Sedimentary and biofacies records in calciturbidites at the Devonian-Carboniferous boundary in Moravia (Moravian-Silesian Zone, Middle Europe)

Summary At the Devonian/Carboniferous boundary, major climatic and oceanographic changes influenced sedimentation on carbonate platforms and in peri-platfrom asreas. Three deep-water carbonate successions in Moravia, which were selected to represent different paleotectonic settings, have been studied with the aim of testing the influence of eustatic, climatic and tectonic controls on sedimentation and conodont paleoecology and taphonomy. On the slopes of the wide carbonate platforms of the Moravian Karst Development (Lesní lom and Grygov sections), an exemplary highstand shedding systems developed in the upper Famennian (expansa Zone), marked by a pronounced thickness of their respective calciturbidite successions and an abundance of shallow-water skeletal grains.Palamatolepis— andBispathodus-dominated conodont assemblages contain an admixture ofPolygnathus representing a transported, near-shore component. The eustatic sea-level fall in the praesulcata Zone and the lowstand conditions at the D/C boundary resulted in a decline of carbonate platform production and condensed deposition or nondeposition. In the Lesní lom section, a condensed sequence of turrbiditic calcarenites and shales (Middle praesulcata—lowermost sulcata Zone) was followed by lime mud calciturbidites (sulcata and duplicata Zones). In the conodont assemblages, the first event in the Lower praesulcata Zone was associated with the reduction of ‘mesopelagic’Palmatopic and a bloom of epipelagicPolygnathus communis. The second event in the Middle praesulcata Zone corresponds to the onset of polygnathidprotogranthodid biofacies, indicating a carbonate slope environment. In the Grygov section, a pronounced thickening and upward-coarsening succession of tubiditic calcilutites through calcarenites and intraclast breccias, with poor palmatolepid-bispathodid connodont assemblages (expansa Zone), indicates a progradation of the calciturbidite system associated with sea-level highstand. After a break in sedimentation, covering the interval from the Lower praseulcata to the base of Lower crenulata Zone, thick-bedded, fine-grained calciturbidites were deposited in the Lower crenulata Zone, and are associated with poor, mixed assemblages where siphonodellids and polygnathids predominate. At the isosticha-Upper crenulata/Lower typicus boundary, coasre grained, turbiditic calcarenites and breccias rich in clastic quartz grains and mixed conodont assemblages with reworked Frasnian and Famennian conodonts indicate a deep erosion of the source area, presumably due totectonic uplift (relative lowstand). In the Jesenec section, on the flanks of the volcanic seamount (the Drahany Development), a deep-water Upper Famennian condensed succession of calciturbidites and presumably winnowed pelagic limestones is marked by conodont assemblages of palmatolepid-bispathodid biofacies. More proximal calciturbidites with mixed deep-water and shallowwater conodonts prograde at the top of the Upper Famennian succession (Middle to Upper expansa Zone). A striking hiatus, covering the interval from the Early preaesulcata to the base of Lower crenulata Zone, resulted from extreme condensation and submarine bottom current erosion due to sea-level lowstand in the late Famennian and early Tournaisian. The renewed middle Tournaisian calciturbidite sedimentation with strong evidence of erosion at the source area indicates global eustatic rise and tectonic uplift of the Drahany Development seamounts (relative lowstand). The earlier occurrence of the uplift in the Jesenec area, relative to the Grygov section, shows the advance of tectonic processes over time in the Moravian-Silesian basin (orogenic polarity) as a consequence of Variscan orogenic movements.     

Famennian conodonts from the Hongguleleng Formation at the Bulongguoer stratotype section,western Junggar,Northwest China

The Hongguleleng Formation, the highest and most important Devonian marine carbonate horizon in western Junggar, contains an endemic shallow-water Icriodus–Polygnathus conodont fauna with rare palmatolepids and other genera. The conodont faunas from the Bulongguoer and the Wulankeshun sections are similar, with high abundance (about 40%) of endemic taxa (13 taxa), indicating isolation of the Junggar Basin during early Famennian. Non-endemic species in the faunas suggest that the Lower Member of the Hongguleleng Formation is assignable to the Pa. rhomboidea Zone to the Pa. marginifera marginifera Zone of early Famennian, not including the Frasnian–Famennian boundary. The Upper Member may be of late Famennian–early Tournaisian in age on the basis of our preliminary faunal analysis.     

A new species of <Emphasis Type="Italic">Pelekysgnathus</Emphasis> (Conodonts) from the Famennian of the east Russian Platform

A new conodont species, Pelekysgnathus aristovi sp. nov., from the Middle Famennian shallow-water carbonate deposits of the South Tatar Dome in the eastern Russian Platform is described.     

华南贵州宾夕法尼亚亚纪牙形类Neognathodus动物群:演化及地层对比意义

以华南斜坡相的罗甸纳庆剖面为代表,我国石炭纪宾夕法尼亚亚纪早–中期地层建立起了基于多个属种的牙形类分带,并可与全球其他地区同期地层进行广泛对比。Neognathodus属是这一时期一类常见的浅水相牙形类分子,在北美、东欧等地的浅水相地层中被广泛用作地层划分对比标志。该属分子在我国北方地区浅水相地层中是重要的带化石分子,而在华南斜坡相剖面中占比非常低。结合现有的生物地层框架,本文厘清了华南贵州罗甸附近3条斜坡相剖面中Neognathodus属分子的延限,尝试利用牙形类P1分子齿台的对称特征将其演化过程归纳为五个阶段,并提出阶段4中对称分子(如:N. bothrops, N. colombiensis, N. nataliae等)的再次出现可作为全球莫斯科阶底界的辅助对比标志。     

Miospores in middle-upper Frasnian to Famennian sediments partly dated by conodonts (Boulonnais,France)

The middle-upper part of the Formation de Beaulieu exposed in the new railroad trench at Caffiers-Ferques and the Formation de Ferques exposed in the Tartinskal quarries contain well-preserved miospore assemblages. They are here restudied in comparison with new conodont data ranging from the middle asymmeyricus to the Ancyrognathus triangularis Zone. The conodonts allow precise correlations with the type Frasnian area as well as with the Russian Platform and Timan-Pechora provinces. The miospore assemblages of the Formation d'Hydrequent are also considered and their age discussed in term of the Frasnian/Famennian boundary.In the systematic part, two new combinations are proposed: Ancyrospora lysii (Taugourdeau-Lantz, 1960) nov. comb., and Pustulatisporites rugulatus (Taugourdeau-Lantz, 1967) nov. comb.     

Cyrtospirifer vjacheslavi, a new cyrtospiriferid species (Cyrtospiriferidae, Brachiopoda) from the Middle Frasnian of the East European Platform

A new spiriferid brachiopod species, Cyrtospirifer vjacheslavi, from the Middle Frasnian of the East European Platform is described. These spiriferide shells from the Middle Frasnian of central European Russia and Middle Timan assigned traditionally to Cyrtospirifer disjunctus for more then a century are not conspecific to British species and are here reassigned to Cyrtospirifer vjacheslavi sp. nov.     

Upper Devonian conodonts of northeastern European Russia

The conodont succession in the Upper Devonian facially different sections of northeastern European Russia (Chernyshev Ridge, Subpolar and Polar Urals, Pai-Khoi) are studied. The sections are subdivided and correlated taking into account the global standards for stages. The Frasnian Montagne Noire zonation (Klapper, 1989) is used for the first time for northeastern European Russia; the authors correlated this zonation with the scale of Ziegler and Sandberg (1990). Famennian deposits are subdivided using scale of Ziegler and Sandberg (1984) and miospore zonation. The age of local geological units (formations) is specified; the formations of different regions of northeastern European Russia are correlated to each other and to the regional subdivisions of EEP and Southern Urals. A total of 93 species of Ancyrodella, Mesotaxis, Palmatolepis, Polygnathus, and Zieglerina are described. Two new species Ctenopolygnathus parallelus sp. nov. and Polygnathus masonae sp. nov. are distinguished and five species are described in the open nomenclature. Special chapter is devoted to the phylomorphogenesis of Ancyrodella.     

Step-wise morphological trends in fluctuating environments: Evidence in the Late Devonian conodont genus Palmatolepis

Long-term morphological changes were investigated in the conodont genus Palmatolepis, using a Fourier analysis of the outline of platform elements. Three time-slices and four Late Frasnian - Early Famennian sections on North Gondwana were studied. No difference existed between locations, but shape variations were recorded associated with the successive Kellwasser events. The Middle Famennian period was analyzed in a section located at the Baltica margin across the annulata event. Some morphological changes may be related to the deposition of the corresponding black shales, but the main feature is a heterogeneity of the populations, which can be split into two morphological types. Latest Famennian conodonts from another North Gondwanan section show only minor shape changes during this time interval, which is environmentally stable prior to the global Hangenberg event. Based on synthetic shape variations across the whole period an morphological trend towards narrower elements is observed. This morphological change happens step-wise in response to global events. The amplitude of the shape shift is proportionally related to the extend of the successive Late Devonian global events.     

Emsian (Lower Devonian) conodonts from the Daliantang Formation at Daliantang,southeastern Yunnan,China

The lower/upper Emsian boundary witnessed prominent diversification of biostratigraphically important genera Polygnathus Hinde, Caudicriodus Bultynck, and Latericriodus Müller. In contrast, conodonts previously reported around this boundary from the South China Block were characterized by relatively low species or subspecies diversity, and only a few widely distributed and extensively studied zone-defining taxa were recorded. In this paper, conodonts from the Daliantang Formation at the Daliantang section (Guangnan, southeastern Yunnan), one of the representative sections of the transitional facies between the benthic Xiangzhou facies and the pelagic Nandan facies, are investigated. The conodont fauna shows a remarkably high species or subspecies diversity, with fourteen taxa that are assignable to the notoperbonus Zone and inversus Zone. Five polygnathid species are described: P. gronbergi Klapper and Jonson, P. inversus Klapper and Jonson, Polygnathus sp. B, P. luciae Martínez-Pérez and Valenzuela-Ríos, and P. mashkovae Bardashev. The latter two are reported for the first time from the South China Block. Additionally, three icriodontid taxa are also described, of which L. guangnanensis n. sp. is characterized by distinctly chevron-shaped transverse rows in the anterior part and a well-developed process branching off to the outer side. The new conodont record increases our understanding of the diversification and faunal composition around the lower/upper Emsian boundary in the South China Block. It contributes to the regional and inter-regional biostratigraphical correlation between shallower- and deeper-water facies and also furnishes important South China material for future discussion and deliberation on the position of the lower/upper Emsian boundary.     

Biostratigraphical correlation of late carboniferous (Kasimovian) sections in the Carnic Alps (Austria/Italy): Integrated paleontological data, facies, and discussion

Summary The fusulinacean faunal content of the Bombaso Fm. and lower part of the Auernig Group (Carnic Alps, Austria/Italy) is reviewed and completed by data on conodonts and algae. Four different faunal associations can be distinguished within this stratigraphic interval. The beginning of the postvariscan sedimentation in the investigated sections is diachronous, shifting in age from early Kasimovian (Krevyakinian) at Zollner Lake and Mt. Auernig, early to middle Kasimovian at Cima Val di Puartis to late Kasimovian (Dorogomilovian) at Mt. Ro?kofel. The sections analyzed consist of shallow-marine sediments, which differ in microfacies of limestones and partly in biotic assemblages. They are geographically isolated and could not be traced laterally for lithologic correlation in the field. The biostratigraphic correlation with the faunas of the stratotype sections in the Moscow Basin is hindered by the searceness of fusulinaceans in the critical levels, especially in the lowermost Kasimovian, and differences in the species composition. A biostratigraphic correlation of the Bombaso Fm. and basal part of the Auernig Group with the Peski Fm. (Myachkovian) of the Moscow Basin, as suggested byDavydov & Krainer (1999), is not confirmed by our results. Due to our taxonomic reinterpretation of the oldest fauna (Protriticites aff.permirus with distinct mural pores and largeBeedeina (Pseudotriticites) asiaticus) a lowermost Kasimovian (Lower Krevyakinian) age is more probable. This correlation is supported by the co-occurring conodont fauna, which is suggested to belong to the zone of “Streptognathodus subexcelsus”. This biozone reaches from the topmost Peski Fm. to the Suvorovo Fm. (Lower Krevyakinian) in the Moscow Basin, and may be correlated with the uppermost Desmoinesian of the Midcontinent North America. Fusulinaceans and conodonts of the overlying strata at Zollner Lake and from the sections at Cima Val di Puartis and Mt. Auernig most probably correspond to the upper Krevyakinian/lowermost Khamovnikian of the Russian platform (Lower Missourian of the Midcontinent North America). The algal associations (Dvinella, Beresella, Herakella) from these lowermost strata are unique for the Carnic Alps. Their stratigraphic range points to Moscovian-Kasimovian as well, and fits with the fusulinacean and conodont data. Sediments of the N?lbling Group (=“untere kalkreiche Schichtgruppe”) have their correlative levels in the upper Khamovnikian, but reach higher into the Dorogomilovian. More reliable correlations are possible with the fusulinacean faunas of the Cantabrian Mts. and Central Asia, based on the coincidence of several species. A revised biostratigraphic correlation with the different remote basins of the Paleotethyan realm and the Russian Platform is given, based on own data and recent results by the members of the SCCS Working group to define a GSSP close to the Moscovian/Kasimovian boundary. The sequence-stratigraphic scheme, the systematics, and the biostratigraphic correlation ofDavydov & Krainer (1999) are discussed.     

Continuing of the revision of Spriferid (Brachiopoda) zonal species from the Frasnian Stage (Upper Devonian) of the Russian Platform

Adolfia siratschoica (Ljaschenko) and Adolfia krestovnikovi (Ljaschenko) are accepted as zonal species of the Petino and Voronezh Horizons of the Frasnian Stage of the Russian Platform. However it was established that these species do not belong to the genus Adolfia. The former species was recognized as the nomenclatural type species of Ljaschenkovia gen. nov. and the latter species was recognized as the type species of Tokmospirifer gen. nov. The comparative analysis provided of the shell structure, microornamentation, and shell interior of the type species of Ljaschenkovia gen. nov., Tokmospirifer brevis gen. et sp. nov., and Adolfia solita Ljaschenko is presented.     

High‐resolution conodont biostratigraphy from the Darriwilian Stage (Middle Ordovician) of the Argentine Precordillera and biodiversity analyses: a CONOP9 approach

Ordovician conodonts have been extensively documented in the Argentine Precordillera, providing a robust database for a diverse set of palaeontological studies. Despite the numerous studies, the published taxonomy and stratigraphical ranges, data remain contradictory for particular time intervals. Data from a new conodont collection from the Gualcamayo Formation exposed at the Cerro La Chilca section, and new information on the occurrence and ranges of species from the Las Chacritas and Las Aguaditas sections are presented herein. We used a computer‐assisted numerical sequencing program (CONOP9) to construct a composite stratigraphical range chart from data of 57 conodont species in four sections from the Argentine Precordillera. The identified zones of Lenodus variabilis, Yangtzeplacognathus crassus, Eoplacognathus pseudoplanus and Eoplacognathus suecicus allowed us to verify and adjust the biostratigraphical scheme for the Darriwilian of the Central Precordillera. Additionally, species of the genera Histiodella, namely Histiodella sinuosa, Histiodella holodentata, Histiodella kristinae and Histiodella bellburnenisis, enable a reasonable correlation between the Histiodella‐based zonation and the Baltoscandian zonation. Conodont diversity is evaluated using conventional measures (total diversity and normalized diversity) and an interval‐free approach with CONOP9 software. Our data show a positive pattern in conodont diversification, increasing rapidly through the L. variabilis to the Y. crassus zones and reaching a peak in the E. pseudoplanus Zone. When analysing diversity fluctuations with respect to the environmental changes within the depositional basin, migrations in and out of the basin related to local sea level fluctuations appear to be an important process driving the conodont diversity pattern in the Precordillera.     

Allometry in Anisian (Middle Triassic) segminiplanate conodonts and its implications for conodont taxonomy

Conodonts are a clade of chordates and are valuable indicator fossils for biostratigraphy. The segminiplanate (neogondolelliform) conodonts represent a major morphological group ranging from upper Carboniferous to Upper Triassic marine sediments. However, the morphological similarity of segminiplanate P₁ elements generates problems for taxonomy, especially in the Permian and Triassic clades. This paper represents the first study of morphological variation in Triassic segminiplanate conodonts using a geometric morphometric approach. The laminar microstructures observed in conodont cross‐sections indicate that, within our analysed specimens, smaller conodonts with fewer laminae are generally from an earlier ontogenetic stage while larger conodonts with more laminae are from a later stage of ontogeny. Using linear regressions between relative warp scores from both upper and lateral views and conodont length, we demonstrate strongly allometric growth patterns for the species Paragondolella bifurcata Budurov & Stefanov. Our results indicate that the species‐group taxon Pg. praeszaboi bystrickyi (Kovacs et al.) is an early growth stage of Pg. bifurcata and thus synonymous. We suggest that the allometry of conodonts should be considered seriously, especially when there are numerous transitional morphologies between large‐ and small‐sized conodonts. Reconstructing the ontogenetic series and using larger‐sized conodonts within the numerous transitional morphologies in the population of a rock sample for the definition of new species are suggested for future studies.     

广西桂林泥盆纪牙形刺组合序列与海平面变化

本文以桂林灵川岩山圩中,晚泥盆世界线剖面,桂林沙河能源疗养院背后信都组－唐家湾组剖面及桂林额头村Ｄ／Ｃ界线剖面的牙形刺资料为基础,结合前人在桂林地区所做的牙形刺生物地层工作,识别出该区中,晚泥盆世牙形刺化石的１６个组合序列,并以此为尺度结合层序地层格架,层序界面及层序中的微相叠加形式,讨论该区中,晚泥盆世高分辨的海平面变化。     

New records of the conodont genus <Emphasis Type="Italic">Polygnathus</Emphasis> from the Lower Famennian of Mugodzhary,Western Kazakhstan

Representatives of the genus Palmatolepis, along with new species of the genus Polygnathus (Po. schinkaryovi sp. nov. and Po. bertchogurensis sp. nov.) are recorded in carbonate deposits of the Burtebayian Formation of the Lower Famennian of Mugodzhary (Western Kazakhstan). They co-occur with Polygnathus polesicus Strelchenko, which is described for the first time in the Lower Famennian of Belarus.     

<Emphasis Type="Italic">Icriodus jejunus</Emphasis>, a new conodont species from the Mosolovian Regional Stage (Middle Devonian,Eifelian Stage) of the Voronezh Anteclise

A new conodont species, Icriodus jejunus sp. nov., from the Mosolovian Regional Stage (Middle Devonian, Eifelian Stage) of the Voronezh Anteclise (central Russian Platform) is described.     

New Frasnian conodonts of the genus Palmatolepis from the Central Tajikistan

New Lower-Middle Frasnian conodonts of the genus Palmatolepis Ulrich et Bassler, 1926 are described from the Kalagach and Kulyali formations of the Sishkat key section of Central Tajikistan. Palmatolepis manzuri sp. nov. descends from Pa. punctata (Hinde) and is an ancestor of Pa. kireevae Ovnatanova, Pa. salibaevi sp. nov., and also of the Pa. rhenana Bischoff branch.     

Uppermost Devonian–Lower Carboniferous conodonts from the Indert Formation in the Shine Jinst area,South Mongolia

In southwestern Mongolia, conodonts from the Indert Formation at its type locality in Shine Jinst were investigated to improve regional and global correlation of the uppermost Devonian–lowermost Carboniferous. The abundance and diversity of the conodont fauna is quite low in general, whereas representatives of Siphonodella, Protognathodus, Pseudopolygnathus, Polygnathus and Bispathodus have been collected from the Indert-Uul section. Five conodont biointervals, from the Bi. costatus-Pr. kockeli Interregnum (ckI) to the Siphonodella sandbergi Zone, could be recognized from the top Heermorit Member and the lower part of the Shombon Member, while the middle and upper parts of the Shombon Member cannot be zoned based on the conodonts. Absence of index fossils Si. sulcata, Pr. kuehni and Pr. kockeli hampered precise recognition of the Devonian–Carboniferous boundary (DCB) at Indert-Uul, but this transition is well delineated by typical uppermost Famennian and Tournaisian conodont assemblages. The DCB is tentatively placed at the base of the Shombon Member, consistent with the lithological boundary and the resuming of carbonate production during the DCB transitional interval.     

On Frasnian ammonoids of the New Siberian Islands

Ammonoids from the basal beds of the Nerpalakh Formation (Lower Frasnian) of Belkovsky Island (New Siberian Archipelago) are systematically studied. Taxonomically, the assemblage studied (Manticoceras insulare sp. nov., Tornoceras typum (Sandberger, 1851), and T. contractum Glenister, 1958) is similar to the Early Frasnian ammonoid assemblage of South Timan, from which its is distinguished by the absence of the genera Timanites and Komioceras. The same beds contain conodonts of the Palmatolepis transitans Zone (= MN 4 Zone of the Montagne Noire standard succession), which allow the correlation of the beds studied with the Timanites keyserlingi and Komioceras stuckenbergi ammonoid zones of South Timan. The Early Frasnian ammonoids could supposedly have entered the region of the New Siberian Archipelago from the southwest at the time of a major transgression, which facilitated the distribution of the genera Manticoceras and Tornoceras. A new species of the genus Manticoceras is described.     

Eustatic trends in conodont diversity across the Frasnian–Famennian boundary in the stratotype area, Montagne Noire, Southern France

Trends in generic diversity of successive conodont communities are analysed in sections of different environmental settings across the Frasnian–Famennian (F–F) boundary in the stratotype area, Montagne Noire, France. The evolution of conodont biofacies and abundances matches the overall pattern already observed in many sections elsewhere in the world and supports the interpretation of an important eustatic sea-level fall during the Upper Kellwasser event. The change from late Frasnian deep-water palmatolepid–polygnathid biofacies to shallower-water polygnathid-icriodid biofacies during the Upper Kellwasser event occurred in all sections studied. The shallowing trend culminated at the end of the Kellwasser Event as indicated by the substantial increase of formerly poorly represented icriodids, whereas palmatolepids concomi-tantly diminished. This event occurred earlier on oxygenated outer platform submarine rises than in oxygen-depleted depressions. The sudden sea-level fall prior to the Frasnian–Famennian boundary was followed, at the beginning of the Famennian, by a deepening trend when palmatolepids dominated again. These changes in conodont generic associations and abundances occurred rapidly and synchronously. As a result, the stratigraphic resolution obtained with the evolution of biofacies is higher: it permits not only a more accurate location of the base of the Upper Kellwasser event in environments where it cannot be distinguished lithologically, but it also allows the recognition of intrazonal gaps.