Conodont Zones Research Articles

Conodonts and Carbon Isotopes during the Permian-Triassic Transition on the Napo Platform, South China

Two Permian-Triassic boundary (PTB) sections (Pojue and Dala) are well exposed in an isolated carbonate platform (Napo Platform) on the southwestern margin of the Nanpanjiang Basin, South China. These sections provide an insight into the transition across the PTB and a detailed investigation of the conodont biostratigraphy and inorganic carbon isotopes is presented. The PTB at the Pojue Section is placed at the base of Bed 10B (a dolomitized mudstone found below a microbialite horizon), defined by the first occurrence of Hindeodus parvus. At the Dala Section, four conodont zones occur. They are, in ascending order, the Hindeodus parvus Zone, Isarcicella staeschei Zone, Isarcicella isarcica Zone and Clarkina planata Zone. Comparison with the Pojue Section suggests the PTB at Dala also occurs at the base of dolomitized mudstone below a microbialite horizon, although the first occurrence of Hindeodus parvus is near the top of a microbialite bed: an occurrence that is also seen in other platform sections. The succeeding microbialite beds developed during the ongoing PTB mass extinction phase. This time was characterized by low carbon isotope values, and a microbialite ecosystem that provided a refuge for selected groups (bivalves, ostracods and microgastropods) that were likely tolerant of extremely high temperatures.

Conodont-based age calibration of the Middle Triassic Anisian radiolarian biozones in pelagic deep-sea bedded chert

The age of pelagic Panthalassic deep-sea bedded chert has been assigned based on radiolarian biostratigraphy. However, Triassic radiolarian biostratigraphy is in many cases not precisely correlated to the conodont zones and the standard geological timescale. In this study, we investigated the conodont biostratigraphy of two radiolarian-controlled bedded chert sections of Anisian age: the Ajiro Island section in Oita Prefecture and the Kurusu section in Aichi Prefecture. We recognised six conodont biozones in the studied sections: the upper Olenekian Novispathodus brevissimus-Icriospathodus collinsoni and Triassospathodus homeri Zones, the lower Anisian Chiosella timorensis Zone, the middle Anisian Paragondolella bulgarica Zone, the upper Anisian Paragondolella excelsa Zone and the uppermost Anisian to lowermost Ladinian Paragondolella trammeri Zone. These conodont zones were successfully correlated to the standard Triassic radiolarian zonation proposed by Sugiyama (1997, Bull. Mizunami Foss. Mus., vol. 24, p. 79–193). Sugiyama’s radiolarian TR 1 Zone, previously considered to be of Olenekian age, extends to the middle Anisian. The TR 2A Zone, the TR 2B Zone and the lower part of the TR 2C Zone are correlated to the middle Anisian, while the upper part of the TR 2C Zone and the lower part of the TR 3A Zone are correlated to the upper Anisian. The upper part of the TR 3A Zone and the lower part of the TR 3B Zone are probably correlative to the uppermost Anisian, but the possibility that they are correlative to the lowermost Ladinian cannot be ruled out.

Frasnian age (upper devonian) key section biostratigraphic characteristic of Voronezh anteclise middle part (well 16, Schigry, Nizhnekrasnoe village, Kursky region)

Conodonts, scolecodonts, and foraminifers were studied from Frasnian age deposits of Well 16 Schigry (Nizhnekrasnoe village, Voronezh anteclise). Six conodont complexes are identified: I in Timan regional stage, II and III in Sargaevo regional stage, and IV and VI in Semiluky regional stage. Correlation by local zonal units and Standard Conodont Zonation is performed. Shallow environment is confirmed for Timan regional stage, the deepest environment settings is confirmed for Semiluky regional stage. Five scolecodont complexes are identified: complexes 1 and 2 for Sargaevo regional stage, complexes 3 and 4 for Semiluky regional stage, and complex 5 for the upper part of Semiluky regional stage and Voronezh regional stage. Foraminifers are presented by two complexes: first for Sargaevo regional stage and the second for the Semiluky regional stage. The characteristic microfossils species are given in plates.

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.

Dynamics of the conodont diversity in the Late Devonian–Early Carboniferous (Famennian–Serpukhovian)

Subject.The article is aimed to evaluate of the conodont diversity dynamics at the species level in the Famennian – Serpukhovian interval.Materials and methods.The database compiled from the published and original data contains information on the stratigraphic ranges of 389 Famennian-Serpukhovian conodont species (https://1drv.ms/x/s!AvPFMTPLPc7T4nFU81CaO5UJ6nlw). Conodont zones compose the geochronological basis of the database. The conodont diversity, origination, extinction, and diversification were calculated. Dynamics of these parameters in the Late Devonian–Early Carboniferous was analyzed.Results.The Famennian-Serpukhovian conodonts demonstrate four cycles in the diversity: the early Famennian (triangularis-early postera zones), the late Famennian (late postera-praesulcata zones), the Tournaisian (sulcata-anchoralis zones), and the Visean-Serpukhovian (texanus-bollandensis zones). The cycles are separated by the low-diversity episodes. The highest diversity (80 species) is detected in the early and late marginifera zones (Famennian).Conclusions.The successive decreasing in diversity comprises interval from the late Famennian through Serpukhovian. The global events gave little influence on the conodont diversity except for the Frasnian/Famennian (about 70% conodont species became extinct) and Devonian/Carboniferous extinction events. Conodont diversity demonstrates weak dependence form the global sea level fluctuations. The transition from the green-house to ice-house climate at the beginning of the Carboniferous and successive changes in the marine ecosystems are considered as main probable cause of the decline in conodont diversity in the late Tournaisian-Serpukhovian.

New timing and geochemical constraints on the Capitanian (Middle Permian) extinction and environmental changes in deep-water settings: evidence from the Lower Yangtze region of South China

The Capitanian (Guadalupian) witnessed one of the major crises of the Phanerozoic and, like many other extinctions, it coincided with the eruption of a large igneous province, in this case the Emeishan Traps of SW China. However, the timing and causal relationships of this event are in dispute. This study concentrates on the deep-water chert–mudstone strata of the Gufeng Formation and its transition to the Yinping Formation at Chaohu. Zircons from tuffs in the uppermost Gufeng Formation yield a U–Pb age of 261.6 ± 1.6 Ma, and comparison with sections around Emeishan suggests that the tuffs appeared in the Jinogondolella altudaensis conodont zone and persisted to the Jinogondolella xuanhanensis zone. This coincides with the Emeishan eruptions, and suggests that the tuffs probably derived from this province. Mineralogical and geochemical characteristics also show the tuffs are of acid volcanogenic origin and have a geochemical fingerprint of the Emeishan large igneous province. Our dating shows that a crisis amongst radiolarian and a subsequent productivity decline occurred during the middle Capitanian, prior to the Guadalupian–Lopingian boundary. The Emeishan eruptions began immediately before this, indicating a likely causal relationship between these events. Major regression and marine anoxia/euxinia are two other important extinction-relevant environmental changes that occurred during this critical interval.

Conodont biostratigraphy and magnetic susceptibility of Upper Devonian Chattanooga Shale, eastern United States: Evidence for episodic deposition and disconformities

Recognition of stratigraphic hiatuses in fine-grained siliciclastic sedimentary rocks can be challenging but is feasible using high-resolution biostratigraphic and chemostratigraphic data within a regional correlation framework. In this case study of the Upper Devonian Chattanooga Shale in the Dupont GHS drillcore from the western margin of the Nashville Dome, the Upper Devonian Chattanooga Shale comprises several depositional units separated by intraformational hiatuses. These features are developed within a 13.3 m interval consisting of 4.2 m of Frasnian strata and 9.1 m of Famennian strata that unconformably overlie the Sellersburg Formation. Three Frasnian, seven Famennian, and one Tournaisian conodont biozones are recognized. The Frasnian-Famennian boundary is on a disconformity. To the northeast in the southern Illinois Basin, the New Albany Shale in the BCC drillcore consists of 35 m of Givetian and Frasnian strata and 30 m of Famennian strata that conformably overlie the Sellersburg Formation. One Givetian, four Frasnian, and three of the four lowest Famennian conodont zones are recognized. The Frasnian-Famennian boundary is conformable and constrained to within a 5 cm interval. Bulk magnetic susceptibility (MS) shows a long-term increase through most of the Frasnian. Shorter-term MS trends were observed in association with depositional pulses linked to global sea-level rises and highstand system tracts, characterized by total organic carbon (TOC) maxima — eight trends were resolved in the DGHS core, and six in the BCC. The high-frequency shifts in δMS likely represent Milankovitch-band sea-level and depositional cycles at a scale that cannot be resolved based on the condensed and irregular nature of the depositional packages. Gamma ray counts in the DGHS peak in association with the eight depositional cycles, with a TOC peak at the base of each cycle.

Global mercury cycle during the end-Permian mass extinction and subsequent Early Triassic recovery

The end-Permian mass extinction (EPME) at ∼252 Ma was the most severe extinction in the Phanerozoic. Marine ecosystems devastated by the EPME had a highly prolonged recovery, and did not substantially recover until after the Smithian–Spathian substage boundary (SSB) of the Lower Triassic (5 to 9 Ma after the EPME). While the Siberian Traps large igneous province (STLIP) has been invoked as the driver of the mass extinction, there remains controversy as to the cause of the protracted Early Triassic recovery; although renewed STLIP volcanism has been suggested. These previous studies though have drawn conclusions based on geochemical records of sediments deposited in northern latitude settings. To investigate the relationship between STLIP and extinction/recovery processes on a global base, we examined mercury chemostratigraphy, including mercury concentrations and isotopes, from high southern latitude and equatorial sections that span the Late Permian Changhsingian to Early Triassic Spathian substage successions; the Guryul Ravine section, Kashmir in northern India, and the Chaohu section in southern China. Organic and inorganic carbon-isotope data define the EPME horizon in the Chaohu section and the SSB in the Guryul Ravine section, respectively. Hg/TOC values are dramatically elevated approaching the EPME horizon and maintain high values until the lower Isarcicella Isarcica conodont zone, the base of which is believed to be the end of the mass extinction. In the stratigraphically overlying beds, Hg/TOC generally displays lower values with slight fluctuations through the two sections. These fluctuations are likely related to the increased terrestrial Hg influx associated with strong chemical weathering in the Early Triassic, as shown by a positive correlation between the contents of Hg and Al, and by less positive Δ199Hg values in Early Triassic samples. Our data, presenting the first Southern Hemisphere Hg record from Guryul Ravine, in combination with previous results, indicates that anomalous high mercury deposition at the EPME occurred globally. The generally positive Δ199Hg values at this time reflects atmospheric-derived Hg, consistent with a volcanic Hg source which we suggest indicates global impact of STLIP eruption. In contrast, there is no evidence for a global Hg/TOC anomaly during the protracted Early Triassic biotic recovery, suggesting that potentially renewed STLIP volcanism had only a northern hemisphere influence on the global Hg cycle. This more limited impact, may still have played a role in the delayed Early Triassic recovery.

Biostratigraphic Characteristic of the Frasnian Age (Upper Devonian) Reference Section in the Central Voronezh Anteclise (Shchigry-16 Borehole, Nizhnekrasnoe Village, Kursk Oblast)

Conodonts, scolecodonts, and foraminifers from the Frasnian Age (Upper Devonian) (Shchigry-16 borehole, Nizhnekrasnoe village, Voronezh anteclise) were studied. Six conodont assemblages were identified: I for the Timan regional stage, II and III for the Sargaevo regional stage, and IV–VI for the Semiluky regional stage. These assemblages were correlated with local zonal subdivisions and the Standard Conodont Zonation. It was established that a shallow-water environment was characteristic of the Timan regional stage; the deepest environment was characteristic of the Semiluky regional stage. Five scolecodont assemblages were identified: 1 and 2 in the Sargaevo regional stage, 3 and 4 in the Semiluky regional stage, and 5 in the upper part of Semiluky and Voronezh regional stages. Two foraminiferal assemblages are distinguished for the Sargaevo and Semiluky regional stages. The characteristic microfossils species are given in plates.

Smithian platform-bearing gondolellid conodonts from Yiwagou Section, northwestern China and implications for their geographic distribution in the Early Triassic

AbstractAbundant platform-bearing gondolellid conodonts, includingScythogondolella mosheri(Kozur and Mostler),Sc.phrynaOrchard and Zonneveld, andSc. cf.milleri(Müller), have been discovered from the Yiwagou Section of Tewo, together withNovispathodus waageni waageni(Sweet) andNv.w.eowaageniZhao and Orchard. This is the first report of Smithian platform-bearing gondolellids from the Paleo-Tethys region. In addition,Eurygnathodus costatusStaesche,E.hamadai(Koike),Parafurnishius xuanhanensisYang et al., and the generaPachycladinaStaesche,ParachirognathusClark, andHadrodontinaStaesche have also been recovered from Dienerian to Smithian strata at Yiwagou Section. Three conodont zones are established, in ascending order:Eurygnathodus costatus-E.hamadaiAssemblage Zone,Novispathodus waageni-Scythogondolella mosheriAssemblage Zone, and thePachycladina-ParachirognathusAssemblage Zone.The platform-bearing gondolellids were globally distributed just after the end-Permian mass extinction, but the formerly abundantClarkinaKozur disappeared in the late Griesbachian. Platform-bearing gondolellids dramatically decreased to a minimum of diversity and extent in the Dienerian before recovering in the Smithian.ScythogondolellaKozur, probably a thermophilic and eurythermic genus, lived in all latitudes at this time whereas other genera did not cope with Smithian high temperatures and so became restricted to the high-latitude regions. However, the maximum temperature in the late Smithian likely caused the extinction of almost all platform-bearing gondolellids. Finally, the group returned to equatorial regions and achieved global distribution again in the cooler conditions of the late Spathian. We conclude that temperature (and to a lesser extent oxygen levels) exerted a strong control on the geographical distribution and evolution of platform-bearing gondolellids in the Early Triassic.

Reconsideration of Dating of the Late Paleozoic Radiolarian Latentifistula crux Ecozone in the Southern Urals

The age of the Upper Paleozoic radiolarian Latentifistula crux Ecozone is revised. The Latentifistula crux assemblage was originally established by Nazarov and Ormiston (1985, 1990, 1993; Nazarov, 1988) in 1985 in the basal deposits of the Asselian Stage of the Nikolskoe section on the Ural River. The new biostratigraphic position of the radiolarian Latentifistula crux Ecozone corresponds to the terminal Streptognathodus bellus and Streptognathodus wabaunsensis conodont zones of the Gzhelian Stage (Chernykh, 2012, 2016).

Conodont association of the Bashkirian-Moscovian boundary interval of the Donets Basin, Ukraine

Ten sections spanning the Bashkirian-Moscovian boundary interval were studied in the Donets Basin. Six of them contain most representative conodont and foraminifer associations. In this paper we focused on three the most complete sections that include stratigraphically important conodont species, which belong to the Declinognathodus, Idiognathoides, Idiognathodus, Neognathodus, “Streptognathodus”, Mesogondolella and Diplognathodus genera. The majority of those species are widely distributed, which makes the correlation to other areas reliable. Two biotic events in conodont evolution were discovered in these sections. Two conodont lineages established here are considered as potential markers for the definition of the lower boundary of the Global Moscovian Stage: D. marginodosus – D. donetzianus and Id. sulcatus sulcatus – Id. postsulcatus. The conodonts D. donetzianus and Id. postsulcatus, both proposed before as potential markers for the de? nition of the GSSP at the Bashkirian-Moscovian boundary, are described and compared to those from the other areas. The entry of D. donetzianus is updated and con? rmed to the top of the limestone K1 in both sections, the Zolota Valley and the Malo-Mykolaivka sections. The other proposals for the de???? nition of the lower Moscovian boundary by conodonts are discussed. Three conodont zones characterize the Bashkirian-Moscovian boundary interval. These are, in ascending order: the Id. tuberculatus – Id. fossatus Zone and D. marginodosus Zone from the upper Bashkirian, and D. donetzianus Zone from the lower Moscovian. They were recently described and shortly given in this paper.

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.

Frasnian (Upper Devonian) integrated facies analysis, magnetic susceptibility and sea-level fluctuations in the NW Algerian Sahara

AbstractChanges in the palaeoenvironment are investigated in two representative Frasnian sections of the NW Algerian Sahara, integrating sedimentology and magnetic susceptibility (MS). The Ben Zireg section is characterized by condensed and ferruginous calcareous deposits; in the South Marhouma section the sedimentation rate is high, dominated by muddy nodular limestones with several hypoxic shale intervals. In both sections, sediments were mostly emplaced on pelagic outer ramps below the limit of storm wave-base, evolving through time from proximal to distal setting. Investigations of the temporal evolution of facies and MS data permit a first estimate of the local sea-level trends in NW Algeria. These trends match the overall long-term rise of sea level recognized worldwide from Frasnian Zone 5 upwards. Noteable positive excursions of the sea-level curve related to the semichatovae transgression, as well as to the late Frasnian transgression prior to the late Kellwasser event, can be established in this area. Although the sharp regression of sea level at the upper Kellwasser level can be confirmed from our data, no particular trend is depicted at the transition of conodont zones (Frasnian Zones 12–13) where the presence of the lower Kellwasser level has not yet been clearly recognized.

Reconstruction of atmospheric CO2 concentration during the late Changhsingian based on fossil conifers from the Dalong Formation in South China

A single species of fossil conifer with well-preserved cuticles from multiple layers of the Dalong Formation in two sections in Duanshan Town, Guizhou Province, Southwest China has been used to reconstruct palaeo-atmospheric pCO2. The age of these layers can be dated back to the late Changhsingian (latest Permian), corresponding to the Clarkina changxingensis and Clarkina yini conodont Zones. Two calibration approaches were employed in this study. Using the stomatal ratio method, the pCO2 curves of the two sections showed matching trends, with levels decreasing in the middle of the profiles, and similar ranges at ca. 340–510 ppm and ca. 300–440 ppm. Similar values (ca. 360–520 ppm), yet with wider error ranges, were obtained when the mechanistic model proposed by Franks et al. in 2014 was applied to one of the sections. Our values are lower than the mean pCO2 values from coeval palaeosols, but partly overlap with them when error ranges are taken into consideration, thus more independent studies are needed to evaluate the discrepancies between the two proxy methods. The low atmospheric CO2 concentrations in this study suggest a cool climate rather than extensive glaciation for the brief period of late Changhsingian, which is supported by the oxygen isotope record of conodont apatite and a major restructuring of Late Permian flora and fauna.

Carboniferous integrative stratigraphy and timescale of China

The Carboniferous period lasted about 60 Myr, from ~358.9 Ma to ~298.9 Ma. According to the International Commission on Stratigraphy, the Carboniferous System is subdivided into two subsystems, i.e., Mississippian and Pennsylvanian, including 6 series and 7 stages. The Global Stratotype Sections and Points (GSSPs) of three stages have been ratified, the Tournaisian, Visean, and Bashkirian stages. The GSSPs of the remaining four stages (i.e., the Serpukhovian, Moscovian, Kasimovian, and Gzhelian) have not been ratified so far. This paper outlines Carboniferous stratigraphic subdivision and correlation on the basis of detailed biostratigraphy mainly from South China, and summarizes the Carboniferous chronostratigraphic framework of China. High-resolution biostratigraphic study reveals 37 conodont zones, 24 foraminiferal (including fusulinid) zones, 13 ammonoid zones, 10 brachiopod zones, and 10 rugose coral zones in the Carboniferous of China. The biostratigraphic framework based on these biozones warrants the precise correlation of regional stratigraphy of China (including 2 subsystems, 4 series, and 8 stages) to that of the other regions globally. Meanwhile, the Carboniferous chemo-, sequence-, cyclo-, and event-stratigraphy of China have been intensively studied and can also be correlated worldwide. Future studies on the Carboniferous in China should focus on (1) the correlation between shallow- and deep-water facies and between marine and continental facies, (2) high-resolution astronomical cyclostratigraphy, and (3) paleoenvironment and paleoclimate analysis based on geochemical proxies such as strontium and oxygen isotopes, as well as stomatal indices of fossil plants.

Stratigraphic Definition and Correlation of Middle Triassic Volcaniclastic Facies in the External Dinarides: Croatia and Bosnia and Herzegovina

Middle Triassic volcaniclastic depositsin the External Dinarides of Croatia and Bosnia and Herzegovina are related to the rifting of the Tethyan Ocean. Three localities in the External Dinarides: Donje Pazariste, Bosansko Grahovo and Zelovo were biostratigraphically analysed in this study. The Middle Triassic carbonate deposits with volcaniclastic interlayers in Donje Pazariste were defined by means of conodonts. Rare ammonoid specimens were collected.Recovered conodont and ammonoid taxa suggest these sections are of Early Illyrian to Early Fassanian Age. The section studied in Bosansko Grahovo is dominantly composed of volcanic and volcaniclastic rocks. Limestone peperites were collected for conodont analysis. Two conodont zones were defined, suggesting volcanic activity in the same, from Lower Illyrian to Fassanian, time interval. The Zelovo Section was biostratigraphically investigated by several authors. The pietra verde deposits from Zelovo are referred as late Fassanian to Early Longobardian Age. Biostratigraphic correlation from mentioned three localities imply that the magmatic activity in the External Dinarides, and formation of different volcaniclastic facies lasted from Illyrian to Longobardian, similar as in the surrounding western Tethyan territories.

Early Triassic Conodonts from the Tahogawa Member of the Taho Formation, Ehime Prefecture, Southwest Japan

The Triassic Taho Formation crops out in Taho, Shirokawa Town, Seiyo City, Ehime Prefecture, Southwest Japan. The formation is newly divided into the Tahogawa and Sakuragatouge members. The Tahogawa Member consists mainly of partly dolomitized light-, dark-, brownish-gray and black bedded limestones, and yields abundant Early to Middle Triassic conodonts, ammonoids, gastropods, bivalves, brachiopods and fish remains. The Sakuragatouge Member is dominated by brownish gray lenticular conglomeratic limestone and massive gray and white limestones that contain Middle to Late Triassic conodonts, gastropods, bivalves, echinoids and fish remains. In the Tahogawa Member, conodont assemblages are composed of 13 genera and 45 species, including three new species: Neospathodus arcus Maekawa sp. nov., Novispathodus shirokawai Maekawa sp. nov., and Nv. tahoensis Maekawa sp. nov. The member is divided into five conodont zones in ascending order: the Ns. dieneri Zone, the Ns. cristagalli Zone, the Nv. ex gr. waageni Zone, the Nv. pingdingshanensis Zone and the Nv. brevissimus Zone. The Nv. ex gr. waageni Zone contains three conodont subzones (the Eurygnathodus costatus Subzone, the Guangxidella bransoni Subzone and the Scythogondolella milleri Subzone), and the Nv. brevissimus Zone includes the Icriospathodus collinsoni Subzone. The conodont biostratigraphy of the member indicates a late Dienerian to early Spathian age, and correlates with that of Tethyan and Panthalassean sections. The Induan-Olenekian boundary is indicated by the first occurrence of Nv. ex gr. waageni. The Smithian-Spathian boundary is immediately below or intercalated within the Nv. pingdingshanensis Zone.

Recognition and significance of the Aurilobodus serratus Conodont Zone (Darriwilian) in lower Paleozoic sequence of the Jeongseon–Pyeongchang area, Korea

A total of 286 disjunct conodont elememets were recovered from 30 productive samples in 5 separate sections of the Haegmae and Hoedongri Formations, 18 m below to 36 m above the boundary between the two formations, in the Jeongseon–Pyeongchang area. Fifteen multielement and form species representing 12 genera are distinguished in the fauna of the two formations. Age-diagnostic species include Acontiodus viriosus Cui, Aurilobodus serratus Xiang and Zhang, A. simplex Xiang and Zhang, Drepanodus arcuatus Pander, Drepanodus reclinatus (Sergeeva), Drepanoistodus suberectus (Branson and Mehl), Eoplacognathus jigunsanenesis Lee and Lee, E. lindstroemi Hamar, Erraticodon tangshanensis Yang and Xu, Panderodus nogamii Lee, Parapanderodus paracornutiformis (Ethington and Clark), Plectodina onychodonta An and Xu, Scandodus choii n. sp., and Triangulodus changshanensis (Zhang). This assemblage was assigned to the Aurilobodus serratus Zone. That zone was first erected from the Middle Ordovician Machiakou Formation in the North China platform and is known also from the Duwibong Formation in Korea. These strata represent tropical, shallow marine paleobiogeographic facies. The presence of the zone on both sides of the boundary between the two formations means that the relationship between the Haengmae and Hoedongri formations is a conformity, not an unconformity, as previously thought. It is more likely that the overlying unsampled strata of the Hoedongri Formation are also Ordovician, rather than Silurian. One new species, Scandodus choii, is described here.

Permian integrative stratigraphy and timescale of China

A series of global major geological and biological events occurred during the Permian Period. Establishing a high-resolution stratigraphic and temporal framework is essential to understand their cause-effect relationship. The official International timescale of the Permian System consists of three series (i.e., Cisuralian, Guadalupian and Lopingian in ascending order) and nine stages. In China, the Permian System is composed of three series (Chuanshanian, Yansingian and Lopingian) and eight stages, of which the subdivisions and definitions of the Chuanshanian and Yangsingian series are very different from the Cisuralian and Guadalupian series. The Permian Period spanned ~47 Myr. Its base is defined by the First Appearance Datum (FAD) of the conodont Streptognathodus isolatus at Aidaralash, Kazakhstan with an interpolated absolute age 298.9±0.15 Ma at Usolka, southern Urals, Russia. Its top equals the base of the Triassic System and is defined by the FAD of the conodont Hindeodus parvus at Meishan D section, southeast China with an interpolated absolute age 251.902±0.024 Ma. Thirty-five conodont, 23 fusulinid, 17 radiolarian and 20 ammonoid zones are established for the Permian in China, of which the Guadalupian and Lopingian conodont zones have been served as the standard for international correlation. The Permian δ 13Ccarb trend indicates that it is characterized by a rapid negative shift of 3–5‰ at the end of the Changhsingian, which can be used for global correlation of the end-Permian mass extinction interval, but δ 13Ccarb records from all other intervals may have more or less suffered subsequent diagenetic alteration or represented regional or local signatures only. Permian δ 18Oapatite studies suggest that an icehouse stage dominated the time interval from the late Carboniferous to Kungurian (late Cisuralian). However, paleoclimate began to ameriolate during the late Kungurian and gradually shifted into a greenhouse-dominated stage during the Guadalupian. The Changhsingian was a relatively cool stage, followed by a globally-recognizable rapid temperature rise of 8–10°C at the very end of the Changhsingian. The 87Sr/86Sr ratio trend shows that their values at the beginning of the Permian were between 0.70800, then gradually decreased to the late Capitanian minimum 0.70680–0.70690, followed by a persistent increase until the end of the Permian with the value 0.70708. Magenetostratigraphy suggests two distinct stages separated by the Illawarra Reversal in the middle Wordian, of which the lower is the reverse polarity Kiaman Superchron and the upper is the mixed-polarity Illawarra Superchron. The end-Guadalupian (or pre-Lopingian) biological crisis occurred during the late Capitanian, when faunal changeovers of different fossil groups had different paces, but generally experienced a relatively long time from the Jinogondolella altudensis Zone until the earliest Wuchiapingian. The end-Permian mass extinction was a catastrophic event that is best constrained at the Meishan section, which occurred at 251.941±0.037 Ma and persisted no more than 61±48 kyr. After the major pulse at Bed 25, the extinction patterns are displayed differently in different sections. The global end-Guadalupian regression is manifested between the conodont Jinogondolella xuanhanensis and Clarkina dukouensis zones and the end-Changhsingian transgression began in the Hindeodus changxingensis-Clarkina zhejiangensis Zone. The Permian Period is also characterized by strong faunal provincialism in general, which resulted in difficulties in inter-continental and inter-regional correlation of both marine and terrestrial systems.