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Stepanova, Kucheva, 2006;
Kulagina et al., 2001, 2002;
The outcrops of the Kizil Formation along the Khudolaz River constitute the stratotype section of the regional stratigraphic subdivisions of the eastern subregion of the Urals, and the hypostratotype of the Averinian (Upper Visan) [Stepanova, Kucheva, 2006], whereas the outcrops of carbonates along the Bolshoi Kizil River constitute the stratotype of the Kizil Formation. The stratotype section along the Bolshoi Kizil River shows a faunal assemblage of the bioherm facies accumulated in an open shallow marine basin with many brachiopod shoals and banks, and with algal and coral bioherms.
Biostratigraphy and lithology The Bolshoi Kizil section begins on the right bank of the Ural River 1.2 km south of the village of Proletarka (situated on the opposite bank) and continues along the left bank of the Bolshoi Kizil River (right tributary of the Ural River). The section is located in the west of the Kizil District of the Chelyabinsk Region.
It follows the Bolshoi Kizil River upstream for almost 7.5 km. Below the Visan part of the section is briefly described, and the Serpukhovian and Bashkirian bioherm facies are discussed in greater detail.
The Upper Visan strata are divided into regional units of substage rank (locally called horizons) including Zhukovian, Kamenskouralian, Averinian and Bogdanovichian. They are exposed in outcrops separated by covered intervals (Figs. 1, 2). Beds lie monoclinally (dipping at an azimuth 250–260°, at an angle of 25–40°). Different researchers have estimated their thickness differently;
the maximum estimate was 1500 m.
Fig. 1. Geological scheme of the outcrops along the Bolshoi Kizil River Fig. 2. Generalized section of the Kizil Formation along Bolshoi Kizil River Upper Visan Substage The Zhukovian (upper part, Outcrop 8, thickness 190–210 m) correlates with the Tulian of the Russian platform. These strata extend along the right bank of the Ural River. The outcrop begins 1.9 km upstream from the confluence of the Ural and Bolshoi Kizil rivers. The Zhukovian is represented by medium and thickly bedded bioclastic packstones and grainstones with peloids and pellets. Bioclasts include foraminifers, crinoids, corals and brachiopods, they are partly rounded and micritized, sometimes slightly dolomitized.
There are occasional nodules of chert at the base of the section. Samples 1–6 contain the fossil alga Koninckopora sp. and the foraminifers Lituotubella glomospiroides Rauser, Endothyranopsis compressa (Rauser et Reitlinger), Globoendothyra orelica Vdovenko, Pojarkovella nibelis (Durkina), Paraarchaediscus koktjubensis (Rauser), P. cyrtus (Conyl et Lys) and numerous other forms. The Zhukovian assemblages of foraminifers characteristically contains large archaeodiscids with a well developed dark layer, numerous pojarkovellids and lituotubellids. The beds correspond to Paraarchaediscus koktjubensis Zone and the upper part of Tulian in the Russian Platform.
The Kamenskouralskian (Outcrop 7, thickness 150 m) correlates with the Aleksinian of the Russian Platform. It is exposed 1.5 km north of the confluence of the Ural and Bolshoi Kizil rivers, consists of foraminiferal grainstones, foraminiferal-algal-bioclastic grainstones and packstones, sometimes dolomitized, with occasional nodules of light-colored chert in the upper part, with the brachiopods Gigantoproductus and numerous foraminifers. Algae Ungdarella uralica, syringoporids, colonial tetracorals and foraminifers are found in the upper part.
The Kamenskouralskian corresponds to the Eostaffella proikensis Zone based on the presence of Lituotubella magna Rauser, Haplophragmella sp., Omphalotis chariessa Conil et Lys, Globoendothyra globules (Eichwald), and G. ishimica, Haplophragmella sp. Eostaffella cf. parastruvei (Rauser), E. cf. proikensis (Rauser), Parastaffella concinna (Schlykova).
The Averinian (Outcrops 7 and 6, thickness over 300 m) is exposed in the land between two rivers in outcrops 7 and 6, and consists of mostly organic limestones with diverse fossils. In Outcrop 7 (thickness 100–130 m), the horizon is composed of thick and indistinctly bedded limestones with accumulations of brachiopods. Algal-foraminiferal packstones and grainstones, algal boundstones, algal-brachiopod wackestones predominate. Algae include Ungdarella uralica and Fasciella kizilia R. Ivanova (= Shartymophycus fusus Kulik). Outcrop 6, along the bend of the B. Kizil River exposes organic limestones, dolomitized in places, with brachiopods. The algal-foraminiferal, foraminiferal and bryozoan-algal packstones prevail. In Stop coral boundstones were observed. Thickness 98 m.
Upward in the section, after a covered interval 22 m thick, we observed medium to thickly bedded bryozoan-crinoidal limestones, in places dolomitized, with colonies of tetracorals and with numerous brachiopods. Thickness 74 m.
The Averinian contains Foraminifers generally continue from the underlying beds while the foraminifers Bradyina rotula, Janischewskina sp., Endothyranopsis crassa (Brady), Eostaffella ikensis Vissarionova, E. ragushensis Ganelina, Cribrostomum eximium regularis Lipina, Archaediscus ovoides Rauser, A. cf. gigas Rauser, Asteroarchaediscus baschkiricus (Krestovnikov et Theodorvich), Permodiscus sizranicus indicative of the Eostaffella ikensis Zone.
The Bogdanovichian (Outcrops 5, 4;
thickness more than 330 m) is exposed along the bend of the left bank of the Bolshoi Kizil River. The Bogdanovichian is composed of boundstone, bioclastic grainstone and dolomite. Crinoidal, foraminiferal, crinoid-brachiopod and oolite limestones are observed on the left bank of the Bolshoi Kizil River near the bridge across the river, on the Sibai – Magnitogorsk highway (Outcrop 5). At Stop 05, on the left of the bridge, in the direction from Sibai to Magnitogorsk thickly bedded wackestones and packstones with brachiopods and crinoids are exposed. Foraminifers were identified in Sample 05 and included Earlandia vulgaris (Rauser et Reitlinger), Forschia mikhailovi Dain, Pseudoglomospira Legend to Fig. 2: 1–4 — limestones: 1 — bedded, 2 — unbedded, 3 — with chertly nodules, 4 — bioclastic, 5 — dolomites, 6 — volcanic rocks, 7 — algae, 8 — foraminifers, 9 — bryozoans, 10 — solitary corals, 11 — colonial corals, 12 — brachiopods, 13 — crinoids, 14 — ostracodes, 15 — ammonoids spp., Endostaffella parva (Moeller), Endothyranopsis sphaerica (Rauser et Reitlinger), Bradyina rotula Eichwald, Biseriella parva (N. Tchernyscheva), Palaeotextularia longiseptata crassa Lipina. Upstream of the river, along the bend of the left bank of the Bolshoi Kizil River there are exposures of younger lithoclastic and bioclastic grainstones with foraminifers of the genera Lituotubella, Globoendothyra endothyranopsis, Bradyina and Janischewskina cf. typica (Mikhailov) (about 140 m;
Samples 06, 07). The above species suggest the presence of the Eostaffella tenebrosa Zone. The Bogdanovichian correlates with the Venevian of the Russian Platform and corresponds to Cf6 Zone of Belgium.
Outcrop 4 exposing the Visan-Serpukhovian boundary beds [Kulagina, Gibshman, 2002, 2005;
Kulagina et al., 2002] is on the Bolshoi Kizil River, 400 m northeast of the on the Sibai – Magnitogorsk highway. This outcrop shows a continuation of the succession described above. The description begins with the rocky exposures on the left bank of the Bolshoi Kizil River (marker Stop 08 a is located 43 m at azimuth 140° from the “Varvara” Cave). The following sequence of thick bedded and indistinctly bedded limestones is observed (bottom to top) (Fig. 3):
1. At Stop 08 a we observed bioclastic packstones, with frequent fragments of coral, echinoids, crinoids and bryozoans, containing corals and brachiopods, matrix is dolomitized and re-crystallized.
2. Bioclastic and crinoidal packstones-rudstones with rare algae and foraminifers, in the upper part with corals. Thickness 7 m.
3. Dolomites. Thickness 11 m.
4. Cavernous dolomites. There is a cave at this level. Thickness 9.5 m.
5. Limestones with calcite accumulations, numerous brachiopods Striatifera. At the bottom of the gully there is an outcrop of crinoid, algal-bioclastic packstones-rudstones, with rare foraminifers. The algae are mostly Calcifolium okense Schwetzov et Birina, there also Koninckpora sp. and Ungdarella sp. (Sample 011 a). Thickness 4.8 m.
Covered interval (bottom of the gully). 12 m.
6. Light limestones are outcropped in the mouth on the right slope of the gully, in thin section — algal packstones-boundstones with many foraminifers (Sample 012): Pseudoglomospira spp., Haplophragmella tetraloculi, Endothyranopsis sphaerica (Rauser et Reitlinger), Janishewskina typica Mikhailov and other.
Thickness 4 m.
Upstream of the river there is a covered interval 6.7 m thick.
Serpukhovian Stage Sunturian Horizon 7. Algal boundstones, sometimes grainstones with remains of thin-shelled brachiopods. Algae Calcifolium okense Schwetsov et Birina. Foraminifers (Samples 15 a, 015) include Pseudoglomospira sp., Haplophragmina cf. beschevensis (Brazhnikova), Endothyranopsis sphaerica (Rauser et Reitlinger), Globoendothyra globula (Eichwald), Howchinia bradyana (Howchin), Bradyina cf. rotula (Eichwald), Janishewskina delicata (Malakhova), Palaeotextulariida, Rugosoarchaediscus akchimensis (Grozdilova et Lebedeba), Asteroarchaediscus baschkiricus (Krestovnikov et Theodorvich), Neoarchaediscus postrugosus (Rauser), Permodiscus vetustus Dutkevich, Eolasiodiscus donbassicus Reitlinger. Thickness 1 m.
Covered interval 18 m.
8. Massive boundstones formed by Calcifolium okense Schwetzov et Birina and Fasciella kisilia R. Ivanova, strongly dolomitized, containing brachiopods, crinoids and corals (Sample 016). Thickness 3 m.
9. Fine- and microbioclastic packstones with recrystallized matrix, containing algal, foraminifers, fragments of bryozoans, brachiopods, crinoids, spicules of sponges and chert. Fossils include algae Calcifolium, Praedonezella, Fasciella, and numerous foraminifers (Samples 017, 019). 5 m.
Covered interval 13 m.
10. Limestones, fissured and dolomite forming small flattened exposures (Sample 020). Thickness 6.5 m.
11. Relict-algal, algal and bioclastic packstones, strongly cavernous and dolomitized. Sometimes caverns are filled with oxidized bitumen;
the matrix is represented by homogeneous, very compact, recrystallized micrite. Bioclasts include crinoids, bryozoans, and echinoids. Often areas with numerous Fig. 3. Distribution of some foraminifers and ostracodes in the Serpukhovian part of the section along the Bolshoi Kizil River. For explanations see Fig. algae may be observed. Presence of single-chambered Eotuberitina sp. (cementing the sediments) and bioencrustations (microspongiostromes) is very characteristic (Samples 021, 022). Thickness 13 m.
12. Algal boundstones formed by the algae Calcifolium okense Schwetzov et Birina with bioencrustations (Plate 1), with foraminifers, frequent fragments of bryozoans, crinoids, a strong smell of bitumen, brachiopod banks in the lower part, in parts strongly dolomitized (Samples 022 a, 2387, 026–029). Thickness 45–52 m.
The thickness of the Sunturian is up to 110 m.
13. At its base, the Khudolazian is composed of boundstone, formed by colonial corals (coral bioherm) and algae (Stop 030, bed 1.3 m) with frequent encrustations, contains bryozoans, spines of echinoids, numerous foraminifers and cysts formed by small Mediocris and Endostaffella. Algal boundstones and packstones overlays, includes (Samples 031, 031 A, 031 B): algae of genera Calcifolium, Ungdarella and Fasciella;
foraminifers: Turrispiroides multivolutus (Reitlinger), Eostafellina cf. paraprotvae (Rauser), Pseudoendothyra cf. kremenskensis Rosovskaya, Globivalvulina eogranulosa Reitlinger, Gl. bulloides (Brady), Bradyina ex gr.
cribrostomata (Rauser and Reitlinger), Br. cf. eonautiliformis Reitlinger. Thickness 3.4 m.
14. The bed forms a vertical wall composed of distinctly laminar limestones. From bottom to top this bed shows a succession of boundstones formed by Calcifolium with bioclasts (Sample 032, Pl. 1, Fig. 2), bioclastic grainstone-packstone (Samples 32 a, G26 v (в), Pl. 1, Figs. 3, 9), wackestone with unidentified tubular remains (Samples 32 b (б) 32 v (в), Pl. 2, Figs. 4, 5), bioclastic wackestone-packstone with brachiopods (Sample 32 g (г)), boundstones formed by structures produced by cyanobacteria in association with bacterial encrustations, and abundant fibrous cement (Sample 32 e) with bacterial inclusions. At the top we observed a bed of “spotty” limestone, microscopically peloid-foraminiferal boundstone with prevailing palaeo nubecularias (encrusting foraminifers), spheres and rhodophytes (Sample 2395, Pl. 2, Figs. 1, 2, 6), sometimes with numerous ostracodes (032 zh (ж), Pl. 2, Fig. 3). Thickness 11 m.
15. In this interval [small outcrops near the quarry], in the separated outcrops before the quarry there are exposed medium-bedded brachiopods wackestones-packstones (Sample 033), followed by algal wackestones and bafflestones (Sample 2396) and peloid grainstones-packstones (Sample 036). In the wall of the quarry, there are exposed thickly bedded bioclastic wackestones-packstones with numerous brachiopods. Algae:
Praedonezella sp., Calcifolium okense Schwetzov and Birina, Ungdarella sp., Fasciella kizilia R. Ivanova.
Foraminifers: Earlandia vulgaris Rauser et Reitlinger, Endothyranopsis sp., Eostaffella cf. proikensis Rauser, E. ikensis Vissarionova, Millerella cf. tortula (Zeller), Asteroarchaediscus baschkiricus (Krestovnikov et Theodorvich), A. parvus (Rauser), Biseriella parva (N. Tchernysheva) (Samples 2397, 2398). 53 m.
The thickness of the Khudolazian is nearly 67 m.
Chernyshevkian Horizon Beds of the Chernyshevkian Horizon are exposed in a steep river bank excavated in a quarry. The upper part of the Chernyshevkian has been taken off by the quarry, and the description below is cited from N.M. Kotschetkova (unpublished), who studied the outcrop before the quarry was excavated in 1975 (Samples 2387–4003 — collected by N.M. Kotschetkova).
16. Bryozoan-algal packstones and wackestones containing corals, numerous brachiopods and foraminifers (Samples 037, 2399): Endothyranopsis sp., E. cf. mirifica Brazhnikova, E. postmosquensis Kireeva, Neoarchaediscus probatus (Reitlinger), N. postrugosus (Reitlinger), Monotaxinoides ex gr. transitorius Brazhnikova et Potievskaya. Thickness 11 m.
17. Fine-bioclastic packstones and wackestones with brachiopods in the some beds, with foraminifers (Samples 038, 038 b, 038 g, 2400): Pseudoglomospira spp., Endothyra ex gr. bowmani (Phillips), Globivalvulina bulloides Brady, Asteroarchaedscus baschkiricus (Krestovnikov et Theodorvich). Thickness 24 m.
Plate 1. Microfacies of the Serpukhovian (Khudolazian Horizon): 1, 7. Boundstone formed by Calcifolium okense Schwetzov et Birina, 1935. 1 — Sample 2387, 7 — Sample 029. 2. Boundstone formed by Calcifolium okense with bioclasts and pelmicrite cement, Sample 032. 3. Algal boundstone with foraminifers Palaeotextularia sp. (upper) and Eostaffella proikensis Rauser-Chernousova, 1948, Sample 029. 4. Algal boundstone with unidentified remains, Sample 029. 5. Eostaffella aff. pseudostruvei Rauser-Chernousova, 1948, Sample 029. 6, 9. Bioclastic grainstone, filling the spaces between the thalluses of Calcifolium, Sample G26 v (в), level of 32 a;
in the Fig. bioclastic grainstone includs Haplphragmina beschevensis (Brazhnikova, 1967). 8. Monotaxinoides subplanus Brazhnikova et Jarzeva, 1956, 180, level of the Sample 017 (from [Kulagina, Gibshman, 2005], Fig. 12, photo 29) Plate Plate 18–19. Mudstones and microbial-lumpy wackestones with numerous thin-walled Glomospira-like tubular organisms, possibly playing a role in cementation of the sediment (Samples 2401, 2402). Thickness 24 m.
Covered interval is 5 m.
20. Bryozoan-crinoidal packstones with numerous foraminifers Archaediscidae (Sample 2403).
Thickness 2.5 m.
The presumed thickness of the Chernyshevkian is over 66 m, while the thickness of the entire Serpukhovian amounts to 250 m.
Serpukhovian – Bashkirian / Mississippian – Pennsylvanian boundary The Serpukhovian – Bashkirian boundary beds are exposed in unnamed gullies opening into the flood plain and cutting into the left bank of the Bolshoi Kizil River 4.5 km upstream of the village of Kizilskoe in Outcrop 1 [Kulagina et al., 2001] (Fig. 4).
1. Pachyspheral mudstones and wackestones, thickly bedded, with rare solitary corals, brachiopods, ostracodes and single foraminifers (Sample 1). Thickness 4.5 m.
2. Bioclastic packstones and rudstones, in places with accumulations of small brachiopod shells, with bryozoans, crinoids, foraminifers and algae Fasciella kizilia R. Ivanova, Praedonezella cespeformis Kulik, Calcifolium okense Schwetzov and Birina (Sample 2). This bed includes archaediscid biofacies and contains numerous Paraarchaediscus, Neoarchaediscus, Asteroarchaediscus, Howchinia, Monotaxinoides, rare Planoendothyra and Eostaffella. Thickness 1.5 m. This bed corresponds to the Bed 20 of Outcrop 4.
Bashkirian Stage Syuranian Substage Bogdanovskvian Horizon The Bogdanovskian is composed of thick-bedded, indistinctly bedded and massive limestones.
3. Peloidal wackestone with rare brachiopods, pelmatozoan bioclasts, and ostracodes and foraminifers (Sample 3): Pectostaffella varvariensis (Brazhnikova et Potievskaya), Plectomediocris sp., Rectoendothyra donbassica Brazhnikova, conodonts Declinognathodus noduliferus inaequalis. Thickness 1.5 m.
This bed is overlain by fine-crystallized dolomite with rare foraminifers and relicts of the micritic grains. Thickness 8.5 m.
4. Algal wackestones, in places recrystallized, with bryozoans, pelmatozoans, and brachiopods. Algae (Sample 5) include numerous Ungdarella sp., Fasciella kisilia R. Ivanova. The bed contains foraminifers and conodonts. Thickness 13 m.
5–6. Bafflestones formed mainly by Ungdarella uralica Maslov (Samples 74, 75). Thickness 15 m.
7–8. Boundstones formed by the algae Fasciella kisilia R. Ivanova with Praedonezella cespeformis Kulik, Ungdarella paralella Kulik, Calcifolium okense Schwetzov and Birina. Bioclasts contains bryozoans, crinoids and rare foraminifers (Samples 6–10, 12 a, b, v). Thickness 19 m.
Covered interval 5 m.
9. Foraminiferal-bioclastic-peloidal grainstones with fragments of brachiopods, crinoids, and corals (Sample 12). Thickness 6 m.
10. Boundstones intricately recrystallized in places with accumulations of thin-shelled ostracodes, in thin sections with Spongiostroma structure and microbial (?) lumps, foraminifers, and brachiopods (Samples 13, 14). Thickness 20 m.
11–12. Bioclastic wackestones and packstones. Thickness 19 m.
Plate 2. All from the Khudolazian: 1. Microbial boundstone, Sample 2395 (4). 2. Ostracodes rich alga-microbial boundsone, Sample, 32 e. 3. Ostracodes rich peloidal wackestones with cavity encrustations, Sample 032 zh (ж). 4, 5. Wackestone including like-tubular encrusting organisms with micro-grain porous wall. 4 — Sample 032 b (б), 5 — Sample 032 v (в). 6. Microbial boundstone with fibrous cementation and encrusting forms, Sample 2395 (4). 7. Boundstone formed by Pseudoglomospira-like encrusting unidentified organisms, Sample 032 d. 8. Microbial-algal boundstone formed by Ortonella sp., Sample 032 z (з) Fig. 4. Distribution of some foraminifers, conodonts and ostracodes in the Syuranian part of the section along the Bolshoi Kizil River. For explanations see Fig. Covered interval 7 m.
13. Bioclastic and foraminiferal-bioclastic wackestones with numerous calcisphaeras, ostracodes, bryozoans, brachiopods. Thickness 4.5 m.
Thickness of the Bogdanovskian is 62 m.
The range of most characteristic microfauna is shown in Fig. 4.
Kammenogorian Horizon The Kammenogorian is represented by medium-bedded wackestones and packstones with foraminifers, brachiopods, ostracodes and echinoderms.
14. Foraminiferal-fine-bioclastic grainstones and packstones with numerous encrusting foraminifers Palaeonubecularia, Tolypammina, Ammovertella. Thickness 7 m. Then Covered interval follows.
The apparent thickness of the entire Syuranian in this section is about 125 m.
Outcrop Akavassian Substage The Akavassian is represented by a bioherm massif formed by a series of bioherms, which may be observed along the latitudinal direction of the steep riverbank almost right across the strike and further, after the turn to the north, almost along the strike.
A small bioherm body can be observed in the mouths of the river channels upstream of the unexposed interval, at the right turn of the steep bank from the meridianal to latitudinal direction. Outcrop 2 (marked stops 23–25, Fig. 5).
1. Boundstones built by algae Donezella lutugini Maslov, Berezella sp., Maslovoporidium sp. and stromatolites, often recrystallized with sparite cement and encrustations. Sometimes the rock is represented by carbonate breccia, with angular intraclasts of micrite and serpulid limestone, in places re-crystallized matrix produced by a decaying carbonate buildup. Fossils include crinoids, ostracodes, gastropods, serpulids and assemblage of foraminifers of the Pseudostaffella antiqua Zone. Thickness 6–7 m.
Further, the section is interrupted by a covered interval (thickness 40–50 m), probably including a tectonic dislocation.
2. At Stop 26 massive stromatolitic boundstones, in places strongly dolomitized, may be observed.
Thin sections show stromatactis structures, in places bitumen. Thickness 4 m.
3. Along the steep bank in the latitudinal direction there are interrupted exposures of a similar massive limestone, in places strongly dolomitized, with accumulations of ostracodes and serpulids. Thickness approximately 65 m.
4. Massive boundstones formed by the algae Maslovoporidium sp. and Donezella lutugini Maslov in combination with radial-fibrous cement and microbial inclusions recrystallized in a lace-like pattern, with encrustations, contains banks of brachiopods, in places with numerous ostracodes, rare foraminifers and ammonoids (Samples 27, 27 a). Thickness about 4 m.
5. A bioherm massif constructed by algal boundstones, ostracode, brachiopod and serpulid banks, and by stromatolite-building algae and structures such as Spongiostroma, in places completely recrystallized and dolomitized, with encrustations Samples 28, 28 a, 33–36, 121/1–121/3). Boundstones with abundant radial-fibrous cement, embracing bioclasts (Pl. 3, Fig. 5). The foraminiferal wackestones (Sample 37, Pl. 3, Fig. 1, 7) and grainstones are occasionally present (121/4, 121 v, Pl. 3, Fig. 4). The bioherm massif contains a limestone lens with numerous ammonoid shells (Fig. 6). Fossils includes: algae Donezella, Ungdarella, Beresella, Girvanella, and Cuneiphycus;
foraminifers: Pseudostaffella antiqua (Dutkevich), Ps. cf. paracompressa Safonova, Ps. compressa (Rauser), Varistaffella korobezikhi (Rauser et Safonova), V. varsanofievae (Rauser);
ammonoids: Bilinguites superbilinguis (Bisat), Stenoglaphyrites sp. nov., Schartymites barbotanus (Verneuil), and Schartymites sp. nov.;
ostracodes by the rich assemblage of the Kirkbyella aperta Zone [Kochetkova, 1983]. Brachiopods were determined by Ya.L. Lutfullin and include Enteletes mesolobus (Jan.), Choristites moelleri (Jan.), Ch. baschkiricus (Jan.) and other [Kochetkova et al., 1977]. The thickness is approximately 30 m.
Fig. 5. Distribution of some foraminifers, ammonoids, conodonts and ostracodes in the Akavassian and Askynbashian parts of the section along the Bolshoi Kizil River. For explanations see Fig. Fig. 6. Ammonoids from Bolshoi Kizil section, Sample 21/2, Bilinguites – Cancelloceras Genozone, Nm2c2 Zone, Akavassian. 1, 2. Bilinguites superbilingues (Bisat, 1924), 1 — Specimen no 4715/40 (1.5), 2 — Specimen no 4715/ (2). 3, 4. Cancelloceras elegans Ruzhencev et Bogoslovskaya, 1978, 3 — Specimen no 4715/30 (1.5), 4 — Specimen no 4715/31 (2) The thickness of the bioherm limestones may only be estimated provisionally because the bedding is not obvious, while the thickness of the bioherm bodies constituting the massif varies. The bioherm massif extends almost along the strike to form rock exposures of the bank for ca. 2 km.
The apparent thickness of the Akavassian is 160–170 m.
Outcrop This outcrop is 7 km upstream of the mouth of the Bolshoi Kizil River. In Outcrop 3 a contact of bioherm massive boundstones and overlying bedded limestones may be observed.
Askynbashian Substage 1. Algal boundstones formed by Donezella lutugini Maslov, rare Berezella sp. Cuneiphycus sp., with rare bioclasts of crinoids, brachiopods, numerous foraminifers (Sample 111): Pseudoglomospira sp., Climacammina sp., Globivalvulina sp., Asteroarchaediscus rugosus (Rauser), Eostaffella spp., Pseudostaffella antiqua (Dutkevich), Ps. cf. conspecta (Rauser), Staffellaeformes sp. Thickness 2 m.
2. Crinoidal rudstones-grainstones with frequent foraminifers, bioclasts of pelmatozoans, bryozoans, brachiopods, and algae Berezella sp. Thickness 2 m.
3. Algal-foraminifers boundstones formed by Donezella lutugini Maslov, Maslovoporidium sp., Berezella sp., Dvinella sp., Pseudostacheoides sp., Stacheoides sp., Epistacheoides sp. with bioclasts of crinoids, bryozoans, pelmatozoans, brachiopods, numerous foraminifers: Pseudoglomospira sp., Globivalvulina sp., Eostaffella spp., Ozawainella spp., Pseudostaffella spp., Asteroarchaediscus sp., and conodonts of the Idiognathodus sinuosus Zone. Thickness 13 m.
4. Foraminiferal bioclastic grainstones containing frequent foraminifers, bioclasts of algae, pelmatozoans, ostracodes, algae Ungdarella sp., Beresella sp. (Samples 109–101). 10 m.
The thickness of the Askynbashian is 27 m.
Plate Sedimentary settings The carbonates of the Kizil Formation were deposited during the Late Tulian-Askynbashian. The Visan beds were deposited on a shallow shelf, in a high wave energy environment. In the Serpukhovian and Bogdanovskian time, sedimentation occurred in the mid-shelf region near bioherm buildups and back-reef lagoons, and was characterized by low energy mudstone accumulation (facial bands 4 and 5 as in J.L. Wilson ). In the Early Serpukhovian (Sunturian), small bioherms formed by the algae Calcifolium okense, Ungdarella uralica and Praedonezella cespeformis and brachiopod banks became widespread. In the Khudolazian time, bacterial-algal buildups with numerous encrusting foraminifers and ostracodes and brachiopod banks were common. In the Late Serpukhovian, among algae, the species Fasciella kizilia become dominant, and boundstones produced as a result of metabolism of cyanobacteria and bacterial encrustation, with abundant radial-fibrous cement are formed. Similar algal-microbial buildups were formed in the Serpukhovian in the Peri-Caspian Region [Gibshman et al., 2007].
A similar environment was present at the beginning of the Bashkirian (Bogdanovskian). In the Late Bogdanovskian time, a low energy environment of a deepened lagoon prevailed, where micritic limestones with numerous thin-shelled ostracodes and brachiopods accumulated. In the Kammenogorian, these were replaced by bedded foraminiferal packstones. In the Akavassian, bioherms reached their maximum development, with large bioherm bodies, which were possibly reef buildups formed by algae and hydroid organisms. Based on I.A. Shchekotova’s  data, the bioherms in the Bashkirian portion of the Kizil Formation formed dispersed bodies and have a small size of 10–15 mm in diameter and 3–5 m in height, whereas the largest bioherm body is 300 m in diameter and 3–30 m in height. The buildups are composed of various boundstones (stromatolotic, algal, ostracodes, serpulid, or brachiopod). Of bioherm-forming algae, Beresella, Donezella, Cuneiphycus, Coactilum, Ungdarella, Maslovoporidium, and Ortonella being widespread. There are also boundstones with an organogenic texture formed by stromatolites and frame-bilding algae Spongiostroma like structures, bacterial inclusions. Limestones of organic origin (boundstones) of all types contain many bacterial inclusions and abundant radial-fibrous cement. Grainstones are subdominant.
In the Akavassian, we observed a limestone lens containing numerous ammonoid shells enclosed in bioherm rocks and connected by radial-fibrous cement. The lens is also in contact with grainstones and boundstones. No other fossils, apart from ostracodes, are present. It is possible that algal bioherms were a suitable ammonoid habitat, while their shells were carried post-mortem by currents toward the base of the buildup and accumulated in local depressions, to subsequently become a substrate for a new buildup.
Biostratigraphy The Serpukhovian is subdivided into the Sunturian, Khudolazian and Chernyshevkian horizons. The base of the Serpukhovian is defined by the FAD of the foraminifers Janischewskina delicata, Eolasiodiscus donbassicus and Neoarchaediscus postrugosus in Outcrop 4 (Sample 015). The Sunturian is characterized by foraminifers of the Neoarchaediscus postrugosus Zone.
The Khudolazian is characterized by foraminifers of the Eostaffellina paraprotvae Zone. This zone contains species continuing from the underlying beds and the newly appearing species Turrispiroides multivolutus, Eostafellina cf. paraprotvae, Bradyina ex gr. cribrostomata, Pseudoendothyra cf. kremenskensis, Globivalvulina eogranulosa. These species are characteristic of the Upper Serpukhovian of the Urals, Donets, and Moscow Basins. The base of the Khudolazian is drawn based on the renovation of the assemblage.
The Chernyshevkian corresponds to the Monotaxinoides transitorius Zone. In this section, the Chernyshevkian is represented by mainly brachiopod wackestones and algal boundstones with low diversity Plate 3. Microfacies of the Bashkirian: 1. Ostracode boundstone, Outcrop 2, Sample 33 (2). 2, 5. Algal boundstone formed by red alga Cuneiphycus (arrows), surrounded by fibrous cement;
algal-microbial wackestone with small foraminifers filled up spaces between algal-fibrous inclusions. Sample 121a (4). 3. Pseudostaffella compressa (Rauser-Chernousova, 1938), 60, specimen No 121/1133, Sample 21 v (в, 11). 4. Bioclastic-algal packstone-wackestone, partly recrystallized, filling spaces between skeletal remains that form a frame of the bioherm buildup. Sample 121 A (5). 6. Wackestones with Tenebrozella sp. and Pseudostaffella sp. Outcrop 2, Sample 37 (1). 7. Algal boundstone formed by Fasciella kizilia R. Ivanova, 25, Sample 7, Bogdanovkian of foraminifers. The foraminifers Pseudoglomospira spp., Endothyra ex gr. bowmani, Globivalvulina bulloides, Neoarchaediscus probatus, N. postrugosus are relatively common. The base of the zone is drawn based on the considerable decrease in the number of Visan species and the appearance of Eostaffella postmosquensis and Monotaxinoides ex gr. transitorius. The uppermost Serpukhovian is represented by bryozoan-crinoid packstone to grainstone lithofacies with abundant Archaediscidae and Howchiniidae (Outcrop 1). The upper part of the horizon contains the conodonts Lochriea nodosa, L. ziegleri, Gnathodus bilineatus bilineatus, and Gn. bilineatus bollandensis, indicative of the Gn. bilineatus bollandensis Zone. The Chernyshevkian corresponds to the Yuldybaevian of the Central-Uralian structural zone of the Southern Urals [Kulagina et al., 2002], Zapaltyubinian of the Donets Basin [Aizenverg et al., 1983], the Arnsbergian of the Franco-Belgian Basin [Laloux, 1987], and the uppermost Mississippian of Arrow Canyon, North America [Brenckle, 1997].
The Bashkirian in this succession includes the Syuranian, Akavassian and Askynbashian substages.
The Syuranian is subdivided into the Bogdanovkian and Kamennogorian [Kulagina et al., 2001].
The Bogdanovkian includes the foraminiferal Plectostaffella varvariensis, Pl. bogdanovkensis – Semistaffella minuscularia and S. variabilis zones and the conodont Declinognathodus noduliferus Zone with the Early and Late Subzones.
The lower Bashkirian boundary is drawn based on the appearance of conodonts of the Early Declinognathodus noduliferus Subzone. The Bolshoi Kizil section is a stratotype of this Subzone (beds 3–8, thickness 57 m). This boundary coincides with changes of foraminiferal assemblages and the appearance of Plectostaffella varvariensis, Plectomediocris sp. and Rectoendothyra sp. The Plectostaffella varvariensis Zone corresponds to the Early Declinognathodus noduliferus Subzone and correlates with the lower Vosnesenskian of the Donets Basin, Ukraine [Aizenverg et al., 1983;
Vachard, Maslo, 1996], Chokerian of the Franco Belgian Basin [Laloux, 1987] and lowermost Pennsylvanian before the appearance of Millerella marblensis Thompson in Arrow Canyon, North America [Brenckle, 1997].
The Plectostaffella bogdanovkensis – Semistaffella minuscularia and S. variabilis zones represents by the ammodiscid-eostaffellid-archaediscacean biofacies, include representatives of Palaeonubecularia, Pseudoammodiscus, Ammovertella, Eostaffella, Plectostaffella, Semistaffella, Monotaxinoides and numerous Archaediscidae. Beds 9–10 (outcrop 1) of the Pl. bogdanovkensis – S. minuscularia Zone corresponds to Late Declinognathodus noduliferus Subzone. The latter was identified based on the disappearance of the genera Gnathodus and Lochriea and on the appearance of Declinognathodus lateralis (Hig. et Bouck.).
Semistaffella variabilis Zone is indicative of the Kamennogorian.
The Upper Bogdanovkian and Kamennogorian of the Southern Urals correspond to the Krasnopolyanian of the Russian Platform, the Upper Voznesenskian and Feninskian of the Donets Basin, Ukraine [Vachard, Maslo, 1996], the Alportian and Kinderscoutian of the Franco-Belgian Basin [Laloux, 1987], the Tagnana-III Member of the Tagnana Formation of the Bechar Basin, Algeria [Van Ginkel, 2002] and the beds with Millerella marblensis Thompson in Arrow Canyon, North America [Brenckle, 1997].
The Akavassian is characterized by foraminifers of the Pseudostaffella antiqua Zone, ammonoids of the Bilinguites – Cancelloceras Genozone (its upper part — Nm2c2 Zone) and assemblage of ostracodes with numerous Javatius kizilensis [Kotschekova, 1983].
Ammonoids are found in Outcrop 2 along with the foraminifers (Samples 121/4, 121 a), Pseudostaffella antiqua, Ps. cf. paracompressa Safonova, Ps. compressa, Varistaffella korobezikhi, V. varsanofievae, and other characteristic of the Pseudostaffella antiqua Zone and the Akavassian. Sample 28 contains numerous ammonoids Cancelloceras sp. and Bilinguites sp., Samples 121/2–121/4 includes Cancelloceras sp. nov., Cancelloceras elegans, Bilinguites superbilinguis, Stenoglaphyrites sp. nov., Schartymites barbotanus, and Schartymites sp.
nov. All these ammonoids indicate the Bilinguites – Cancelloceras Genozone (namely its upper part — Nm2c2 = Bilinguites superbilinguis Zone). Ammonoids of this age are scarcely known in the Southern Urals.
Until now only a few outcrops containing ammonoids of this age were recorded in the Orenburg Region (near the villages of Novo-Samarskaya and Utyagulovo). However, ammonoids of this age are widespread in Central Asia (Fergana and Middle Tien-Shan), where the assemblages are dominated by Cancelloceras and Bilinguites, in China, North America and Western Europe. The presence of B. superbilinguis allows a direct correlation with the Upper Namurian G1 Zone (Yeadonian) in Great Britain and Germany. The Pseudostaffella antiqua Zone corresponds to the Severokeltmensky of the Russian platform, the Manuilovsky Horizon of the Donets Basin [Vachard, Maslo, 1996].
Conclusions Carbonates exposed along the Bolshoi Kizil River display an almost complete, apparently uninterrupted succession of Carboniferous substages from the Tulian to Askynbashian (equivalent to the Upper Visan to Yeadonian in Western Europe). However, because of the several large intervals covered, it is impossible to observe some stratigraphic boundaries. However, this is one of the best sections in the Southern Urals showing the transition from the Lower to Upper Carboniferous (Mississippian-Pennsylvanian boundary). The base of the Pennsylvanian is fixed by the FAD of the conodont Declinognathodus noduliferus.
No contact between the Visan and Serpukhovian stages has been observed, but the limestones yielding Serpukhovian foraminifers are exposed 6.7 m above the uppermost observed bed of the Visan limestone.
The Serpukhovian age is based on the foraminifers Janischewskina delicata, Eolasiodiscus donbassicus and Neoarchaediscus postrugosus. This section shows a simultaneous appearance of three foraminiferal species marking the base of the Serpukhovian. The Akavassian is represented by massive bioherms dated by foraminifers, ammonoids, and ostracodes. The boundary between the Akavassian and Askynbashian is drawn near the contact of massive and bedded limestones based on foraminifers of the Staffellaeformes staffellaeformis – Pseudostaffella praegorskyi Zone and conodonts of the Idiognathodus sinuosus Zone.
The work was supported by RFBR grants No 04-05-65022 and 07-05-997.
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SOME MIDDLE CARBONIFEROUS RUGOSA FROM THE SOUTHERN URALS O. L. Kossovaya Karpinsky All-Russia Research Geological Institute, St-Petersburg, Russia, e-mail: firstname.lastname@example.org НЕКОТОРЫЕ РУГОЗЫ ИЗ СРЕДНЕКАМЕННОУГОЛЬНЫХ ОТЛОЖЕНИЙ ЮЖНОГО УРАЛА О. Л. Коссовая Всероссийский научно-исследовательский геологический институт им. А.П. Карпинского, Санкт-Петербург;
e-mail: email@example.com Создание Международной стратиграфической шкалы и обновление Общей шкалы каменно угольной системы потребовало обоснования границ подразделений в различных фациях, в том числе и анализа распределения различных видов ругоз вблизи измененной границы баш кирского яруса [Постановление МСК …, 1997]. Изменение таксономического состава ругоз, характеризующееся вымиранием около 90 процентов раннекаменноугольных таксонов, свя зано со среднекаменноугольным оледенением [Vassiljuk, Polyakova, 1996;
Существенные изменения климата подтверждаются позитивным трендом дельта 18O and 13C, полученным при анализе экземпляров брахиопод из разреза Аскын [Brand, Bruckschen, 2002;
Grossman et al., 2002]. Раннебашкирский комплекс характеризуется преобладанием ветвистых форм. Ранее имевшиеся данные по разрезу Аскын дополнены видом Koninckophylloides uralicum regularis Gorsky и впервые описанным в данной статье видом ?Pseudolytvophyllum askynensis sp.
nov. Комплекс, характерный для подольских отложений разреза Дальний Тюлькас (Горная Башкирия), включает преимущественно одиночные «каниноморфные» формы. Мелкие ко раллы без диссепиментов характерны для конденсированной части разреза — верхней пачки ташлинской свиты мячковского горизонта. Последний комплекс имеет определенное сходство с фауной формации Picos de Europe (Кантабрийские Горы) и Мидконтинента.
Creation of the International Stratigraphic Scale and changes in the General Stratigraphic scale for Russia have demanded tracing of the recently ratified boundaries in various facies which sometimes lack index species. The ratification of the Pennsylvanian boundary has resulted in the change of the Bashkirian boundary in the Russian General Stratigraphic Scale [Resolution..., 1997] and thus there is a need for more accurate data on the distribution of species.
About 90 percent of the Lower-Carboniferous rugose genera became extinct at about the Mid Carboniferous boundary [Vassiljuk, Polyakova, 1996;
Kossovaya, 1996]. This event correlates with the Mid-Carboniferous global glaciation marked in the region by a positive shift of delta 18O and a positive shift of delta 13C according to data from the Southern Urals [Brand, Bruckschen, 2002;
Grossman et al., 2002].
Isotopic data also show the onset of the mid-Carboniferous glaciation in the Askyn section [Brand, Bruckschen, 2002;
Grossman et al., 2002]. Also the appearance of a new Bashkirian assemblage of rugose corals, including fasciculate colonies described earlier as Fisherina Stuckenberg, Profisherina Cotton, Heintzella Fedorowski, Lytvophyllum Soshkina, Protodurhamina Kozyreva and others, is well known in contemporaneous deposits of the Urals, Northern Timan, Russian Platform (Voronezh Anteclise) and Novaya Zemlya [Kossovaya, 2002]. Some of these generic names are synonyms, but detailed analyses await future re-study of the holotypes.
Rugose corals are widely distributed especially in the shallow-water deposits of the Urals (Fig. 1), but some occur in the deep-water facies (Fig. 2). In spite of fairly numerous monographic descriptions [Gorsky et al., 1975;
Kossovaya, 2007] information on the exact position of the corals in particular sections is insufficient. Changes in specific and generic concepts, which are now based mostly on the features of the holotype or topotype specimens, demand an accurate revision of specific and generic diagnoses. A few well exposed sections already have been measured in detail and have been recollected.
Askyn section. The Askyn section is situated on the southern slope of Asatau Mountain on the right bank of the Askyn River near the abandoned Solontsy Village. For a long time it was considered one of the most complete stratigraphic sections of the Bashkirian stage. The interval underlying the boundary is represented by secondary dolostone and oolitic grainstone with Chaetetidae colonies (Bed 3) and packstone with horizontally oriented brachiopod shells. The mid-Carboniferous boundary in this section is marked by a regional unconformity which is well shown via the cut shells in the Striatifera shell limestone (Bed 4). The overlying bed 5 is represented by shoal oolititic grainstone. The boundary is placed below the first appearance of Plectostaffella bogdanovkensis (fusulinids) [Kulagina et al., 2001]. The remainder of the section is composed of shallow-water algal and foraminiferal grainstone and packstone, with rather rare colonies or small bioherms of tabulates. According to I.I. Gorsky  the Askyn section contains “Zaphrentis” ex gr. delanouei M. Edw.
et H., Lophophyllum (Arachnolasma) singulare Gorsky, Lytvophyllum antiquum Gorsky, Campophyllum contortulum Gorsky (С2m), Lithostrotion ineptum Gorsky, and Orionastraea (?) sp. indet. Two typical assemblages in the Askyn section were distinguished by Degtyarev [Degtyarev, 1975]: a Bashkirian assemblage with Fig. 1. Distribution of rugose corals in the Bashkirian deposists of the Askyn Section ([Giedbook, 1995;
Ogar’ 1995 mns], the authors collection treated in this paper are in bold line). The postilion of isotope samples by P. Bruckschen pers. Com. (1998). The isotope data is from U. Brand, P.Bruckschen , E.L. Grossman et al. ) Koninckophylloides juresanense Gorsky, Koninckophyllum vesiculosa Gorsky, and K. riphaecum Gorsky, and a Moscovian assemblage containing Bothrophyllum simplex Gorsky, Hapsiphyllum cf. usvense Gorsky, Lithostrotion peculiare Gorsky, Fischerina stuckenbergi Dobrolybova, F. aff. stuckenbergi Dobrolybova, and Corwenia aff.
toulai Gorsky. V. Ogar , who also revised the taxonomy of the corals in the Askyn section, showed that the “horizons” he recognized also contain different faunal assemblages. All these data were used in the Guidebook  where detailed bed by bed distribution of corals was documented for the first time for the Askyn section. Data on corals from different sections demonstrates that the lower boundary coincides with the change from the typical Early Carboniferous corals to assemblages with various fasciculate colonial corals [Kossovaya, 1996]. According to our analyses the fasciculate corals with variable and rather complex axial structures are mostly typical of the lower part of the Bashkirian stage within the scope of the Syranian – Askynbashian substages. The first colonial corals appear in the bed 11 [Guidebook …, 1995] (Fig. 1). The underlying deposits contain solitary Caninia sp. and rare isolated fragments of Protokionophyllum facilis Vassiljuk.
Abundant colonies of fasciculate corals represented by ?Pseudolytvophyllum askynensis sp. nov. (Plate 1, fig. 1–7), that earlier was included in Lytvophyllum antiquum Gorsky [Gorsky, 1978;
Kossovaya, 2002], and Koninckophylloides uralicum regularis Gorsky (Plate 1, figs. 10–11) are present in bed 17. The first species needs substantial revision as was pointed out by several authors [Gorsky, 1978;
Ogar’, 1985 manuscript;
Fedorowski et al., 2007]. Koninckophylloides uralicum regularis Gorsky originally described from the Bashkirian deposits of the Min’ar River [Gorsky, 1978, plate XIX, fig. 1] was found in the bed 24.
This bed was assigned to C2C considered as upper middle Carboniferous in age. Our specimens were found in the Askynbashian Substage of the Bashkirian Stage (Fig. 1;
Plate 1, fig. 10–11).
Short remarks on taxonomy. The genus Lytvophyllum Dobrolyubova, 1941 was based on the material collected at two different outcrops: from Artinskian deposits of the Lytva River and from conglomerates of Sim Factory. A description based on the re-study of the lectotype was published recently [Fedorowski et al., 2007]. The specimens from the Sim Factory were proclaimed by the same authors as belonging to Lytvophyllum sp. nov. undescribed The new thin sections of the original topotype specimen, specimen 925/146, Paleontological Museum (Moscow) are considerably different from those of the lectotype of Lytvophyllum from Lytva River.
Gorsky  proposed assignment of the specimens from Sim Factory to his new species Lytvophyllum antiquum which also occurs in the Askyn section. New longitudinal sections of the topotypes from Sim Factory (Specimen 925/146 Pin RAN) show that the specimens have a biform tabularium and they lack lonsdaleoid dissepiments (Plate 1, fig. 8, 9). So, the specimens from Sim do not belong to Lyvophyllum according to the emended diagnosis of J. Fedorowski et al. . In addition, Lytvophyllum antiguum Gorsky  is represented by a holotype which does not show the typical features of the lectotype from Lytva River so it also can not be assigned to Lytvophyllum as was pointed out by J. Fedorowski et al. .
Our data show that specimens collected in the Askyn section in the bed 17 are identical to some of Gorsky’s specimens [Gorsky, 1978, Plate XXI, Fig. 6, 9] included by him in Lytvophyllum antiguum Gorsky, but are different from the holotype of this species. Therefore we propose the new species ?Pseudolytvophyllum askynensis Kossovaya sp. nov. to embrace these specimens. We assign this species questionably to Pseudolytvophyllum X. Yu et H.D. Wang [Yu et al., 1983] and not to Lytophyllum because it has weakly developed lonsdaleoid dissepiments, a simple columella and short minor septa.
The Moscovian deposits considered here from bed 31 and above contain Alekseeviella sp., and Bothrophyllum sp. So, above this boundary the colonial coral fauna is replaced by more tolerant solitary ones.
Dalnyi Tyulkas section. Two assemblages are distinguished in Dalnyi Tyulkas section located in the vicinity of the town Krasnousolsk in Usolka River Valley. The lower assemblage occurs in the lower carbonate unit of the Tashly Formation [Stepanov, 1941]. This unit consists of light-gray and white dolomitized crinoid packstone with numerous chert nodules. Beds are separated by wavy surfaces with accumulations of yellow fusulinid packstone nearby. The lower assemblage consists of large solitary corals in shallow-water limestone in the Podolskian interval. The age is based on conodont and fusulinid data [Alekseev et al., 2002].
Corals of the lower unit were collected from 3 levels and are most abundant at the top of second bench of the quarry and the base of the third bench. In the latter they were found also in thin lenses close to bedding surfaces. Rugose corals are abundant and include: Pseudotimania sp., P. kasimovi Dobrolyubova et Kabackovich, Pseudotimania irregularis Gorsky, Siedleckia mutafii (Gorsky), ‘Caninia’ remotetabulata Gorsky, and others (Fig. 2). Rare representatives of the ‘Cyathaxonia fauna’ were also found: Lophophyllidium (Lophbillidium) Plate Fig. 2. Distribution of rugose corals in the Podolskian-Myachkovian deposits of the Dalnyi Tyulkas Section (Usolka River).
Stratigraphy is based on fusulinid and conodont data from [Stepanov, 1941;
Chuvashov et al., 1983, 1990;
Alekseev et al., 2002] Legend: 1 — limestone;
2 — bioclastic limestone;
3 — shell limestone;
4 — oolitic limestone;
5 — clay;
6 — clayey limestone;
7 — limestone with colonial corals (tabulate and rugose ones) 8 — marl;
9 — cherty limestone;
10 —cherty nodules;
11 — crinoids;
12 — corals;
13 — brachiopods;
14 — trace fossils Plate 1. 1–7. ?Pseudolytvophyllum askynensis Kossovaya sp. nov. 1 — (3), transverse section of the part of colony. 2, 3, 4, 5 (7) — transversal section of the isolated corallites from the same colony;
6, 7 (9) — longitudinal sections of the same colony Specimen 17/1, Askyn section, bed 17. Akavassian Substage. 8–9. “Lytvophyllum tschernowi Dobrolyubova”, 1941;
Specimen 925/ Paleontological museum, PIN RAS, originals from outcrop near Sim Factory. Fig. 7 (5) — longitudinal section with well visible biform tabularium;
Fig. 8 (5) — transversal section mature stage without lonsdaleoid dissepiments. Middle Carboniferous.
10–11. Koninckophylloides uralicum regularis Gorsky, 1978;
Specimen 24/1. 10 (2) — transversal section of the part of the colony.
11 (3) — transversal section of the axial part of the corallite with well development of axial structure with irregular axial plate. Askyn section, bed 24, Akavassian Substage, the base aff breimeri De Groot, 1963 and L. (Lophophyllidium) minus De Groot, 1963 [De Groote, 1963, emend by Fedorowski, 2004]. Outside the Uralian Basin, a similar “caninomorph” coral fauna is known from the northern Timan region, Moscow Basin, Novaya Zemlya, and Spitsbergen. The lower boundary of the Myachkovian is not easily recognized.
The upper assemblage occurs in the condensed part of the section in the uppermost part of the Tashly Formation. This part of the section, called unit 2 of the Tashly Fm., includes clays, mudstones, and tuffs.
A late Myachkovian age of this unit is suggested by the occurrence of Neognathodus roundyi and Gondolella magna [Alekseev et al., 2002]. The ‘Cyathaxonia fauna’ in these rocks is characterized by Lophophyllidium interseptatum Kossovaya [Kossovaya, 2007], Lophophyllidium sp. (“cyathaxonimorph” type), Wannerophyllum?
incertum Rodriguez and Kullmann, Cyathaxonia aff. cornu Michelin, Neaxon ? multitabulatus Rodriguez and Kullmann, and Soshkineophyllum sp. 1. The taxonomic replacement by the upper assemblage coincides with an abrupt change in lithology from carbonates to strata with considerable amounts of terrigeneous, tuff, and siliceous material triggered by deepening of the basin.
The above assemblage shows a considerable similarity in species and genera with that in contemporaneous deposits of the upper part of the Picos de Europa Fm. (Spain) [Rodriguez, Kullmann, 1999]. The collection from the Dalnyi Tyulkas section comprises 22 species of Laccophyllidae Grabau, 1928, Lophophyllidiidae Moore and Jeffords, 1945, Polycoeliidae Fromentel, 1861, and Wannerophyllidae Fedorowski, 1986 (Plate 2).
Besides the Dalnyi Tyulkas section, the latest Myachkovian “Cyathaxonia fauna” is known in a few outcrops in the Cis-Urals [Gorsky, 1978], usually accompanied by appearance of deep-water deposits.
An increase of 18O and decrease of 13C was measured in the upper Myachkovian in Kamen’ Perevalochnyi by E.L. Grossmann et al. . These geochemical trends are interpreted as reflecting deepening of the Pre-Uralian foredeep accompanied by a slight decrease in temperature. The presence of the “Cyathaxonia fauna” in the latest Myachkovian is rather unusual (Fig. 2), but the occurrence of a similar fauna in the coeval deposits in the Cantabrian Mountains [Rodriguez, Kullmann, 1999;
de Groot, 1963;
Fedorowski, 2004] and Mid-Continent USA [Jeffords, 1947] indicates the widespread occurrence of this assemblage.
Systematic description ? Pseudolytvophyllum askynensis Kossovaya sp. nov.
Plate 1, Figs. 1–7.
part Lytvophyllum antiquum Gorsky, 1978, page 153–157, Plate XXI, figs. 3, 4, 6, 7.
Holotype. Specimen 17-1 (fasciculate colony), CNIGR museum, section Askyn, Gornaya Bashkiria, Akavassian Substage, Bashkirian Stage.
Diagnosis. Fasciculate colonies consist of cylindrical corallites. Colonies up to 15 cm in diameter.
Diameter of corallites 5–6 mm. Major septa up to 2/3 of the radius. Extremely short minor septa restricted to the dissepimentarium. The simple columella originates from the inner part of the counter septum. One row of regular slightly convex or interseptal dissepiments. Flattened lonsdaleoid dissepiments are very rare in mature stage. Tabulae mainly horizontal.
Comparison. From Lytvophyllum tschernowi Dobr., re-described based on the lectotype specimen [Fedorowski et al., 2007], the present species differs in having rare lonsdaleoid dissepiments, a lack of a biform Plate 2. 1–5. Pseudotimania kasimovi Dobroljubova et Kabackovich, 1941. 1, 2 — sequential transverse sections of young stages (3), 3, 5 — sequential transverse sections of mature stage (2), 4 — longitudinal section (2), Specimen 1-0-1e, Dalnyi Tyulkas section, the top of the second step of the quarry, Tashly Fm, lower part, Podolskian. 6–9. Siedleckia mutafii Gorsky, 1938, 6 (3), 7 (2), 9 (2), sequential transverse sections, 8 — longitudinal section (2), Specimen 1-0-1a, Dalnyi Tyulkas section, the top of the second step of the quarry, Tashly Fm., lower part. Podolskian. 10–12. Pseudotimania kasimovi Dobroljubova et Kabackovich, 1948. 10 — transverse sections of young stage (3), 11 — transverse sections of mature stage (2), 12 — longitudinal section (2), Specimen 1-0-13, Dalnyi Tyulkas section, the top of the second step of the quarry, Tashly Fm., lower part. Podolskian. 13–15. Lophophyllidium (Lophophyllidium) minor De Groot, 1963. 13 (9) — transverse section of the young stage;
14 (6) — longitudinal section;
15 (8) — transverse section of the mature stage, Specimen 01-2, Dalnyi Tyulkas section, the base of the third step of the quarry, Tashly Fm., lower part, Podolskian. 16–18. Lophophyllidium (Lophbillidium) interseptum Kossovaya, 2007. 16, 17 — Specimen 21-1. 16 (10) — transversal section of the early stage;
17 (10) — longitudinal section 2;
18 — Specimen 21-1/2 (7), transversal section of the mature stage. Dalnyi Tyulkas section, Upper part of the third step, upper part of Tashly Fm., Myachkovian Plate tabularium, minor septa restricted to the dissepimentarium, and the character of tabulae. The connection of columella with the counter septum also differentiates this species from L. tschernovi. From topotype 925/146 Coll. PIN the new species differs in having flattened horizontal tabulae, short minor septa, presence of lonsdaleoid dissepiments, and lack of a biform tabularium (Plate 1, fig. 8–9). The specimens from author’s collection are identical to the specimens 441, 452, 455, 467 coll. 5766 CNIGR museum [Gorsky, 1978, plate XXI, figs. 3, 4, 6, 7].
Discussion. The species described here can not be assigned to Lytvophyllum because of its very narrow dissepimentium, elongation of the counter septum, and lack of a biform tabularium. It is questionably assigned to Pseudolytvophyllum X. Yu et H.D. Wang because of the similarity of small dissepiments, which are rarely lonsdaleoid, and a simple columella joined with the counter? septum, and the small minor septa.
Material. 1 fasciculate colony from bed 17 of the Askyn River, four isolated specimens and part of a colony from collection 5766 CNIGR museum. Askyn section, Asatauian Substage.
Acknowledgments. This study is supported by RFBR grant 09-05-00101, 08-05-00155. I am very thankful to Dr. Dieter Weyer for important comments on morphological structure of Lytvophyllum and Pseudolytvophyllum and associated groups and Prof. Calvin Stevens for his remarks and English revision of the manuscript.
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PALEONTOLOGICAL CHARACTERISTICS OF LATE PENNSYLVANIAN IN USOLKA SECTION V. V. Chernykh 1, B. I. Chuvashov 1, V. I. Davydov Zavaritsky Institute of Geology and Geochemistry, Urals Division, Russian Academy of Sciences, Ekaterinburg, Russia, e-mail: firstname.lastname@example.org Permian Research Institute, Dept. Geosciences;
Boise State University, email@example.com The section is located on the left bank of Usolka River near resort of Krasnousolsk city (Bashkortostan).
Moscovian through Artinskian carbonate-siliciclastic deep-water succession with frequent conodont horizons is exposed in the section. Turbiditic fusulinid horizons are rare. Section is previously published [Chuvashov et al., 1990, 1991,1993;
and other] and in this paper only measurements (meters above the base of the section) and beds are used. Thickness of these beds and position of the samples can be seen on the log (Figure).
Bed 2 (1.2 m): Idiognathodus aff. sagittalis Kozitskaya, Id. delicatus Gunnell, Id. tersus Ellison, Id. swadei Barrick et Rosscoe, Id. sulciferus sulciferus Gunnell, Streptognathodus cancellosus (Gunnell), Gondolella sinuata Gunnell, G. merrilli Gunnell (Plate 1, 2).
Bed 4/1 (4.7 m): Streptognathodus firmus Kozitskaya, S. gracilis Stauffer et Plummer, S. zethus Chernykh et Reshetkova, S. pawhuskaensis Harris et Hollingsworth, S. praenuntius Chernykh, S. aff. pictus Chernykh, Idiognathodus ex gr. sulciferus Gunnell, Id. undatus Chernykh, Gondolella merrilli Gunnell;
Quasifusulina ex gr. longissima (Moeller), Pseudofusulinella minuta (Grozdilova), Ps. pulchra (Rauser et Belyaev), Schwageriniformis petchoricus brevis (Rauser et Belyaev), Sch. petchoricus varsanofieva (Z. Mikhailova), Sch. schwageriniformis mossquensis (Rosovskaya), Sch. baisunensis (Bensh), Sch. (Tumefactus) sp., Rauserites bashkiricus (Rosovskaya), R. shikhanensis compactus (Rosovskaya), R. dictiophorus (Rosovskaya).
Bed 4/2 (4.9 m): Streptognathodus firmus Kozitskaya, S. elegantulus Stauffer et Plummer, S. gracilis Stauffer et Plummer, S. pictus Chernykh, S. makhlinae Alekseev et Goreva, S. simulator Ellison, S. sinistrum Chernykh, S. auritus Chernykh, S. pawhuskaensis Harris et Hollingsworth, Idiognathodus dolioliformis Chernykh, Id. n. sp. 2.
Bed 5/1 (6.4 m): Streptognathodus firmus Kozitskaya, S. auritus Chernykh, S. pawhuskaensis Harris et Hollingsworth, S. luganicus Kozitskaya, S. aff. luganicus Kozitskaya, S. sinistrum Chernykh, S. aff. simulator Ellison, Gondolella sublanceolata Gunnell.
Bed 7/1 (11.0 m): Streptognathodus luganicus Kozitskaya, S. pawhuskaensis Harris et Hollingsworth, S. pictus Chernykh, S. aff. simulator Ellison, Idiognathodus ex gr. sagittalis Kozitskaya. Fusulinids (8.2 mab):
Pseudofusulinella eopulchra (Raus.), Ps. usvae (Dutk.), Quasifusulina cf. eleganta Schlyk., Rauserites compactus Plate 1 (all figures are 50, except otherwise mentioned) Kasimovian;
bed 2. Figure: 1, 2, 3. Idiognathodus swadei Barrick et Rosscoe, 2009: 1 — No U12-27 (70);
2 — No U12-29;
3 — No U12-24 (70). 4, 5. Idiognathodus n. sp. (40): 4 — No U12-6;
5 — No U12-2. 6. Idiognathodus ex gr. sulcifer sulcifer Gunnell, 1933, No U12-5. 7. Idiognathodus delicatus Gunnell, 1931 (40), No U12-18.
Kasimovian, firmus-zethus zone;
bed 4/1. Figure: 8. Idiognatodus undatus Chernykh, 2005, (40), holotype No U13-3. 9. Streptognathodus pawhuskaensis Harris et Hollingsworth, 1933 (60), No U15-7. 10, 19. Streptognathodus gracilis Stauffer et Plummer, 1932: 10 — No U15-16 (60);
19 — No U15-34. 11. Streptognathodus aff. pictus Chernykh, 2005, No U15-35. 12. Streptognathodus praenuntius Chernykh, 2005, (40), No U13-22. 13. Streptognathodus zethus Chernykh et Reshetkova, 1987, No U15-20. 14. Streptognathodus firmus Kozitskaya, 1978, (40), No U15-26. 15, 16. Idiognathodus ex gr. sulciferus Gunnell, 1933: 15 — No U15-5;
16 — No U15-35.
17. Streptognathodus aff. simulator Ellison, 1941, No U15-27. 18. Idiognathodus magnificus Stauffer et Plummer, 1932, (40), No U13-13.
Gzhelian, simulator zone;
bed 4/2. Figure: 20. Streptognathodus gracilis Stauffer et Plummer, 1932, No U14-29. 21. Idiognathodus dolioliformis Chernykh, 2005, holotype No U14-5. 22. Streptognathodus makhlinae Alekseev et Goreva, 2001, No U14-1. 23. Idiognathodus sp., No U14-3, transitional specimen to S. simulator Ellison, 1941. 24. Streptognathodus pictus Chernykh, 2005, No U14-22. 25.
Streptognathodus elegantulus Stauffer et Plummer, 1932, No U14-28. 26, 27. Streptognathodus firmus Kozitskaya, 1978: 26 — No U14-12;
27 — No U14-27.
Plate Figure. Distribution of late Pennsylvanian conodonts in Usolka section Limestone: 1 — micritic;
2 — silty;
3 — dolomitized;
4 — siltstone;
5 — phosphatic concretions (Ros.), R. cybea (Putrja), R. shikhanensis (Ros.), R. dictiophorus (Ros.);
(10.8 mab): Quasifusulina cf. eleganta Schlyk., Rauserites petchoricus (Raus.
and Bel.), R. triangulus (Ros.), R. elongatissimus (Ros.), R. variabilis (Ros.), R. mogutovensis Ros., R. noinskyi (Raus.), R. tjanshanensis (Bensh), R. samaricus (Raus.), R. sphaericus Ros., Daixina rugosa Ros., Schwageriniformis kurshabensis (Bensh), S. perstabilis (Scherb.), S. baisunensis (Bensh), S. fusiformis (Bensh) Bed 11 (16.0 m): Streptognathodus virgilicus Ritter, S. oppletus Ellison, S. pawhuskaensis Harris et Hollingsworth, Idiognathodus sulciferus sulciferus Gunnell.
Bed 12/1 (18.2 m): Streptognathodus vitali Chernykh, S. pawhuskaensis Harris et Hollings worth, S. zethus Chernykh et Reshetkova, Idiognathodus swadei Barrick et Rosscoe, I. aff.
Bed 13/1 (22.8 m): Streptognathodus vitali Chernykh, S. aff. virgilicus Ritter, S. triangularis Chernykh, S. oppletus Ellison, Idiognatodus aff.
lobulatus Kozitskaya, Id. n. sp. 1, Id. n. sp. 2.
Fusulinids: Daixina azantashiensis Dav., D.
enormis Scherb., D. jaikensis Dav., Schellwienia Plate 2 (all figures are 40, except otherwise mentioned) Gzhelian, simulator zone. Figure: 1, 3, 7. Streptognathodus simulator Ellison, 1941: 1 — No U1-5, dextral;
3 — No U1-4, dextral;
7 — No U1-8, sinistral;
bed 4/2. 2. Streptognathodus sinistrum Chernykh, 2005, holotype No U1-9;
bed 4/2. 4. Streptognathodus auritus Chernykh, 2005, holotype No U1-18;
bed 4/2. 5. Idiognathodus n. sp. 2, No U14-24;
bed 4/2. 6. Streptognathodus aff. simulator Ellison, 1941, No U1-26, separation of transverse ridges, without laying the median furrow;
bed 4/2. 8. Streptognathodus aff. luganicus Kozitskaya, 1978, No U1-22, sinistral with poorly developed median furrow;
bed 4/2. 9. Streptognathodus aff. simulator Ellison, 1941, No U1-25, sinistral with pronounced с median furrow;
bed 4/2. 10. Idiognathodus n. sp., No U1-16, dextral with short carinae as in simulator type but without median furrow;
bed 4/2. 11, 12. Streptognathodus auritus Chernykh, 2005: 11 — No U2-15;
12 — No U2-23, dextral with fairly developed median furrow;
bed 5/1. 13. Streptognathodus n. sp. 1, No U2-1;
bed 5/1. 14. Streptognathodus luganicus Kozitskaya, 1978, No U2-5;
bed 5/1. 15. Streptognathodus aff. simulator Ellison, 1941, No U3-4;
bed 7/1. 16. Idiognathodus ex gr. sagittalis Kozitskaya, 1978, No U3-12;
bed 7/1. Gzhelian, vitali zone. Figure: 17. Idiognathodus swadei Barrick et Rosscoe, 2009, (50), No U43-42;
bed 12/1. 18, 21. Stheptognathodus vitali Chernykh, 2002: 18 — No U43-14;
21 — No U 4-16.
19, 20. Streptognathodus ex gr. virgilicus Ritter, 1995: 19 — No U45-3;
20 — No U45-2;
evolutionary advanced forms;
22. Streptognathodus triangularis Chernykh, 2005, No U45-7;
bed 13/1. 23. Streptognathodus oppletus Ellison, 1941, No U45-14;
bed 13/1. 24. Idiognathodus n.sp. 1, No U45-5;
bed 13/1. 25. Idiognathodus n. sp. 2, No U45-15;
bed 13/1. Gzhelian, bellus zone.
Figure: 26. Streptognathodus bellus Chernykh et Ritter, 1997, No U17-2;
bed 14/1. 27. Solkagnathus velivolus Chernykh, 2005, (50), holotype No U17-7;
bed 14/1. 28. Diplognathodus expansus (Perlmutter), 1975, (100), No U17-25;
bed 14/1. 29. Streptognathodus variabilis Chernykh, 2005, No U18-3;
bed 15/1. Gzhelian, wabaunsensis zone. Figure: 30. Streptognathodus longus Chernykh, 2005, No U19-25;
bed 16/1. 31, 32, 34, 35. Streptognathodus wabaunsensis Gunnell, 1933: 31 — No U19-11;
32 — No U19-16;
34 — No U20-2;
35 — No U20-1;
bed 16/2. 33. treptognathodus bonus Chernykh, 2005, holotype No U19-6;
bed 16/ Plate arctica (Schellw.), Sch. biformis (Bensh), Sch. malkovslyi (Ketat), Sch. krushiensis (Alksne), Quasifusulina longissima (Moeller) etc.
Bed 14/1 (24.9 m): Streptognathodus bellus Chernykh et Ritter, S. tenuialveus Chernykh et Ritter, S. longilatus Chernykh et Ritter, Diplognathodus expansus (Plummer), Gondolella kazakhstanica Akhmetshina, Solkagnathus velivolus Chernykh.
Bed 15/1 (29.0 m): Streptognathodus bellus Chernykh et Ritter, S. fissus Chernykh, S. variabilis Chernykh, S. tenuialveus Chernykh et Ritter, S. longilatus Chernykh et Ritter, S. pseudonodatus n. sp.
Fusulinids: Schellwienia cf. ulukensis (Bensh).
Bed 16/1 (30.0 m): Streptognathodus bonus Chernykh, S. acuminatus Gunnell, S. longus Chernykh, S. aff. longilatus Chernykh et Ritter, S. wabaunsensis Gunnell.
Bed 16/2 (30.1 m): Streptognathodus acuminatus Gunnell, S. wabaunsensis Gunnell, S. flangulatus Gunnell, S. rectangulatus Chernykh et Ritter.
Bed 16/3 (32.5 м), First appearance of Streptognathodus isolatus Chernykh, Ritter et Wardlaw, of Lower Asselian, Cisuralian.
1. Beds 2–4/1 belong to Kasimovian;
first appearance of morphotype Streptognathodus zethus in bed 4/1 (5.1 mab) suggest upper Kasimovin.
2. The FAD of St. simulator and therefore the base of the Gzhelian Stage is at 4/2 (4.9 m).
3. Gzhelian divided into following conodont zones: simulator (beds 4/2–10 ?), virgilicus (bed 11), vitali (beds 12–13), bellus (beds14–15), wabaunsensis (beds 16/1–16/2).
References Chuvashov B.I., Djupina G.V., Mizens G.A., Chernykh V.V. Key-sections of the Upper Carboniferous and Lower Permian of the western slope of the Urals and Pre-Urals / Uralian Branch, USSR Academy of Sciences. Sverdlovsk, 1990. 368 p. (In Russian).