Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section, South Urals, Russia: potential candidate for the GSSP for the Viséan-Serpukhovian boundary

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Newsletters on Stratigraphy © Gebrüder Borntraeger 2009Vol. 43/2: 165–193, March 2009

Paleontology and Microfacies of the Serpukhovianin the Verkhnyaya Kardailovka Section, South Urals, Russia: potential candidate for the GSSP for the Viséan-Serpukhovian boundary

S.V. Nikolaeva1, E. I. Kulagina2, V. N. Pazukhin2, N. N. Kochetova2,and V.A. Konovalova1

With 9 figures, 3 plates and 1 table

Abstract. A uniquely complete carbonate sequence spanning a large portion of the Viséan and the entire Ser-pukhovian is exposed on the Ural River, opposite the village of Verkhnyaya Kardailovka (South Urals,Bashkortostan, Russia). The Upper Viséan and Serpukhovian beds in this section are composed of deep- watercarbonates containing ammonoids, conodonts, ostracodes and foraminifers. The section is well-sampled,measured, its lithology is now described, and a sedimentary environment near the seaward end of a carbonateplatform and deep shelf is suggested. Abundant fossils allow the recognition of four successive ammonoid andfour successive conodont zones, which allow reliable correlations of the regional Serpukhovian stages outsidethe South Urals, although the type section of the Serpukhovian in the Moscow Basin is in the shallow-waterfacies. The base of the Serpukhovian in the Moscow Basin and in the South Urals is defined by the first ap-pearance datum (FAD) of the conodont Lochriea ziegleri. This level coincides with the base of the Koso-gorskian in the Urals, correlates with the entry of the foraminifer “Millerella” tortula near the base of the Taru-sian in the Moscow Basin and is close to the earliest occurrences of Dombarites paratectus and Cravenocerasat the base of the Uralopronorites-Cravenoceras Genozone and of the latter genus at the base of the BritishE1 Zone. Because of its accessibility, abundant fossils, and its well studied lithology, the Verkhnyaya Kar-dailovka Section is an excellent candidate for the GSSP of the Viséan-Serpukhovian boundary.

Key words. Carboniferous, stratigraphy, Viséan, Serpukhovian, GSSP, Verkhnyaya Kardailovka.

DOI: 10.1127/0078-0421/2009/0043-0165 0078-0421/09/0043-0165 $ 7.25© 2009 Gebrüder Borntraeger, D-14129 Berlin · D-70176 Stuttgart

Authorsʼ adresses:1 Paleontological Institute, Russian Academy of Sciences, Moscow, ul. Profsoyuznaya 123, Moscow, 117997 Russia(E-Mail: [email protected]; [email protected])2 Institute of Geology, Ufa Research Center, Russian Academy of Sciences, ul. Karla Marksa 16/2. Ufa, Russia (E-Mail:[email protected])

Corresponding author: S. V. Nikolaeva, Paleontological Institute, Russian Academy of Sciences, Moscow, Profsoyuz-naya 123, Moscow, 117997 Russia (E-Mail: [email protected])

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1. Introduction

The Serpukhovian stage, first established in Russia byNikitin (1890), is included in the Global StratigraphicScale of the Carboniferous. The definition of its lowerboundary, which is also the base of the Upper Missis-sippian, and the selection of the GSSP are high priori-ty tasks of the International Subcommission on Car-boniferous stratigraphy (Richards 2005, 2006, 2007;Gradstein and Ogg 2007). In the type Serpukhovianarea in the Moscow Basin, the Serpukhovian is com-posed of the carbonate-clayey sequence identified asthree regional stages (Tarusian, Steshevian, and Prot-vian) overlain by the Pestovo Beds (Table 1). Thebasal Serpukhovian (Tarusian) is represented by shal-low-water, lagoonal carbonates overlying the karstsurface of the Venevian rhizoid limestone (Osipovaand Belskaya 1965). In the lectostratotype of the Ser-pukhovian stage, in the Zaborie Quarry, this intervalwas originally unexposed, having been covered by thelake at the base of the quarry (Kabanov 2003, 2004;Hecker and Osipova 2007). Later, the Zaborie section

has been re-examined and re-sampled (Barskov andAlekseev 1979; Makhlina et al. 1993; Gibshman 2001,2003; Kabanov 2003, 2004). The basal Serpukhovian(Tarusian) foraminiferal assemblage (N. postrugosusZone followed by the Pseudoendothyra globosaZone), although being more impoverished than that ofthe Viséan Eostaffella tenebrosa Zone, contains Janis-chewskina delicata (Malakhova), “Millerella” tortulaZeller, and Neoarchaediscus postrugosus Reitlinger(Gibshman 2001; 2003). The same beds contain theconodonts Lochriea senckenbergica, L. cruciformis,and L. ziegleri (Barskov et al. 1984; Skompski et al.1995) while a few ammonoids of the Uralopronorites-Cravenoceras Zone were also recorded from this sec-tion (Nikolaeva et al. 2002, based on A.V. Shkolin’sdata). These studies confirmed that the appearance ofthe Serpukhovian taxa in the Zaborie section is large-ly facies-controlled, and therefore the paleontologicalevidence for the base of the Serpukhovian is insuffi-cient.

Considering all the shortcomings of the Serpukhov-ian in its type area, sections in the Urals have attractedconsiderable attention for having exceptional potentialfor understanding the real ranges of the Serpukhoviantaxa, and for providing the possibility of interregionalcorrelations. In the Verkhnyaya Kardailovka Section,the Serpukhovian is complete, with no visible or re -corded gaps, and is composed of deep-water carbon-ates in a condensed succession. The total thickness ofthe Serpukhovian part of the section is 37 m. Nikolae-va et al. (2005) proposed this section as a possible can-didate for the GSSP of the base of the Serpukhovian

Librovitch (1936) was the first to briefly describethe section near Verkhnyaya Kardailovka. LaterRuzhencev and Bogoslovskaya (1971) described thissection bed-by-bed and subdivided it, based on am-monoids, into two genozones (Uralopronorites –Cravenoceras and Fayettevillea – Delepinoceras) andfour species zones to which they proposed the follow-ing codes: Nm1b1, Nm1b2, Nm1c1, and Nm1c2).Malakhova (1971, 1973) and Kotschetkova et al.(1977) listed foraminifers from this section. However,until the 1980s the Viséan-Serpukhovian transitionalbeds were not exposed and therefore remained unex-amined.

The present authors began studying this section inthe 1980s, but the studies first focused primarily on theUpper Serpukhovian part of the section (Kulagina1985; Kulagina et al. 1992). In recent years we re-ceived new data on the biostratigraphy of the Viséan-Serpukhovian boundary (Nikolaeva et al. 2001; 2002;

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Table 1 Regional Stratigraphical Subdivisions of the Up-per Visean and Serpukhovian in the Russian Plat-form and the South Urals.

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Pazukhin and Gorozhanina 2002; Pazukhin et al.2002), mainly from examining the trenches and pits inthe previously unexposed transitional interval aroundthe boundary. These studies resulted in the reconstruc-tion of a complete succession of the Upper Viséan andSerpukhovian conodont zones in a single outcrop, inwhich the crucial conodont-defined Viséan-Ser-pukhovian boundary interval contains ammonoids. Inthis paper we summarize the results of the biostrati-graphic and lithological-sedimentological studies ofthis important section.

2. Material and methods

The whole of the Verkhnyaya Kardailovka section wasre-sampled and re-measured, and its fossil content wasre-examined by a joint team of paleontologists andstratigraphers from Moscow and Ufa. E. I. Kulaginaexamined foraminifers, V. N. Pazukhin – conodonts,N. N. Kochetova – ostracodes, and S. V. Nikolaeva andV. A. Konovalova – ammonoids. Kulagina also de-scribed the carbonate microfacies. E. N. Gorozhaninastudied thin sections of volcanic-terrigeneous rocks(Pazukhin and Gorozhanina 2002).

The Upper Viséan at Verkhnyaya Kardailovka issubdivided according to the regional stratigraphicschemes of the Russian Platform into regional in-trastage subdivisions, so-called “horizons” (Kagar-manov and Donakova (Eds.) 1990). These are the Tulian, Mikhailovian, Aleksinian, and Venevian hori-zons. It has proved to be more practical because theUpper Viséan beds in the Verkhnyaya KardailovkaSection do not contain abundant foraminifers and bra-chiopods, while these two groups were traditionallyused for recognition of the regional stages in the Urals(Stratigraphicheskie. . . 1993), but instead contain con-odonts commonly found on the Russian Platform, al-lowing direct correlations between these two regions.However, the Serpukhovian beds in the VerkhnyayaKardailovka Section are subdivided using the regional“horizons” (cited below without inverted commas)proposed and accepted in the Urals and include theKosogorskian, Khudolazovian and Chernyshevian(Yuldybaevian) horizons.

3. Geographical and geological background

The section is located on the right bank of the Ural River, opposite the village of Verkhnyaya Kardailovka(which is on the left bank), 2 km east-north-east of the Uralian division of the Zilairskii Farm (village of Prigo rodnyi), in the southeast of the Baimak District(Republic of Bashkortostan) (Fig. 1). Tectonically, thesection belongs to the eastern wing of the KardailovkaSyncline, which is located in the center of the Mag -nitogorsk Megasynclinorium. Here, the continuous Lower Viséan to Moscovian outcrops extend for 3 kmin the east-north-east to the west-south-west direction.The Lower Viséan sequence is mainly bioclastic and is underlain by the Upper Tournaisian-Lower Viséan volcanic-terrigeneous series of the Berezovskaya Formation.

In the Lower Viséan sequence (thickness over300 m) two foraminiferal zones are recognized (Eo p-arastaffella simplex and Uralodiscus rotun dus).Thesebeds are conformably overlain by crinoidal limestoneswith the foraminiferal assemblage of the Paraar-chaediscus koktjubensis Zone equivalent to the lowerpart of the Tulian Regional Stage, with a total thicknessof 21 m. These beds are overlain by 6 m of unexposedsequence, followed by a condensed section of the Up-per Viséan-Serpukhovian beds (Fig. 2). This section isterminated by a limestone bed with Lower Bashkirianconodonts. Above that level, the section is interruptedby a fault extending from the southeastern to north-western direction.

To the east of this fault, in a small quarry, we record-ed a series of strongly re-worked clayey-cherty shalewith poorly preserved imprints of ammonoids of thegenus?Cancelloceras, which provisionally date thesebeds as the Bilinguites – Cancelloceras Genozone(= G1 Zone in Europe = Akavas Regional stage (Bash -kirian) in the South Urals). East of this outcrop is anexposure of polymictic sandstones, siltstones, sandyand clayey limestones with limestone bullions dated asBashkirian. The total thickness of this series is 250–300 m. The youngest Carboniferous rocks in this areaare represented by the Moscovian Kardailovka For-mation composed of limestone breccias, sandstones,and shale, with a total thickness of over 300 m(Kotschetkova et al. 1977).

The Upper Viséan to Serpukhovian portion of thesection is in this paper described beginning fromBed 19 (Figs. 2, 3) (Beds 1–18 are Lower-MiddleViséan and are not included in this description). The

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beds dip to 235°, at an angle of 20–25°. The lowerbeds in this sequence are incompletely exposed and aseries of pits and trenches were excavated up in a line0.2 km north of the main profile to examine and meas-ure the lowermost Upper Viséan portion, stratigraphi-cally immediately below the rocky exposures of Ser-pukhovian limestone. The trenches overlap each otherto form a continuous reconstruction (see Fig. 1). SeeAppendix for a complete description of the lithology.

4. Sedimentary settings and facies

In the Early Viséan, the territory under considerationwas part of a marine basin with massive accumulationof mainly carbonate sands followed by a significantchange in the Late Visean (Tulian) leading to the de -position of crinoidal limestones. This was later re-placed by the mixed carbonate-volcanic sedimentation

168 S.V. Nikolaeva et al.

Fig. 1. Location map of the Verkhnyaya Kardailovka Section. The photograph shows the disposition of the trenches ex-posing the Viséan -Serpukhovian boundary beds, and levels of the samples collected.

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169Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

Fig. 2. Viséan-Serpukhovian boundary beds in the Verkhnyaya Kardailovka Section. The arrow marks the FAD of Lochrieaziegleri.

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(Beds 18–19.3) in the Late Tulian (Pazukhin andGorozhanina 2002). A bed of calcareous sandstone(Bed 19.4), rich in glauconite, suggests a hardgroundsurface, as glauconitic minerals are associated withhard grounds, while glauconitic greensands commonlyoccur above a shoaling-upward facies sequence (vanHouten and Purucker 1984). Upward (Bed 20a), thesection contains beds of micritic limestone with radio-larians, fragments of sponge spicules, juvenile am-monoid shells and numerous conodonts suggesting adeepening of the basin.

Later in the Late Viséan (Beds 21.9–21.12) the de position of microbioclastic wackestones and pack-stones (Fig. 4, photograph 7) with ammonoids and co no donts, thin-shelled ostracodes and rare small eury facial foraminifers prevailed. The deposition most

likely occurred at the lower-middle part of the slope ofa carbonate platform (Facial Zone 4 in terminology ofWilson, 1975), with low water turbulence.

At the beginning of the Serpukhovian (Koso-gorskian time) the sedimentation of the relatively deepouter shelf (seaward slope of the carbonate platform)with low water turbulence continued. Dominant rocksinclude mudstone, wackestone (Fig. 4, photographs 5and 6) and microbioclastic packstone. In places therocks contain large bioclasts, which were evidentlytransported from zones of higher turbulence. Remainsof benthic fauna occur rarely, while ammonoids, con-odonts, and thin-shelled ostracodes are common.

In the Khudolazovian, a decrease in water depth re-sulted in features indicating higher energy. This levelalso contains beds with algae, foraminifers, bryozoans,

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Fig. 3. Distribution of microfacies in the Verkhnyaya Kardailovka Section. For explanations see Fig. 2.

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171Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

1 2

43

6 75

Fig. 4. Photographs of the microfacies from the Verkhnyaya Kardailovka Section.1. Bioclastic grainstone, � 45, Sample 2741 (11), Chernyshevian; 2. Bioclastic packstone with algae Beresella sp., � 30,Sample 2745(1), Chernyshevian; 3. Bioclastic packstone/grainstone, � 30, Sample 2729, Khudolazovian; 4. Microbioclas-tic packstone with Bryozoa, � 30, 2745(6), Chernyshevian; 5. Wackestone, sample 013(1), Kosogorskian. 6. Mudstone/wackestone with a shell of an ammonoid, � 25, sample 011/1, Kosogorskian. 7. Microbioclastic packstone, � 25, Sample015, Venevian

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Fig. 5. Distribution of foraminifers in the Verkhnyaya Kardailovka section.

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and fragments of brachiopod shells (Fig. 4, photograph3). Bioclasts are relatively well-sorted, medium-rounded, and large grains indicate traces of micritiza-tion. Small crinoidal banks and bioherms (Bed 24) arerecorded at this level. In the Late Khudolazovian timethe basin again became deeper, resulting in the pre-dominance of micritic limestones with numerous ostracodes of Thüringian ecotype, ammonoids, andconodonts.

At the end of the Late Serpukhovian (Chernyshe-vian = Yuldybaevian) the basin again became shallow-er. Bed 26 contains layers of bryozoan-crinoidal grain-stone/packstone with remains of algae, foraminifers,and brachiopods (Fig. 4, photographs 1, 2, and 4). Thismicrofacies suggests the presence of a bryozoan-algalbank at the upper slope of a carbonate platform.

At the very beginning of the Bashkirian, sedimenta-tion continued on the open shelf on a slope of acrinoidal bank. The overlying Bashkirian and Moscov-ian beds are represented by slope facies (graded cal-careous sandstones and siltstones with interbeddedwith breccia and limestones) represented by the flyschseries of the Kardailovka Formation.

5. Fossil record of the Viséan

5.1 Foraminifers

Foraminifers are restricted to the beds of packstones.The fauna consists of small forms of low diversity.The Upper Viséan in this section (Venevian) referredto as “Beds with Endostaffella asymmetrica” (Beds21.8–22a, lower part) is 3 m thick and contains smallshells of foraminifers (Fig. 5). Most of these fora -minifers have a wide stratigraphic distribution. How-ever, the Late Viséan age is based on Astero -archaediscus parvus (Rauser-Chernousova), which isalso found in the upper part of the Mikhailovian Re-gional Stage of the Moscow Basin (Rauser-Chernousova et al. 1948).

5.2 Ammonoids

Two distinct ammonoid assemblages are found in theViséan part of the section (Fig. 6). The basal part of thesection contains the assemblage of the Beyri-choceras – Goniatites Genozone of Bogoslovskaya(1966) and Ruzhencev and Bogoslovskaya (1971)(Samples 2711/4 and 20–25 cm higher 2711/2 inTrench 2). The lower assemblage contains Goniatitessphaeroides Bogoslovskaya, 1966 and Goniatites

crenifalcatus Bogoslovskaya, 1966, which we consid-er as two distinct species (originally described as sub-species in Bogoslovskaya 1966). Because no reliablerecords of either species exist outside the South Urals(possibly with the exception of one by Liang and Wang1991), the interregional correlation may only be pro-visional. We suggest that this level approximately cor-relates with the interval of the upper part of the Asbianto the basal part of the Brigantian. The second am-monoid assemblage belongs to the Upper Viséan Hy-pergoniatites – Ferganoceras Zone (= Nm1a). This assemblage is first found 1 m above Sample 2711 inTrench 3. Ammonoids are recovered from Samples015/5, 015/3 and 015. The assemblage containedNeogoniatites milleri Ruzhencev and Bogoslovskaya,Prolecanites librovitchi Ruzhencev,?Lyrogoniatitessp., and numerous undeterminable Prolecanitidae. InWestern Kazakhstan (Dombar Hills) all the above taxaare found in both the Upper Viséan Hypergoniatites –Ferganoceras Zone and the Serpukhovian Uralo-pronorites – Cravenoceras Zone (Ruzhencev and Bo-goslovskaya 1971; Nikolaeva 2006), but their highestconcentration was found in the upper part of the Viséanat the level Nm1a2. Samples 015/5, 015/3 and 015 inthe Verkhnyaya Kardailovka Section did not yield taxarestricted to the Uralopronorites-Cravenoceras Zonein the Dombar Hills. Therefore we tentatively date thebeds with this fossil assemblage in the VerkhnyayaKardailovka Section as Late Viséan.

5.3 Conodonts

The section contains numerous conodonts (Fig. 7). Theassemblage of the Gnathodus texanus Zone was foundin Bed 18 (thickness 2.0 m), and is equivalent to thatof the lower part of the Upper Viséan Tulian RegionalStage. The overlying beds up to the base of the L. zieg-leri Zone were opened in pits and trenches and there-fore the upper boundary of this zone cannot be pre-cisely identified.

Bed 19.1 (Pit 2) contains a transitional impover-ished assemblage of the Gnathodus austini Zone(Bed 19.1; thickness 0.3 m). It included a few Gnatho-dus austini Belka, Gn. aff. austini Belka, and Pseudo -gnathodus homopunctatus (Ziegler). The interval of6.3 m between the Gnathodus austini and Gn. bilinea-tus bilineatus Zones did not contain age indicativeconodonts.

The Gnathodus bilineatus bilineatus Zone (Beds19.4–21.5 – lower part; thickness 6.0 m) is identifiedbased on the appearance of Gnathodus bilineatus bi-

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Fig. 6. Distribution of ammonoids in the Verkhnyaya Kardailovka Section.

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lineatus (Roundy), Gn. girtyi girtyi Hass, Gn. girtyicollinsoni Rhodes, Austin and Druce and Lochrieacommutata (Branson and Mehl).

The Lochriea mononodosa Zone (Beds 21.5–21.10;thickness 1.5 m) is recognized based on the presenceof the index species.

The Lochriea nodosa Zone (Beds 21.11–21.12;thick ness 0.63 m) is recognized by the appearance ofLochriea costata (Pazukhin and Nemirovskaya),L. monocostata (Pazukhin and Nemirovskaya), andL. nodosa (Bischoff).

5.4 Ostracodes

Zainakaeva (2004) was the first to identify ostracodesfrom the Upper Viséan of the Verkhnyaya KardailovkaSection. Bed 21 and lower part of 22a contains Shiv-aella longa Tschigova, Shishaella porrecta (Zanina),Shish. cf. subsymmetrica Kotschetkova, Micro chei -linella aff. subcorbuloides (Jones and Kirkby), Bairdiarecta Buschmina, Acratia deloi Geis, and Bohlenatiabanffensis (Green) – which are all typical Viséanspecies. These beds also showed the first appearance of

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Fig. 7. Distribution of conodonts in the Verkhnyaya Kardailovka Section.

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Rectonaria accepta N. Kotchetova, Rectoplacera ex-plicata N. Kotchetova, Orthonaria spp., and Bairdio-cypris? ambigens N. Kotchetova, which are usuallywidespread in the Serpukhovian.

6. Fossil record of the Serpukhovian

6.1 Foraminifers

In the Serpukhovian part of the section we were ableto recognize three foraminiferal zones. The lower ofthem is a Uralian regional zone (Stratigraficheskie . . .1993) and two upper ones are zones of the Generalstratigraphic Carboniferous scale of Russia (Kulaginaand Gibshman, 2002). Foraminifers are very rare in the lowermost Serpukhovian of this section. The firstforms of stratigraphic relevance were encountered1.5 m above the base of the Serpukhovian.

(1) The lowermost Eolasiodiscus donbassicusZone is accepted for the eastern subregion of the SouthUrals (Beds 22a (without lowermost part) – 22b; totalthickness 16 m). Compared to the Upper Visean beds,the quantity of foraminifers decreased (see Fig. 3).Shells of Eolasiodiscus muradymicus Kulagina (Sam-ple 2668, Pl. 1, fig. 41), the species originally de-scribed from the section of Muradymovo in the ZilairSynclinorium, South Urals (Kulagina et al. 1992) arerecorded 1.5 m above the base of Bed 22a. Additional-ly, Sample 2722 also contains Monotaxinoides (?) sp.,and Planospirodiscus sp., and very small-sized repre-sentatives of Neoarchaediscus are recorded in the up-per part of Bed 22a and Bed 22b (Pl. 1, figs. 31, 33).(2) The Eolasiodiscus donbassicus Zone is overlainby the Eostaffellina paraprotvae Zone (Beds 22c – 25;total thickness 15.2 m). Its lower boundary is definedby the first appearance of Eostaffellina paraprotvae(Rauser-Chernousova), E. decurta (Rauser-Chernou -sova), E. actuosa Reitlinger, and Eostaffella mirificaBrazhnikova (Samples 2727, 2727a). This assemblageis followed by Eostaffella postproikensis Vdovenko4.8 m above (Sample 2731). Eostaffellina paraprotvaeallows correlation with the middle Steshevian andProtvian (both upper Serpukhovian) of the MoscowBasin (Gibshman 2003) and upper Serpukhovian ofthe Peri-Caspian (Gibshman et al. 2007). E. post-proikensis was also recorded from the type Khudola-zovian section on the eastern slope of the Urals (Strati-graphicheskie . . ., 1993). A specimen of Plectostaffel-la primitiva Rumjanzeva indicates the Upper Ser-

pukhovian age. In this zone Eostaffella ex gr. ikensisVissarionova, Omphalotis sp, Endothyranopsis ex gr.crassa (Brady), Eostaffella parastruvei Rauser-Chernousova and other species common in the UpperViséan are present, as in other regions of the Urals(Ivanova 1973). In Bed 25 foraminifers are rare and itis only provisionally referred to the Eostaffellina para-protvae Zone.(3) Monotaxinoides transitorius Zone (Bed 26; totalthickness 4.8 m). Foraminifers are found in the beds ofcrinoidal-bryozoan limestones (Samples 2741 and2745). The assemblage contained diverse species ofMonotaxinoides (see Fig. 5) and also Janischewskinasp., Eostaffella pseudoovoidea Reitlinger, E. mirificaBrazhnikova, Biseriella cf. minima (Reitlinger), whichare common in the Serpukhovian and are recordedfrom the Urals and Donets Basin (Aizenverg et al.1983 and others). The assemblage contained one spec-imen of Pseudoendothyra propinqua magna Fominaoriginally recorded from the Upper SerpukhovianPestovo Formation of the Moscow Basin (Fomina1977). Based on Monotaxinoides transitorius we cor-relate this interval with the Zapaltybinian of theDonets Basin and the upper part of the Arnsbergian Cf 7 Zone of the Dinant Basin (Belgium) (Laloux1987).

6.2 Ammonoids

In the Serpukhovian part of the Verkhnyaya Kar-dailovka Section, we were able to recognize three dis-tinct ammonoid assemblages.

The species composition of the ammonoid assem-blages of the Verkhnyaya Kardailovka Section is typi-cal of the South Urals, but is different from the assem-blages of Western Europe (Bisat 1924; 1928; 1930;1932; Dorlodot and Delépine 1930; Delépine 1943;Moore 1946; Currie 1954; Horn 1960; Kullmann1961; Yates 1962; Wagner-Gentis 1963; Ruzhencevand Bogoslovskaya 1971; Riley 1987; Korn 1988;1997; Korn and Horn 1997; Korn and Tisley 2002,Kullmann et al. 2008 and others), North Africa(Delépine and Menchikoff 1937; Delépine, 1941;Korn et al. 1999; 2006, and others) and North Ameri-ca (Miller and Furnish 1940; Miller and Youngquist1948; Miller et al. 1952; Gordon 1965; McCaleb et al.1964; Manger 1979; Saunders 1973; Saunders et al.1977; Rambottom and Saunders 1989; Meeks et al.1997; Meeks and Manger 1999; Saunders and Work1999; Titus 1999, 2000; Titus and Manger 2001, andothers), although the generic composition is similar.

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Hence the ammonoid-based interregional correlationis only provisional.

(1) The lower of the three assemblages belongs to the Uralopronorites – Cravenoceras Genozone(= Nm1b). The earliest occurrence of this assemblageis in Sample 012/3 about 1.2 m above the last occur-rence of the ammonoids of the Hypergoniatites –Ferganoceras Genozone (Sample 0.15). It is alsofound higher up in the section (upper part of Bed 21,Beds 22–24; total thickness 25.7 m; Samples 011, 010,09, 08, and 03), i. e. in the whole of the Kosogorskianand the lower part of the Khudolazovian (Fig. 6). Themost typical species of this assemblage is Dombaritestectus, which appears for the first time in Sample 011.This assemblage most likely belongs to the upper partof Uralopronorites – Cravenoceras Genozone (= Nm1

b2).The equivalents of this genozone also contain am-monoids, which are commonly found in the SouthUrals, especially in the Orenburg Region. The 2 m in-terval between Samples 015 and 012/3, where am-monoids are absent may correspond to the lower partof the Uralopronorites – Cravenoceras (= Nm1b1)Genozone. We cannot support the assumption ofRuzhencev and Bogoslovskaya (1971) that the wholeinterval above Trench 4 and below Sample 03 belongsto the lower horizons (Nm1B1) of the Uralo-pronorites – Cravenoceras Genozone. We thereforeprovisionally correlate this interval with of thePendleian Stage of Great Britain (Bisat 1924, 1928)and Lower Namurian of Germany (Horn 1960; Kornand Horn 1997). This correlation is largely based onindirect evidence because in Great Britain and Ger-many sequences contain no reliable occurrences of thegenus Dombarites; whereas the base of the Pendleianand Lower Namur ian is defined by the entry of thespecies of the genera Edmooroceras or Cravenoceras(both of these genera are uncommon in theVerkhnyaya Kardailovka section). Cravenocerasleionoides Ruzhencev and Bogoslovskaya is very sim-ilar to the species Cravenoceras leion – one of themarkers of the basal Pendleian (Bisat 1930 and others)is well established (Ruzhencev and Bogoslovskaya1971). The occurrence of Tumulites eurinus in Bed 24(Sample 03) can indirectly support this correlation.The presence of Tumulites is useful for correlation ofthe Namurian in Europe and in the USA (Arkansas)(Gordon 1965; Saunders et al. 1977). Until recentlyoccurrences of Tumulites eurinus in the South Uralswere only recorded from the younger beds (Fayet-tevillea – Delepinoceras Genozone = Nm1c), whereasin Western Europe the first Tumulites enter in the Tu-

mulites angustus Zone, approximately in the middlepart of the Pendleian (E1 Zone) (Moore, 1946; Horn,1960). Based on the presence of Tumulites eurinus inassociation with Cra veno ceras leionoides it is possibleto suggest that the interval from the top of Bed 21 to24 (Uralopronorites – Cravenoceras Genozone), cor-responds to the E1 of the European scale. In the ab-sence of obvious contradictions, and based on the pres-ence of Tumulites in Bed 24, it is possible to suggestthat the Nm1b2 Zone in this section approximately cor-relates with the basal part of the North AmericanT. varians Zone (Meeks et al. 1997). In the stratotypeSerpukhovian section (Zaborie), ammonoids of thisage (mainly of the genus Cravenoceras) are recordedfrom the Tarusian and Steshevian.

(2) The next assemblage upward in the section isthat of the Fayettevillea – Delepinoceras Genozone(= Nm1c1).This assemblage is found at two levels inBed 25 (total thickness is 6 m; Samples 2736 and2738) and corresponds to the Upper Khudolazovian.The earliest ammonoids of this assemblage (Sample2736) are found approximately 1–1.5 m above am-monoids of the Uralopronorites – CravenocerasGeno zone. The assemblage contains Uralopronoritesmirus Librovitch, Eumorphoceras transuralenseRuzhencev and Bogoslovskaya, Proshumardites urali-cus (Librovitch), and Fayettevillea sp. This assem-blage indicates the lower part of the Fayettevillea –Delepinoceras Genozone (= Nm1c1). We provisional-ly correlate the basal beds of the Fayettevillea –Delepinoceras Genozone (= Nm1c1) with the lowerpart of the E2 (basal Arnsbergian) Zone in Western Europe, based on the entry of Eumorphoceras trans -uralense, which is not found in Western Europe, but isvery similar in the shell shape and ornamentation tothe Eumorphoceras species from the E2 Zone in Eu-rope and North America (from?E. cf. transuralenseand E. paucinodum – E. rotuliforme zones in NorthAmerica (Titus 1999) and to Eumorphoceras beta Ri-ley from the E2 Zone in Great Britain (Riley 1987));(3) Levels above this assemblage contain a totally dif-ferent ammonoid fauna which belongs to the upperpart of the Fayettevillea – Delepinoceras Genozone(= Nm1c2).This assemblage comes from Bed 26 (totalthickness 4.8 m) (Sample 2741), ca. 2–2.5 m above theupper occurrence of Assemblage 4 (Fig. 6) and belongsto the Chernyshevian (Yuldybaevian). In Western Eu-rope this assemblage approximately correlates withthe assemblages of the upper part of the E2 Zone of theBritish Isles (Bisat 1924, 1928; Hudson 1945; Currie1954; Rambottom 1969; Ramsbottom and Saunders

177Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

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179Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

Plate 1. Foraminifers from the Verkhnyaya Kardailovka SectionSpecimens 2, 4–6, 8, 9, 26, 28 come from the Upper Viséan, and the remainder from the Serpukhovian (numbers of thinsections are in brackets).1. Endothyra bowmani Phillips, 1846, � 60; specimen no. 121/792, Sample 2741(4), Bed 26; Chernyshevian (Yuldybaevi-an). 2. Omphalotis sp., � 100; specimen no. 121/1122, Sample 015/2(3), Bed 21; Upper Viséan. 3. Endothyra ex gr. similisRauser-Chernousova et Reitlinger, 1936, � 80; specimen no. 121/791, Sample 2745b (1) (level of Sample 2745), Bed 26;Chernyshevian (Yuldybaevian). 4–6. Endostaffella asymmetrica Rosovskaya, 1963, � 100; 4 – specimen no. 121/1103,Sample 014/1(1), Venevian; 5 – specimen no. 121/1104, Sample 015/2(1), Upper Viséan; 6 – specimen no. 121/1105, Sam-ple 014/1(1), all from Bed 21,Venevian. 7. Endostaffella parva (Moeller, 1880), � 100; specimen no. 121/762, Sample2731(1), Bed 24; Khudolazovian. 8. Planoendothyra sp., � 80; specimen no. 121/1106, Sample 015/2(5), Bed 21; Upper Vi-séan. 9, 10. Endostaffella delicata Rosovskaya, 1963, � 100; 9 – specimen no. 121/1107, Sample 014/1(1), Bed 21, Vene-vian; 10 – specimen no. 121/6, Sample 2741(13), Bed 26, Chernyshevian (Yuldybaevian). 11. Priscella sp. � 100; specimenno. 121/1108, Sample 015/2(2), Bed 21; Upper Viséan. 12. Eostaffellina decurta (Rauser-Chernousova, 1948), � 80; speci-men no. 121/764, Sample 2727a (7) (level of Sample 2727), Bed 22c; Khudolazovian. 13, 14. Eostaffellina paraprotvae(Rauser-Chernousova, 1948), 80; 13 – specimen no. 121/766, Sample 2734(5), Bed 24, 14 – specimen no. 121/765, Sample2727a(3), both – Bed 22c; Khudolazovian. 15, 20. Eostaffellina actuosa Reitlinger, 1963, � 80; 15 – specimen no. 121/775,Sample 2727a(3), Bed 22c; 20 – specimen no. 121/1120; sample 2729(8), Bed 23; Khudolazovian. 16. Eostaffellina actuo-sa subsymmetrica Reitlinger, 1977, � 80; specimen no. 121/799, Sample 2745(24), Bed 26; Chernyshevian (Yuldybaevian).17. Eostaffellina sp. � 80; specimen no. 121/1109, Sample 2745(7); age as above. 18. Eostaffella pseudoovoidea Reitlinger,1980; � 80; specimen no. 121/767, Sample 2730(1), Bed 24; Khudolazovian. 19. Paraarchaediscus koktjubensis (Rauser-Chernousova, 1948), � 80; specimen no. 121/787, Sample 2731(3), Bed 24; Khudolazovian. 21. Eostaffella mirificaBrazhnikova, 1967, specimen no. 121/801, Sample 2741(19), Bed 26; Chernyshevian (Yuldybaevian). 22. Plectostaffellaprimitiva (Rumjanzeva in Kulagina et al. 1992), � 80; specimen no. 121/774, Sample 2727a(2) Bed 22c; Khudolazovian.23. Janischewskina cf. delicata (Malakhova, 1956), � 40; specimen no. 121/798, Sample 2741(8), Bed 26; Chernyshevian(Yuldybaevian). 24. Rectocornuspira buskensis (Brazhnikova, 1956), � 80; specimen no. 121/1110; sample 2741(20), ageas above. 25. Endotaxis brazhnikovae (Bogush et Juferev, 1966), � 80; specimen no. 121/46, Sample 2745b(1), the same asabove. 26. Archaediscus sp., � 100; specimen no. 121/1111, Sample 015(1), Bed 21; Upper Viséan. 27. Planoarchaediscussp., � 100; specimen no. 121/1112, Sample 012 (1), Kosogorskian. 28. Asteroarchaediscus parvus (Rauser-Chernousova,1948), � 100; specimen no. 121/1115, Sample 015(4), Bed 21, Upper Viséan. 29. Asteroarchaediscus rugosus (Rauser-Cher-nousova, 1948), � 100; specimen no. 121/1116, Sample 2727(5), Bed 22c; Khudolazovian. 30. Paraarchaediscus stilus(Groz dilova and Lebedeva, 1953), � 100; specimen no. 121/11, Sample 2741(10), Bed 26, Chernyshevian (Yuldybaevian).31, 32. Neoarchaediscus postrugosus (Reitlinger, 1949), � 100; 31 – specimen no. 121/1117, Sample 09(10), Bed 22b; Ko-sogorskian; 32 – specimen no. 121/785, Sample 2727a (4), Bed 22c; Khudolazovian. 33, 34. Neoarchaediscus sp., � 100;33 – specimen no. 121/1038, Sample 08(10), Bed 22b; Kosogorskian; 34 – specimen no. 121/784, Sample 2731(1), Bed 24;Khudolazovian. 35. Neoarchaediscus incertus (Grozdilova and Lebedeva, 1954), � 100; specimen no. 121/788, Sample2731(1), Sample 2731(1), Bed 24; Khudolazovian. 36, 37. Planospirodiscus spp., � 100; 36 – specimen no. 121/1113, Sam-ple 2723(1); 37 – specimen no. 121/1114, Sample 010(1), Bed 22a; Kosogorskian. 38. Rugosoarchaediscus sp., � 100; spe-cimen no. 121/10; sample 2741(18), Bed 26; Chernyshevian (Yuldybaevian). 39, 40, 44. Monotaxinoides transitorius Brazh -nikova and Jarzeva, 1956, � 100; 39 – specimen 121/744, Sample 2745b(1); 40 – specimen 121/1001, Sample 2741(7), 44 –specimen 121/1121, Sample 2745(11), all from Bed 26, Chernyshevian (Yuldybaevian). 41. Eolasiodiscus muradymicus Ku-lagina, 1992, � 100; specimen no. 121/1119, Sample 2668(4), 22a; Kosogorskian. 42. Monotaxinoides sp., � 100; specimenno. 121/777, Sample 2734(7), Bed 24; Khudolazovian. 43. Howchinia bradyana (How chin, 1888), � 80; specimenno. 121/15, Sample 2741(4), Bed 26; Chernyshevian (Yuldybaevian). 45, 46. Monotaxinoides cf. subplanus Brazhnikovaand Jarzeva, 1956, � 100; 45 – specimen no. 121/1102, Sample 2745(18); 46 – specimen no. 121/17, Sample 2745 (14); ageas above. 47. Monotaxinoides gracilis Dain in Reitlinger, 1956, � 100; specimen no. 121/18, Sample 2741(18); age as abo-ve. 48. Monotaxinoides subplanus Brazhnikova and Jarzeva, 1956, � 100; specimen no. 121/48, Sample 2741(13); age asab ove.

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1985; Riley 1987), in the USA it correlates to the Eu-morphoceras girtyi, Cravenoceratoides nititoides, andDelepinoceras thallasoide Zones (Gordon 1965;Miller and Youngquist 1948; Elias 1956; Titus 2000).

6.3 Conodonts

Several conodont zones were recognized within theSerpukhovian part of the section (Fig. 7).

(1) The Lochriea ziegleri Zone comprises theKosogorskian and lower Khudolazovian (Bed 22a.1 tolower part of Bed 24; total thickness 23.5 m). The low-er boundary was identified based on the first appear-ance of Lochriea ziegleri. The assemblage containsfirst Gnathodus girtyi simplex Dunn and G. aff. pseu-dosemiglaber Thompson and Fellows and many otherconodont taxa (see Fig. 7). Lochriea ziegleri is thespecies completing the evolutionary lineage L. com-mutata – L. mononodosa – L. nodosa – L. ziegleri (Nemirovskaya et al. 1994). The species L. ziegleri iswidely distributed in Eurasia. Its first appearance isrecorded in the basal Namurian and Serpukhovian inthe sections of the Donets Basin and French Pyrenees(Nemirovskaya et al. 1994; Nemyrovska with an ap-pendix by Samankassou 2006). In Germany thisspecies enters within the Emstites schaelkensis am-monoid zone (Skompski et al. 1995, fig. 3). L. zieglerishows high consistency in appearance in many sec-tions in the basal layers of the Serpukhovian and istherefore presently considered as the best candidate forthe definition of the Viséan-Serpukhovian boundary(Richards 2006, 2007).

(2) The Gnathodus bilineatus bollandensis Zone isrecognized in the upper Khudolazovian and Cherny-shevian (= Yuldybaevian) (Bed 24–26; thicknessca. 14 m). The base of the zone is drawn by the first ap-pearance of the index species. Gnathodus bilineatusbilineatus (Roundy) and a number of other speciescontinue from the underlying beds (Fig. 7). A fewspecimens of conodonts transitional from Gn. girtyisimplex to D. noduliferus have been found in this zone.

6.4 Ostracodes

The Serpukhovian beds contain a few distinct associ-ations of ostracodes (Nikolaeva et al. 2001; Pazukhinet al. 2002).

Beds with Cribroconcha magna (Beds 22a–c, 23,24) corresponding to the Kosogorskian and lowerKhudolazovian contain numerous ostracodes (Figs. 8,9).

The overlying beds with Pseudoparaparchites cel-sus correspond to the Upper Khudolazovian (Bed 25)and typically contain Pseudoparaparchites celsusN. Kotchetova in association with relatively frequentCarbonita? subquadrata N. Kotchetova.

These beds are overlain by those with Aurigeritessolitarius (Chernyshevian = Yuldybaevian) (Bed 26),containing many species continuing from the under -lying rocks, but also a few Shivaella evidens Kot -schetkova, Microcoeloenella orbiculata Kotschet -kova, Dorsoobliquella ovalis Kotschetkova, Bairdiachudolasensis Kotschetkova, Basslerella subcrassaKotschetkova, and Polycope? rugosa Kotschetkova,

181Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

Plate 2. Ammonoids from the Verkhnyaya Kardailovka SectionAll sizes (except mentioned particularly) are natural1, 2. Goniatites sphaeroides Bogoslovskaya, 1966: 1 – specimen no. 4920/1; 2 – specimen no. 4920/2; Bed 21, Sample2711/4; Beyrichoceras – Goniatites Genozone. 3. Goniatites crenifalcatus Bogoslovskaya, 1966; specimen no. 4920/3;Bed 21, Sample 2711/2; Beyrichoceras – Goniatites Genozone. 4. Cravenoceras leionoides Ruzhencev and Bogoslovskaya,1971; specimen no. 4920/4 (� 2); Bed 24, Sample 03; Serpukhovian, Uralopronorites – Cravenoceras Genozone. 5. Dom-barites tectus Librovitch, 1957; specimen no. 4920/5 (� 2.5); Bed 24, Sample 03; Serpukhovian, Uralopronorites – Crave-noceras Genozone. 6. Tumulites eurinus Ruzhencev and Bogoslovskaya, 1971; specimen no. 4920/6 (� 2); Bed 24, Sample03; Serpukhovian, Uralopronorites – Cravenoceras Genozone. 7. Pericleites uralicus (Librovitch, 1941); specimenno. 455/28054; Bed 25, level of Sample 2738; Serpukhovian, Fayettevillea – Delepinoceras Genozone (coll. by Ruzhencevand Bogoslovskaya). 8. Eumorphoceras transuralense Ruzhencev and Bogoslovskaya, 1971; holotype no. 455/6720 (� 2);Bed 25, level of Sample 2738; Serpukhovian, Fayettevillea – Delepinoceras Genozone (coll. by Ruzhencev and Bogos-lovskaya). 9. Eumorphoceras paucinodum Gordon, 1964; specimen no. 455/6721 (� 2); Bed 26, level of Sample 2742; Ser-pukhovian, Fayettevillea – Delepinoceras Genozone (coll. by Ruzhencev and Bogoslovskaya). 9. Delepinoceras bressoniRuzhencev, 1958; specimen no. 4920/7 (� 2.5); Bed 26, Sample 2742; Serpukhovian, Fayettevillea – Delepinoceras Geno-zone. 10. Proshumardites delepinei Schindewolf, 1939; specimen no. 4920/8 (� 2); Bed 26, Sample 2742; Serpukhovian,Fayettevillea – Delepinoceras Genozone. 11. Fayettevillea orientalis Ruzhencev and Bogoslovskaya, 1971; holotypeno. 455/33842 (� 2); Bed 26, level of Sample 2742; Serpukhovian, Fayettevillea – Delepinoceras Genozone (coll. by Ruz-hencev and Bogoslovskaya).

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which were first described by Kotschetkova (1983)from the Lower Bashkirian of the South Urals, and arealso found in the equivalent beds of the Middle Tien-Shan (Kulagina et al. 1992).).

The following species are found across the entiresection as isolated or incomplete shells: Bairdia rectaBuschmina, Bairdia adiposa Zanina, Microcheilinellaextuberata Samoilova and Smirnova, Scrobicula scro-biculata (Jones, Kirkby and Brady), and also Chami -shaella exiqua (Cooper), Basslerella firma (Kellett),Polycope perminuta (Kellett), Roundyella simplicis -sima (Knight), and Macrocypris lenticularis Cooper.Ectodemites planus Cooper and E. cf. tumidus Coop-er, originally from the Chesterian of the USA, are forthe first time recorded in the South Urals.

7. Biostratigraphy of the Viséan-Serpukhovian boundary beds

In recent years there have been many discussions ini-tiated by the International Working Group on theViséan-Serpukhovian Boundary (Richards 2006,2007). Many workers agree that the best correlativepotential lies with the evolutionary appearance of theconodont species Lochriea ziegleri in the lineageLochriea nodosa – L. ziegleri (Skompski et al. 1995;Richards 2006). The holotype of this species comesfrom the French Pyrenees, and its first appearance in

Western Europe is known beginning from the terminalBrigantian (Nemirovskaya et al. 1994), which is some-what lower than the Viséan-Serpukhovian boundarydefined by the entry of Cravenoceras leion (Skomps-ki et al., 1995). The species Lochriea ziegleri is wide-spread in Eurasia (Western Europe, Russian Platform,Urals, and South China). The use of Lochriea zieglerias a global marker is convenient because it enters nearthe level of the first appearance of the ammonoidgenus Cravenoceras and the species Edmooroceraspsedudocoronula, which are commonly used formarking the Viséan-Namurian boundary in WesternEurope (Bisat 1950; Horn 1960; Korn and Horn 1997).Of two conodont species competing for the role of theV-S global marker (L. cruciformis (Clarke) and L. zieg-leri Nemirovskaya, Perret and Meischner), L. ziegleriis a preferred candidate because it occurs everywhereand is represented by larger number of specimens (Nemyrovska with an appendix by Samankassou2006)

In the Verkhnyaya Kardailovka Section the FAD ofLochriea ziegleri falls in the interval between the oc-currence of the ammonoids Goniatites sphaeroides aswell as G. crenifalcatus and the first occurrence ofDombarites tectus, slightly above the occurrence ofNeogoniatites milleri, and is near the base of theE. donbassicus foraminiferal zone. The Viséan-Ser-pukhovian boundary as defined by the FAD of L. zieg-leri is recognized in many sections worldwide, being

183Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

Plate 3. Conodonts from the Verkhnyaya Kardailovka SectionIn all cases the magnification is � 51. Lochriea mononodosa (Rhodes, Austin and Druce, 1969), specimen no. 104/681, Bed 21.5, Sample 015/4; Upper Viséan.2. Lochriea monocostata (Pazukhin and Nemirovskaya, 1992), specimen no. 104/682, Bed 22a, Sample 2722/1; Serpukho-vian, Kosogorskian. 3, 5. Lochriea costata (Pazukhin and Nemirovskaya, 1992), 3 – specimen no. 104/683, Bed 21.11, Sam-ple 014/1; Upper Viséan, Venevian; 5 – specimen no. 104/684, Bed 22a, Sample 2722/1; Serpukhovian, Kosogorskian. 4.Lochriea nodosa (Bischoff, 1957), specimen no. 104/685, Bed 21.12, Sample 014/1; Upper Viséan, Venevian. 6, 8. Loch-riea ziegleri Nemirovskaya, Perret and Meischner, 1994: 6 – specimen no. 104/686, Bed 23, Sample 2715, Serpukhovian,Khudolazovian; 8 – specimen no. 104/700, Bed 22a, Sample 012/1; Serpukhovian, Kosogorskian. 7. Gnathodus bilineatusbollandensis Higgins and Bouckaert, 1968, specimen no. 104/687, Bed 26, Sample 2741; Serpukhovian, Chernyshevian(Yuldybaevian). 9. Gnathodus austini Belka, 1985, specimen no. 104/689, Bed 19.1, Sample Pit 2; Upper Viséan. 10. Pseu-dognathodus homopunctatus (Ziegler, 1962), specimen no. 104/690; Bed 21.2, Sample 2711/2; Upper Viséan. 11. Gnatho-dus texanus Roundy, 1926, specimen no. 104/691, Bed 18, Sample 2704; Upper Viséan, Tulian. 12. Declinognathodus inae-qualis (Higgins, 1975), specimen no. 104/692, Bed 27, Sample 2747; Lower Bashkirian, Syuranian (lower part). 13. Mesto-gnathus bipluti Higgins, 1961, specimen no. 104/693, Bed 21.1, Sample 2711/1; Upper Viséan. 14. Gnathodus girtyi soniaeRhodes, Austin and Druce, specimen no. 104/694, Bed 21.2, Sample 2711/2; Upper Viséan. 15. Gnathodus girtyi simplexDunn, 1965, specimen no. 104/695, Bed 24, Sample 2733; Serpukhovian, Khudolazovian. 16. Gnathodus girtyi simplexDunn, 1965 – Declinognathodus noduliferus (Ellison and Graves, 1941), specimen no. 104/696, Bed 24, Sample 2734; Ser-pukhovian, Khudolazovian. 17, 18. Gnathodus aff. pseudosemiglaber Thompson and Fellows, 1970; 17 – specimenno. 104/697, Bed 22b, Sample 07; Serpukhovian, Kosogorskian; 18 – specimen no. 104/698, Bed 22a, Sample 010; the ageas above. 19. Gnathodus bilineatus bilineatus (Roundy, 1926), specimen no. 104/699, Bed 21.2, Sample 2711/2; Upper Vi-séan.

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Fig. 8. Distribution of ostracodes in the Verkhnyaya Kardailovka Section.

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near the levels of the first appearances of the am-monoids Cravenoceras leion and Edmooroceraspseudocoronula (Bisat, 1950) at the base of the Na-murian of England, Poland, and close to the base of theSerpukhovian of Russia and Ukraine (Skompski et al.1995; Nikolaeva and Kullmann, 2001, 2003, and oth-ers). The same level can be found in the type Ser-pukhovian section in Zaborie, where near the levelwith L. ziegleri, Gibshman (2001; 2003) recorded theforaminifers “Millerella” tortula in association withNeoarchaediscus postrugosus. Based on the latterspecies she correlated the base of the Tarusian in Zaborie with the base of the Middle Chesterian GlenDean Limestone of Kentucky (Zeller, 1953; Gibshman2001; 2003).

8. Correlation

The Upper Viséan and Serpukhovian in the Verkh -nyaya Kardailovka Section contain richs faunas offoraminifers, ostracodes, ammonoids, and conodonts.Because of the rich faunal content and continuity ofthe sequence, the correlation of zones based on differ-ent groups can be reliably established.

The uppermost Viséan Venevian Regional Stage inVerkhnyaya Kardailovka is dated by the conodontsLochriea mononodosa and L. nodosa. In contrast to thesections in the Moscow Basin (Skompski et al. 1995),the Verkhnyaya Kardailovka Section, in addition,yields ammonoids of the Hypergoniatites – Fer ga -noceras Genozone. Based on the presence of Neogo-niatites this level approximately correlates with theupper Brigantian in Western Europe and Morocco (forrecords see Korn et al. 1999, 2006; Korn and Feist2007) and provisionally with the S. ornatissimum Zoneof Texas (Titus 1999).

The lowermost Serpukhovian (Eolasiodiscus don-bassicus foraminiferal Zone) correlates with the lowerpart of the Uralopronorites-Cravenoceras ammonoidGenozone, the lower part of the Lochriea ziegleri con-odont Zone, and the lower part of the beds with the os-tracodes Cribroconcha magna. This combination ofzones suggests a correlation with the lower Tarusian inthe Moscow Basin, largely based on the presence ofthe conodonts Lochriea ziegleri and foraminifersNeoarchaediscus (for the records from the MoscowBasin see Skompski et. al. 1995; Gibshman 2001,

2003; Nikolaeva et al. 2002) and basal and middlePendleian of Western Europe, based on the first ap-pearances of the conodonts Lochriea ziegleri (seeSkompski et al. 1995; Nemirovskaya et al. 1994; Ne-myrovska with an appendix by Samankassou 2006;)and the ammonoid genus Cravenoceras (see Bisat1930, 1950; Moore 1936; Calver and Ramsbottom1961; Skompski et al. 1995; Korn and Tisley 2002 andothers).

The next Serpukhovian foraminiferal Eostaffellinaparaprotvae Zone corresponds to the upper part of theammonoid Uralopronorites – Cravenoceras (= Nm1

b2) and lower part of the Fayettevillea-DelepinocerasGenozones (= Nm1c1), upper part of the beds with theostracodes Cribroconcha magna and lower part of thebeds with the ostracodes Pseudoparaparchites celsus,upper part of the conodont Lochriea ziegleri Zone, andlower part of the Gnathodus bilineatus bollandensisZone. This combination of zones suggests the correla-tion with the Steshevian Horizon in the MoscowBasin, largely based on the conodont Gnathodus bilin-eatus bollandensis and the foraminifer Eostaffellinaparaprotvae (Barskov et al. 1984; Kulagina et al.1992; Makhlina et al. 1993; Kulagina and Gibshman2002; Gibshman 2003 and others), upper Pendleian-lower Arnsbergian of Western Europe, based on theconodont Gnathodus bilineatus bollandensis (Skomp-ski et al. 1995; Nemyrovska 1999; Nikolaeva et al.2002, 2005; Nemyrovska with an appendix bySamankassou 2006 and others) and indirectly by theammonoid genus Tumulites (Moore 1946; Horn 1960and others).

The upper most Serpukhovian Monotaxinoidestransitorius foraminiferal Zone corresponds to theupper part of the Fayettevillea – Delepinoceras am-monoid Genozone (Nm1c2), beds with the ostracodesAurigerites solitarius, and the upper part of theGnathodus bilineatus bollandensis conodont Zone.Synchronous beds are not exposed in the stratotypeSerpukhovian Section in Zaborie, and are provision-ally correlated with the Pestovo Formation of otherSerpukhovian sections in the Moscow Basin (Bars -kov et al. 1984; Makhlina et al. 1993; Kulagina andGibshman 2002; Gibshman 2003 and others). InWestern Europe, this level approximately correlatedwith the upper Arnsbergian (Riley 1987; Skompski etal. 1995; Nemyrovska 1999; Kullmann et al. 2008and others).

185Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

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186 S.V. Nikolaeva et al.

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187Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section

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9. Conclusions1. The Verkhnyaya Kardailovka Section contains anumber of levels with high potential for correlation.Some of these levels can now be used for importantcorrelation, such as the Visean-Serpukhovian bound-ary. Others allow correlations within the region of theSouth Urals, with the type Serpukhovian area in theMoscow Basin and occasionally direct correlationswith Western Europe.

2. The base of the Serpukhovian in the VerkhnyayaKardailovka section is defined by the FAD of the con-odont Lochriea ziegleri, which appears to be so far the best marker for this boundary in many sections in Europe and Asia. This level coincides with the base ofthe Kosogorskian in regional stratigraphic schemes ofthe Urals. It also correlates with the entry of Neo -archaediscus postrugosus in Zaborie.3. The uppermost Venevian horizon (Upper Viséan) inVerkhnyaya Kardailovka is dated by the conodontsLochriea nodosa and L. mononodosa and by the am-monoids of the Hypergoniatites-Ferganoceras Geno-zone found in the same samples.4. In the Verkhnyaya Kardailovka Sections, the con-odont Lochriea ziegleri enters approximately 90 cmabove the last occurrence of the ammonoids of the Hy-pergoniatites-Ferganoceras Genozone (Neogoniatitesmilleri), and 35 cm below the first occurrence of am-monoids of the Uralopronorites-Cravenoceras Geno-zone (Dombarites tectus, Dombarites paratectus andothers).5. The appearance of the assemblage Eostaffellinaparaprotvae foraminiferal zone coincides with thebase of the Khudolazovian.6. The upper part of the Fayettevillea-DelepinocerasGenozone (E2) corresponds to the Monotaxinoidestransitorius foraminiferal Zone and with the Yuldy-baevian.

Acknowledgements. We are grateful to N. B. Gibshman(State University of Oil and Gas) for valuable consultationsin analyzing the carbonate microfacies and for discussionsof the Serpukhovian correlations. A. S. Alekseev providedvaluable advice. The study was supported by the RussianFoundation for Basic Research, grant no. 04–05–65022 andthe Program by the Presidium of Russian Academy of Sci-ence “Coevolution of Biotic and Abiotic Events in the Bio -sphere”.

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Appendix

Lithology (from bottom to top)The beds are consecutive numbered from 19 to 27(from Upper Viséan to Bashkirian). If a bed is onlyopen in a pit or trench, it is mentioned in the descrip-tion below.

Bed 19.1. Exposed in Pit 2 and Trench 2. Thickness0.3 m. Calcareous sandstone, at the base dark-gray,strongly siliceous, compact, with infrequent crinoids.Pazukhin and Gorozhanina (2002) showed that thissandstone (Sample Pit 2) contains up to 40%, of vol-canoclastic material (crystals of plagioclase, basalt anddacite clastics, and plates of stilpnomelane. The insol-uble residue contained bryozoans, bivalves, am-monoids, ostracodes, fish teeth, and conodonts. UpperViséan (Tulian).

3 m of unexposed interval.Bed 19.2. Exposed in Pit 3. Thickness 0.3 m. Pla-

gioclase tuffaceous light brownish-gray, medium-grained, medium-sorted sandstone, with calcite ce-ment. Upper Viséan (Tulian).

1.5 m of unexposed interval.Bed 19.3. Exposed in Trench 1. Thickness 1.5 m.

Fine-grained calcareous sandstone with numerouscrinoids (Sample 2706). Upper Viséan (Tulian).

Bed 19.4. Exposed in Trench 1 and Pit 4. Thickness0.5 m. Dark-gray, fine- and small-grained calcareous,medium-sorted sandstone with glauconite and vol-canic-terrigeneous admixture (semi-rounded grains ofquartz, plagioclase, basalt and basaltic sludge, withcarbonate-clayey cement of basal type (Sample 2707).Pit 4 opens calcareous siltstone with crinoids, spongespicules and volcanic fragments (plagioclase, basalts)in clayey-carbonate cryptograined matrix, with chal-cedone filled fissures. Upper Viséan (Aleksinian andMikhailovian).

Bed 20a. Trench 1 and Pit 5. Thickness 3.7 m.Dark-gray, thinly laminated, mudstone with radiolari-ans (Samples 2708, 2709, Pit 5). Upper Viséan (Alek-s inian and Mikhailovian).

Bed 20b. Thickness 0.72 m. The bed is exposed ina small crest and examined both in this crest and in atrench (Trench 2 at azimuth 230°). Dark-gray, medi-um-bedded, weakly clayey mudstone (Samples 2710,2710/2; 2710/1, 2711/5, and 2711/6). Age – UpperViséan. Aleksinian and Mikhailovian Regional Stages.

Beds 21.1–21.4. Thickness 0.8 m.m. Gray mud-stone with fragments of spicules and re-crystallized radiolarians, occasionally with fragments of crinoids(Samples 2711/1–2711/4, and 2711). At the level of

Sample 21.3 with tetracorals. Upper Viséan. UpperViséan (Aleksinian and Mikhailovian).

A distinctive limestone marking layer (2711) at thetop of Bed 21.4 is tracked down the slope in Trench 3,and from this level the section is described based onTrench 3. Azimuth of the trench is 235, its length is8.4 m.

Bed 21. 5. Thickness 0.5 m. Gray, medium-bedded,fine-grained microbioclastic wackestone-packstonewith infrequent tetracorals, crinoids, juvenile am-monoid shells, fragments of trilobite carapaces, ostra-codes, and fish teeth (Samples 15/6, 15/5, 15/4). Up-per Viséan (Aleksinian and Mikhailovian).

Bed 21. 6. Thickness 0.25 m. Light-gray, microbio-clastic wackestone-packstone with nodule-like cleav-age, cemented by loose calcareous-clayey material, inthin sections occasionally with juvenile ammonoidshells, crinoids and ostracodes Sample 15/3). UpperViséan (Aleksinian and Mikhailovian).

Bed 21. 7. Thickness 0.2 m. Light-gray microbio-clastic packstone, with occasional crinoid fragments,tetracorals, in thin sections – tiny foraminiferal tests,spheres, and sponge spicules (Sample 015/2). UpperViséan (Aleksinian and Mikhailovian).

Beds 21.8–21.12 are open in Trenches 3 and 4.Bed 21. 8. Thickness 0.4 m. Gray, medium-bedded

microbioclastic wackestone with little admixture ofcrinoidal debris, in thin sections – thin-shelled ostra-codes, juvenile ammonoid shells, and calcispheres(Samples 15/1). Age – Upper Viséan. Aleksinian andMikhailovian Regional Stages.

Beds 21.9 and 21.10. Thickness 0.45 m. Light-graymicrobioclastic packstone-wackestone, with infre-quent gastropods, ammonoids, ostracodes, crinoids,fish teeth, and conodonts (Samples 13/8, 015, 014/2,013/7, and 013/6). Insoluble residue contained glau-conite and limonite. Upper Viséan. (Aleksinian andMikhailovian).

Beds 21.11 and 21.12. Thickness 0.6 m. Light-gray, medium-bedded, wackestone-mudstone, inpla ces becoming packstone, with crinoidal debris, inthin sections – fragments of sponge spicules,spheres, tiny foraminifers, thin-shelled ostracodes,juvenile ammonoid shells, and fragments of trilobitecarapaces (Samples 013/1–13/5, 014, 014/1). Sam-ple 13/3 contained a few tetracorals. Upper Viséan(Venevian).

The following beds are described from Trench 4,immediately below the lowermost visible rock on theslope. The succession examined in the trench is con-tinued in the rock exposure above.

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Bed 22a. 1. Thickness 0.32 m. Light-gray, microbio-clastic wackestone, in thin sections – with spheres, ra-diolarians, juvenile ammonoid shells, and occasional-ly large crinoidal ossicles (Samples 013, 012/4). Insol-uble residue contained fish teeth and limonite pseudo-morphs after pyrite. Serpukhovian (Kosogorskian).

Bed 22a.2–22a.4. Thickness 0.54 m. Light-gray,wackestone/mudstone with nodule-like cleavage, in-frequent crinoids, ammonoids and conodonts (Sam-ples 012/1–012/3, 012). Insoluble residue containedfish teeth, limonite pseudomorphs after pyrite and oc-casionally rounded quartz grains. Serpukhovian(Kosogorskian).

Bed 22a.5. Thickness 0.2 m. Light-gray, micriticmudstone/wackestone, with nodule-like cleavage.Contained infrequent crinoidal and trilobite debris(Sample 011/1). Insoluble residue contained a lowquantity of rounded quartz grains and limonite. Ser-pukhovian (Kosogorskian).

Bed 22a.6. Thickness 11.5 m. Light-gray medium-bedded micro-grained wackestone and packstone, inplaces with diverse faunal remains, occasionally with ac-cumulations of crinoidal debris. Fossil remains: am-monoids, ostracodes, conodonts, and infrequent fora -minifers (Samples 011, 2668, 2722, 2722/1, 010; 2723,2724, 2726, 2726a, 2725). Sample 010; 2722/1 takenfrom the basal part of the bed contained tetracorals, gas-tropods, algae, fish teeth. Insoluble residue contained in-frequent grains of glauconite and chalcedone micronod-ules. Age – Serpukhovian. Kosogorskian Regional Stage.

Bed 22b. Thickness 5 m. Gray, medium-bedded, fine-grained packstone and wackestone, with ammon oids, os-tracodes, crinoids, infrequent foraminifers and algae(Samples 09, 08, 07). Serpukhovian (Kosogorskian).

Bed 22c. Thickness 2 m. Light-gray, medium-bed-ded, micritic limestone, at the base with a bed of bio-clastic grainstone with numerous foraminifers, algae,brachiopods, bryozoans, corals, crinoids, conodonts(Samples 2727, 2727a, and 2728). Serpukhovian(Khudolazovian).

Bed 23. Thickness 2.2 m. Gray and light-gray,medium-bedded, medium- and coarse-grained bioclas-

tic packstone/grainstone, with lenses of light-graychert. In places carbonates are silicified. Fossils: re-mains of the algae Konickopora, foraminifers, bry-ozoans, crinoids, echinoid spines, and conodonts(Samples 2729, 2713–2715). Serpukhovian (Khudola-zovian).

Bed 24. Thickness 5 m. Light-gray and grayunbedded, boundstone and wackestone with numerousammonoids, crinoids, bryozoans, ostracodes, and con-odonts, horizontally replaced by bedded limestonewith bryozoan-pelmatozoan grainstone in the basalpart. Upward in the section packstone prevails (Sam-ples 2730–2734, 2734a, 03, 07). Serpukhovian (Khu-dolazovian).

Bed 25. Thickness 6 m. Gray, medium-bedded,platy limestone. The basal part of the bed is composedof grainstone (Sample 2735), overlain by packstoneand wackestone with numerous radiolarians, am-monoids, ostracodes, and conodonts (Samples 2736–2740). Serpukhovian (Khudolazovian).

Bed 26. Thickness 4.8 m. Light-gray, medium-bed-ded, micritic limestone, with numerous ammonoids,occasional interbeds of bryozoan-pelmatozoan pack-stone/grainstone and grainstone (0.05–0.2 ) with algae Calcifolium okense Schwvetzov et Birina, Fas -ciella kizilia Ivanova, Praedonezella cespeformis Ku-lik, Dvinella sp. and foraminifers. Micritic varietiescontain many ammonoids, ostracodes, and conodonts.Insoluble residue contained infrequent semi-roundedquartz grains (Samples 2741–2746). Serpukhovian(Chernyshevian (Yuldybaevian)).

Bashkirian (Syuranian Substage, Bogdan ov skianHorizon)Bed 27. Thickness 0.2 m. Light-gray small-grainedresidual packstone, contains conodonts, infrequent al-gae, and foraminifers (Sample 2747). Bashkirian. Syu-ranian Substage (Bogdanovskian Horizon).

Manuscript received: August 13, 2008, rev. version receiv -ed: November 10, 2008, accepted for print: November 11,2008.

193Paleontology and Microfacies of the Serpukhovian in the Verkhnyaya Kardailovka Section