A NEW DATA ON UPPER ORDOVICIAN CONODONTS FROM THE GURYANOVKA FORMATION, NORTHEAST OF GORNY ALTAI

The detailed study of the Guryanovka Formation key sections at the northeast of Gorny Altai (Biya and Bura sections) for the first time revealed the representative collection of conodonts. The conodont fauna is composed of 12 species belong to 9 genera: Belodina compressa (Branson and Mehl, 1933), Phragmodus undatus Branson and Mehl, 1933, Panderodus gracilis (Branson and Mehl, 1933), Panderodus acostatus (Branson, Branson, 1947), Tasmanognatus careyi Burret, 1979, Aphelognathus sp., Panderodus sp., Drepanoistodus sp., Drepantodus sp., Colaptoconus sp., Paltodus sp., Scandodus sp. For the first time, the precise position of the P. undatus conodont Zone was defined in Gorny Altai (continuous Biya Section, base of unit 3).

Sequence composition of the Izyayu Formation (Upper Devonian–Lower Carboniferous) in the type area – the south of Tchernyshev Uplift

Research subject. The article considers the Famennian‑Tournaisian sequence of the South-Eastern part of the Tchernyshev Uplift (North Cis-Uralian). The sequence corresponds to the Izyayu Formation.Materials and methods. The article is focused on the clarification of the stratigraphy, composition and depositional environment of this formation. Research data about the Izyayu Formation in the type area (Izyayu River) were used. The stratigraphic framework of this study included data on conodonts, foraminifers and carbonate carbon isotopic shifts.Results. In the type area under study, the Izyayu Formation corresponds to the interval from the upper part of the Famennian (upper part of the Palmatolepis marginifera utahensis conodont Zone) up to the middle part of the Tournaisian (Lower crenulata conodont Zone). The formation is 100– 120 m thick. The Izyayu Formation grades to the upper part of the deep-water Syvyu Formation in the east, and to the shallow-water Kamenka Formation and the lower part of the Ydzhid Formation. The areal of the Izyayu Formation comprises the South-Eastern part of the Tchernyshev Uplift. The Formation was deposited in the environment of a gentle prograding slope of a carbonate platform.Conclusions. The Izyayu Formation in the type area is composed of thin clayey-carbonate graded cycles. It covers the stratigraphic interval from the Zelenets Regional Stage through the Tcherepet Regional Stage. This formation is easily distinguishable by lithological features in outcrops and borehole cores.

Lower Famennian (Upper Devonian) rhynchonellide and athyride brachiopods from the South Armenian Block

The lower Famennian ‘Cyrtospirifer’ orbelianus brachiopod Zone established in Armenia by Abrahamyan (1957) (coeval to the crepida conodont Zone) contains an abundant and diverse brachiopod fauna that still remains poorly studied. In an effort to revise and update its systematic classification and to assess the brachiopod diversity in this area after the Kellwasser extinction event at the end of the Frasnian, our attention is here focused on rhynchonellides and athyrides. Six rhynchonellide species are described belonging to five genera as well as a single athyride species (Crinisarina pseudoglobularis n. sp.), which is new to science. The genus Crinisarina is reported for the first time in the South Armenian Block (SAB), which was then part of the northern margin of Gondwana. Some of the rhynchonellides identified were previously recognized in this area, but they require modern documentation and taxonomic reassessment. More particularly, it is the first time that the internal structure of Sartenaerus baitalensis (Reed, 1922) is illustrated, taking into account that it is the type species of a biostratigraphically significant Famennian genus. One of the oldest punctate rhynchonellide species, Greira transcaucasica Erlanger, 1993, is described for the first time from Armenia and its intraspecific morphological variability is documented quantitatively. From a paleobiogeographic viewpoint, the studied brachiopod fauna clearly shares affinities with contemporaneous ones from other regions of the Gondwanan northern margin that extend eastwards of the SAB to Afghanistan and Pamir, although there are also some endemic elements.UUID: http://zoobank.org/798eb5f9-ad15-4d90-bc6a-ff22ee936438

The Devonian/Carboniferous boundary interval in Poland: multidisciplinary studies in pelagic (Holy Cross Mountains and Sudetes) and ramp (Western Pomerania) successions

A multidisciplinary study of the Devonian–Carboniferous boundary interval in pelagic successions of the Holy Cross Mountains and Sudetes and the ramp successions in the Western Pomerania region (Poland) is presented herein. The analysis applies the results of new palaeontological and biostratigraphic studies based mainly on conodonts, ammonoids and palynomorphs, biostratigraphic results interpreted earlier by different authors that have been re-examined, and geochemical and mineralogical characteristics, as well as magnetic susceptibility measurements across the Devonian–Carboniferous boundary interval. The study is focused on the interval from the Famennian ultimus conodont Zone to the Tournaisian duplicata conodont Zone, and from the Famennian lepidophyta–explanatus (LE) miospore Zone to the Tournaisian verrucosus–incohatus (VI) miospore Zone, respectively. The paper highlights sections, which are the most representative for the Devonian–Carboniferous boundary in each region, illustrates and summarises current knowledge on the uppermost Famennian to lowermost Tournaisian in these regions, gives data and correlation of the important stratigraphic markers for each region, and briefly correlates them outside the region. The sedimentary successions and specific phenomena, together with microscale environmental perturbations, recognised close to the Devonian/Carboniferous boundary in Poland, display a pattern similar to that observed in many areas in Europe during the Hangenberg Event.

Upper Cambrian and Lower Ordovician conodont biostratigraphy and revised lithostratigraphy, Boothia Peninsula, Nunavut

The strata exposed along Lord Lindsay River on southern Boothia Peninsula were previously named the Netsilik Formation, and then recognized as the Turner Cliffs Formation; the interpretation of the age and correlation was based on limited data. New detailed field investigation at 23 localities along the section resulted in the discovery of over 640 identifiable conodont specimens, with 35 species representing 16 genera, among which a new species, Rossodus? boothiaensis sp. nov., is recognized. Five North American standard conodont zone/subzone-equivalent faunas are documented from the section, namely the Hirsutodontus hirsutus Subzone-equivalent, Cordylodus angulatus, Rossodus manitouensis, Acodus deltatus/Oneotodus costatus and Oepikodus communis Zone-equivalent faunas. These faunas enable a new understanding of the age and stratigraphic position of the Netsilik and Turner Cliffs formations on southern Boothia Peninsula. The Netsilik Formation can be correlated with the lower member (except for the lowest part) and upper member of the Turner Cliffs Formation; the previously unmeasured upper part of the section can be associated with the lower Ship Point Formation. Based on the new conodont data, these three units are dated as early Age 10, late Cambrian to middle Tremadocian, Early Ordovician; late Tremadocian, Early Ordovician; and early Floian, Early Ordovician, respectively. This study fills a gap in upper Cambrian and Lower Ordovician biostratigraphy on Boothia Peninsula, and links the regional biostratigraphy to that of Laurentia.

Conodont biostratigraphy and depositional history of the Darriwilian (Middle Ordovician) Pygodus serra Zone, western Argentina

The stratigraphic record of the Pygodus serra conodont Zone in the Cuyania terrane of western Argentina is discussed in this contribution. Three well-known sections were sampled in Precordillera and the San Rafael Block. The studied successions are composed mainly by clastic rocks with variable amount of carbonate. The lower part of Ponón Trehué Formation of the San Rafael Block and the La Cantera Formation of the Eastern Precordillera are composed of conglomerate and represent the input of coarse clastic deposits to the Cuyania basin. The Los Azules Formation, in Los Amarillitos section of the Central Precordillera, has a massive sandstone bed with carbonate nodules in a section largely of black shale. Key conodonts recovered from these sections indicate a correlation to the E. robustus and E. lindstroemi subzones of the Pygodus serra Zone of the upper Darriwillian Stage (Middle Ordovician Series). The species in the Ponón Trehué Formation are almost all the same as those in the Precordillera sections. Correlation of the clastic sedimentary successions between the three sections indicates that vertical facies changes were not controlled by eustasy. More likely, they were controlled by differential tectonic subsidence.

Definition of Foraminiferal Zones in the Famennian Stage (upper Devonian) of Tajikistan

Seven foraminiferal zones [Parathurammina dagmarae–Saltovskajina scitula–Neoarchaesphaera, Septaglomospiranella primaeva, Quasiendothyra (Eoquasiendothyra) bella, Q. (Eoendothyra) communis, Q. (E.) regularis, Q. (Q.) kobeitusana–Endoglomospiranella imminuta, and Q. (Q.) konensis–End. Nigra] have been identified from Famennian Stage carbonate sections in Tajikistan and compared to foraminiferal sequences from the Franco-Belgian Basin, the Russian part of the Eastern European Platform, the Ural Mountains (Russia), and Kyrgyzstan. The lower Famennian boundary is marked by the rapid extinction of all Frasnian Stage multicameral forms, which are replaced by a complex of single-chambered foraminifers of the P. dagmarae–S. scitula–Neoarchaesphaera Zone. This boundary practically coincides with the base of the middle Palmatolepis triangularis conodont zone. The upper Famennian boundary is recognized by the sharp change from endothyroid foraminifers of the Quasiendothyra konensis–Endoglomospiranella nigra Zone to a complex of simple mono- and bilocular forms of the Carboniferous Bisphaera malevkensis–Earlandia minima Zone. This boundary in the most intensely studied section at Shishkat is located 16 cm below the boundary of the Siphonodella praesulcata and S. sulcata conodont zones.

Geochemical features and formation conditions of Early-Devonian cherty-argillaceous shales and the underlying basalts in the Ishkildino section (eastern slope of the Southern Urals)

Research subject.The West Magnitogorsk zone of the Southern Urals in the vicinity of the Ishkildino village features a subaerially exposed basaltic sequence superposed by cherts and siliceous-clay shales. The basalts and the overlying shales are assumed to have formed during the Ordovician and Silurian (?)–Early Devonian (up to the conodont zone excavates inclusive) periods, respectively. The aim of this research was to reconstruct, using geochemical data, the conditions under which the rocks present in this geological location were formed.Materials and methods. Five samples of the basalts (XRD and ICP-MS methods), 27 samples of the siliceous-clay shales and 10 samples of the cherts (XRD and ICP-AES methods) were analyzed.Results.According to the ratio of SiO2, Na2O and K2O, the volcanic rocks from the lower part of the section are represented by basalts and trachybasalts. Their geochemical composition corresponds to the N-MORB and is established to be similar to that of the basalts in the Polyakovskaya formation (the Middle–Upper Ordovician). In terms of main elements, the shales under study consist of quartz and illite with a slight admixture of organic matter, goethite, quartzfeldspar fragments, etc. The degree of the sedimentary material weathering according to the CIA, CIW and ICV index values is shown to be moderate. The values of Strakhov’s and Boström’s moduli correspond to sediments without the admixture of underwater hydrothermal vent products. The values of Cr/Al, V/Al and Zr/Al correspond to those characteristic of deposits in deep-water zones remote from the coasts of passive and active continental margins, basalt islands and areas adjacent to mid-ocean ridges. For most samples, the values of Ni/Co, V/Cr, Mo/Mn are typical of deposits formed under oxidative conditions. However, several samples from the upper part of the section, which is comparable to the kitabicus and excavatus conodont zones, demonstrate the Ni/Co, V/Cr, and Mo/Mn values corresponding to deposits formed under reducing atmospheres. An assumption is made that the existence of these deposits can be associated with the Bazal Zlichov event.Conclusion.The investigated pre-Emsian shales have shown no signs of volcanic activity in the adjacent areas. The studied deposits are established to correspond to the central part of the Ural Paleoocean.

Rare Middle and Upper Devonian dalmanelloid (Orthida) of the Cantabrian Mountains, N Spain

Rare Cantabrian Dalmanellidae (Costisorthis lisae nov. sp.), Dicoelosiidae (Teichertina cf. peregrina, T. cf. ?tzroyensis), and Mystrophoridae (Mystrophora sp., Biernatium sucoi nov. sp., and Biernatium sp. 2) are described and ?gured for the ? rst time in Spain. Most of them are scarce forms that occur only in certain localities. All the species but one came from the lower part of the Portilla (province of León) and Candás (province of Asturias) formations, Faunal Interval 21, Polygnathus rhenanus/P. varcus conodont zone, middle Givetian. The exception is Biernatium sp. 2 that occurs in Asturias in FI 25, Piñeres Fm., Palmatolepis transitans zone, lower Frasnian. Costisorthis ranges from Pragian to Eifelian rocks in central Europe. C. lisae nov. sp., from the Givetian of Asturias di?ers from other Costisorthis species in the weaker development of the distinctive ventral and dorsal plications.