence starts by an intrusive sill of quartz-dole-

ritic basalt. It is overlain by dark grey calcareous shales30 cm thick, metamorphosed at the contact. It follows alarge lens of grey micritic limestone with remains of thenon-vascular plant Prototaxites. The lens is overlain by70 cm of dark grey to dark calcareous shales with re-mains of Prototaxites, with the graptolites M. dubius parvusand Gothograptus nassa, the brachiopods Strophochonetes ze-phyrus, Mezounia bicuspis, Ravozetina quaziprokopia, "Lingula"unguis, Giraldibella cognata, Bracteoleptaena bracteola and Lissa-trypa sp., the trilobite Decoroproetus miser miser, "Plumulites"minimus and "Ortotheca" pulchra.The sequence follows up by 400 cm of dark grey calca-

reous shales with common thin lenses of grey bioclasticlimestones and relatively small concretions of dark greymicritic limestone. In the upper parts of this level andhigher up M. dubius frequens occurs and the chitinozoansEisenackitina branikensis sp. n., Conochitina tuba, Conochitina pa-chycephala and Ancyrochitina gr. ancyrea. This association isvery similar to the association found at the KoneprusySection in the M. dubius frequens-Gothograptus nassa Interre-gnum.Next in the section is another sill of quartz-doleritic ba-

salt overlain by 50 cm thick grey to grey brown tuffa-ceous shales with thin calcite veins and rare concre-

~ limestones

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no. 48 in the shales rich fossils occur represented byjuvenile pyritized cephalopods (KOLEBABA,1973), thebivalves Cardiola agna, Isiola lyra, Butovicella migrans, andthe graptolites M. testis, C. hamatus and C. lundgreni. Inthe shales about 100 cm below the intrusive basaltthe graptolites M. testis and M. priodon fleming;; and thebivalves Cardiola agna and Isiola lyra occur abundantly.The uppermost part of the section is metamorphosedby 420 cm thick intrusive basalts. The shales whichoverlay the basalts are at the base also metamor-phosed. 350 cm above the basalt a lens of grey lime-stone is developed. In the shales below there are stillcommon indeterminable graptolites and cephalo-pods corresponding most probably to the M. testisSubzone. About 450 cm higher in the shales a cha-racteristic fauna of the C.colonus Zone occurs: Bohemo-graptus bohemicus, M. dubius s.l., deformed cephalo-pods, Aptychopsis sp. and Ceratiocaris sp.

[[[I intrusivebasa It .shales

Text-Fig.6.Kavci Hory Section near Praha-Pankrac with fossil ranges.

CI:III contact me- ~ limestonesIIIIIIII tamorphism _~ enoostroticliiIIiIiIij b ren 10

815


BRANIK764

Text-Fig.7.Branik Section (no. 764) in Praha-Branik with fossil ranges.

tions of dark grey micritic limestone with juvenilestages of Cardiola, gastropods and remains of thenon-vascular plant Pachytheca.This level is overlain by a 800 cm thick se-

quence of grey brown tuffaceous and calcareousshales with scattered larger concretions of darkgrey micritic limestone. In the upper 200 cm theshales contain very commonly M. vulgaris and M.dubius s.1. Concretions in the upper part contain arich association of cephalopods, the graptolitesM. vulgaris and M. dubius s.l., the community of bi-valves Cardiola aff. agna, Butovicella migrans, Manuliculamanulia, Lunulacardium cf. simplex, Hemicardium aff.baro and Slava cf. pelerina. The non-vascular plantPachytheca occurs too and juvenile gastropods.The community has closest relationships to the

Cardiola agna and Cardiola gibbosa Communities(KAlt, 1992).Occurrences of conodonts are indicated in

Text-Fig. 7. Most important is the proof of Ozarkodi-na bohemica (Pa and Pb elements) within the range

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of Monograplus vulgaris in limestone lenses within the upper part oflevel 8. In its lower portion O. e. excavata was found.The upper part of the section is formed by granulated effusive

basalts (60 cm thick) which are overlain by grey brown tuffaceousshales with lenses of grey tuffaceous limestone (60 cm thick). Thetop of the exposed section is formed by a hyaloclastite.

4.5. The Central Segment of the Prague Basin:Konvarka Section - No. 785

The Konvarka Section is located in the road cut of the U DivcichHradu Street in Praha-Konvarka, above the Smichov Railway Sta-tion (Text-Fig. 1). The section was studied by J. KRlt in 1991.The section starts with 110 cm of brown tuffite with local admix-

ture of crinoid detritus, thallophyts and fragmented brachiopods.Above several levels of endostratic breccia are developed whichare overlain by two beds with nectobenthic cephalopods and thebivalves Cardiola aff. gibbosa, Butovicella migrans, Slava cf. pelerina, Odonto-pleura sp., Plumulites sp. and commonly M. priodon flemingii. Up to thislevel the section corresponds to the zone of C. lundgreni. The follow-ing 300 cm of the section are covered by the scree .Further up the sequence continues with 130 cm thick yellow

brownish tuffaceous shales with common bioclasts, fragments ofbrachiopods and trilobites. The brachiopod Ravozetina cf. quaziproko-pia was determined. In the shales a 37 cm thick bed of brownishdark grey tuffite is developed which is more calcareous in its higherparts. It contains a characteristic fauna of the M. dubius parvus Bio-zone: the brachiopods Ravozetina quaziprokopia, Orhoria amelia, Brac-teoleptaena bracteola, Giraldibella cognata, Terazkia expandens, Araspirifer ara-neus, Miriospirifer dichotomus, RessereIla canalis, Mezounia bicuspis, Septatry-pa sp. and the graptolite Gothograptus nassa. In the shales above M.dubius s.1. and Gothograptus nassa occur. The rest of the section is notexposed.

4.6. The Central Segment of the Prague Basin:Nova Ves Volcanic Centre,Butovice Section - No. 584

The section which is part of the Nova Ves Volcanic Centre is situ-ated south of the Kacni Quarry, south-west of Praha-Butovice(Text-Fig. 1, 8). The sequence starts by effusive basalts which areoverlain by 1050 cm of dark grey calcareous shales with rare con-cretions of dark micritic limestone. In the shales the graptolites C.lundgreni, Plectograptus praemacilentus and Monograptus sp. and remainsof the non-vascular plant Prototaxites occur. The decalcified laminaecontain common juvenile stages of cephalopods, bivalves and dis-articulated stem plates of crinoids. In the uppermost parts the chi-tinozoans Ancyrochitina gr. ancyrea, Conochitina tuba and C. pachycephalaoccur.The section succeeds by about 1155 cm of hyaloclastite repre-

senting the north-east marginal part of the Nova Ves Volcanic Cen-tre. Inside of the volcaniclastics a level of dark grey-green tuffiticshales is developed in which stratigraphically unimportant chitino-zoans Ancyrochitina sp. and Conochitina tuba occur.Above the volcaniclastics the sequence of dark brown grey-

green tuffaceous shales is 870 cm thick. They contain in the upper-most part Colonograptus colonus and Colonograptus roemeri indicating theC. colonus Biozone. The sequence is terminated by a 7 cm thick bedof dark micritic limestone.

816


It is overlain by a level of rusty-brown shalesabout 50 cm thick with two levels of concretions.The lower level contains relatively large concre-tions (up to 50 cm in diameter). Each concretionis represented in cross-section by two differentlithologies. The lower half is formed by grey bio-clastic limestone with common cephalopodsand graptolites and the upper half is formed bydark-grey, micritic limestone with ontogeneticstages of bivalves and gastropods. In the upperlevel the concretions are smaller and are formedby dark-grey, micritic limestone with relativelyrare graptolites and ontogenetic stages of Cardio-la gibbosa.

Locally the nodules are accumulated andchaotically arranged due to sliding. The levelswith concretions are overlain by a 200 cm thickcoarse-grained tuffite. Where the concretionsare chaotically arranged, part of the concretionsis enveloped by tuffite (KRit, 1961, 1962).

4.7. The Central Segment of the Prague Basin:Nova Ves Volcanic Centre, Praha-Reporyje,

Arethusina Gorge - No. 687

The section (KRlt, 1992) is part of the Nova Ves Volcanic Centrearea. It starts in the Arethusina Gorge east of Praha-Reporyje(Text-Fig. 1) and south of the Velka Ohrada Village, by shales of ther testis Biozone which contain in the upper part lenses and levels ofcephalopod limestone. In the shales r testis, Cyrtograptus hamatus, C.lundgreni, Monograptus priodon flemingii a.o occur commonly. In the ce-phalopod limestone the Cardiola agna Community (= type locality,KRlt, 1993) occurs. It consists mainly of nektobenthic cephalopodsand epibyssate bivalves: Cardiola agna, Maminka sp., Slava fibrosa, Slavapelerina, Isiola lyra, Spanila sp., Butovicella migrans, "Cypricardinia" sp., Mod-iolopsis sp., Lunulacardium sp., Dualina sp., Praeostrea cf. bohemica, Sfavadiscrepans, Procarinaria zephyrina, rare brachiopod Bleshidium papalas andtabulates, the trilobite Aulacopleura sp. Very common are fragmentsof the non-vascular plants Prototaxites and Pachytheca, fragments ofthe graptolite M. priodon flemingii and juvenile bivalves, gastropodsand cephalopods.

At this level Ozarkodina sagitta sagitta co-occurs with early represen-tatives of Ozarkodina bohemica.

The sequence continues above the shales into basalts and volca-niclastics which represent the western part of the Nova Ves Volca-noes. The activity started here by the initial eruption and the subse-quent degasation. At the base amygdaloidal basalt is developedfollowed by a tuffoagglomerate. Above there are granulated spilit-ized basalt pillow-lavas and the sequence ends by volcaniclasticswith tuff intercalations. The overall thickness of the volcaniclasticsand basalts is about 45 m.

The volcaniclastics are overlain by a sequence of brown-grey tuf-fitic shales alternating with lenses and concretions of grey fine-grained limestone (5-10 cm thick, exceptionally 25 cm thick).

In the concretions a rich fauna of the Cardiola gibbosa Community(KRlt, 1992) occurs with dominant Cardiola gibbosa (37 %), Manuliculamanulia, Butovicella migrans, Cardiola contrastans, Slava bohemica, Maminkacomata, Spanila div.sp., Slava decurtata, Isiola amplians, Slava pelerina, Lunu-lacardium div.sp., Cardiola agna, Modiolopsis senilis, Slava discrepans, Pro-carinaria zephyrina, Praeostrea bohemica, Dualina div.sp., Mila div.sp., Sla-vinka acuta, nektobenthic cephalopods, e.g. most commonly Protobac-trites styloideum, gastropods, monoplacophorids Undicornu carens, Dra-homira sp., very rare brachiopods Sufetirhynchia radvani, Septatrypa brek-vice, Septatrypa lissodermis, Striispirifer sp. and trilobites Bumastus sp.n.,Odontopleura ovata ovata and Kosovopeltis inopinata, graptolites Neodiverso-graptus nilssoni, Colonograptus colonus, Colonograptus roemeri, Bohemograptusbohemicus bohemicus, Monograptus uncinatus, Plectograptus macilentus, a.o.,and very commonly non-vascular plants Prototaxites and Pachytheca.

Conodonts from sample no. 10 yielded abundant representativesof Ozarkodina bohemica (Pa and Pb elements), O. e. excavata and Kockelellavariabilis. These data well agree with the observation of WALLISER(1964) who also recorded O. bohemica from this section. His locality,however, was named "Jinonice". At the same horizon the indexgraptolite species Colonograptus colonus occurs (Text-Fig. 8).

The Cardiola gibbosa Community was adapted to the, life in the ce-phalopod limestone biofacies. Epibyssate bivalves are most com-mon (76 %). Local accumulation of articulated juveniles of bivalvesand brachiopods indicate short periods of abiotic conditions.

Text-Fig.8.ButoviceSection(no. 584) in Praha-Butovicewith fossil ranges.

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The trilobite spcies Cromus storchi was found about270 cm above the base. The first graptolites were found100 cm higher and the species Bohemograptus bohemicusbohemicus, Colonagraptus colonus, Monograptus chimaera semi-spinosus, Spinograptus spinosus, M. scanicus, Dendrograptus (S.)fruticosus indicate the M. chimaera Biozone.The limestone lenses are more fossiliferous immedi-

ately in front of the Muslovka Quarry and in the quarrybelow the thick bed (layer no. 1/2).ln the lenses the trilo-bites Encrinuraspis beaumonti, Eophacops bulliceps, Otrarion (0.)diffractum, Balizoma transiens, Diacanthaspis (Acanthalomina)minuta, Bohemoharpes (B.) ovatum, Leonaspis geinitziana, Didrepa-non squarrosum, Sphaerexochus paramirus a.o. occur, the bra-chiopods Bleshidium patellinum, Agarhyncha famula, Dubaria sa-phina, Leptostrophiella nebutosa, Cadudium sphaeruleum, Bleshi-dium paucicosta, Xeniopugnax modicus, Gracianella umbrella,Claratrypa clarula, Septatrypa alumna, Septatrypa caprilupa, Septa-trypa sapho, Dubaria megaera, Cromatrypa orbis, C. pentagona, Atry-poidea linguata, Protozeuga miliana, Pseudoprotathyris daeles, Cyr-tia bedya bedya, Cyrtia humilis, Tenellodermis tenellus, Alaskospiracarens, Spirinella tureki, a.o., the bivalves Cardiola docens, Car-diola consanguis, Slava cubicula, Butovicella migrans, Slavinka tani-ta, S. amarygma, S. elevata, Spanila div. sp., Dualina div. sp.,common cephalopods, the graptolites Bohemograptusbohemicus bohemicus and Monograptus fritschi linearis, a.o. HAV-

liCEK & STORCH (1991) described this assemblage as theEncrinuraspis beaumonti-smooth Atrypid Community andsuggested that it occupied the Benthic Assemblage 3-4life zone.The overall thickness of the M. chimaera and M. fritschi

tinearis Biozones is about 35 m.

The shales are overlain by more than 150 cm of grey-greentuffites with rare nodules of dark grey micritic limestone inthe lower part which contain Bracteoleptaena bracteola, Delops?orbus a.o.The sequence continues by granulated basalts and tuffs,

which are exposed on the north-eastern side of Beroun-Listice in an abandoned quarry. The basalts and tuffs areoverlain by tuffaceous shales which were exposed tem-porarily during the pipeline construction north east of Be-roun-Listice in the section no. 579 (Text-Fig. 9).This section starts by a 275 cm thick sequence of grey

brownish tuffaceous shales with more calcareous to lime-stone levels. In the shales a mass occurrence of M. vulgarisand of the non-vascular plant Prototaxites was recorded.

- M. gerhardi, Ozarkodina bohemica,Kockelella obsidata

4.8. The Northern Segmentof the Prague Basin:

Listice Section - No. 170,Listice Pipeline Section - No. 579

The sections are exposed in the Beroun-Listice Village(Text-Fig. 1). The sequence is not continuous but sincethe sections no. 770 and 579 are close to each other it ispossible to present them as one composite section.The section no. 770, 25 m north-east of the house no.

725/14 in Beroun-Listice starts by intrusive basalt whichis overlain by about 180 cm thick calcareous grey tuffa-ceous shales. They contain in lower parts (about 123 cm)the graptolites M. dubius parvus, Gothograptus nassa, the bra-chiopods Aulacatrypa squama, Bracteoleptaena bracteola, Lissa-trypa sp., Strophochonetes zephyrus, Ravozetina quasiprokopia,Giraldibella cognata, Mezounia sp., Bleshidium papalas, Joneseamyrmido, "Lingula" unguis, the trilobites Rabuloproetusborekensis, Decoroproetus miser miser, Raphiophorus roualti, De-lops? orbus, Miraspis simara, Odontopleura cf. betina, "Plumulites"minimus, "Ortotheca" pulchra, the conodont subspecies Ozar-kodina sagitta rhenana and the non-vascular plants Pachythecasp. and Prototaxites sp. In higher parts the graptolites M.dubius frequens and G. nassa occur which indicate the M.dubius frequens-G. nassa Interregnum.

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- M. gerhardi

- M. gerhardiM. dubius frequens

- M. gerhardi- M. gerhardi- M. vulgaris- M. vulgaris

- M. vulgaris- Ozarkodina bohemica

- M. vulgaris

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Text-Fig.9.Listice PipelineSection(no. 579) nearBerounwith fossil ranges.

818

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sholes~ limestone _ biodetrital_ intercalations limestones


Text-Fig. 10.Vysoky Ujezd Section (no. 567) near Vysoky Ujezd with fossil ranges. VYSOKY UJEZD

567

spirifer viator, Dyctionella bohemica, Lissatrypa fu-mida, Gracianella umbrella, Dolerorthis kopaninensisa.o., the trilobites Interproetus soncobrinus, I.cf. consobrinus, I. sp.n., Odontopleura ovata ovata,Scharyia wenlockiana, Ktenoura oronapi, Kosovopel-tis aff. inopinata, Eophacops alter, Coniproetus(Ryckholtia) sp.n., Conoparia clarimonda, Trapi-docoryphe? praecurrens, Dicranopeltis scabra, 8u-mastus sp.n., Harpidella sp., Otarion aff. verru-cosum, Selenopeltoides hawlei, 8ohemoharpes sp.,the gastropodes and monoplacophoridsUndicornu aff. carens, Temnodiscus cristatus, Tropi-dodiscus sp.n., Kodymites vulcanus, Prosoptychuscf. globulus, Lytospira sp., Euomphalopterus sp.,Murchisonia (Sinuspira) tenera, Spirina patula, Spiri-nacf. tubicina, the bivalves Cardiola agna, 8utovi-cella migrans, Manulicula manulia, Rhombopteriaaff. mira, Lunulacardium emaciatum, Maminka co-mata, Slava bohemica, S. pelerina, "pterinea" cf.cometula, Maminka tenax, Cardiola contrastans, Lu-nulacardium initians, "Modiolopsis" aff. tenera,"Modiolopsis" senilis, "Mytilarca" rara, Spanila cf.culter, "Astarte" composita, Spanila cardiopsis,fragments of nektobenthic cephalopods,the non-vascular plant Prototaxites sp. andthe graptolite Colonagraptus colonus indicatingthe Colonagraptus colonus Biozone.

The 90 em thick limestones with cepha-lopods contain such conodonts like Ozarko-dina crassa, O.e. excavata, Kockelella variabilis andK. absidata (Text-Fig. 10). Yet, no representa-tive of O.bohemica has been found at this le-vel corresponding to the base of the C. colo-nus graptolite biozone.

o

2m

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4.9. The Northern Segment of the Prague Basin:Hacka Section - No. 758,

Vysoky Ujezd Section - No. 567

The section no. 758 WNW of Vysoky Ujezd is situated between theHacka Hill and Kolo Hill and starts by a basalt intrusion. Above the intru-sion there are about 50 cm of calcareous grey brown shales with bio-clasts and large fragments of volcanic glass and with the brachiopodsRavozetina quasiprokopia, Strophochonetes zephyrus, Giraldibella cognata, "Lingula"unguis, Salopina accedens, Craniops nana, 8racteoleptaena bracteola, Mezounia bicu-spis, 81eshidium cf. papalas, Lissatrypa cf. cibia, Pseudoprotathyris sp., the trilobi-tes Delops? orbus, Radnoria sp.n., Odontopleura sp., Raphiophorus roualti, Rabulo-proetus borekensis, "Plumulites" minimus, "Ortotheca" pulchra, Kolihaia eremita, non-vascular plants Pachytheca sp. and Prototaxites sp., and graptolites M. dubiusparvus, G.nassa. The horizon corresponds to the M. dubius parvus Biozone.The level is overlain by grey calcareous shales with graptolites of the M.

dubius frequens - G.nassa Biozone.The section no. 567 is exposed more eastward on the truck road NW of

the Vysoky Ujezd Village (Text-Fig. 1, 10). Between the section no. 758and no. 567 are most probably volcanites and volcaniclastics. The sec-tion no. 567 starts by grey greenish tuffaceous shales which are overlainby 295 cm of grey greenish coarse tuffs. Higher up there is a sequence ofweathered light-yellow and greenish-yellow tuffaceous limestones. It isfollowed by a 90 cm thick bed of grey biomicritic to biodetritallimestonefollows which contains the brachiopods Indaclor sulcicarens (dominant),Septatrypa caprilupa, Leangella tufogena, Cadudium sp., Cyrtia ludlowensis, Gotatrypasp., Orhoria orhor, 81eshidium paucicosta, Skenidioides sp., Orbiculoidea sp., Macro-pleura sp., RessereIla sp., Conchidium sp., Spirinella tureki, "Lingulella" sp., Janiuscf. nObilis, Stenorhynchia sp., Anastrophia deflexa, Macropleura reluctans, Ravozetinasp., Eospinatrypa sp., Antirhynchonella sp., Tenellodermis sp., Schizotreta sp., Strii-

Higher up the 275 cm of tuffaceous shales contain large nodules andlenses of grey micritic to biodetritallimestone with common brachiopodsIndaclor sulcicarens, Gypidula vestita, Strophoprion euglypha, Ravozetina quasiprokopia,Striispirifer viator, Miriospirifer cf. dichotomus, Janius nobilis, Lissatrypa fumida, Te-nellodermis elatus, Leptostrophiella nebulosa, Meristina mora, Amphistrophiella standi-nia, Atrypa fumosa, Leangella tufogena, Septatrypa alumna, Isorthis (Arcualla) manon,Dicoelosia sp., Gotatrypa sp., Orhoria cf. orhor, 8leshidium sp., Kirkidium (P.) bo-hemicum, Cyrtia cf. ludlowensis, Cyrtia sp.n., Dalejina sp., RessereIla sp., Dionaegi-ria sp., the trilobites Cheirurus (Ch.) insignis, Odontopleura prevosti ssp., Otarion(0.) aff. verrucosum, Interproetus cf. clarimonda, Richterarges cf. ambiguus, Eophacopssp., the bivalves Cardiola contrastans, C. aff. gibbosa, gastropods, fragmentsof cephalopods, and the conodonts Ozarkodina e. excavata, Kockelella absidataand O.bohemica (Text-Fig. 9), the non-vascular plant Prototaxites sp. and co-rals. The occurrence of the graptolites M. gerhardi and M. dubius frequensindicates the upper levels of the M. vulgaris Biozone. This level with lime-stones corresponds to the uplift which increased the role of volcanic ac-cumulations prior to the M. vulgaris Biozone during the global regression.The sequence continues by 137 cm of grey brown shales with tuffitic

laminae which contain graptolites of the C. colonus Biozone: C. colonus, M.dubius frequens, 8. bohemicus bohemicus, Plectograptus macilentus and dendroids.Higher up are coarse grey-greenish brown calcareous tuffites with com-mon nektobenthic cephalopods oriented by current in NE-SW direction.Above tuffites with cephalopods are 75 cm of grey greenish massive tuffoverlain by rusty brown tuffaceous shales to tuffites followed by 280 cmthick massive rusty brown tuffs. They are succeeded by 50 cm of rustybrown tuffaceous shales followand more than 100 cm of massive green-ish grey coarse-grained tuff.

819


The top of the sequence is formed by rustybrown tuffaceous shales with lenses of grey-brown micritic limestone with Atrypoidea renitens, Te-neltodermis sp., Septatrypa caprilupa, Gracianella sp., Gipi-dula sp., Orhoria sp. and Atrypina inops.

4.10. The Central Segmentof the Prague Basin:

Svaty Jan Volcanic Centre,Listice - No. 759,

The section no. 759 (Figs. 1,11) was in generaldescribed and discussed by HORN!' (1955, 1962and 1971). It starts above the path south of thequarry in the volcaniclastics, south-west of Be-roun-Listice. The volcaniclastics are overlain bylenses of grey micritic limestone (no. 3) with cri-noid detritus, volcanic glass and the Buceqia obolinaCommunity. Besides dominant brachiopod spe-cies the community contains the brachiopodsCryptatrypa philomella, Bleshidium papa las, Aratoechia mi-nerva, Hircinisca cf. rhynchonelliformis, Striispirifer aure-lius, the trilobites Cheirurus obtusatus, Kosovopeltis ino-pinata, Odontopleura prevosti prevosti, Aulacopleura kon-incki, the bivalves "Nucula" simplicitor, Butovicella mi-grans, Isiola tyra, Slava cf. pelerina, Cardiola aff. agna, or-thocone cephalopods and the conodont Ozarkodinasagitta sagitta. Diversified acritarchs and rare sporsoccur. Only long ranging species of the chitino-zoans Ancyrochitina ancyrea and Conochitina tuba whichare characteristic for the upper Wenlock and lowerLudlow of the Prague Basin were observed.The limestone is overlain by 15 cm of greenish-

grey tuffite (no. 4). It is followed by another layer ofgrey limestone (no. 5) and the layer of greenish-

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I~<!:

.E.....Cl ClC C

II)ex: EC1J c.......... .....

UJ -:c Cl 5III 0 C m-0 II)

:E II) 0 C:::Jot: c.- Cl..0 . -0

0 :JL 0"Cl .><:

::i '-c:x: I I NaI

o

grey tuffitic shales (no. 6) with the graptolites Monograptus dubius s.1.and M. priodon flemingii, the brachiopod Buceqia obolina, the trilobiteCheirurus obtusatus and the nonvascular plant Pratotaxites sp.The section continues by 560 cm of grey-green coarse-grained

tuffites with lenses of grey bioclastic crinoidal limestones (no.7-no. 9) with the Buceqia obolina Community. The sequence of tuf-fites is overlain by a 70 cm thick layer of massive grey limestone(no. 10-no. 11) which in the uppermost level contains large rhab-dosomes of M. priodon flemingii.At this level (no. 10) Ozarkodina ex. excavata and Kockelella absidata

occur.About 300 cm of tuffitic shales, tuffites and tuffs in exposed

parts of the sequence (no. 12-16) follow.

4.10.1. U Drdu Section - No. 760

The section no. 760 (Figs. 1, 12) starts approximately 38 m ofreal thickness above the section no. 759 by a sequence of volca-niclastics and granulates in the lower part and alternating green-ish more and less massive tuffites with lapilli and fragments of lavain the upper part (nos. 1-19). In the past the section was describedby KODYM,BOUCEK& SULC(1931), by HAVLfCEK,HORNY,CHLUpAC&SNAJDR(1958), by HORNY(1955, 1962, 1965, 1971), KUKAL (1955)and KRlt (1991).The volcaniclastics transitionally pass into a sequence of crinoi-

dallimestones with tuffite levels. Most fossiliferous are the lowerlimestone layers no. 24 and no. 25. They contain a brachiopodcommunity with dominant Mendacella venustula, Resserella canalis, Isor-this (A.) cliens, Rhynchotreta cunicula, Anastrophia deflexa, Cyrtia spiriferoides,Rufispirifer nucula, Protomegastrophia miranda, Striispirifer aurelius, Atrypamargarita, Nucleospira lentilca, Whitfieldella ypsilon, Kozlenia kozlensis, Atrypi-na paulula, Eospirifer praesecans, Amphistrophia harperi, Dicoelosia sp., Stro-phochonetes gluma, Skenidioides sp., rostraconch Conocardium sp., the tri-lobite Harpidella hama, the corals Heliolites decipiens, H. irregutaris, H. bo-hemicus, H. spongoides, Helioplasmolites wentzeli, Stelliporella lamellata, Pro-pora poctai, Favosites fidelis, F gotlandicus, F forbesi, Halysites catenularia,"Barrandeolites" bowerbanki, Entelophyllum confusum, E. prosperum, stro-matoporoids, bryozoans, a.o.Higher the section consists of massive lenticular grey tuffitic

bioclastic crinoidal limestone with levels of brown tuffites withsmall lenses of grey bioclastic crinoidal tuffitic limestones. Themassive limestones show at some levels cross-bedding and sili-cification. In levels with tuffites a graded bedding may be seen. Atthe base of the thin layers lapilli, volcanic glass and coarse crinoi-dal detritus are concentrated which is fining up (KUKAL, 1955). Inthe uppermost 11 m of the section limestones are prevailing andtuffitic layers are almost missing. The fauna consists mostly ofcorals and stromatoporoids. On top of level no. 60 the brachio-pods Meristina mora, Resserella canalis, Atrypa margarita, Strophoprion eug-Iypha, Leptostraphiella nebulosa, Shagamella margarita, Cyrtia spiriferoides,Isortis (Arcuala) cliens and Protomegastraphia miranda, the trilobites Proe-tus kopaninensis, Tropidocoryphe? praecurrens, tnterpraetus sp., Eophacopstrapeziceps, Richterarges sp.n.aff. ambiguus and Cheirurus obtusatus andstromatoporoids have been found.The conodont fauna from sample levels 24, 28, 30, 40 top, 70

bottom, 73 bottom, 82 top, 86 centre and 86 top all contain a uni-form fauna characterized by Ozarkodina bohemica.Tuffaceous limestones and shales contain common trilete mio-

spores and cryptospores of early land plants. The diversity, densi-ty and mode preservation vary in different samples and the num-ber of individual spores per slide is 15 to 20 times higher than the

820

1:-: -: -: :.:1 hyaloclastite... 'I~=~=~=~~tuttiles

~ ~ioclcstict:::::::::::::: IIme s ton es

.sholes Text-Fig. 11.Listice Section (no. 759) near Beroun with fossil ranges.


4

2

3

o42

42

8554, 41'

10m

84

9

53'•. 8

762

30

647'

5

_tuffaceous

shales ~

.~ bi?cl~stic,.:.". crmold

limestones

r':7';T~~8tUffitP.S

r.;;7~-:;;Jcoorsp'~~ 1,-1,:';, vot(oniclastics

Text-Fig. 12.U Drdü Section (no. 760) near Beroun with fossil ranges.

821


Text-Fig. 13.U Vitackü Section (no. 581) near Beroun. U VITACKO

581

~--- -~ tuffites

amount of the individuals of the phytoplankton-acritarchs. The assemblageof the sporomorphs is characteristic for the sporomorph zone cf. protophanus -verrucatus which was established for the upper Homerian and lower Gorstian(RICHARDSONand MCGREGOR,1986). From the type region of Wenlock,Shropshire, England, BURGESS& RICHARDSON(1991) described an assembl-age of miospores and cryptospores with almost the same species as found inthe Listice Section. The assemblage from Shropshire is dated as upper C.lundgreni Biozone up to the M. vulgaris (M. ludensis) Biozone. This observation byDUFKA(KAlt, 1992) represents another evidence forthe dry land conditions ontop of the Svaty Jan Volcanoe emerged during the uppermost Wenlock.The overall thickness of the limestone complex called also "Kozel" lime-

stone complex is 63 m. Laterally the thickness is changing very quickly. Onthe other side of the Berounka River Valley 400 m to the south-west the thick-ness of the limestone complex is only 14 m. According to brachiopod andtrilobite fauna the age of the limestones is uppermost Wenlock. The last grap-tolite found below the complex on top of the section no. 759 is the graptoliteM. priodon flemingii. The highest occurrence of this graptolite was recorded inthe C. lundgreni Biozone. The age of the limestone complex could thus corres-pond only to the period between the M. dubius parvus Biozone and the M. vulgarisBiozone.Another evidence for the age of the "Kozel" limestone complex represents

the development of the nearby Listice no. 579 section in the Northern Seg-ment (Text-Fig. 16). Here the sedimentation of carbonates starts in the middlelevels of the M. vulgaris Biozone as the result of uplift during the global regres-sion the role of which was increased in the Central Segment and in the nearbyNorthern Segment by local accumulations of volcanics during the volcanicactivity of the Svaty Jan Volcanic Centre in the period between the M. dubiusparvus Biozone and M. deubeli Biozone.

:z

I-

a

, ,,. ... ' ... \"\ ... ,,"''' ".. , ... ,,,,,,, "... " .... ,... '"

6 " , ... ,,\ '" ,

, " ... " ... , .., ... " ,...50 -

2m

o

[[IIJ effusivebo salts

\ ... " I , bioclastic~ ~\'~"'~ limestones

4.10.2. U Vitacku Section - No. 581The section "U Vitacku" is on the left side of the Berounka River and 350 m

SES of the U Drdu Section (Text-Fig. 1, 13).Exposed here is the top of the volcaniclastic complex (no. 1). It is overlain

by 400 cm thick effusive basalts (no. 2) with calcitic amygdales. On the top ofthe basalt is developed grey bioclastic limestone (no. 3) with brachiopodsand corals, some of them found directly attached on the basalt hard-ground.The fauna consists mainly of the brachiopods "Oglupes" sp., Meristina mora, Lep-taena odeon, Leptostrophiel/a nebulosa, Amphistrophiel/a standinia, Strophoprion euglypha,Howel/el/a crispina, Janius bauskai, Hebetoechia sphaerulea, Isorthis (Arcual/a) sp., thetrilobites Odontopleura prevosti neumanni, Cheirurus obtusatus, Aulacopleura sp., Bumas-tus bouchardi var.nov., Sphaerexochus paramirus, Eophacops sp., the corals Heliolitessp., Halysites cf. catenularia and large crinoids.Yet, two conodont samples from levels 3 and 5 did not produce any signi-

ficant results.The fauna has closest relationships to the lower parts of the horizon with C.

beaumonti, Gorstian, Ludlow in the Amerika Anticline and with the lower partsof the Kopanina Formation at the Kosov Quarry. Volcaniclastics below thelimestones may thus correspond to the maximum eruptions in the Svaty JanVolcanic Centre in the uppermost Wenlock and lowermost Ludlow, and ap-proximately correspond to the maximum of volcanic activity in the KosovVolcanic Centre and Nova VesVolcanic Centre.The limestones with brachiopods are overlain by a sequence of grey bio-

clastic crinoidallimestones (no. 6 - exposed sequence 450 cm).

4.11. The Central Segment of the Prague Basin:Svaty Jan Volcanic Centre, Pod TeUnem Section - No. 573The section is located in the railway cut below the Telin Village, south-west

of Beroun (Text-Fig. 1, 14).lt was studied by HORNY(1955c, 1971)and in detailby J. KAlt in 1989.

822

The section is equivalent to the sec-tion at the other side of the BerounkaRiver. It is first represented by the lime-stone complex "Kozel", which is only14 m thick and overlain by 200 m ofcoarse volcaniclastics. The Pod Te-linem Section (no. 573) starts above by22 m thick effusive basalts with calciticamygdales. It is overlain by 0-32 cmthick greenish-grey tuffaceous crinoid-allimestone which fills the irregularitiesin the surface of the basalt. At the baseflat colonies of stromatoporoids andcorals are developed, accompanied bylarge indeterminable atrypids, Meristinamora and Kirkidium (Pinguael/a) sp. Higherup the brachiopods are more common.80 cm of rusty, dark reddish tuffites fol-low with 1 to 10 cm thick lenses of fin-e-grained tuffaceous limestones withthe brachiopods Hebetoechia sp., Leptaenaodeon, Leptostrophiel/a cf. nebulosa, Oglupesscarabeus, Meristina mora, Strophoprion eugly-phus relata, Mesopholidostrophia papyracea,Isorthis (Arcual/a) sp., Kozlenia sp., the tri-lobite Calymene desmoder, and indeter-mined ostracodes.

The next level is up to 20 cm thickand is formed by tuffaceous limestonewith very abundant lapilli and rare largebrachiopods (Meristina mora). The upper


Text-Fig. 14.Pod Tetinem Section (no. 573) near Beroun. POD TETINEM

573

part of the sequence is formed by 390 cm thick, thick-bedded, grey,biodetrital to tuffaceous, crinoidallimestones with rare intercalations oftuffite. In higher parts a level (no. 13) of rusty brown tuffites with lenses ofcrinoidal limestones is developed. The whole section corresponds ac-cording to the brachiopod fauna to the lower Ludlow (presence of thebrachiopods Hebetoechia sp., Leptostrophiella cf. nebulosa and Mesopholidostro-phia papyracea).

SMOKINGQUARRYTRENCH

o

2m

!Tl bioclasticL-l..J limestones

[[DJ effusivebasalt

z

I-

a

4.12. The Central Segment of the Prague Basin,Kozolupy, Smoking Quarry Section-Trench

The sequence was exposed in an artificial trench east of theabandoned quarry near the road from Mofina to Bubovice,north west of the "Amerika" Quarry (Text-Fig. 1, 15).The oldest rocks exposed in the trench are represented by a

sequence of brown tuffites several metres thick. They areoverlain by almost 1 m of light rusty brown to grey bioclastic,crinoidallimestones (no. 2) with abundant brachiopods Inda-clor sellarius, Septatrypa lissodermis, Aratoechia arabella, Atrypina paulula,Lissatrypa cibia, Kozlenia pirola, Cyrtia spiriferoides, Cyrtia maior maiar,Mendacella venustula, Niorhynx niobe, Eospirifer pollens, Janius nobilis,Spurispirifer cf. spurius, Sufetirhyncha radvani a.o., the trilobitesOtarion (Conoparia) clarimonda, Interproetus soncobrinus, Ktenoura oro-napi, Hemiarges heteroclytus, Eophacops alter. Dicranopeltis scabra prop-inqua, Cheirurus sp., indet. bivalves, bryozoans and diversecorals. HAVLICEK & ~hORCH (1990) defined the assemblage asthe Septatrypa lissodermis- Cyrtia maior Community. It can be inter-

The sequence of,limestones is overlain by 35 m thick coarsevolcaniclastics. On top of them there is a sheet of effusive ba-salt, about 10 m thick, with calcitic amygdales. The basalt isoverlain by 20.5 m of the Pozary Formation, Pffdolf.

5m

_ micritic limestones

o

Indoclor selloriusHemiorges heteroclytusNiorhynx niobe

- Favosites

- Atrypoidea renitens

- (ramus orizabaIndaclor sulc icorens

- (ramus orizoba

- Atrypoideo renitens

- Gototrypo copperi

~======~tuffiles- --

a

0::

I-

«

26

z:

25

,

_ tuffaceous shales Text-Fig. 15.Smoking Quarry Section-Trench, near Kozolupy with fossil ranges.

823


preted as the Benthic Assemblage 3 life zone. In the testpit described by HORNY(1955) which was situated more tothe east, the overall thickness of the layer was approxi-mately 5 m. According to the fauna this level is uppermostWenlock in age.

The next 11.5 m (layers no. 3 to 16) are represented by asequence of yellow to brown-grey tuffites to tuffitic shaleswith severallevels of concretions to lenses of grey-green-ish to brown-grey biomicritic to bioclastic tuffitic lime-stones with the common trilobites Cromus orizaba and Balizo-ma transiens, the brachiopods Atrypoidea renitens, Septatrypasulciplicata, Indaclor sulcicarens, Gotatrypa copperi, Atrypinella fu-xina, Gracianella crista, Tenellodermis elatus, Dalejina ambigena, Sufe-tirhyncha radvani, Dicoelesia sp. a.o. HAVLiCEK& ~hORCH(1990)defined this association as the Atrypoidea renitens Commun-ity and postulated for it a Benthic Assemblage 3 life posi-tion. The fauna corresponds to the fauna of the M. chimaeraZone

About 10.5 m of brown to yellow-brown tuffites to greytuffitic shales without fossils follow.

The top of the sequence in the trench is represented by2 m of brownish calcareous tuffitic shales alternating withlenses and concretions of brown to brown-grey biomicrit-ic to bioclastic limestones. In the shales occur rarely colo-nies of tabulates. This part of the sequence correspondsto the horizon with Cromus beaumonti which is best exposedin the near Smoking Quarry.

4.13. The Central Segmentof the Prague Basin:

TachloYice, ProsHedni Mill Section - No. 713

The section is situated on the left side of the RadotinBrook, about 145 m north of the pond dam near the Pro-stfednf Mill.

It starts with a sequence of brown tuffites and tuffa-ceous limestones which contain a characteristic fauna ofthe T. testis Biozone with M. priodon flemingii. From the localityM. SNAJDRdescribed in several papers the trilobites Odon-topleura ovata ovata, Odontopleura rataji, Kosovopeltis inopinata,Ceratocephala verneuili, Ktenoura aravaka, Dicranopeltis scabra pro-pinqua, Scharyia wenlockiana, Delops sp., Raphiophorus roualti, £0-phacops bulliceps subsp., Proetus kopaninensis, Interproetus xenon,I. susy, I. alban, I. pralux, I numvertus, Decoroproetus miser knemix,Conoparia sp. and Cyphoproetus putzkeri hedvicaki. He inter-preted the age of the trilobites as the boundary rocks be-tween the Motol Formation and Kopanina Formation.

Apart from the trilobites indeterminable cephalopodsoccur, the common non-vascular plant Prototaxites, the bi-valve Cardiota aff. agna and the brachiopods Placotriptesiamoerra, Orhoria orhor, Strophoprion sp., Indaclor sellarius, Stropho-chonetes zephyrus, Gypidula sp., Cadudium sp., Rhynchotreta cu-nicula, Septatrypa conjunctus and Atrypa margarita.The section continues by 33 m of brown tuffaceous

shales with brown and grey tuffaceous limestone levelswith rare fragments of brachiopods and crinoidal detritus.13 m of the section are covered. The uppermost part com-prises about 20 m of grey, tuffaceous, fine-grained,thick-bedded limestones intercalated in brown, yellow-ish-brown to grey-brown, tuffaceous shales.

The fauna is equivalent to the facies which is exposednear Kozolupy in the Smoking Quarry and corresponds tothe horizon with Cromus beaumonti.

824

4.14. The Western Segment of the Prague Basin:Kosoy Volcanic Centre,Kosoy Quarry Section -No. 767 and No. 776

The section is exposed in the Kosov Quarry on thenorth-west side of the Kosov Hill near Beroun-Jarov (Text-Fig.1).The lower part of the Kosov Quarry Section was studied

in detail by TUREK (1983, 1990). The whole section wasstudied by BOUCEK(1941, 1951), HORNY(1955c, 1971) andKRlt (1992).The top of section no. 767, exposed on the 6th level of the

quarry (TUREK,1990; KRlt, 1992) is formed by dark calcar-eous shales with dark micritic limestone concretionswhich overlay the endostratic breccia (layer no. 14).55 emabove the endostratic breccia the shells contain first re-presentatives of T. testis indicating the base of the T. testisSubzone. Cyrtograptus hamatus and M. priodon flemingii occurtogether.The total thickness of this subzone has been estimated

in the Kosov Quarry to be 20 m, together with basalt intru-sions included up to 30 m (TUREK,1983). The characterist-ic pioneer benthic community described by TUREK(1983)occurs 90 to 100 em above bed no. 14. Most characteristicfor this community are nektobenthic cephalopod shellsdeposited at the bottom and providing the firm substratefor the attachment of epibyssate forms of benthos. Insome cases graptolite clusters ("comets") formed by theinterception of rhabdosomes on an orthoceracone nauti-loid shell sticking obliquely in the bottom sediment wereobserved. They represent good evidence for the orienta-tion of the shells by bottom current which had a dominanttrend from WSW to ENE (TUREK, 1983). Smooth indeter-minable cephalopods are the common. Other forms be-long to the following genera: Parakionoceras, Geisonaceras, Ri-zoceras and Peismoceras. The frequent occurrence of apty-chopsids in some layers is interesting.The epifauna is related to the substratum which in most

cases was provided by empty cephalopod shells, algae orliving benthic organisms: The brachiopod Lissatrypa, crin-oids of the group F1exibitia, the epibyssate bivalves Cardiolaagna and Butovicella migrans, the gastropod Platyceras, the an-nelid Spirorbis and bryozoans. The reclining bivalve Dualinaand infaunal Slava cf. fibrosa represent the only fauna relateddirectly to the bottom sediment.Graptolites as planktic organisms are very abundant

and are represented by a characteristic association of T.testis, C. lundgreni, M. priodon flemingii (rhabdosomes up to35 em long), M. dubius, M. pseudodubius, P. aff. lodenicensis, Mo-noclimacis f1umendosae and C. trilleri. The complete absence ofretiolitids (TUREK, 1983) is striking. Besides graptolitescarbonized fragments of the nonvascular plants Prototaxitesand Pachytheca of different size occur as representatives ofplankton.The shales of the T. testis Subzone are overlain by volcan-

ics which correspond to the uppermost Wenlock andwhich are exposed on the 5th level of the quarry. They arerepresented by volcaniclastic agglomerate which is re-placed in the central thickest part (up to 40 m according toHORNY, 1955a) towards NE by effusive basalts with anamygdaloidal structure, carrying calcitic amygdales. Atthe base and in the uppermost parts the agglomerate con-tains large fragments up to several tens of centimetres ofthe graptolite shales with common M. priodon f1emmingii in-dicating the T. testis Subzone.


The effusive basalts and volcaniclastics correspond inthe Kosov Volcanic Centre to the period from the M. dubiusparvus Biozone up to the M. gerhardi/ M. vulgaris Biozone. Dur-ing the upper Wenlock this part of the Prague Basin shal-lowed due to the formation of a subsurface volcanic domecaused by many basalt intrusions which produced a ce-dar-tree laccolith structure (KODYM,1925). Feeders to theKosov Volcanic Centre followed the Tobolka Fault. Thiscomplex comprises more than 300 m of peperites, glasspicrites and granulates.The volcaniclastics are overlain in the Kosov Quarry by

dark shales with thin intercalations of tuffites with calciteand pyrite (HORNY,1955a) in which the graptolites M. vul-garis and M. dubius s.1. occur indicating the M. vulgaris Bio-zone.The sequence continues 5-10 m above the base by

10m thick grey-green tuffites and tuffaceous shales inwhich the bioclastic content increases continuously(HORNY, 1955a). In the upper .30 m of the sequence thegraptolites M. scanicus, M. chimaera, M. dubiuss.1. and Bohemo-graptus bohemicus bohemicus occur which correspond to theM. chimaera Biozone. In the higher parts of the sequence thebrachiopods Leptostrophiella nebulosa and Cyrtia bedya, the tri-lobite Balizoma transiens, and the bivalve Butovicella migrans arecharacteristic too. In the middle part of the tuffaceous se-diments HORNY(1955a) discovered in severallevels endo-stratic breccias formed of volcaniclastics, tuffite, micriticto biodetrital and shale fragments, commonly rounded. Inthe breccias occur the corals Propara conterta, "Barrandeolites"bowerbanki, Clathrodiction bOhemicum, the trilobite Hemiargesheteroclytus, brachiopods and crinoidal detritus. Theselevels were interpreted by HORNY(1955a) as derived fromthe "Kozel" limestone complex. More probably, theselevels are derived from local accumulations on the KosovVolcanic Centre which correspond to the M. vulgaris Bio-zone.In the upper part of the sequence (section no. 776 be-

hind the canteen in the old Kosov Quarry (KRi!, 1992) in thebrown calcareous tuffites with several levels of grey bio-clastic tuffitic limestone and grey-brown tuffitic shales thegraptolite Monograptus massai occurs, known from Libya inthe horizon just below M. tritschi linearis (JAEGER,1991),together with the brachiopods Leptostrophiella nebulosa, Ala-skospira carens, Amphistrophiella standinia, Striispirifer viator, Is-orthis manon, Spirinella tureki, Ancilotoechia tinea, Resserella canalis,Dalejina sp., "Atrypa" sp.n., Cyrtia bedya, Lissatrypa tumida, thetrilobites Balizoma transiens, Cheirurus sp., the bivalve Cardiolacf. docens and the monoplacophorid Undicornu carens. Thispart of the sequence represents high levels of the M. chi-maera Biozone.

5. Correlationof the Wenlock/Ludlow Boundary

in the Prague Basin

The discovery of a complete set of graptolite zones atthe Vseradice Section (Text-Figs. 2, 16) enabled the cor-relation with other sections within all segments of theSilurian Prague Basin and with the contemporary volca-nism. The M. dubius parvus Biozone with a characteristicbrachiopod and trilobite community was also discoveredin the Western Segment of the Prague Basin (KoneprusySection and Borek), the Northern Segment (Listice Sec-tion and Hacka Section), the Pankrcic Segment (Pankrac,

Branik Section) and in the Central Segment (KonvarkaSection).The occurrence of the brachiopod and trilobite Decoro-

proetus-Ravozetina Community in the M. dubius parvus Biozoneis very important. This community appears abruptly.Some of its representatives are entirely new for the PragueBasin like the trilobite genus Delops known from older rocksof the Welsh Borderland. Some of the genera reoccur inthe Silurian of the Prague Basin like the brachiopod genusRavozetina which is known from upper Ordovician rocks.Some of the species have ancestors in the underlying T.testis Subzone and few of them occur in the T. testis Sub-zone. The community is restricted to the M. dubius parvusBiozone and may be characterized by the quite commonoccurrence of complete trilobites (Raphiophorus roualti, De-coroproetus miser miser, Borkopleura goretla, Miraspis simara ba-baricha, Rabutoproetus borekensis a.o.). The facies was influ-enced by volcanic activity. In the shales fragments of vol-canic glass and tuffaceous laminae occur. It is possiblethat the common occurrence of complete trilobites re-presents short catastrophic events, possibly involving ad-verse changes in the chemistry of the environment, similarto the environment of "Aulacop/eura Shales" in the underly-ing T. testis Subzone. Characteristic for the community isthe presence of thallophyt fragments, the hyolithid "Or-totheca" pulchra and the plumulitid "Plumu/ites" minimus.In most of the volcanic centres of the Prague Basin, in-

tensive volcanic activity started in the M. dubius parvus Bio-zone (in the Kosov Volcanic Centre, Svaty Jan VolcanicCentre and Nova Ves Volcanic Centre). In the Kosov Vol-canic Centre the volcanic activity terminated below the M.vulgaris Biozone, in the Svaty Jan Volcanic Centre volcanicactivity was interrupted prior to the M. vulgaris Biozonewhen the "Kozel" Limestone complex was deposited, andcontinued again in the C. c%nus Biozone. In the Nova VesVolcanic Centre the volcanic activity terminated in the M.vulgaris Biozone.The "Kozel" Limestone complex was deposited on the

shores of the volcanic accumulation of the Svaty Jan Vol-canic Centre. These limestones occur just above the vol-canics which overlay the limestones with M. priodon flemingiiand the brachiopod community characterized by the al-most monospecific association of Buceqia obo/ina. Presum-ably they were deposited in the upper parts of the C. tund-greni Biozone. The volcanics correspond most probably tothe M. dubius parvus Biozone and continue up to the lowerportions of the M. vulgaris Biozone. Sedimentation of the"Kozel" Limestone complex in the Central Segmentstarted due to accumulation of volcanics and regressionin the middle portion of the M. vulgaris Biozone (Text-Figs. 12,16).In the very shallow-water "Kozel" Limestone complex

the community is mainly characterized by the presence ofcorals, stromatoporoids and by leptaenid brachiopods.Only at the base of the complex the high diversity Hirci-nisca-Ancillotoechia Community is developed.In the Northern Segment the contemporary but deeper

water limestones of the M. vulgaris Biozone from the Listicepipeline temporary exposure (Text-Fig. 9,16), the com-munity dominated by Indaclor sulcicarens contains also thegenus Ravozetina which is known only from the older M. du-bius parvus Biozone. Other brachiopods show either rela-tionships to older Wenlockian communities or to theCoral-Crinoid Community (HAVliCEK and STORCH,1990)known from the lower Ludlow Kopanina Formation in theKozolupy Smoking Quarry and in the Amerika Quarries.

825


L1STICE-TETiNSECTION

LOCHKOV

tuffs, tuffites

effusive basalts

o

100m

[J)ß intrusive basalt

.shales

mlimestones

- M.chimaera- M.fritschi linearis

- C. colonus

- M.dubius parvus- C. lundgreni

PRiDOLI

Pod Tetinem SectionI 'limestonesI\I

I \\ I

\ II I\ II II I\ II II I

I'\ '\ I, II II I, \

I II II I, I

I', II'I II'I I

I I

1\, I, I,,I I, I

"III I ~

\\ VSERADICE\\ SECTION""""I

M.priodon fleming~------

,,,,,,,"KOZEL" "limestone "complex " ,,,,,,,,,

..... - ..... '

"', .......\ \,'~;~~/~,~:\

---

---------

---

M.chimaera -

M.dubius -porvus

T. testis

Text-Fig. 16.Correlation of the Wenlock/Ludlow boundary in the Northern Segment (Listice Pipeline Section), the Central Segment (Listice-Tetin Section) and theSouthern Segment (Vseradice Section) of the Prague Basin.

With the M. vulgaris Biozone may be also correlated thelowermost part of the sequence exposed in the trenchclose to Smoking Quarry near Kozolupy. The communityhere differs from all other communities known from thislevel but contains forms characteristic for the lower part ofthe "Kozel" limestone complex like the brachiopods Aratoe-chia arabella, Atrypina paulula, Pseudoprotathyris ephemera, Cyrtiamaior maior, Janius nobilis, Mendacella venustula and Amphistrophiaharperi. The rare brachiopod Niorhynx niobe represents a typ-ical Wenlockian species and the occurrence of Indaclor sel-larius indicates that the community is closely related to thecommunities with dominant Indaclor characteristic for theboundary rocks between the M. vulgaris Biozone and C. col-onus Biozone. The community is also closely related to thecommunity from the Listice locality 579 - pipeline ex-posure - with concern to the presence of the trilobites In-terproetus soncobrinus, Conoparia clarimonda and Cheirurus sp.During the C. colonus Biozone the maximum of volcanic

activity in the Svaty Jan Volcanic Centre was reached. It

was interrupted in the lower Ludlow, most probably in theM. chimaera Biozone, for a shorter period to continue againin the middle Ludlow. In the slightly deeper environment inthe Northern Segment (Vysoky Ujezd) the sedimentationof carbonates with a brachiopod-trilobite communitycharacterized by dominant Indaclor sulcicarens continuedfrom the M. vulgaris to the C. colonus Biozone.

It is possible to characterize the benthic communitiesdevelopment in the Prague Basin during JAEGER'S"BigCrisis" as an abrupt change. The deeper water Cardiola agnaCommunity developed in the uppermost C. lundgreni Bio-zone but disappeared before the sedimentation of the M.dubius parvus Biozone and was not replaced by another bi-valve-dominated community.Rich relatively shallow water brachiopod-trilobite com-

munities of the upper C. lundgreni Biozone were replaced bythe Decoroproetus-Ravozetina Community which shows a dif-ferent structure and an adaptation to deeper water en-vironment.

826


Concerning the development of benthiccommunities at the boundary between theM. vulgaris Biozone and the C. colonus Bio-zone it may be stated that relatively deeperwater carbonate sediments below andabove the boundary contain the same bi-valves dominated by the Cardiola gibbosaCommunity and in the relatively shallowwater sediments the same brachiopod-dominated community characterized bythe dominant occurrence of Indaclor sul-cicarens. The situation with the trilobites issimilar. Communities below and above theboundary are characterized by the domin-ance of Interproetus and Eophacops in relative-ly shallow water sediments.The crisis in the graptolite evolution de-

scribed by JAEGERwas also contemporarywith the distinct change of the chitinozoanassociation. According to DUFKA (MS) thealmost monospecific assemblagecharacterized in the r testis Subzone byConochitina tuba was abruptly replaced atthe base of the M. dubius parvus Biozone byan assemblage with ?Eisenackitina sp. andEisenackitina cf. intermedia.

6. International Correlation

The development of the graptolite bio-zonation at the Wenlock/Ludlow boundaryin the shale facies is very similar to thescheme described by JAEGER (1991) fromThuringia, South Spain, Gotland and Lat-via. The benthic Decoroproetus-RavozetinaCommunity is till now characteristic onlyfor the Prague Basin.It is interesting that the "Kozel" lime-

stone complex with a thickness of14-63 m shows similar features with theMuch Wenlock Limestone in the WelshBorderland. Both limestone formationsformed in shallow water and both maydirectly or indirectly correspond to the M.vulgaris (M. ludensis) Biozone.

7. Significanceof Stratigraphically Important

Animal and Plant Groupsin Defining

the Wenlock/ludlow Boundaryin the Prague Basin

7.1. Graptolithina(By JIAi KAit)

H. JAEGERhad been visiting Bohemia al-most every year since 1958 to systematic-ally collect graptolites in the Silurian andDevonian of the Prague Basin. During hislast visit in August 1991 we collected grap-tolites at the locality Vseradice (no. 717).Later, during the end of the year 1991

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827


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Subzone

more graptolites were found by J. KRlt at the sectionsKoneprusy (no. 781), Hacka (no. 758), Vysoky Ujezd (no.567), Listice Pipeline Section (no. 579) and ListiceSection (nos. 759 and 770) and identified by H. JAEGERduring the visit of J. KRlt and P. DUFKA in Berlin in March,1992.

The results of H. JAEGER'S research were included intothe sections figured and described in this paper since hewas unable to complete his whole life work.

When summarized, it was discovered that at the end ofthe r testis Subzone (C. /undgreni Biozone) the Prague Basinwas influenced by the same event which was responsiblefor the "big crisis" (JAEGER,1991) in other regions.

It was demonstrated at the only complete section in theshale facies which was exposed as the Vseradice Section(KRlt, 1992) where all upper Wenlock zones above the rtestis Subzone up to the C. c%nus Biozone were discoveredby H. JAEGERin 1991.

Text-Fig.17.Range-chart of conodonts across the Wenlock/Ludlow boundary.

828

7.2. Conodonta(H.P. SCHÖNLAUB; Plate 1)

In terms of the currently used Silurian conodont zona-tion, the boundary between the lower and upper Silurian,i.e. the boundary between the Wenlock and Ludlow Serieshas been poorly defined (R.J. ALDRIDGE, 1975, R.J. ALD-RIDGE& H.P. SCHÖNLAUB, 1989). This applies to the strato-type at Pitch Coppice quarry near Ludlow (A. MARTINSSONet aI., 1981) as well as to other areas of the world for whicha conodont-based zonation for the Silurian has been es-tablished in recent years (for summary see B.J. COOPER,1980; R.J. ALDRIDGE,1985).

Since the study of a.H. WALLISER(1964), however, it be-came clear that the Bohemian sections of the shelly faciesmay provide additional data as some shale interbeds alsocontain graptolites which serve as leading fossils for thedefinition of the Wenlock/Ludlow boundary. In addition, awhole set of new records of graptolites from strata as-

signed to the upper Wen-lock has been found re-cently which supply usefulinformation to tie cono-donts into the graptolite-based framework of thisparticular timespan.

This report summarizesthe available conodont da-ta from 36 samples of sev-eral sections listed and de-scribed in the foregoingtext. They span the intervalfrom the upper range of Tes-tograptus testis to the C%no-graptus c%nus Biozones .The corresponding range-chart is shown in Text-Fig.17.

Yet, limestone samplesfrom only 8 out of 20 sec-tions produced conodonts,i.e. Branfk, Butovice, Are-thusina Gorge, Listice 770,Listice 579, Listice 759,Vysoky Ujezd and U Drdu.The remaining sectionswere either not sampledor were as yet not produc-tive.

The long ranging taxonOzarkodina e. excavata occursin strata assigned to the rtestis Biozone (Listice sec-tion 759 in association withO. s. sagitta), the interval be-tween the M. dubius parvusand the M. vulgaris Biozones(Branfk 764 section), the in-terval between the M. vu/-garis and the C. c%nus Bio-zones (Listice Pipelinesection 579) and in the C.c%nus Biozone (Butovice584 section, Vysoky Ujezdsection 567 and outcropbetween Listice sectionnos. 770 and 759). In addi-


tion, it co-occurs with O. bohemica in the Kozel Lst. of the UDrdu section.

Ozarkodina s. sagitta has yet only been recovered from theListice section 759 within the range of the index graptolitespecies T. testis and from the Arethusina Gorge section 687in strata corresponding to the upper T. testis Biozone. At thelatter locality the name-bearer of the sagitta conodont Zoneis associated with "early" representatives of Ozarkodinabohemica.

Ozarkodina occurs in a short section below the ListicePipeline section 579 in strata assigned to the M. dubius par-vus Biozone (for the accompanying fauna see chapter4.8.).

Ozarkodina bohemica has its first appearance in the upperpart of the T. testis Biozone (Arethusina Gorge section 687).It ranges through the M. vulgaris Biozone (Branik section764, Listice Pipeline section 579) to the basal part of the C.c%nus Biozone (Butovice section 584). This latter occur-rence confirms the data of WALLISER, 1964 who named thesame locality "Jinonice".O. bohemica is the most characteristic conodont species

of the Kozel Lst. at the U Drdu section 760. They representintermediate "morphotypes" between early occurrencesof the Arethusina Gorge section (T. testis Zone) and thosefrom the Branik and Butovice sections of the M. vulgaris andC. c%nus Biozones, respectively. Hence, for the Kozel Lst.an age within the late Wenlock is concluded.

Kocke/el/a absidata ranges from the T. testis Biozone (Listicesection 759) to the lower portion of the C. c%nus Biozone(Vysoky Ujezd section 567). A record from an interval inbetween was provided in the Listice Pipeline section 579within the upper M. vulgaris Biozone.

Kocke/el/a variabi/is has yet only been found in strata con-taining index graptolites of the basal Ludlow, i.e. at Buto-vice section 584 and Vysoky Ujezd section 567. In addi-tion, the latter section yielded the only characteristic re-presentatives of O. crassa.

In sample 774/2 from an outcrop between the Listicesections 770 and 759 Ozarkodina e. inflata is the dominatingconodont taxon. Based on associated graptolites for thishorizon an age within the C. c%nus Biozone, i.e. basal Lud-low can be concluded.

The available conodont fauna suggests a low diversity. Itis dominated by different species of Ozarkodina and Kocke/e/-/a which represent long and short ranging taxa, respec-tively. From the time relationship and morphological simi-larities it is most obvious that Ozarkodina s. rhenana evolvedfrom the nominate subspecies in the M. dubius parvus Bio-zone. Whether this subspecies is also the ancestor of Ozar-kodina bohemica seems quite possible. Such a relationshipcan be found in a sample from the upper T. testis Zone of theArethusina Gorge section in which both taxa co-occur. Weillustrate those specimens on Plate 1.

The interval from the base of the following "dubius-nas-sa-Interregnum" to the base of the C. c%nus Zone ischaracterized by the main occurrence of Ozarkodina bohe-mica. Most apparently, the phylogenetic development ofthis species reflects three distinct stages named hereinmorphotype 1 to 3:

~ Morphotype 1is the oldest representative occurring in the upper partof the T. testis Zone in conjunction with O. s. sagitta. Inlateral view the Pa element strongly resembles O. s. sa-gitta showing a blade steadily decreasing in height. Themain difference is the outline of the basal cavity whichoccupies the posterior part of the blade. In oral view it

is significantly expanded in comparison with the ar-row-like shape of that of O. s. sagitta and O. s. rhenana.

~ Morphotype 2occurs in sample 712/34 in the uppermost M. vulgarisZone of the Listice Pipeline section 579. In oral viewthis representative of O. bohemica is characterized by abroadly expanded flat and subcircular basal cavity thesurface of which is ornamented by short oblique ridgesof fused denticles. The anterior part of the straightblade bears the highest denticles which become fusedabout midlength and above the basal cavity to form aridge of more decreased height than at the anteriorportion.

~ Morphotype 3co-occurs with the former representative but extendsto strata assigned to the basal C. cotonus Biozone of thelower Ludlow Series. The Pa element suggests a veryclose relationship with O. bohemica subsp.nov. illus-trated and shortly described by R.J. ALDRIDGE, 1985.Also, it may be related to specimens named Spathogna-thodus s. bohemicus and Hindeodel/a snajdri described byL.E. FAHRAEUS, 1969 and L. JEPPSSON, 1983 from thelate Wenlock Halla and Mulde Beds of Gotland, re-spectively. Typical representatives of O. snajdri,however, are distinguished from O. bohemica by a bladeof varying height and a more broadly expanded andmore or less asymmetrical cavity. In the central Appa-lachians C.T. HELFRICH (1975) used similar althoughnot identical specimens to define a special conodontzone bridging the Wenlock/Ludlow boundary.

As far as the degree of fusion and height of the blade isconcerned Morphotype 3 shows a great variation. At handare those specimens with an evenly high blade at the an-terior and middle part of the blade which decreases fairlyabruptly at the posterior termination. Three to five den-ticles above the flat basal cavity may be fused. The subcir-cular and rarely also heart-shaped cavity may be symme-tricalor asymmetrical. Generally, the flat cavity is flaringfrom the midpoint and extends to or almost to the pos-terior end of the blade (for comparison see Plate 1).

The specimen illustrated by a.H. WALLISER (1964) onPI. 18, Figs. 25 and cited as Spathognathodus cf. sagitta sug-gests a close similarity with our Morphotype 3. At Cellonsection it is derived from sample bed 15B, , i.e. the bedimmediately below the appearance of the zonal index Ozar-kodina crassa. In the Vysoky Ujezd section of the Barrandianregion this taxon together with Kocke/et/a variabi/is and O. e.inflata first occurs in strata corresponding to the lowermostLudlow Series of the stratotype. This well comparable ord-er of appearance in both the Barrandian and the CarnicAlps seems reliable and thus suggests contemporaneity.It may help to define a conodont-based Wenlock/Ludlowboundary as shown on Text-Fig. 17 of our report. Conse-quently, we conclude that the Series boundary at Cellonsection must be drawn at the shale interbed between sam-ple nos. 15A and 15B2.

7.3. Chitinozoa(P. DUFKA; Plates 2-3)

A number of recent studies emphasize the importanceof chitinozoans for the Silurian biostratigraphy of thePrague Basin. Upper Silurian chitinozoans were studied inthe type sections of the Silurian/Devonian boundary(PARIS et aI., 1981) and of the Pi'idolf Series (KRit et aI.,1986). Subsequently, several biostratigraphic studies on

829


varies. Chitinozoans have not been recorded in the "Au/a-cop/eura Shales" (C. /undgreni Biozone) on the Spicaty Hillnear Lodemice and in the tuffitic shales of M. dubius parvusBiozone south of Hacka Hill near Lod{mice (section no.758). In the vicinity of Listice Village (section no. 770) veryrare chitinozoans « 1 specimen per gram of rock) wererecorded from the micritic limestone of the M. dubius parvusBiozone. At Vseradice Section (no. 717), only one sampleof micritic limestone from the base of the C. c%nus Biozoneyielded several poorly-preserved specimens of chitino-zoans. By contrast, abundant chitinozoans (e.g. > 800specimens per gram of rock in sample 10 in section no.781) were found in shales of the M. dubius parvus Biozoneand the C. nassa-M. dubius frequens Interregnum near

Text-Fig.18.Chitinozoarangesand graptolite biozona-tion at the Wenlock/Ludlow boundary inthe PragueBasin.

chronostra- graptolitetigraphy biozones

3 z M.chimaeraa oe(

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a -a: M.dubius frequens....J w G.nassa

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w :I: M.dubius parvus

3c: T. testisell Subzone'-CI"0c::l C. radiansu Subzone

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the lower Silurian chitinozoans ofgraptolite shale sequences werecarried out (DUFKA, 1992; DUFKA,1993a; DUFKA& FATKA, 1993).The present study of the Wen-

lock/Ludlow boundary beds isbased on samples from 15 sec-tions within the upper Wenlock(Motol Formation) and lower Lud-low (Kopanina Formation) strata(T. testis to M. chimaera Biozones).From the total number of 190processed samples, 63 samplesfrom 10 sections yielded deter-minable chitinozoans. Unfortu-nately, chitinozoans are almostabsent within the Vseradice Sec-tion (no. 717) which is nowadaysthe only accessible locality with acomplete set of graptolite bio-zones around the Wenlock/Lud-low boundary in the Prague Ba-sin.Ten chitinozoan taxa have been

determined in the studied interval(Fig. 18). Such a low chitinozoandiversity is not exceptional for thelate Homerian and lower Gorstiansequences, as it was previouslydocumented in Estonia (NESTOR,1990), Gotland (Klintenberg Beds- LAUFELD, 1974), southern Swe-den (LAUFELD et aI., 1975) andEngland (DORNING, 1981).The chitinozoan distribution

through the basin, as well as theirabundance and diversity withinthe individual sections, seem tobe controlled by a particular facialdevelopment in each segment ofthe basin. In the shallow water vol-cano-carbonate facies surround-ing the Svaty Jan Volcanic Centreof the Central Segment, the chiti-nozoans are rare (e.g. section no.759) or absent in the biodetritic limestone and the tuffiticshales of the T. testis Biozone. They are also missing in allsamples of tuffitic limestone and calcareous tuffites of the"Kozel" facies (M. dubius parvus to M. vulgaris Biozones),characterized by the dominance of the sporomorphs ofland plants (DUFKA, 1993b). In the Nova Ves Volcanic Cen-tre (section no. 687; T. testis to C. c%nus Biozones) of theCentral Segment and in the eastern part of the CentralSegment (section no. 764; M. dubius parvus to ?M. vulgarisBiozones), well-preserved but not abundant chitinozoans« 5 specimens per gram of rock) were recovered from thelenses of micritic limestone enclosed in tuffitic shales.In adjacent segments of the basin with calcareous or

tuffitic shale facies, the occurrence of chitinozoans

830


Eisenackitina pregranosa sp.noY.(PI. 3, Figs. 1-5)

7.3.2. Description of New Species

Genus: Eisenackitina JANSONIUS, 1964Typ e s p e ci es: Eisenackitina castor JANSONIUS, 1964

Com par iso n: Conochitina lagena EISENACKhas a differenttrend of the UDp variations (see EISENACK,1968, Fig. 9)and, according to the original diagnosis, "fine granulateornamentation". Conochitina gutta LAUFELDis ornamentedby low ruggae, arranged more or less in a polygonal pat-tern (LAUFELD, 1974, Fig. 25:E) and dispersed over thewhole vesicle.

S t rat i g rap h i c dis tri but ion: M. dubius parvus Biozoneto M. dubius frequens-G. nassa Interregnum (sections no.781 and no. 764).

? Eisenackitinatagenomorpha(EISENACK) - NESTOR, PI. 15, Fig. 12.

Holotype: PI. 3, Fig. 2. Sample 687-8, slide GSP-135,deposited in author's collection in the Czech GeologicalSurvey, Prague.

Typ e 10 c a lit Y and typ e ho r i z 0 n : Reporyje, sectionno. 687 (Muslovka), Prague Basin (Bohemia); M. chimaeraBiozone, Gorstian, Ludlow.

Mat e ria I: 50 three-dimensional specimens from thesections no. 770 and no. 687. All specimens are depo-sited in the authors collection at the Czech GeologicalSurvey, Prague.

Dc

5859

52-68

Dp

98105

94-124

L

224228

177-296

HolotypeMeanRange

Eisenackitina branikensis sp.noY.(PI. 3, Figs. 6-10)

1992? Eisenackitinasp.- KRlt, p. 16, p. 3, Fig. 4.1992 Eisenackitinacf. intermedia; KRlt, p. 16, PI. 3, Fig. 5.

Holotype: P1.3, Fig.10, sample 781-7-9, slideGSP-296, deposited in author's collection at the CzechGeological Survey, Prague.

Type locality and type horizon: Koneprusy, sec-tion 781, Prague Basin (Bohemia); M. dubius parvus Bio-zone, Homerian, Wenlock.

Mat e ria I: 480 partially flattened specimens from thesection 781 and 135 three-dimensional specimens fromthe section 764. All specimens deposited in the authorscollection at the Czech Geological Survey, Prague.

Dia 9 nos is: Eisenackitina species with a club-shapedchamber terminated by distinct collarette. The basalmargin is rounded or inconspicuous and the base isconvex, provided by broad, protruded mucron. The or-namentation consists of tubercles, short spines andcoalescent rugae. The latter are developed especiallyaround the basal margin.

Dim ens ion s: Based on 32 three-dimensional speci-mens and 32 partially flattened specimens. Flatteningcorrected for Dc and Dp values by multiplying with a 0.8coefficient. Measurements in fLm.

7.3.1. Biostratigraphy

Seven chitinozoan taxa have been determined from theupper part of the T. testis Biozone (Text-Fig. 18). Five ofthem, Ancyrochitina gr. ancyrea (EISENACK),Margachitina margari-tana (EISENACK),Conochitina tuba EISENACK,Linochitina cf. erra-tica (EISENACK)and Linochitina cf. odiosa LAUFELDpass in thePrague Basin from the Sheinwoodian to the Homerian(DUFKA, 1993). Conochitina pachycephala EISENACKoccurs forthe first time in the T. testis Biozone and? Urnochitina sp. B isrestricted to the upper part of this biozone.The boundary between the C. lundgreni and the M. dubius

parvus Biozones is characterized by a distinct change in thechitinozoan assemblages (Text-Fig. 18). This change cor-responds to an extensive crisis in the graptolite evolutiondescribed by JAEGER (e.g., 1991). ?Urnochitina sp. BandMargachitina margaritana disappears at the top of the T. testisBiozone. Eisenackitina branikensis sp. novo and Eisenackitina pre-granosa sp.nov. appear in the M. dubius parvus Biozone. E.branikensiscoincides in the first occurrence with the grapto-lite M. dubius parvus and ranges up to the G. nassa-M. dubiusfrequens Interregnum. E. pregranosa has a longer stratigraphicrange as compared with E. branikensis; however, it was onlydetermined as a rare form in several samples from the M.dubius parvus Biozone (section no. 770) and then from the M.chimaera Biozone (section no. 687).No new chitinozoan forms have been recorded in the G.

nassa and M. dubius frequens Interregnum. Similarly as in theunderlying M. dubius parvus Biozone, Eisenackitina branikensisand Conochitina pachycephala are of major biostratigraphicimportance. Linochitina cf. odiosa and Linochitina cf. erratica aremissing in samples from the G. nassa and M. dubius frequensInterregnum.The succeeding upper Homerian graptolite biozones (M.

praedeubeli, M. deubeli and M. vulgaris) are recently accessibleonly at the Vseradice Section (no. 717), where chitino-zoans are absent in this interval.

Cingulochitina wronai PARIS & KRlt has been recorded forthe first time in the upper part of the M. vulgaris Biozone(section 597). In the younger strata, C. wronaiwas recordedfrom the M. chimaera Biozone and from the Ludlow/Pi'fdoliboundary beds, where it was originally described (PARIS&KRrt, 1984). Besides the Prague Basin, it was reportedfrom the M. chimaera Biozone of the lower Ludlow in thePalencia Province, Spain (SCHWEINEBERG,1987).Chitinozoans are not significant for the definition of the

Wenlock/Ludlow boundary (between M. vulgaris and C. col-onus Biozones) in the Prague Basin. No change in the chiti-nozoan species spectrum has been recognized within theC. colonus Biozone and probably all species known from theupper Homerian pass to the lower Gorstian (Text-Fig. 18).The dominant chitinozoans recorded from the lower

Gorstian strata are long-ranging taxa like the A. ancyreagroup and the C. tuba-C. claviformis complex (variable formswith affinities to C. tuba, C. elegans and C. claviformis).

Koneprusy (section 781), similarly as in the tuffitic shalesand limestone of M. vulgaris Biozone near Listice Village(section no. 597).The chitinozoan absence in some shale sequences is

questionable. Decrease of any insoluble organic residuein shales of the C. lundgreni to C. colonus Biozones in Vsera-dice Section suggests that the rocks are barren of chitino-zoans due to their recent or fossil alteration.

831


Dia g nos is: Eisenackitina species with barrel-shapedchamber, short collarette and inconspicuous basalmargin. The central part of the base is slightly concave,provided with a discrete anteapertural mark consistingof the central scar and the central pit. The vesicle or-namentation is composed of distinct granas and cones,1.5-2 f.Lmin high and 2-3 f.Lmin width.

Dim ens ion s: Based on 25 three-dimensional spe-cimens. Measurements in f.Lm.

The close resemblance between the sporomorph as-semblages of the Prague Basin and coeval assemblagesfrom the Great Britain Wenlock Limestone (e.g. BURGESS&RICHARDSON,1991), Libya (RICHARDSON& IOANNIDES,1973),Spain (RODRIGUEZ,1978) and North America (STROTHER&TRAVERSE,1979; MCGREGOR& NARBONNE, 1978) suggeststhe parallel early evolution of higher land plants in theseregions.

Com par iso n: Eisenackitina pregranosa has the identicalsculpture and the character of the anteapertural mark asEisenackitina granosa (LAUFELD) which is a typical upperLudlow taxon. However, both species distinctly differ inthe vesicle size and shape. The dimensions of the origi-nally described population of E. granosa are following(LAUFELD, 1974, p. 61): "length 95-120 f.Lm, greatestwidth 48-55 f.Lm,width of aperture 33-42 f.Lm".

S t rat i g rap h i c dis tri but ion: M. dubius parvus Biozone(section no. 770), probably M. vulgaris Biozone (sectionno. 759), M. chimaera Biozone (section 687).

7.4. Sporomorphs(PAVELDUFKA)

Highly-diversified assemblages of dispersed triletemiospores and cryptospores were recovered from the up-per Homerian tuffitic shales and limestones in the regionof the Svaty Jan Volcanic Centre. Local occurrence ofabundant sporomorphs as well as their dominance overthe marine microphytoplankton, documented in the sec-tion no. 760 (Listice near Beroun), indicate the vegetationof higher land plants on the emerged Svaty Jan Volcanicelevation during the uppermost Wenlock.Twenty-nine sporomorph forms were reported by DUFKA

(DUFKA, 1993b). Among these forms are included severalindex species typical for the Artemopyra brevicosta-Hispanae-discus verrucatus Sporomorph Biozone (RICHARDSON &MCGREGOR, 1986; BURGESS& RICHARDSON,1991): Artemo-pyra brevicosta BURGESS & RICHARDSON, Hispanaediscus ver-rucatus (CRAMER), Emphanisporites protophanus RICHARDSON&IOANNIDES,Synorisporites libycus RICHARDSON& IOANNIDESandSynorisporites cf. verrucatus RICHARDSON& LISTER.

HolotypeMeanRange

L

156154

140-182

Dp

104105

94-120

Dc

6865

62-73

8. ConclusionsIt may be concluded that in the Prague Basin the crisis in

the graptolite evolution at the boundary between the C.lungreni Biozone and the M. dubius parvus Biozone (JAEGER,1991) was accompanied by a distinct change in the chiti-nozoan association development and by the appearanceof new benthic forms in the distinct Decoroproetus-RavozetinaCommunity.The tectonic development of the Prague Basin during

the M. dubius parvus Biozone, M. dubius frequens-G. nassa Inter-zone, M. praedeubeli Biozone and M. deubeli Biozone was ac-companied by a prominent volcanic activity in all volcaniccenters along the deep synsedimentary faults which re-presented the margins of the Central Segment where thelargest subsidence during the Silurian was recorded(Text-Fig. 16). Due to the volcanic activity, the Svaty JanVolcano elevation developed and was emerged above sealevel (KRlt, 1991). The finds of spores (DUFKA, 1993a) in itsmarginal shallow water carbonates of the "Kozel" Lime-stone complex document the presence of a diversified as-sociation of land plants on the island.It may be presumed that all described changes in the

Prague Basin which were contemporary with JAEGER'S"Big Crisis" (JAEGER, 1991) are related to a global changein water circulation (currents transported new benthicforms from other regions into the basin), and to synse-dimentary tectonic changes at least in this part of Gond-wana which were responsible in the Prague Basin for vol-canic activity at the base of M. dubius parvus Biozone in allvolcanic centres.The shallowing of the Prague Basin during the M. vulgaris

Biozone in the Northern Segment and in the Central Seg-ment may be related to the global regression the effect ofwhich was locally increased by earlier accumulation ofvolcanics during the M. dubius parvus Biozone and the M.deubeli Biozone interval.JAEGER'S "Big Crisis" in graptolite evolution (JAEGER,

1991) represents a distinct bioevent which may be directlyrelated to global plate tectonic regimes.

Figs.2,5:

Fig. 6:

Fig. 7:

Fig. 8:

Fig. 9:

Plate 1

Figs. 1,3,4: Ozarkodina bohemica (WALLlSER), Morphotype 1.ProsHedni Mill Section No. 713, sample no. 10; r. testis Zone.Figs. 1,3: Lateral and oral views.Fig. 4: Oral view.Ozarkodina s. sagilla - Ozarkodina bohemicatransitional type.Arethusina Gorge section No. 687; r. testis Zone.Ozarkodina sagilla sagilla (WALLISER).Arethusina Gorge section No. 687; r. testis Zone.Ozarkodina sagilla rhenana (WALLISER).Listice section No. 770; M. dubius parvus Zone.Ozarkodina excavala intlala (WALLlSER).Listice, outcrop between sections Nos. 770 and 759;C. colonus Zone.Ozarkodina bohemica (WALLISER), Morphotype 2.Listice Pipeline section No. 579 (sample 712/34); M. vulgarisZone.

832

Fig. 10: Ozarkodina bohemica (WALLISER), Morphotype 3.Fig. 10: Oral view from Butovice section No. 584/10;

C. colonus Zone.Fig. 11: Oral view from Branik section No. 764;

M. vulgaris Zone.Fig. 12: Oral view from Listice Pipeline section No. 579,

sample No. 21; M. vulgaris Zone.Fig. 13: Lateral view from Butovice section No. 584/10;

C. c%nus Zone.Fig. 14: Lateral view from Branfk section No. 764;

M. vulgaris Zone.Fig. 15: Kocke/eUa absidiala (LANE).

Butovice section No. 584/10; C. c%nus Zone.Fig. 16: Kocke/eUa variabilis (BRANSON & MEHL).

Lateral view from Listice Pipeline section No. 579, sampleNo. 34; M. vulgaris Zone.

Figs. 17-18: Ozarkodina crassa (WALLISER).Fig. 17: Lateral view from Vysoky Ujezd section No. 567,

sample No.1 0 (uppermost 30 cm); C. colonus Zone.Fig. 18: Lateral view from Butovice section No. 584/10;

C. colonus Zone.All photos by Dr. H. PRIEWALDER,Geologische Bundesanstalt, Wien.



( Plate 2 J

Figs. 1- 2: Cingulochitina wronai PARIS & KRIt..Section no. 597, sample 36, M. vulgaris Biozone, GSP 277.Fig. 1: x 400.Fig. 2: Detail of the anteapertural end showing the rim of carina; x 800.

Figs. 3- 4: Cingulochitina wronai PARIS & KRIt.z.Section no. 597, sample 8, M. vulgaris Biozone, GSP 256.Fig. 3: Flattened specimen adhered to the basal part of the proceeding vesicle; x 275.Fig.4: Detail of carina; x 850.

Fig. 5: Linochitina cf. erratica (EISENACK).Section no. 781, bed 1, sample 2, T. lestis Biozone, GSP 287; x300.

Fig. 6: Linochitina cf. odiosa LAUFELD.Section no. 781, bed 1, sample 2, T. testis Biozone, GSP 287; x 300.

Figs. 7- 8: ?Urnochitina sp. B.Section no. 584, T. testis Biozone.Fig.7: Bed 2, sample 1, GSP-11 0; x 250.Fig.8: Bed 2, sample 3, GSP-113; X230.

Fig. 9: Conochitina cf. tuba EISENACK.Section no. 597, sample 60, M. vulgaris Biozone, GSP 277; x 300.

Fig. 10: Margachitina margaritana EISENACK.Section no. 781, bed 1, sample 1, T. testis Biozone, GSP 287; x 350.

Figs. 11-12: Conochitina pachycephala EISENACK.Section no. 597, sample 36, M. vulgaris Biozone.Fig. 11: GSP 277; x 250.Fig. 12: GSP 277; x 250.

Fig. 13: Conochitina cf. pachycephala EISENACK.Section no. 764, bed 6, sample 12, M. dubius frequens - G. nassa Interregnum, GSP-94; x 180.

Fig. 14: Conochitina cf. pachycephala EISENACK.Section no. 764, bed 6, sample 11, M. dubius frequens - G. nassa Interregnum, GSP-90; x 150.

834


835


[ Plate 3 J

Figs. 1-5: Eisenackitina pregranosa sp.noY.Section no. 687, sample 8, M. chimaera Biozone, GSP 135.Fig. 1: x 350.Fig.2: Holotype; X400.Fig. 3: Aboral view on the specimen illustrated on Fig. 2, showing the basal scar and the basal pit; x 600.Fig.4: Oral view of the specimen illustrated on Fig. 1 showing a low collarette and operculum; x 600.Fig. 5: Detail of ornamentation composed of granas and cones on the specimen from Fig. 1; x 2500.

Figs. 6,9: Eisenackilina branikensis sp.noY.Section no. 764, bed 6, sample 12, M. dubius frequens- G. nassa Interregnum, GSP-95; x 375.

Figs. 7,8,10: Eisenackilina branikensis sp.noY.Section no. 781, bed 7, sample 9, M. dubius parvus Biozone, GSP 297.Fig. 7: Detail of tiny tuberculate to echinate ornamentation of the holotype; x 2500.Fig. 8: x 325.Fig. 10: Holotype; x 350.

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Documents

The Wenlock/ludlow Boundary inthe Prague Basin (Bohemia) · PDF fileälteren Ludlows. Für biostratigraphische Zwecke wurde die vertikale Verbreitung von Graptolithen, Conodonten,