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INTRODUCTION. This paper presents the data on Late Ordovician conodonts from siliceous and silicious-terrigenous sec- tions of Kazakhstan. In contrast to ...
ISSN 0031-0301, Paleontological Journal, 2009, Vol. 43, No. 11, pp. 1498–1512. © Pleiades Publishing, Ltd., 2009.

Conodonts from the Upper Ordovician Siliceous Rocks of Central Kazakhstan T. Yu. Tolmachevaa, K. E. Degtyarevb, A. V. Ryazantsevb, and O. I. Nikitinac aKarpinsky

Russian Geological Research Institute (VSEGEI), Sredny pr. 74, 199106 Saint Petersburg, Russia e-mail: [email protected] bResearch Organization of the Russian Academy of Sciences, Geological Institute RAS, Pyzhevskii per. 7, 119017 Moscow, Russia e-mails: [email protected]; [email protected] cSatpaev Institute of Geological Sciences, Almaty, Kazakhstan e-mail: [email protected] Received March 10, 2009

Abstract—Several conodont localities of the upper Sandbian Stage are known in siliceous deposits of Central Kazakhstan. All of them produced similar assemblages overwhelmingly dominated by Periodon grandis with insignificant admixture of Scabbardella altipes, Hamarodus europaeus, Pygodus anserinus, Protopanderodus sp., and Drepanodus sp. The main feature of this fauna is in the co-occurrence of H. europaeus and P. grandis, forms characteristic for deep-water facies at shelf or microcontinents margins of temperate and warm-water paleobiogeographic provinces. The Ordovician paleo-oceanic basin of Kazakhstan and southern Urals were parts of the uniform biogeographic area as indicated by similarity of Ordovician conodont assemblages in siliceous deposits of these regions. Key words: conodonts, Ordovician, Kazakhstan. DOI: 10.1134/S0031030109110136

INTRODUCTION This paper presents the data on Late Ordovician conodonts from siliceous and silicious-terrigenous sections of Kazakhstan. In contrast to other regions of the world, nearly all publications on Ordovician conodonts of Kazakhstan are devoted to their finds in siliceous, but not in carbonate rocks. This is partly due to the fact that siliceous deposits whose Ordovician age can be estimated by conodonts only are widespread in Kazakhstan. The other diagnostic organisms are usually extremely rare in siliceous rocks. The majority of local publications considered conodonts as a tool for age determination of siliceous deposits (Gridina and Mashkova, 1977; Kurkovskaya, 1985; Dubinina et al., 1996; Nikitin, 2002). Only few papers provided conodont descriptions and illustrations (Dvoichenko and Abaimova, 1986; Dubinina, 2000; Zhilkaidarov, 1998; Tolmacheva et al., 2004). Another characteristic feature of Kazakhstan is a low content of conodonts in the Lower Paleozoic carbonate rocks. The exception is the Upper Cambrian and Lower Ordovician sequences of the Malyi Karatau Range (Southern Kazakhstan) where conodonts were systematically investigated and described (Dubinina, 2000) in association with other groups of fauna.

More than two hundred of Early and Middle Ordovician conodont localities in Kazakhstan are known at present. Relatively common are the late Middle and early Late Ordovician conodont assemblages with Pygodus anserinus Lamont et Lindström, 1957 and Periodon aculeatus Hadding, 1913. In contrast, occurrences of younger assemblages are very rare and known only in a few sites. About ten specimens of Katian conodonts Eobelodina fornicata (Stauffer, 1935) (= Belodina sp.), Icriodella sp., and Acodus similaris Rhodes, 1955 (=Scabbardella altipes (Henningsmoen, 1948) were found in organogenic Oisui limestones (the Chokpar Formation) of the Dulankara Mountains of the DzhalairNaiman Zone of the Chu-Ili region (Ordovician–Silurian Boundary, 1980). Katian and Hirnantian conodont faunas represented by abundant elements of Belodina compressa (Branson et Mehl, 1933) were found in limestones in the upper parts of the Shundy Formation in the Aktau-Mointy Massif (Besstrashnov et al., 1989). All other publications report only lists of Late Ordovician conodont taxa (Gerasimova et al., 1992; Nikitin et al., 1999; Nikitin, 2002; and others). Some finds of Late Ordovician conodonts remained unpublished but their identifications were used in the regional stratigraphic scheme of Kazakhstan (Decision …, 1991).

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Authors of the present paper recently discovered two new localities of the Upper Ordovician conodonts in cherts of the Erzhan Formation of the Boshchekul’ Zone in the northeast of Central Kazakhstan. In addition, much more material has been collected from siliceous siltstones of the Kyzylkain Group in the southwest of the Chingiz Mountain Range region. Specific Features of Conodont Studies in Siliceous and Silicious-Terrigenous Rocks Methods of conodont studies in siliceous rocks markedly differ from those utilized for limestones. Conodonts from cherts as well as from limestones can be extracted by hydrofluoric acid (Zhilkaidarov, 1998; Obut et al., 2006). However, this common technique is efficient only in case of relatively weakly altered rocks containing conodonts with preserved phosphatic material. But when conodont elements are preserved as cavities or replaced by silica or ferruginous material, this technique is not appropriate. In these preservation cases conodonts can be studied only on bedding plane surfaces, surfaces of rock chips, and in specially prepared translucent thin plates or thin sections. Identification of conodonts in thin sections or on surfaces of rock chips is seriously hampered by lack of three dimensional morphological picture of elements. In addition, insufficient morphological information of elements in most cases is not compensated by their numbers. As a rule, it is impossible to get a more or less rich collection of conodont elements from siliceous rocks, comparable with materials that can be obtained from carbonates. In poor collections the exact determination is possible only for dominant taxa. If present, rare species are usually represented in collections by sporadically occurred elements and in most cases are identified with a certain degree of ambiguity. The accuracy of identification of conodont taxa in Ordovician siliceous deposits is also depends on what conodont taxa are recorded in cherts. The most diagnostic Ordovician conodonts in cherts are S elements of Paracordylodus gracilis Lindström, 1955, Oepikodus evae (Lindström, 1955), and Periodon species. Platform elements of Pygodus are easily can be recognized too. All these species are easily identified even in case of individual finds and are always represented in lists of conodont taxa from Ordovician localities. The Upper Ordovician diagnostic species of Kazakhstan include Periodon grandis (Ethington, 1959) and Hamarodus europaeus (Serpagli, 1967). Conical elements with simple morphology such as S. altipes are much more difficult for determination because it requires a statistically representative sample to judge on the apparatus composition in the found species. Individual Sb and Sd elements of S. altipes are almost indistinguishable from the corresponding elements of the genus Dapsilodus. The same is true for PALEONTOLOGICAL JOURNAL

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Panderodus, which species level determination requires a relatively high number of elements. In general, conodonts collections from siliceous rocks are strongly biased toward complete taxonomic composition of assemblages. But in spite of all problems, the study of conodonts from cherts is unique chance to get information on pelagic fauna in regions distant from areas of carbonate sedimentation and important for precise dating of siliceous sections. Collections of Upper Ordovician conodonts from Kazakhstan are represented by conodont elements in rock chips and thin sections. The most complete collection from the locality on the left bank of the Balga River in the southwestern part of the Chingiz Mountain Range includes more than 100 thin sections. Localities and Taxonomic Composition of Conodont Assemblages At present the Upper Ordovician conodonts in siliceous rocks are known from three structural formational zones of the Dzungarian-Balkhash area in Central Kazakhstan (Fig. 1). In the north Balkhash zone, conodonts of this age were found by M.Z. Novikova, N.A. Gerasimova and L.A. Kurkovskaya in several sites in siliceous siltstones and tuffites of the Zhamanshuruk and Obali formations. The conodont assemblage includes P. grandis, Protopanderodus insculptus (Branson et Mehl, 1933), Protopanderodus aff. varicostatus (Sweet et Bergström, 1962), and Drepanoistodus suberectus (Branson et Mehl, 1933) s.f. (Nikitin, 2001). In the Agadyr Zone, conodonts were collected from jaspers and siliceous siltstones of the upper part of the silicious-basalt Taldyespe Formation. This association includes H. europaeus, P. insculptus, Icriodella superba Rhodes, 1953, Distacodus victrix Moskalenko, 1973 and some other forms in the monoelement nomenclature (Nikitin et al., 1999). In the Tekturmass Zone, Upper Ordovician conodonts P. grandis, D. suberectus, Panderodus gracilis (Branson et Mehl, 1933), Dapsilodus mutatus (Branson et Mehl, 1933), A. similaris, and P. insculptus were collected from the upper part of the Bazarbai and the middle part of the Sarytau Formations (Gerasimova et al., 1992). In addition, rich conodont assemblages were found by one of the authors (T.Yu. Tolmacheva, A.Ya. Kvyatkovskii, and N.A. Afonichev in silicious-tuffaceous sequence of the Kyzylkain Group in the Balga River in southwestern part of the Chingiz Mountain Range (Degtyarev, 1999). The upper part of Kyzylkain Group is represented by 400 m thick sequences of red and brown siliceous siltstones, argillites, and sandstones. Conodonts were found in the most silicified and, therefore, more transparent rock varieties. The Kyzylkain Group is overlain by the Lower Silurian olistostrome sequence of green-colored sandstones and siltstones

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Fig. 1. A. Structural tectonic scheme of Central Kazakhstan. B. Schematic map of tectonic zonation of Paleozoic formations in the northeast of Central Kazakhstan (Mesozoic-Cenozoic cover is removed): (1) Famennian-Carboniferous terrigenous carbonate formations (platform cover); (2) Silurian-Upper Devonian molasse, volcanites and terrigenous. carbonate deposits trans-arc depressions; (3) Devonian volcanites of continental margin; (4)–(11) Early Paleozoic structural. formation zones: (4) Akdym Fm., sialic Precambrian, cherts ( C 3-O2); (5) East Erementau, complex of underwater mountains (V- C1); (6) Ashchikol, volcanic complexes of continental margin (O1–3); (7) Boshchekul’, complexes of island volcanic arches and trans-arc basins ( C1–3), cherts (O1–3), flysch and olistostromes (O3); (8) Kendekty Fm., island-arc complexes (O1–2), (9) Karaaigyr Fm., flysch and molasse (O3–S1); (10) Maikain-Kyzyltau, ophiolites ( C3–K2); (11) Satpak Fm., island-arc volcanites (O1–3); (12) granitoids (PZ2–3); (13) faults dividing zones: a. surface; b. cryptic; (14) other faults. C. Structure of Early Paleozoic formations in Zhel’dyadyr (compiled with the use of materials by Khromykh): (1) Tynkuduk (O3a sˇ ), sandstones, conglomerates, limestones; (2) Erkebidaik and Koskol’ Fms. undivided (O3), sandstones, siltstones, conglomerates, tuffites; (3) Erzhan and Zhel’dyadyr Fms. (O1–3), cherts, tuffaceous siltstones; (4) Olenty Fm. (O1t), andesites and their tuffs; (5) Koyandy Fm. (∏3), sandstones, limestones; (6) Cambrian complexes of island arches and trans-arc basins; (7) faults. D. Structure of Early Paleozoic formations in the Semizbugu Mountain area: (1) Cenozoic deposits; (2) Kurtozek Fm. (D2ef), tuffaceous rocks; (3) Erkebidaik Fm. (O3), terrigenous and tuffaceous flysch; (4) olistostrome (O3); (5–6) Erzhan Fm. (O1–3): (5) limestones, (6) cherts, siliceous tuffites; (7, 8) Erementau Group (V– C1?): (7) tholeiitic basalts, (8) alternating limestones, subalkaline basalts, cherts; (9) faults.

with blocks and large outliers of siliceous siltstones. One of the blocks yielded the conodont assemblage identical to those from the underlying Kyzylkain Group (Degtyarev, 1999). Several years ago, additional study of the Kyzylkain Group sections considerably enlarged the collection of conodonts. Abundant conodont elements show a chaotic orientation in rocks. Rare thin interbeds of siliciclastic sandstones with siliceous matrix are enriched with conodont elements. Elements in these beds are damaged and sorted by size. This association includes P. grandis, S. altipes, Drepanoistodus sp., Protopanderodus sp., and P. anserinus. Elements of P. grandis strongly dominate, making up to 90% of the assemblage. Several tens of elements belong to S. altipes. Drepanoistodus sp. is represented by drepanodiform elements only, Pygodus sp. by two ramiform and one platform element. Recently the authors of this paper found two new localities of the Upper Ordovician conodonts in siliceous rocks of the Erzhan Formation in the Boshchekul’ Zone in the northeast of Central Kazakhstan. The Erzhan Formation has a tectonic contact with the older Vendian-Cambrian volcanogenic formations, which were formed in suprasubduction setting. The Erzhan formation is underlain by tectonized olistostrome enclosing blocks of overlying cherts and limestones with the Upper Cambrian fossils (Ryazantsev, 2005). The Erzhan Formation consists of red and gray siliceous siltstones, red clay jaspers, cherts and siliceous tuffites, siltstones and sandstones. These deposits are from 50 to 300 m thick. At the eastern slope of the Semizbugu Mountain, in 10 m above the base of the Erzhan Formation, siliceous siltstones yielded Pygodus serra (Hadding, 1913), P. aculeatus, Protopanderodus sp., Drepanodus arcuatus Pander, 1856 (determination of L.A. Kurkovskaya) indicating the upper Darriwilian (Ryazantsev, 2005). These conodonts indicate the Middle Ordovician age of the Erzhan formation, which is in agreement with the latest stratigraphic scheme of Kazakhstan (Decision …, 1991). The presence of Middle

Ordovician conodonts in the Erzhan Formation was also confirmed by our study. The Erzhan Formation is overlain by the Erkebidaik Formation up to 800 m thick with basal beds of siliciclastic breccia. Sandstones and siltstones of the Erkebidaik Formation yielded Caradocian graptolites (Nikitin, 1972). The most representatives sections of the Erzhan Formation were studied in two localities. The lower part of the formation exposed on the eastern slope of the Semizbugu Mountain consists of red and wine-colored siliceous siltstones, tuffites sandstones, and rare beds of cherts. Upper parts of the section that was studied in the lower western slope of the Semizbugu Mountain is composed of gray cherts and siliceous siltstones containing P. grandis, S. altipes, and rare elements of Pygodus. Cherts are overlain by a variably thick (up to several m) bed of gray pelitomorphic limestones that in turn is covered by green sandstones of the Erkebidaik Formation. In the north of the Boshchekul’ Zone, the Erzhan Formation was studied in the Zhel’dyadyr gorge located 6 km SSE from the Aksak-Koyandy Mountain. In that locality, gray and white cherts and siliceous tuffites of the Erzhan Formation overlies the island-arc andesites, tuffs and sandstones of the Olenty Formation. The Tremadocian age of the latter formation is proved by the occurrence of fossils in rare carbonate lenses. The Erzhan Formation is overlain by deposits of the Erkebidaik Formation represented by alternating sandstones and siltstones with interbeds of conglomerates and tuffaceous rocks. In the Zhel’dyadyr gorge, the upper parts of the Erzhan Formation contain conodont assemblages dominated by P. grandis. The new conodont records in cherts of the Erzhan Formation allow expanding it age range from the upper part of the Darriwilian to the upper part of the Sandbian (Fig. 2).

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Composition of Conodont Assemblages and Their Age All studied Upper Ordovician conodont assemblages have nearly uniform taxonomic composition with dominance of P. grandis and very low content of PALEONTOLOGICAL JOURNAL

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other species. Among them S. altipes and H. europaeus are determined in association with Protopanderodus and Drepanodus that are not identified to species. Two of the three studied sites yielded rare elements of P. anserinus.

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gracilis teretiusculus

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Regional stratigraphic scheme of Kazakhstan (Resolutions..., 1991; Nikitin, 2002; authors additions) Lithostratigraphic units

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Fig. 2. The stratigraphic scheme of the Upper Ordovician structural formational zones of Kazakhstan, age of formations determined based on conodonts. Gray color marks a possibly narrower stratigraphic interval of the studied assemblages.

Published lists of conodont taxa from the Upper Ordovician of Kazakhstan also include P. grandis and elements of Drepanodus sp. and Protopanderodus sp. (e.g., Nikitin, 2002). The occurrence of other listed species requires a confirmation. Elements of P. gracilis, D. mutates, and D. victrix are very similar in morphology to elements of S. altipes. All of them has a very high and laterally flattened base, and a lateral ridge or groove. In small collections when elements are observed only from one side, they can be incorrectly identified. It is possible that different scholars could refer elements of S. altipes to different species. The same is true for H. europaeus which, except for our records, was found only in a single site in jaspers of the Taldyespe Formation. This species is easily recognized only when P elements are available, whereas S and M elements are nearly identical to corresponding elements of Periodon. All species from the studied localities have a broad stratigraphic range spanning nearly the entire Upper Ordovician. The most long-living taxon is S. altipes which is recorded from the upper part of the Middle Ordovician (Rasmussen, 2001; Dzik, 1994). The first occurrence of P. grandis is reported from the uppermost part of the Sandbian, in the upper part of the Amorphog-

nathus tvaerensis Zone, near to the base of the Diplacanthograptus caudatus Zone (McCracken, 2000; Goldman get al., 2007). First records of H. europaeus are also known from the upper parts of the Sandbian (Agematsu et al., 2007). In northern Europe sections, this species appears only in the Katian time (Dzik, 1994). The three considered species went extinct more or less simultaneously in the second part of the Hirnantian. Representatives of the genera Protopanderodus and Drepanodus were widely distributed during nearly the entire Ordovician. The studied assemblages show the earlier unknown co-occurrence of P. anserinus with P. grandis and H. europaeus. P. anserinus is characteristic for older deposits of the upper Darriwilian and lower Sandbian and usually occurs with P. aculeatus, a species ancestor to P. grandis.The co-occurrence of P. anserinus with younger conodonts can indicate either a reworking or a strongly condensed sedimentation at some time intervals. As elements of P. anserinus were recorded in assemblages from both Erzhan Formation and Kyzylkain Group, it is more probable that P. anserinus has a longer range in oceanic environment, as known for some species in siliceous facies (Tolmacheva and Purnell, 2002).

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Fig. 3. Paleogeographic reconstruction of the southern Hemisphere for the Late Sandbian and Early Katian time (450 Ma) (after Cocks and Torsvik, 2002; Agematsu et al., 2007) with localities of P. grandis ( ) and H. europaeus () (1. this paper (Kazakhstan); 2. Dubinina and Ryazantsev, 2008; 3. Korinevskii and Moskalenko, 1988; 4. Melnikov, 1999; 5. Kanygin et al., 1982; 6. our data (Altai); 7. Tolmacheva and Roberts, 2007; 8. Ortega et al., 2008; 9. McCracken, 2000; 10 Harris et al., 1979; 11. Zhen, Percival, and Farrell, 2003; 12. Wang and Zhou, 1998; 13. Ochard, 1980; 14. Dzik, 1994; 15. Ferretti and Serpagli, 1999; 16. Agematsu et al., 2007; 17. Bergström, 1990).

If the assemblage with P. grandis, S. altipes, and H. europaeus can indicate a wide age range from upper parts of the Sandbian to the end of the Hirnantian, the presence of P. anserinus considerably narrows the corresponding time interval. Therefore, all conodont assemblages, recorded in siliceous rocks of different structural formational zones of Kazakhstan, possibly date to the same interval of the Upper Sandbian. As was long noted by different researchers, Kazakhstan cherts repeatedly yield simultaneous conodont assemblages. The same phenomenon was recognized during conodont studies in terrigenous sequences of North America, where there are two conodont-rich stratigraphic levels in the lower part of the Upper Ordovician, at the boundary interval of the Darriwilian and Sandbian, and in the uppermost part of the Sandbian (Leslie et al., 2006). It is supposed that these levels indicate the highest stands of the ocean with the minimal terrigenous sedimentation (Leslie et al., 2006). The Sandbian–Katian boundary interval slightly lower the base of the Diplacathograptus caudatus Zone in sections of Arkansas and Oklahoma is enriched in conodonts P. grandis, S. altipes, and Amorphognathus tvaerensis Bergström, 1962 (Leslie et al., 2006). Conodonts of this age are also found in siliceous sections of Kazakhstan. PALEONTOLOGICAL JOURNAL

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Paleogeography and Paleoecology of Conodonts in the Late Ordovician of Kazakhstan All three species found in the studied associations, P. grandis, S. altipes, and H. europaeus, have a wide geographic distribution (Fig. 3). S. altipes is recorded on all continents in a wide spectrum of facies from shallow to deep-water ones. It is absent only in the most shallow and warm-water deposits of Central America and Siberia. Though this species, together with H. europaeus, is included in the deep-water biofacies H. europaeus–D. mutatus-S. altipes of the Katian and Hirnantian time, it can also be abundant in older, Sandbian deposits (Dzik, 1994; Ortega et al., 2008). H. europaeus was most widely distributed in the deep-water parts of cold water basins of the North Atlantic province located at relatively high latitudes. This species is the typical representative of the Late Ordovician assemblages of Northern Europe (Ochard, 1980; Dzik, 1994; Ferretti and Serpagli, 1999) though it also occasionally occurs in relatively deep-water deposits of America (Nowlan, 1983; Sweet, 2000). It was also found in Southeast and Northeast Asia (Agematsu et al., 2007; Zhang and Barnes, 2007), in southern China (Bergström, 1990), and in the Ural Mountains (Dubinina and Ryazanzev, 2008) (Fig. 3). P. grandis also occurs on many continents, including America (Bergström and Sweet, 1966; Harris et al., 1979), Canada (McCracken, 2000), Australia

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(Zhen et al., 2003) and northeastern Russia (Zhang and Barnes, 2007). In Russia, it was found in the Ural Mountains (Korinevskii and Moskalenko, 1988; Dubinina and Ryazantsev, 2008), in the Timan-Pechora region (Melnikov, 1999), in northeastern Russia (Tarabukin, 2006), and in Altai (unpublished data T.T.). In the northern Europe, P. grandis is absent; its rare elements were found only in Scotland (Sweet and Bergstrom, 1984; Bergstrom, 1990). Sporadic specimens of this species were also found in marble blocks of the “Upper Allochthone” of the Trondheim area (Tolmacheva and Roberts, 2007). In the latter region, however, the assemblage has a distind character of the Laurentian or Midcontiental biogeographic province, in contrast to the North Atlantic fauna of the other regions of northern Europe. P. grandis occurs nearly in all facies from relatively shallow to deep-water ones. But in contrast with the earlier species of this genus, P. aculeatus, it is more characteristic for more shallow water deposits of the Midcontinental biogeographical province. In comparison with H. europaeus, the geographic distribution of P. grandis is limited to mainly warm-water oceanic and the shelf areas (Fig. 3). In shallow deposits, elements of P. grandis are typically not numerous, whereas it is usually abundant in relatively deep-water sequences (Leslie et al., 2006; McCracken, 2000). In North America, associations with P. grandis are considered as characteristic of the most deep-water facies (Sweet and Bergström, 1984). This species dominate also in the studied siliceous deposits of Kazakhstan. The main feature of the investigated conodont fauna from siliceous deposits of Kazakhstan is in the cooccurrence of H. europaeus and P. grandis. These species do not normally co-occur in the same associations, and reports of their common finds are sporadic and ambiguous (Nowlan, 1983; Sweet, 2000). The exception is known their record in siliceous deposits of Southern Urals (Dubinina and Ryazantsev, 2008). The recently proposed paleobiogeographic conodont zonation defines shallow-sea and open-sea realms subdivided in warm-water, moderately warmwater, and cold water domains (Zhen and Percival, 2003). Based on the benthic fauna similarity (Fortey and Cocks, 2003), and the paleomagnetic data (Collins et al., 2003), Kazakhstan in the Late Ordovician was situated in the equatorial zone and thus belonged to a warm-water region. This is further evidenced by conodont assemblages from relatively shallow-water carbonates of the Middle Darriwilian Naiman Formation of the Chingiz Mountain Ridge. These conodonts have a warm-water appearance and a high degree of endemicity (unpublished data Tolmacheva). At the end of Middle and the beginning of Late Ordovician, the southern port of the east margin of the East European paleocontinent was situated in more southern areas, possibly at 30–45° S. (Cocks and Tors-

vik, 2005, and others). A colder, temperate climate of this region is supported by a cold-water character of shallow conodont communities of the southern Urals (Nasedkina, 1975). Caradocian conodonts from carbonate rocks in southern Urals are poorly studied. The Darriwilian associations include Baltoniodus and Amorphognathus, forms indicative of North Atlantic relatively cold-water biota. On the other hand, conodonts of the Upper Ordovician of Subpolar and Polar Ural belong to Midcontinental warm-water province with the widespread genera Oulodus and Aphelognathus. Conodont associations including both H. europaeus and P. grandis were found only in siliceous deposits of Kazakhstan and south Urals. It can be inferred that these two regions are distinct in the co-occurrence of deep-water species and forms that inhabit more shallow-water settings of shelves of different, warm-water and temperate warm-water paleobiogeographic domains. Similarity of oceanic faunas of Kazakhstan and Urals allows assuming that the Ordovician oceanic biogeography was controlled by very large circulating systems covering different climatic belts. Therefore, the division of deep-water oceanic areas into warmwater, moderately warm-water, and cold-water domains according to climates of adjoining shelves (Zhen and Percival, 2003) is premature. CONCLUSIONS Several localities of the Upper Sandbian conodonts are known in siliceous deposits of Central Kazakhstan. All of them yielded the uniform conodont assemblage with dominating elements of P. grandis and insignificant numbers of S. altipes, H. europaeus, P. anserinus, Protopanderodus sp., and Drepanodus sp. The main feature of this fauna is the co-occurrence of H. europaeus and P. grandis, which is nearly unknown elsewhere, except for the south Urals. The geographic distribution of P. grandis was limited to mainly warmwater areas oceanic and shelves areas, whereas H. europaeus was distributed in the deep-water basins of North Atlantic province situated in relatively high latitudes. The co-occurrence of these species indicates that Ordovician oceanic basins of Kazakhstan and south Urals that were probably located in different climatic zones belonging to a large oceanic biogeographic area. In the siliceous deposits of Kazakhstan, the typical S, P, and M elements of P. grandis are associated with M elements identical to the corresponding elements of the older species P. aculeatus. Many researchers noted that the conodonts from the Upper Ordovician of different regions show wide variations. However, the material available to the authors is not sufficient to assume that in addition to P. grandis there is another species of the same genus.

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M M Fig. 4. Schematic image of elements included in the apparatus of P. grandis.

SYSTEMATIC PALEONTOLOGY Descriptions are given only for the species that are abundant in the collections. The P. anserinus, Protopanderodus sp., and Drepanoistodus sp. are not described as they represented by sporadic specimens only. Protopanderodus sp. is not illustrated due to failure to obtain a quality picture. Conodonts were photographed in thin sections in transmitted light. The conodont collection is deposited in the Chernyshev TsNIGR Museum (Saint Petersburg). Genus Hamarodus Viira, 1974

T y p e s p e c i e s. Distomodus europaeus Serpagli, 1967. C o m m e n t s . It is currently believed that Hamarodus is represented by the single Ordovician species H. europaeus. The existence of other Hamarodus species (Nowlan, 1983; Zhang and Barnes, 2007) is proposed but the number of specimens in collections is usually insufficient to evaluate variability and define stable species characters.

lateral corners of the base. The anterior margin of Sa base is often obscured by the enclosing rock. The M element (Fig. 6f) is geniculate, with a narrow strongly inclined cusp and the antero-posteriorly elongated base. The anterior margin is smooth. The middle ledge of the basal margin is clearly expressed. The P element (Fig. 6j) can be only confidently referred to the genus Hamarodus. This is an angulate to bipennate element with two short processes or elongated and denticulate anterior and posterior margins of the basis. The anterior angle of the basal margin bends laterally. R e m a r k s. Both M and S elements of H. europaeus are relatively well recognized in thin sections, though the most diagnostic are P elements. No typical P elements of H. europaeus were found in the studied material, and the only bipennate element, presumably referred to Hamarodus, has a considerably smaller cusp than typical Hamarodus, and more developed denticulation on posterior and anterior margins.

Hamarodus europaeus (Serpagli, 1967) Fig. 3 f, i, j Distomodus europaeus: Serpagli, 1967, p. 64, pl. 14, figs. 1–6. Hamarodus europeaus: Dzik, 1976, p. 435, text-fig. 36: a–g; 1978, text-fig. 2; Orchard, 1980, p. 21, pl. 4, figs. 22, 25, 29–31; Ferretti, Barnes, 1997, p. 22, 23, pl. 3, figs. 1–14; Ferretti and Serpagli, 1999, p. 226, 228, pl. 2, figs. 1–14; Sweet, 2000, fig. 9-1, 9-2; Agematsu et al., 2007, fig. 12, p. 25–27; Zhang and Barnes, 2007, fig. 7.31–7.37, p. 499–501. Hamarodus brevirameus (Walliser): Dzik, 1994, p. 111, 112, pl. 24, figs. 14–19, text-fig. 31: a.

A recent opinion of J. Dzik that H. europaeus is a younger synonym of Hamarodus brevirameus (Walliser, 1964) (Dzik, 1994) was not supported by a majority of researchers (Ferretti and Serpagli, 1999; Zhang and Barnes, 2007). They conclude that this question cannot be solved prior to the additional study of the material from the type section of Northern Europe that would prove the existence of only one Hamarodus species.

D e s c r i p t i o n . (Fig. 3f, 3i, 3j). The S element is small, with high base and long posterior process with strongly pronounced alternating denticulation. The Sb element (Fig. 6i) has the anterior angle that is bent inward. The Sa element has a rounded edge on antero-

D i s t r i b u t i o n. Outside Kazakhstan the species occurs in Northern Europe (Ochard, 1980; Dzik, 1994; Ferretti and Serpagli, 1999), in America (Sweet, 2000; Nowlan, 1983), Southeast and Northeast Asia (Agematsu et al., 2007; Zhang and Barnes, 2007), in south

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Fig. 5. Periodon grandis Ethington, 1959. Except no. 7/13184 (c) all specimens are from the outcrop 2551, Kyzylkain Group, southwest Pre-Chingiz region. No. 7/13184 (c), from outcrop T702, Erzhan Formation, Semizbugu Mountain. (a) Sc element, no. 5/13184, (×75); (b) Sc element, no. 6/13184, (×65); (c) Sd element, no. 7/13184, (×63); (d) Sd element, no. 8/13184, (×55); (e) Sa element, no. 9/13184, (×80); (f) Sc element, no. 11/13184, (×74); (g) Pb element, no. 10/13184, (×54); (h) Pb element, no. 12/13184, (×75); (j) Pa element, no. 14/13184, (×85); (l) M element, no. 17/13184, (×82); (n) Pa element, no. 18/13184, (×70); (o) M element, no. 19/13184, (×77). ? Periodon grandis bellus Moskalenko, 1988, Kyzylkain Group, outcrop 2551: (i) M element, no. 13/13184, (×60). ? Periodon grandis Ethington, 1959, Kyzylkain Group, outcrop 2551: (k) ?P element, no. 15/13184, (×65); (m) ?P element, 16/13184, (×105).

China (Bergström, 1990), and in Russia (Dubinina and Ryazanzev, 2008). M a t e r i a l. Two Sb, one Sa, one M and one ?P element from cherts of the Kyzylkain Group, Balga River, southwest Pre-Chingiz region. One Sb and one M element from the Erzhan Formation. Semizbugu, Boshchekul’ Zone. Genus Periodon Hadding 1913

T y p e s p e c i e s . Periodon aculeatus Hadding, 1913. R e m a r k s . In the original multielement description, this genus was referred to seximembrate group (Bergström and Sweet 1966), although two years earlier Lindström (1964) showed that the transitional series of S elements of the species Periodon flabellum consists of four morphotypes. Later, it was re-diagnosed as having a semtimembrate apparatus (Stouge, 1984), including Sc, Sb, Sd, and Sa elements (Stouge and Bagnoli, 1988; Rasmussen, 2001). But in S elements series of younger species P. aculeatus and P. grandis often only three morphotypes Sc, Sb and Sa are recognized (Zhen et al., 2004). Two pairs of Sb elements (Armstrong, 1997) are sometimes defined. The most widespread and widely known species of this genus are P. flabellum, P. aculeatus, and P. grandis, with a number of other species described. P. macrodentata (Graves et Ellison, 1941) was discriminated from P. aculeatus (Rasmussen, 2001); P. selenopsis (Serpagli, 1974), from P. flabellum (Stouge and Bagnoli, 1988); P. zgierzensis Dzik 1976 is considered as a transitional form between P. flabellum and P. aculeatus; P. grandis bellus Moskalenko, 1988 is transitional subspecies between P. aculeatus and P. grandis. Later, it was probably described as P. mirnyensis Zhang et Barnes, 2007. The most primitive representative of the genus is P. primus Stouge et Bagnoli, 1988. Periodon grandis (Ethington, 1959) Loxognathus grandis Ethington, 1959, p. 281, pl. 40, fig. 6. Periodon grandis: Bergström and Sweet, 1966, pl. 30, figs. 1– 8, p. 363–365; Melnikov, 1987, pl. XI, figs. 7–11, not 12; Lindström in Klapper et al., 1981, p. 243–244, Periodon: pl. 1, figs. 13–18; McCracken and Nowlan, 1989, p. 1889, Pl. 3, figs. 7–9; Zhang and Chen, 1992, figs. 13–16; Trotter and Webby, 1994, p. 484, Pl. 4, figs. 13, 14, 27, 28; Zhen and Webby, 1995, p. 284, pi. 4, figs. 3, 4; Zhen, Webby, and Barnes, 1999, figs. 8:19, 21, not 20, p. 90; FureyGreig, 1999, p. 310, pi. 2, figs. 21, 22, pl. 3, figs. 1, 2; Melnikov, 1999, pl. 9, figs. 18–26, p. 49; Zhen, Percival, and Farrell, 2003, figs. 6: D–L, p. 41–43; Tolmacheva and Roberts, 2007, figs. G, H; Periodon aff. grandis: McCracken, 2000, pl. 1, fig.14, pl. 2, figs. 28, 29, p. 192–193,

D e s c r i p t i o n . (Figs. 5a–5o). The M element is geniculate with a relatively high triangular base. Basal

margin is convex in it central part. Anterior margin bear small, compact denticles that are larger near the cusp (Fig. 5l). The Pa element is angulate (Fig. 5j). The denticulation is typically equidentate, but there are specimens with an alternative style of denticulation. Pb elements are angulate to bipennate. The Sc element is dolaborate, with anterior margin bearing small densely spaced denticles and denticulate posterior process. Lateral sides are smooth or slightly convex. Denticulation of the posterior process is usually alternative. The Sc element, in comparison with Sd and Sa elements, have a higher base and straighter cusp, which forms larger angle with the posterior process. Denticles on the posterior process of Sc elements are less inclined in comparison with those of Sd and Sa elements (Fig. 5a). The Sa element is alate with a strongly inclined cusp, and denticulate posterior and lateral processes. Denticulation at the distal end of the posterior can be alternative. The Sd element is tertiopedate. It has the inclined cusp, small anterior process that is strongly bent inward and lateral costa or small process on the outer side of the element. The pattern of denticulation of the posterior process is variable, but with the alternative denticulation in most of the specimens (Fig. 5c). All elements show a significant variability in relative height of the base, length of processes, and of the denticulation pattern. All elements, except Sa, have the well developed central ledge at the basal sides. The enclosing rock sometimes obscures the presence of denticles on anterior margin of S elements. R e m a r k s . P. grandis was originally described as Loxognathus grandis s.f. Ethington, 1959. The type specimen of Loxognathus grandis was later considered as Sb element. Etington (1959) described two new formal species, Trichonodella insolita Ethington, 1959 and Eoligonodina magna Ethington, 1959, corresponding to Sa and Sc elements, and Falodus prodentatus (Graves et Ellison, 1941) taken for M element. In the multielement taxonomy, P. grandis was described in 1966 (Bergström and Sweet, 1966). Six elements are included in this species: Loxognathus grandis Ethington, 1959, Trichonodella insolita Ethington, 1959, Eoligonodina magna Ethington, 1959, Falodus prodentatus (Graves et Ellison, 1941), as well as Prioniodina araea Webers, 1966 and Ligonodina tortilis Sweet et Bergstrom, 1962 corresponding to Pa and Pb elements.

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Fig. 6. Scabbardella altipes (Henningsmoen, 1948), all elements are from outcrop 2551, Kyzylkain Group: (a) Sb element, no. 22/13184, (×80); (b) Sb element, no. 23/13184, (×90); (c) Sb element, no. 24/13184, (×88); (d) Sc element, no. 25/13184, (×79); (e) Sc element, no. 26/13184, (×100); (h) Sb element, no. 27/13184, (×230). Hamarodus europaeus (Serpagli, 1967): (f) M element, no. 1/13184, (×75); (i) ?Sb element, no. 2/13184, (×80); (j) P element, no. 3/13184, (×55). Drepanodus sp.: (g) Sc element, no. 4/13184, (×60). Pygodus anserinus Lamont and Lindström, 1957: (k) P element, no. 20/13184, (×120); (l) Sa element, no. 21/13184, (×200).

Though P. grandis is one of most easy identifieble species of the Late Ordovician, there is still no clear concept of its apparatus composition. One of the main problems is in extremely variable morphology of geniculate M elements co-occurring with typical S elements of P. grandis. It is worth noting that geniculate or falodiform M elements with typically large triangular

base and relatively flat basal and short anterior margins bearing compact denticles, are justifiably considered to be the most diagnostic element of the species (Bergström and Sweet, 1966). But as was repeatedly noted, the described characters of M elements, as direct basal and relatively short anterior margin, are characteristic only for part of gen-

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iculate elements co-occurring with S and P elements of P. grandis. Quite often typical grandis M elements cooccur with M elements showing strongly elongated denticulate anterior margin and posteriorly extended base, that is bearing characters of the older species P. aculeatus (Kennedy et al. 1979; Melnikov, 1999; Zhang and Barnes, 2007). The presence of transitional forms with a short denticulate anterior margin and strongly elongated posterior one is frequently observed too (McCracken, 2000). Basal margin in morphologically typical M elements of grandis can be also convex that is most strongly pronounced in P. aculeatus (Zhen and Webby, and Barnes, 1999; Zhen, Percival, and Farrell, 2003). The co-occurrence of aculeatus M elements and typical grandis S elements with alternative denticulation is known in many regions, including the Ural Mountains and northeast of Russia (Moskalenko in Korinevskii and Moskalenko, 1988; Tarabukin, 2006; Zhang and Barnes, 2007). Some researchers interpreted these observations as an indication of another species, parallel with P. grandis, in the upper parts of the Ordovician (Nowlan, 1983; McCracken, 2000; Sweet, 2000). But it was also supposed that P. aculeatus and P. grandis could coexist during a long interval of time, forming a mixed assemblage (Bergström and Sweet, 1966; Kennedy et al., 1979). The conodonts collection from the Kyzylkain Group frequently contains both typical aculeatus geniculate elements (Fig. 5i) and typical grandis elements (Fig. 5l). In addition, transitional forms with shortened anterior margin (Fig. 5o) also occur. Grandis elements prevail, accounting for approximately 70% of the overall number of geniculate elements. The collection of P. grandis from Gorny Altai contains all four S elements (unpublished data T.T.). Elements with the laterally bent anterior margin and the expressed ridge on other lateral side are referred to Sb, and forms with anterolateral position of the anterior margin and with a short ridge/process, to Sd elements. Series of S elements from Kazakhstan sites contain only Sc, Sd, and Sa elements (Fig. 4). No unambiguous Sb elements have been recognized because it is difficult to seen in thin sections the degree of lateral inflection of the anterior margin. Among S elements there are forms with more (Fig. 5a) or less strongly pronounced alternative denticulation. Sometimes the cusp and the largest denticle of the posterior process are divided by 7–8 relatively uniform denticles. The alternative denticulation is generally better expressed in Sc, than in Sa and Sd elements. Elements with the completely preserved distal part of the posterior process are common in cherts. This part is nearly always broken in conodonts extracted from carbonates. There are also Sd elements without alternative denticulation in the anterior part of the process, but it is perfectly expressed in its distal part (Fig. 5c). PALEONTOLOGICAL JOURNAL

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The presence of aculeatus M elements in the Upper Ordovician of Kazakhstan cannot be interpreted as a survival of P. aculeatus as no typical S elements of aculeatus were found. On the other hand, there is also no evidence of a co-existence of P. grandis and other forms, in particular, P. grandis bellus Moskalenko, 1988. In the studied collections, continuous morphotype transition of M elements from grandis to aculeatus is observed. It somewhat contradicts the idea of the two species coexistence. This problem can be addressed in future in case of extensive collections of P. grandis. In this study we consider P. grandis sensu lato, as a species including M elements of various morphotypes. The collection contains some specimens questionably referred to ?P elements (Figs. 5k, 5l). These are dolaborate with straight short cusp and the posterior process bearing 5–6 large and wide denticles. The anterior margin is smooth. The base has slightly inflated lateral sides and ledges at the basal margin. Similar elements found in southeastern Australia were referred to ?Sd elements (Zhen et al., 2003). The presence of these elements also confirms a possible co-occurrence of P. grandis with another species of the same genus. D e s t r i b u t i o n . Outside Kazakhstan, it occurs in Canada and North America (Harris et al., 1979; McCracken and Nowlan, 1989; McCracken, 2000; Sweet, 2000), South America (Ortega et al., 2008), Europe (Bergström, 1990), Australia (Zhen et al., 2003; Trotter and Webby, 1994; Zhen, Webby, and Barnes, 1999; Fowler and Iwata, 1995), China (Wang and Zhou, 1998), and in Russia (Kanygin et al., 1982; Melnikov, 1999; Korinevskii and Moskalenko, 1988; Dubinina and Ryazantsev, 2008). M a t e r i a l . Thirty nine Sc, fifteen Sd, eight Sa, twenty eight P and four ?P elements from cherts of the Kyzylkain Group, Balga River, southwest of the PreChingiz area. Ten Sc, five Sd, two Sa, and five P elements from the Erzhan Formation, Semizbugu, Boshchekul’ zone. Seven Sc, three Sd, and one Pa element came from Zhel’dyadyr gorge, the Erzhan Formation, Boshchekul’ Zone. Genus Scabbardella Orchard, 1980 Scabbardella altipes (Henningsmoen, 1948)

Ty p e s p e c i e s . Drepanodus altipes Henningsmoen, 1948. Drepanodus altipes: Henningsmoen, 1948, pl. 25, fig. 14, p. 420. Acodus similaris Rhodes: Hamar, 1966, pl. 2, figs. 3-9, 13, textfig. 4, p. 48–50; Serpagli, 1967, pl. 7, figs. 1–10, p. 14–16. Scabbardella altipes: Orchard, 1980, 26, pl. 5, figs. 2–5, 7, 8, 12, 20, 23, 24, 28, 30, 33, 35, text-fig. 4, p. 25: c; Dzik, 1994, p. 64, 66, pl. 11, figs. 36–39, text-fig. 6: e; Ferretti and Barnes, 1997, p. 34, pl. 1, figs. 17–22; Leslie, 2000, fig. 3:36, 3:37; Sweet, 2000, fig. 9:14, 9:15; Zhang and Barnes, 2007, fig. 8:16–8:20, p. 505; Agematsu et al., 2008, fig. 11 : 4, 8–10, 12–17, p. 29–31.

D e s c r i p t i o n . (Fig. 6 a–6e, 6h). Only Sc and Sb elements of this species were found. All elements are coniform with keeled anterior and posterior margins.

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Lateral sides of Sc elements are smooth. Lateral sides of Sb elements bear a keel running to the basal margin. R e m a r k s . No forms with keels on both lateral sides have been found in the studied association from siliceous deposits of the Erzhan Formation and Kyzylkain Group. Though Sc elements are well seen in siliceous rock, the presence of a keel on one or both lateral sides is difficult to observe. In transmitted light, ridges can obscure each other, and in the reflected light, the opposite side of a conodont element is often not visible. D i s t r i b u t i o n . This species has a cosmopolitan distribution and occurs in variable numbers in different facies deposits of the late Ordovician. M a t e r i a l . Seven elements from cherts of the Kyzylkain Group, Balga River, Southwest Pre-Chingiz region. Four elements, from the Erzhan Formation, Semizbugu, Boshchekul’ zone. One element, from Zhel’dyadyr, the Erzhan Formation, Boshchekul’ zone. ACKNOWLDGMENTS This work was supported by the Program of the Department of Earth Sciences, Russian Academy of Sciences no. 10 and the Russian Foundation for Basic Research, project no. 06-05-65311. REFERENCES 1. A Geologic Time Scale 2004, Ed. by F. M. Gradstein, J. G. Ogg, and A. G. Smith (University Press, Cambridge, 2004). 2. S. Agematsu, K. Sashida, S. Salyapongse, and A. Sardsud, “Ordovician Conodonts from the Satun Area, Southern Peninsular Thailand,” J. Paleontol. 81 (1), 19– 37 (2007). 3. A. I. Antoshkina, N. Ya. Antsygin, T. M. Beznosova, et al., Reference Sections of the Upper Ordovician and Lower Silurian of the Subpolar Urals (Komi Fil. Akad. Nauk SSSR, Syktyvkar, 1987) [in Russian]. 4. H. A. Armstrong, “Conodonts from the Ordovician Shinnel Formation, Tweeddale Member (Middle Ordovician), Southern Uplands, Scotland,” Palaeontology 40, 763–797 (1997). 5. S. M. Bergström, “Relations between Conodont Provincialism and the Changing Palaeogeography during the Early Palaeozoic,” Mem. Geol. Soc. London, 12, 105– 121 (1990). 6. S. M. Bergström and W. C. Sweet, “Conodonts from the Lexington Limestone (Middle Ordovician) of Kentucky and Its Equivalents in Ohio and Indiana,” Bull. Am. Paleontol. 50 (229), 271–441 (1966). 7. V. M. Besstrashnov, N. A. Gerasimova, and L. A. Kurkovskaya, “Stratigraphy of the Ordovician Aktau–Mointy Uplift,” in Stratigraphy of the Paleozoic of Kazakhstan (Kaz. Inst. Mineral. Syr’ya, Alma-Ata, 1989), pp. 68— 77 [in Russian]. 8. L. R. M. Cocks and T. H. Torsvik, Earth Geography from 500 to 400 Million Years Ago: A Faunal and Palaeomagnetic Review,” J. Geol. Soc. London 159, 631–644 (2002).

9. A. Q. Collins, K. E. Degtyarev, N. M. Levashova, et al., “Early Paleozoic Paleomagnetism of East Kazakhstan: Implications for Paleolatitudinal Drift of Tectonic Elements within the Ural Mongol Belt,” Tectonophysics 377, (3–4), 229–247 (2003). 10. K. E. Degtyarev, Tectonic Evolution of the Early Paleozoic Active Margin in Kazakhstan (Nauka, Moscow, 1999) [in Russian]. 11. S. V. Dubinina, Conodonts and Zonal Stratigraphy of the Cambrian–Ordovician Boundary Beds: Proceedings of the Geological Institute of the Russian Academy of Sciences, Issue 517 (Nauka, Moscow, 2000) [in Russian]. 12. S. V. Dubinina and A. V. Ryazantsev, “Conodont Stratigraphy and Correlation of the Ordovician Volcanogenic and Volcanogenic Sedimentary Sequences in the South Urals,” Russ. J. Earth Sci. 10, (ES5001), 1–31 (2008). 13. S. V. Dubinina, A. R. Orlova, and L. A. Kurkovskaya, “Co-Occurrences of Conodonts and Graptolites in the Cherty Terrigenous Sequences of the Lower Ordovician of Northern Betpak-Dala (Kazakhstan),” Byull. Mosk. Ob-va Ispyt. Prir., Otd. Geol. 71 (5) (1996). 14. N. K. Dvoichenko and G. A. Abaimova, “Conodonts and Biostratigraphy of the Cherty Volcanogenic Sequences of the Lower Paleozoic of Central Kazakhstan,” in Microfauna and Biostratigraphy of the Phanerozoic of Siberia and Adjacent Regions: Proceedings of the Institute of Geology and Geophysics of the Academy of Sciences of the USSR, Issue 651 (Novosibirsk, 1986), pp. 160–178 [in Russian]. 15. J. Dzik, “Conodonts of the Mójcza Limestone: Ordovician Carbonate Platform Ecosystem of the Holy Cross Mountains,” Palaeontol. Pol., No. 53, 43–128 (1994). 16. A. Ferretti and C. R. Barnes, “Upper Ordovician Conodonts from the Kalkbank Limestone of Thuringia, Germany,” Palaeontology 40 (1), 15–42 (1997). 17. A. Ferretti and E. Serpagli, “Late Ordovician Conodont Faunas from Southern Sardinia, Italy: Biostratigraphic and Paleogeographic Implications,” Boll. Soc. Paleontol. Italiana 37 (2–3), 215–236 (1999). 18. R. A. Fortey and L. R. M. Cocks, “Palaeontological Evidence Bearing on Global Ordovician–Silurian Continental Reconstructions,” Earth Sci. Rev. 61, 245–307 (2003). 19. T. J. Fowler and K. Iwata, “Darriwilian–Gisbornian Conodonts from the Triangle Group, Triangle Creek Area, New South Wales,” Austral. J. Earth. Sci 42, 119– 122 (1995). 20. T. Furey-Greig, “Late Ordovician and Silurian Conodonts from the ‘Uralba Beds’ East of Manilla, New South Wales,” Alcheringa 23 (1), 83—99 (1999). 21. N. A. Gerasimova, M. Z. Novikova, L. A. Kurkovskaya, and A. S. Yakubchuk, “New Data on the Stratigraphy of the Lower Paleozoic Tekturmas Ophiolitic Belt,” Byull. Mosk. Ob-va Ispyt. Prir., Otd. Geol. 67 (3), 60–76 (1992). 22. D. Goldman, S. A. Leslie, J. Nõlvak, and S. Young, “The Black Knob Ridge Section, Southeastern Oklahoma, USA: The Global Stratotype-Section and Point (GSSP) for the Base of the Katian Stage of the Upper Ordovician Series: The Global Ordovician and Silurian, Proceedings,” Acta Palaeontol. Sin. 46, 144–154 (2007).

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CONODONTS FROM THE UPPER ORDOVICIAN SILICEOUS ROCKS 23. N. M. Gridina and T. V. Mashkova, “Conodonts in the Cherty Terrigenous Sequences of the Atasu Anticlinorium,” Izv. Akad. Nauk Kaz SSR, Ser. Geol., No. 6, 47– 48 (1977). 24. G. Hamar, Preliminary Report on Conodonts from the Oslo-Asker and Ringerike Districts,” Norsk Geol. Tidsskrift 46, 27–83 (1966). 25. A. G. Harris, S. M. Bergström, R. L. Ethington, and R. J. Ross, Jr., “Aspects of Middle and Upper Ordovician Conodont Biostratigraphy of Carbonate Facies in Nevada and Southeast California and Comparison with Appalachian Successions, Brigham Young Univ. Geol. Studies 26 (3), 7–43 (1979). 26. G. Henningsmoen, “The Tretaspis Series of the Killatorp Core,” Bull. Geol. Inst. Univ. Uppsala 32, 374–432 (1948). 27. A. V. Kanygin, T. A. Moskalenko, A. G. Yadrenkina, et al., Ordovician of the Siberian Platform: The Reference Section on the Kulyumbe River, Ed. by B. S. Sokolov (Nauka, Moscow, 1982) [in Russian]. 28. D. J. Kennedy, C. R. Barnes, and T. T. Uyeno, “A Middle Ordovician Conodont Faunule from the Tetagouche Group, Camel Back Mountain, New Brunswick,” Can. J. Earth Sci. 16, 540—551 (1979). 29. G. Klapper, M. Lindström, and W. C. Sweet, Catalogue of Conodonts. Volume IV (Schweizerbart, Stuttgart, 1981). 30. V. G. Korinevskii and T. A. Moskalenko, “Ashgillian Conodonts in the Southern Ural Mountains,” in Fauna and Stratigraphy of the Paleozoic of Central Siberia and the Ural Mountains: Proceedings of the Institute of Geology and Geophysics of the Academy of Sciences of the USSR, Issue 718 (Nauka, Novosibirsk, 1988), pp. 113–126 [in Russian]. 31. V. G. Korinevskii, M. K. Apollonov, and T. A. Moskalenko, “Find Upper Ordovician Deposits on Southern Urals,” Dok. Akad. Nauk SSSR 291 (5), 1196–1199 (1986). 32. L. A. Kurkovskaya, “Conodont Assemblages from the Cherty and Cherty Volcanogenic Sequences of the Ordovician of Central Kazakhstan,” in Geology of the Early Geosynclinal Complexes of Kazakhstan (Mosk. Gos. Univ., Moscow, 1985), pp. 164—177 [in Russian]. 33. S. A. Leslie, “Mohawkian (Upper Ordovician) Conodonts of Eastern North America and Baltoscandia,” J. Paleontol. 74 (6), 1122—1147 (2000). 34. S. A. Leslie, D. Goldman, J. E. Repetski, and J. Maletz, “Sea-Level Control on the Concentration of Ordovician Conodonts from Deep-Water Siliciclastic Settings,” in Pander International Conodont Symposium. Leicester. Abstract Volume (2006), p. 53. 35. M. Lindström, Conodonts (Elsevier Publ. Company, 1964). 36. A. D. McCracken and G. S. Nowlan, “Conodont Paleontology and Biostratigraphy of Ordovician Carbonates and Petroliferous Carbonates on Southampton, Baffin, and Akpatok Islands in the Eastern Canadian Arctic,” Can. J. Earth Sci. 26, 1880–1903 (1989). 37. A. D. McCracken, “Middle and Late Ordovician Conodonts from the Foxe Lowland of Southern Baffin Island, Nunavut,” in Geology and Paleontology of the Southeast Arctic Platform and Southern Baffin Island, PALEONTOLOGICAL JOURNAL

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2009

1511

Ed. by A. D. McCracken and T. E. Bolton, Geol. Surv. Canada Bull. 557, 159–216 (2000). S. V. Mel’nikov, Conodonts of the Ordovician and Silurian of the Timan–Northern Urals Region (Izd. Kartfabriki VSEGEI, St. Petersburg, 1999) [in Russian]. V. A. Nasedkina, “On Ordovician Conodonts of the Western Slope of the Ural Mountains,” in New Miospores, Foraminifers, Ostracodes, and Conodonts of the Paleozoic and Mesozoic of the Urals: Proceedings of the Institute of Geology and Geochemistry of the Uralian Division of the Academy of Sciences of the USSR, Issue 119 (1975), pp. 110–135 [in Russian]. I. F. Nikitin, Ordovician of Kazakhstan: Part 1. Stratigraphy (Nauka, Alma-Ata, 1972) [in Russian]. I. F. Nikitin, “On the Ordovician Cherty Volcanogenic Sequences of the Northeastern Lake Balkhash Area,” Kaz. Geol., No. 1, 1–9 (2001). I. F. Nikitin, “Ordovician Cherty and Cherty Basaltic Complexes of Kazakhstan,” Geol. Geofiz. 43 (6), 512– 527 (2002). I. F. Nikitin, A. M. Zhilkaidarov, Yu. P. Nenashev, et al., “Ordovician Cherty Volcanogenic Complex of the Zhaman–Sarysu Anticlinorium (Central Kazakhstan),” Kaz. Geol., No. 3, 19–30 (1999). G. S. Nowlan, “Biostratigraphic, Paleogeographic, and Tectonic Implications of Late Ordovician Conodonts from the Grog Brook Group, Northwestern New Brunswick,” Can. J. Earth Sci. 20, 651—671 (1983). O. M. Obut, M. M. Buslov, K. Iwata, and F. I. Zhimulev, “Timing of the Collision between the Kokchetav Massif and the Stepnyak Island Arc Based on Conodonts and Radiolarians from Siliceous Rocks of Superimposed Terranes of Different Geodynamic Settings,” Geol. Geofiz. 47 (4) 455–462 (2006). M. J. Orchard, “Upper Ordovician Conodonts from England and Wales,” Geologica et Palaeontologica 14, 9–44 (1980). Ordovician–Silurian Boundary in Kazakhstan (Nauka, Alma-Ata, 1980) [in Russian]. G. L. Ortega, A. L. Albanesi, and G. L. Peralta, High Resolution Conodont–Graptolite Biostratigraphy in the Middle–Upper Ordovician of the Sierra de La Invernada Formation (Central Precordillera, Argentina),” Geol. Acta 6 (2), 161–180 (2008). J. A. Rasmussen, Conodont Biostratigraphy and Taxonomy of the Ordovician Shelf Margin Deposits in the Scandinavian Caledonides: (Fossils and Strata, No. 48) (Blackwell Publ., Oxford, 2001). Resolutions of III Kazakhstan Stratigraphical Conference on the Precambrian and Phanerozoic: Part 1. Precambrian and Paleozoic (Alma-Ata, 1991) [in Russian]. A. V. Ryazantsev, “Structural Zoning of the Lower Paleozoic Complexes in the Boshchekul Island-Arc System in Northeast-Central Kazakhstan,” in Studies of Regional Tectonics, Vol. 2: Kazakhstan, Tien Shan, Polar Urals (Nauka, Moscow, 2005), pp. 5–39 [in Russian]. T. J. M. Serpagli, “I conodonti del’Ordoviciano Superiore (Ashgilliano) delle Alpi Carniche,” Boll. Soc. Paleontol. Italiana 6, 30—111 (1967).

1512

TOLMACHEVA et al.

53. S. Stouge, Conodonts of the Middle Ordovician Table Head Formation, Western Newfoundland: (Fossils and Strata, No. 16) (Blackwell Publ., Oxford, 1984). 54. S. Stouge and G. Bagnoli, “Early Ordovician Conodonts from Cow Head Peninsula, Western Newfoundland,” Palaeontogr. Italica 75, 89–179 (1988). 55. W. C. Sweet, “Conodonts and Biostratigraphy of Upper Ordovician Strata Along a Shelf to Basin Transect in Central Nevada,” J. Paleontol. 74 (6), 1148–1160 (2000). 56. W. C. Sweet and S. M. Bergström, “Conodont Provinces and Biofacies of the Late Ordovician,” Geol. Soc. Am. Spec. Pap. 196, 69–87 (1984). 57. V. P. Tarabukin, Biostratigraphy and Conodonts of the Ordovician Deposits of Northeastern Asia (Yakutsk. Nauchn. Tsentr Sib. Otdel. Ross. Akad. Nauk, Yakutsk, 2006). 58. T. Tolmacheva and M. Purnell, “Apparatus Composition, Growth, and Survivorship of the Lower Ordovician Conodont Paracordylodus gracilis Lindström, 1955,” Palaeontology 45 (2), 209–228 (2002). 59. T. Ju. Tolmacheva and D. Roberts, “New Data on Upper Ordovician Conodonts from the Trondheim Region, Central Norwegian Caledonides,” Norges Geol. Undersøkelse Bull., No. 447, 5–15 (2007). 60. T. Tolmacheva, L. Popov, I. Gogin, and L. Holmer, “Conodont Biostratigraphy and Faunal Assemblages in Radiolarian Ribbon-Banded Cherts of the Burubaital Formation, West Balkhash Region, Kazakhstan,” Geol. Mag. 141 (6), 699–715 (2004). 61. J. Trotter and B. D. Webby, “Late Ordovician Conodonts from Malongulli Formation, Cliefden Caves Area, Central New South Wales,” AGSO J. 15, 474–494 (1995).

62. Z. H. Wang and T. R. Zhou, “Ordovician Conodonts from Western and Northeastern Tarim and Their Significance,” Acta Palaeontol. Sin. 37 (2), 173–193 (1998). 63. Sh. Zhang and C. R. Barnes, “Late Ordovician to Early Silurian Conodont Faunas from the Kolyma Terrane, Omulev Mountains, Northeast Russia, and Their Paleobiogeographic Affinity,” J. Paleontol. 81 (3), 490–512 (2007). 64. J. H. Zhang and M. J. Chen, “Evolutionary Trends and Stratigraphic Significance of Periodon,” Acta Micropalaeontol. Sin. 9 (4), 391–396 (1992). 65. Y. Y. Zhen and B. D. Webby, “Upper Ordovician Conodonts from the Cliefden Caves Limestone Group, Central New South Wales, Australia,” Cour. Forschungsinst. Senckenb. 182, 265–305 (1995). 66. Y. Yi. Zhen and I. G. Percival, “Ordovician Conodont Biogeography—Reconsidered,” Lethaia 36 (4) 357–369 (2003). 67. Y. Y. Zhen, B. D. Webby, and C. R. Barnes, “Upper Ordovician Conodonts from the Bowan Park Group, New South Wales, Australia,” Geobios 32, 73–104 (1999). 68. Y. Y. Zhen, I. G. Percival, and J. R. Farrell, “Late Ordovician Allochthonous Limestones in Late Silurian Barnby Hills Shale, Central Western New South Wales,” Proc. Linnean Soc. New South Wales 124, 29–51 (2003). 69. Y. Y. Zhen, I. G. Percival, and B. D. Webby, “Conodont Faunas from the Mid to Late Ordovician Boundary Interval of the Wahringa Limestone Member (Fairbridge Volcanics), Central New South Wales,” Proc. Linnean Soc. New South Wales 125, 141–164 (2004). 70. A. Zhylkaidarov, “Conodonts from Ordovician Ophiolites of Central Kazakhstan,” Acta Palaeontol. Pol. 43 (1), 53–68 (1998).

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2009