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Introduction Devonian-Carboniferous boundary is an exciting issue for researchers all over the world. In this boundary, significant events have occurred on marine organisms (specially conodonts elements) and terrestrial organisms, consisting of weather and sea-level changes, and relative coincidence with the Hangenberg bioevent (Mc. Ghee, 1998; Sandberg et al., 2002; Caplan & Bustin, 1999; Kaiser et al., 2006, 2011, Bahrami et al., 2011, 2019; Konigshof et al., 2021; Sattari et al., 2021). According to ICS, the Devonian-Carboniferous boundary, as defined by the first Appearance Datum (FAD) of the conodont species Siphonodella sulcata within the Siphonodella praesulcata- Siphonodella sulcata lineage and the GSSP is located in the La Serre Trench E’ section in France (Paproth et al. 1991). Khoshyeilagh Formation in Zoo section consists of shallow marine deposits attributed to the Late Devonian (Frasnian-Famennin) (Najjarzadeh, 1997). This study focuses on identifying and reviewing the Devonian-Carboniferous boundary in a part of the Eastern Alborz area and study the biostratigraphy of deposits near this boundary based on conodont fauna. Materials and Methods 58 carbonate and 11 non-carbonate samples (3-4 kg/each) were collected and processed for conodonts. The samples were processed with the conventional acetic acid technique, but formic acid 10% with 10 hours was also used for some silty samples and compacted limestones. Then picked remaining deposits with the handpicking method. The following steps include pasting the conodont specimens on stab, photographing them under an SEM microscope, and naming conodonts elements based on available references (e.g., Branson & Mehl, 1934; …). Accordingly, the biozonation of the studied sequence using the global standard zonings of Ziegler & Sandberg (1990), Sommervile (2008), Poty et al. (2006), Spalletta et al. (2017). Discussion and Conclusion Khoushyeilagh and Mobarak formations Late Devonian-Carboniferous conodonts fauna of Zoo section, (NE Jajarm), led to identifying 10 conodont genera, 23 species, and 8 subspecies. The conodont faunas which be obtained in this research indicate the presence of these biozones: Bispathodus ultimus Zone (Latest Famennian), From the base of Siphonodella duplicata to within Siphonodella crenulata interval (Tournaisian), and Pseudopolygnathos multistriatus Zone (Visean). According to this study, the Fm/T boundary is located at the end of Khoushyeilagh formation, 6m above the diabase layer. The conodonts, as mentioned above, are indicators for Polygnathid biofacies. These sequences are similar to other Famennian- Tournaisian deposits in the east Alborz, both in the litho-facies and bio-facies peculiarities. The conodont Color Alteration Index in the Carboniferous conodonts element increased compared to the Late Devonian elements. [ABSTRACT FROM AUTHOR]

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Horseshoe crabs are extant chelicerates with a fossil record extending back to the Ordovician. Despite the documentation of their long evolutionary history, xiphosurids are rarely preserved within fossil assemblages due to their unmineralized cuticular exoskeleton. However, in exceptional circumstances, an abundance of fossil xiphosurid specimens have been documented. The Moscovian-aged Mazon Creek Konservat-Lagerstätte represents one such fossil deposit with a high abundance and diversity of xiphosurids. Although fairly well known, the Paleolimulus specimens from the Mazon Creek have not yet been subject to a thorough taxonomic examination. In the light of recent efforts to organise Paleolimulus, we revisit this undescribed material, erect Paleolimulus mazonensis n. sp., and present a phylogenetic analysis that places P. mazonensis n. sp. as a sister taxon to P. signata (Beecher, 1904). The palaeoecology and possible ontogeny of P. mazonensis n. sp. are presented, as well as a statement on the future directions for understanding this xiphosurid genus. [ABSTRACT FROM AUTHOR]

Three new genera Heslerodoides gen. nov., Gzhelodus gen. nov., and Samarodus gen. nov. were erected on the basis of numerous isolated teeth found in the late Carboniferous of European part of Russia. The teeth of the ctenacanthiform Heslerodoides resemble the teeth of Heslerodus and demonstrate the morphological variations of teeth in their dentition. The protacrodontid euselachian Gzhelodus is closely related to Deihim and Tiaraju. The peculiar teeth of Samarodus possess a combination of features previously unknown in the Palaeozoic chondrichthyans. The new taxa contribute to the knowledge of the variety of dentitions in the Carboniferous shark. [ABSTRACT FROM AUTHOR]

The genus Provisocyntra Nazarov et Ormiston, 1987 is revised and its diagnosis is emended. The features of the simultaneous centrifugal and tangential types of growth of the Provisocyntra test are analyzed. The presence of an internal framework in the form of a microsphere is confirmed. The species composition is expanded to include ten species from the Carboniferous–Middle Permian. Four new species of Early Tournaisian radiolarians from the Volga-Ural Basin are described: Provisocyntragrandis sp. nov., P. kononovae sp. nov., P. magniporosa sp. nov., and P. valminazae sp. nov. A new family Provisocyntridae fam. nov. is established. The diagnosis and composition of the order Spongiata Afanasieva et Amon, 2003 are emended. [ABSTRACT FROM AUTHOR]

The geological structure of coal formations of the Sukharysh syncline, which is located in the Kopeysk-Bredy subzone of the Alapaevsk-Adamovka structural-formational zone, was studied. The focus was specifically on the deposits of the Fedorovskaya sequence (C2fd) with outcrops in the sections along the Uvelka River and in few roadside pits. The width of the sequence is about 1000 m. The Middle Carboniferous (Bashkirian) age of the deposits was reliably dated based on the fossil faunal finds. It was shown that shales and aleurolites, which are widespread in the limestones of the Fedorovskaya sequence, belong to the low-carbon type and fall into the field of the siliceous-carbonate unit. The carbonaceous matter is developed in the form of scattered impurities, concentrated in the ultrafine veinlets and laminas, and corresponds to higher kerites subjected to catagenesis and the early stage of green shales facies. The organic carbon content is up to 20%, and, thus, the rock appears to be opaque. Sedimentation process took place in the isolated local shallow-water depressions under the geodynamic conditions of collision. The terrigenous material was formed as a result of the destruction of the underlying rocks of the major and average element composition of the Berezinskaya sequence. The maturity of the deposits consistently increases from the Tugundinskaya to Fedorovskaya sequences.

The Black Country UNESCO Global Geopark, located in central England, joined the Global Geopark Network in July 2020. It is the most urban Geopark in the network with a population of approximately 1.1 million people. Located in an area rich in raw materials (Carboniferous coal, iron, and clay; Silurian limestone), it was quarried and mined extensively to fuel the Industrial Revolution. These activities created exposures which contributed greatly to the development of geoscience, including the establishment of the Silurian System. It also revealed and led to the collection of a rich and extremely well-preserved fossil fauna from the Upper Carboniferous and especially from the Silurian Much Wenlock Limestone Formation, with trilobites, crinoids, and numerous other taxa from the Geopark adorning museum collections across the world. Internationally important geological exposures, surviving within what is now an extremely urban and populated setting, provide a range of challenges and opportunities, and these continue to drive innovation and good practice in geoconservation, education and tourism within the geopark, where robust conservation and management of Geosites is combined with innovative ways to engage with local communities and visitors. UNESCO Global Geopark status will play an important role in opening doors to make the Black Country’s geoheritage, including its paleontology, accessible to many more people.

The break-up processes of the northern margin of East Gondwana remain uncertain, especially regarding the Lhasa Terrane. In this paper, we conduct a systematic field geological survey, detrital zircon U Pb dating, and zircon trace element and Hf isotope analyses in the Carboniferous rift basin in the eastern part of the Lhasa Terrane, including the Nuocuo and Laigu Formations, to reconstruct the break-up history of East Gondwana. The overall Carboniferous depositional environment in the eastern part of the Lhasa Terrane changed from near-shore and shallow marine to slope and moderately deep sea facies, reflecting a transgression. The weighted average age of several of the youngest detrital zircons from the Nuocuo Formation is 346.8 ± 6.4 Ma (4 grains), whereas that of the Laigu Formation is 328.7 ± 6.1 Ma (6 grains). The detrital zircon ages in the Carboniferous strata show similar distributions, dominated by zircons from the Indian continent (∼950 Ma), Australian continent (∼1170 Ma), and Lhasa Terrane (∼340 Ma). The paleogeographic position of the Lhasa Terrane was near the Indian and Australian continents during the Carboniferous. The increase of the ∼340 Ma detrital zircon age peak from the Mississippian to the Pennsylvanian demonstrated that the rift basin recorded a Mississippian magmatic event. The ε Hf (t) and oxygen fugacity values of partial zircons of ∼340 Ma are similar to those of zircons from intraplate magmatic rocks, further implying the intracontinental rifting in the Lhasa Terrane. Combined with the previous research on magmatic rocks in East Gondwana, including the Lhasa, South Qiangtang, and Himalayan Terranes, our study on sedimentation found that the Lhasa Terrane was in a passive continental margin rifting context during the Mississippian and the rift gradually expanded to become the Sumdo Paleo-Tethys Ocean basin. [Display omitted] • Carboniferous strata in eastern part of the Lhasa terrane are transgressive sequence. • These strata record the Carboniferous magmatism in the Lhasa terrane. • Carboniferous detrital zircons may mainly originate from intraplate magmatism. • The Lhasa terrane broke up and the Sumdo Paleo-Tethys Ocean opened in ∼340 Ma. [ABSTRACT FROM AUTHOR]

The types of volcanic edifices and volcanic eruption patterns control the accumulation and distribution of oil and gas. By means of drillings, seismic data, and geochemical analysis, the types and distribution of the Carboniferous volcanic edifices in the Shixi area of Junggar Basin were studied, the formation mechanism of magma was clarified, and the eruption patterns of volcanoes were investigated. The results show that the types of the Carboniferous volcanic edifices in the Shixi area mainly include stratovolcanic edifices, shield basic volcanic edifices, and mound superimposed volcanic edifices. Stratovolcanic edifices and mound superimposed volcanic edifices are developed around the Shixi fault, while single stratovolcanic edifices are developed around the Mobei fault. Shield basic volcanic edifices are only developed in the south of the Shixi area. Vertically, volcanic edifices are mainly developed on the hanging walls of the faults. When the faults develop, the volcanic vents are dendritic, forming mound superimposed volcanic edifices in space. On the plane, there are more volcanic edifices in the Shixi salient than in the Mobei salient. Intermediate-acid volcanic edifices are distributed in beaded shapes along one side of the Shixi fault and the Mobei fault, while basic volcanic edifices are distributed in sheet shapes on both sides of the Dinan fault. In the early Carboniferous, the Shixi area was in the island arc environment under the subduction of the oceanic crust. The basic magma came from the melting of the subduction plate, and the intermediate-acid magma came from the partial melting of the crust. In the late Carboniferous, the extensional environment formed by the retraction of the subduction plate led to the formation of large-scale volcanic eruptions. The extensional environment formed by the retreat of the subduction plate in the later stage resulted in large-scale volcanic eruptions.

As an unconventional petroleum reservoir, the volcanic reservoir is essential for finding large-scale oil and gas reserves in deep sedimentary basins. Based on basin modeling, organic geochemistry, and organic petrology, this study evaluates the exploration potential of the Carboniferous volcanic-petroleum system in the Jimsar Sag of the southeastern Junggar Basin. The Carboniferous source rocks in the study area were developed in the Lower Carboniferous Songkharsu Formation, a set of marine–terrigenous transitional source rocks, lithologically composed of carbonaceous mudstone, mudstone, and coal. The kerogen is characterized by type II2–III, indicating a gas-prone source rock. Carbonaceous mudstones, mudstone, and coal are classified as medium–good, medium, and poor source rocks, respectively. The hydrocarbon-generating potential is close to that of the Kelameili gas field. The Carboniferous-reservoir oil in well J15 is characterized by 13C-enriched stable carbon isotopes, relatively high ƩC31–35/C30 and Pr/Ph ratios, relatively low density, gammacerane index, regular C29-sterane content, and undetected β-carotene, indicating a Songkharsu origin. The Carboniferous-reservoired gas from well J3301 has stable carbon isotope composition enriched in 13C, similar to the gas from the Kelameili gas field, and should be from the Songkharsu source rock. This set of source rocks is widely distributed in the Jimsar Sag with considerable thickness, among which thickness >100 m reaches 580 km2, accounting for 38.7% of the whole sag. The Songkharsu source rocks entered the main oil-generating window at the end of the Early Jurassic. The area of Songkharsu source rocks in the Jimsar Sag with gas-generating intensity greater than 20 × 108 m3/km2 reaches 1,015 km2, whereas that with oil-generating intensity greater than 500 × 104 t/km2 reaches 1,146 km2. However, 13 Carboniferous volcanic lithological traps were found in the sag, covering an area of 230 km2. The Carboniferous volcanic-petroleum system in the Jimsar Sag has the resource potential to form large and medium oil and gas fields, which could become a critical replacement field for volcanic oil and gas exploration in the Junggar Basin after the Klameili gas field.

Multiple sets of source rocks developed in the Carboniferous on the northeastern margin of Junggar Basin. Modelling the thermal evolution history of source rocks is of great importance to deepen the understanding of hydrocarbon accumulation. Based on the study of basin evolution and source rock development characteristics, this paper applies a TSM Basin Simulation and Resource Evaluation System to establish one-dimensional and three-dimensional basin simulation models so as to reconstruct the burial, thermal evolution and hydrocarbon generation histories of different structural units. There are obvious differences in the hydrocarbon generation and evolution process of Carboniferous source rocks in different sags on the northeastern margin of the Junggar Basin. The Carboniferous source rocks in the Wulungu Depression entered the low-maturity evolution stage at the end of the Carboniferous, stagnated due to uplifts in the Permian, reached the threshold of secondary hydrocarbon generation at the end of Triassic when burial resumed, and are now in the over-mature stage, mainly generating dry gas (Ro>2.0%). The Carboniferous source rocks in the Sannan Sag entered the low-maturity stage in the Permian and are now in the high-maturity gas-producing stage (Ro=1.5%-1.9%). The Carboniferous source rocks in the Dishuiquan Sag entered the low-maturity stage in the Triassic and are now in the mature oil-producing stage (Ro=0.8%-1.3%). Simulation calculations show that the cumulative hydrocarbon generation of the source rocks in the Carboniferous Jiangbasitao Formation in the Wulungu Depression amounts to 20.5×109 t, in which the cumulative hydrocarbon generation until the end of Carboniferous is 10.3×109 t, which is the main oil generation stage. The cumulative gas generation at the end of Cretaceous is 18.4×109 t, which is the main gas generation period.

The precise timing of subduction initiation of the Paleo-Asian Ocean (PAO) in the northern margin of the North China Craton (NCC) remains controversial. In this study, we have conducted zircon U Pb dating, whole-rock major and trace elements, and zircon Hf isotope analyses on metadacites and metamorphic greywackes from the Changde volcano-sedimentary rocks, feldspar quartz sandstones and argillaceous siltstones from the Luquantun Formation and the Sidao sedimentary rocks in central-eastern Jilin Province (NE China), to constrain the initial closure of the PAO. We obtained Early Carboniferous zircon U Pb ages (345 ± 2 Ma and 351 ± 7 Ma) from the Changde volcano-sedimentary rocks. The metadacites are characterized by the enrichment in light rare earth elements and large ion lithophile elements, depletion in heavy rare earth elements and high field strength elements, and rare earth element ratios similar to those of the continental crust, indicating that these rocks originated from crustal melting. The metadacites exhibit affinity with the peraluminous A-type granite, with high zircon ε Hf (t) values (+3.46 − +12.21) and T DM2 of 1132–571 Ma, suggesting that they formed in a post-collisional extensional setting. Detrital zircon U Pb ages from the Luquantun Formation and Sidao sedimentary rocks constrain their maximum depositional ages to the Late Carboniferous (319 ± 5 Ma) and Early Permian (284 ± 4 Ma), respectively. Most detrital zircons have age peaks at 1800 Ma with negative zircon ε Hf (t) values, and 2500 Ma with positive zircon ε Hf (t) values, suggesting that the Carboniferous–Early Permian sediments from these two formations were mainly sourced from the NCC. Moreover, the chemical index of alteration, index of compositional variability, and plagioclase index of alteration values suggest that the sediments of the Changde volcano-sedimentary rocks originated from a mafic igneous source with a low degree of weathering and a sedimentary recycling history, while the samples from the Luquantun Formation and Sidao sedimentary rocks were sourced from an intermediate-felsic igneous rock with a moderate to intense degree of weathering and mainly influenced by source composition. The crystallization age curves and summary plots of detrital zircons indicate that the Early Carboniferous metamorphic greywackes from the Changde Formation were mainly deposited in a passive margin, while the Carboniferous–Early Permian sediments of the Luquantun Formation and Sidao sedimentary rocks were mainly deposited in an active margin. We suggest that the tectonic transition from passive to active margin occurred at ∼333 Ma, marking subduction initiation in the PAO close to the northern margin of the NCC. [Display omitted] • The Carboniferous–Early Permian sediments in central-eastern Jilin Province (NE China) are mainly sourced from the NCC. • During the Carboniferous, the eastern part of the northern margin of the NCC transitioned from passive to active. • The precise subduction initiation of the PAO occurred at approximately 333 ± 5 Ma along the northern margin of the NCC. [ABSTRACT FROM AUTHOR]

Widespread calcite and quartz pseudomorphs, interpreted as originally gypsum crystals, occur within hemipelagic calci-mudstone accumulated in subtidal offshore environments in the broad marine foreland basin developed on the southern flank of the Ouachita–Alleghanian–Variscan Orogen during mid-Carboniferous times, which acted as a marine corridor connecting the Panthalassa and Palaeo-Tethys Oceans during the Mississippian, and progressively narrowed during the assembly of Pangea. In this study, 67 outcrops of radiolaria-bearing calci-mudstone deposits that contain calcite and quartz pseudomorphs located in northern Spain and southern France were studied to constrain the gypsum spatial distribution and sedimentological features. The recognised microfacies indicate intrasediment gypsum precipitation, accompanied by less abundant bottom-grown precipitates and gypsum cumulates, in extensive offshore, probably several ten to a few hundred metres deep, basinal environments. Gypsum precipitation took place during a short-lived temporal episode during the early Bashkirian time (Voznesenkian), which can be correlated, on the basis of benthic foraminifera, with the coastal (inter- to supratidal) gypsum evaporites identified in NW Africa (Tindouf and Reggan successions in Morocco and Algeria) that would represent the shallow-water counterparts. The occurrence of gypsum precipitates both in offshore hemipelagic calci-mudstones of the Variscan foreland basin and in inter- to supratidal environments of the epeiric Sahara Platform indicates that hypersaline conditions affected vast marine areas, roughly coinciding with the estimated age of closure of the Panthalassa and Palaeo-Tethys marine connection. Therefore, the studied succession represents the trace of a basin-wide evaporitic episode extending for hundreds of kilometres driven by foreland basin restriction, mid-Carboniferous sea-level fall and arid climate. This study provides new insights for the interpretation of gypsum precipitates in offshore marine environments encountered in the Phanerozoic and whose genesis is poorly understood. [Display omitted] • Gypsum precipitation occurs in mid-Carboniferous offshore of a Variscan foreland basin. • These evaporites are broadly distributed marine deposits indicating a regional evaporitic event. • The proposed model provides new light into Carboniferous marine evaporite deposition. [ABSTRACT FROM AUTHOR]

The formation of the East Kunlun Orogen (EKO) was related to the tectonic evolution of the Proto-Tethys and Paleo-Tethys Oceans. However, how the Paleo-Tethys Ocean transited from the Proto-Tethys Ocean, and whether the Paleo-Tethys Ocean subducted northward beneath the East Kunlun–Qaidam Terrane in Carboniferous to Permian times, is still highly debated. Early Carboniferous Halaguole and Late Carboniferous to Early Permian Haoteluowa formations are extensively outcropped in the EKO, north Tibetan Plateau, and have thus recorded key information about the tectonic processes of the Paleo-Tethys Ocean that have implications for the reconstruction of the Northern Paleo-Tethys Ocean (Buqingshan Ocean). Siliciclastic rocks within these formations are collected for petrogeological, geochemical, and detrital zircon U–Pb dating research. Our results show that sandstones from Halaguole and Haoteluowa formations have an average total quartz–feldspar–lithic fragment ratio of Q67F12L21 and Q50F20L30, respectively, indicating relatively high compositional maturity. The geochemical results suggest that the average values of the Chemical Index of Alteration (CIA) are 57.83 and 64.66; together with their angular to subangular morphology, this indicates that their source rocks suffered from weak weathering and the sandstones are the result of proximal deposition. Geochemical features such as the low La/Th, TiO2, and Ni values suggest that the parental rocks in the provenance area are mainly acidic igneous rocks with minor intermediate igneous and old sedimentary components. The detrital zircon U–Pb age spectrum of these samples is dominated by age peaks at ~405–503 Ma and ~781–999 Ma, with subordinate age peaks at ~1610–2997 Ma and ~1002–1529 Ma, which show tectono–thermal events similar to those of the North Qimatag Belt (NQB), North Kunlun Terrane (NKT), and South Kunlun Terrane (SKT). These features suggest a contribution from the Early Paleozoic magmatic arc and Proterozoic basements in the NQB, NKT, and SKT to the Halaguole and Haoteluowa formations in these areas. In addition, the youngest zircon age of ~440 Ma from these sandstones is greater than the depositional age of Halaguole and Haoteluowa formations, which is a typical basin depositional feature in a passive continental margin. Geochemical tectonic discrimination diagrams, based on a major and trace element Ti/Zr–La/Sc plot, in combination with a detrital zircon age distribution pattern, all suggest a passive continental margin setting. Considering this together with the previous data, we argue that the Paleo-Tethys Ocean did not begin to subduct northward and that there was no oceanic subduction zone in the south EKO during Carboniferous to Early Permian times. Combining this information with that from previous studies suggests that the initial opening of the Paleo-Tethyan Ocean may have occurred before the Early Carboniferous time, and all the branches of the Paleo-Tethys Ocean constituted a complex ocean–continent configuration across parts of what is now Asia during the Early Carboniferous to Early Permian.

Early Carboniferous (359.3–323.4 Ma) volcanic complexes are widespread in the Southern Ural tectonic province, a fragment of the western (in present-day coordinates) segment of the Central Asian Orogenic Belt. Here, the Lower Carboniferous sequences crop out within the following N–S-trending tectonic zones (from west to east): Magnitogorsk, Ui River, East Ural, Transural, and Valeryanovka. We describe and discuss the geology and geochemistry of the Early Carboniferous volcanic complexes on the basis of published and newly obtained data, with implications for paleo-tectonic models. The western zones are dominated by bimodal rhyolite-basalt series, with the basalts relatively enriched in Ti and Zr but depleted in Nb. The volcanics of the Valeryanovka zone belong to the typically evolved calc-alkaline series, with the derivatives depleted in Ti and Nb. Almost all of the selected groups of volcanics bear geochemical signatures transitional between those of subduction-related and intraplate igneous rocks. The relative enrichment of the volcanics of the East Ural and Transural Zones may be interpreted as a result of a contribution from asthenospheric mantle and/or from subcontinental lithospheric mantle. The volcanics of the Valeryanovka zone reveal features common to subduction-related series of the Andean type. The data obtained allow us to compare the Early Carboniferous geodynamic settings in the western zones with the modern setting of the Northeastern Pacific, whereas the geodynamic setting of the Valeryanovka zone resembles that at the western margin of South America.

Time indications for the correlation and calibration of the Rotliegend of Germany are integrated and presented in a new way. The correlations are based on the visual balance of bio- and ecostratigraphic indications and radio-isotopic age determinations (RIA), whereby confidence limits, equivalent to those of the RIA, are applied also for other time indications (conchostracans, aquatic tetrapods, fishes, insects, macroflora, and ecostratigraphic indications). In contrast, terrestrial tetrapods and their tracks, chemo- and sequence stratigraphy, and magnetic susceptibility did not contribute to correlations in the Rotliegend in Central Europe. The Illawarra Reversal of the Earth' magnetic field (≈ 265 Ma) is fundamental for correlation and calibration. In general, however, the Regional Stratigraphic Scale is calibrated using U-Pb CA-ID-TIMS-RIA on zircon, Ar-Ar- and Rb-Sr-based RIA and, in addition, in the Early and Late Rotliegend using orbital-climatically controlled eccentricity cycles (≈ 100 ka, ≈ 400 ka). The boundary ages of the subgroups and of most formations are rounded to 0.5 Ma to avoid overinterpretation. Because of some inconsistent time indications alternative interpretations are also offered. The hitherto differing ages for the global Carboniferous-Permian boundary are the result of different dating methods: The ≈ 296 Ma in the Stratigraphic Tables of Germany 2002 and 2016 A (STG 2002; STG 2016 A) is an integrative age based on RIA from Central Europe, whereas the ≈ 299 Ma in the Global Stratigraphic Scales 2004 ff. and the STG 2016 B is based on a CA-ID-TIMS RIA on zircon from the southern Ural area. The age of ≈ 299 Ma is plausible from the perspective of the current Rotliegend RIA because the Rb-Sr age of 290.7 ± 0.9 Ma for the Donnersberg Formation (Lippolt & Hess 1989) has been replaced by the age of 294.5 ± 2.2 Ma, as recalculated in the present work. The updated time scale developed here will be integrated in the Stratigraphische Tabelle von Deutschland Kompakt 2022 (STDK 2022) and into the Stratigraphic Table of Germany Compact 2022 (STGC 2022). The age of the base of the Rotliegend in the Saar-Nahe Basin (SN, base Remigiusberg Formation and Glan Subgroup) is ≈ 299 Ma (U-Pb CA-ID-TIMS, zircon) resp. ≈ 300 Ma (Ar-Ar); the balanced compromise age of both is ≈ 299.5 Ma. In the Thüringer Wald (TW), the Rotliegend begins with the Ilmenau Formation (Subkommission Perm-Trias 2011) at ≈ 299.5 Ma (U-Pb CA-ID-TIMS). On the Flechtingen Block, at the southern margin of the Central European Basin, the oldest volcanic rock of the Altmark Subgroup is dated at 302 ± 3 Ma (U-Pb SHRIMP data). Accordingly, the Rotliegend in the STG 2002 and STG 2016 A starts at ≈ 302 Ma. However, the mean age calculated in the present work for the SHRIMP data of Breitkreuz & Kennedy (1999) is 298.6 ± 1.9 Ma, so that the base of the Altmark volcanic succession is here re-dated as ≈ 300.5 Ma. Thus, the ages of the present lithostratigraphic lower limits of the Rotliegend in northern Germany (CEB), in the TW and in the SN are, with ≈ 300.5 Ma to ≈ 299.5 Ma, only weakly diachronous if the nominal (face) values, which are both in the latest Carboniferous, are compared without the confidence intervals. For the first time, the Rotliegend of Germany is geochronologically subdivided into Early (≈ 300.5-295.5/294 Ma), Middle (≈ 295.5/294-266 Ma) and Late Rotliegend (≈ 266-257.5 Ma). The very long lasting Middle Rotliegend includes numerous and also extremely long stratigraphic gaps as a result of the amalgamation and the associated immense uplift of Pangaea in the area of Central and Western Europe. A very large stratigraphic gap in the Central European Basin (CEB) of ≈ 15 Ma (≈ 281-266 Ma, here called the Pangaea Gap) is supported by conchostracans, the Illawarra Reversal and the different palaeomagnetic properties of the sediments below and above the gap, which are discussed here for the first time. The Middle Rotliegend (duration of ≈ 29.5/28 Ma) is approx. twice as long as the Early (≈ 5.5/7 Ma) and Late Rotliegend (≈ 8.5 Ma) combined. The latter, however, contain the thickest successions in the Saar-Nahe Basin and the Central European Basin, respectively, which are free of gaps in the basin centre, with 'gaps' being defined in this context as time spans of ≤ 100 ka and ≤ 400 ka, respectively. In the CEB, the Elbe Subgroup is cyclostratigraphically calibrated to 5.6 Ma. A gapless area in the Saar-Nahe Basin is the Glan Subgroup, which covers only 4 Ma and 3 Ma, respectively; correspondingly, its subunits G1 to G10 (Glan 1 to Glan 10), introduced here, last on average 0.4 Ma and 0.3 Ma, respectively. This results in a maximum accumulation rate of 870 Bubnoff (Bub, m/Ma, mm/ka) and of 1150 Bub, respectively, which can be explained by a maximum of tectonic activity along the Hunsrück Southern Border Fault. For the lower Nahe Subgroup (N1 to N5, Nahe 1 to Nahe 5), the maximum accumulation rates are ≈ 450-200 Bub and for the upper Nahe Subgroup (N6-N8), at an estimated duration of 12 Ma ≈ 125 Bub and ≈ 50 Bub at a duration of 30 Ma, respectively. In the Central European Basin the maximum accumulation rates are much lower compared to the Glan Subgroup, with 200 Bub in the Elbe Subgroup and ≈ 360 Bub in the Havel Subgroup (Fig. 27), although here the subsidence rate may have been higher than the accumulation rate, as the basin was ≈ 130 m below sea level at the end of Folge ro4 (Top of the Hannover Formation; this paper). We recommend (1) Bubnoff (Bub) as unit of measure of the accumulation rate and (2) the stratigraphic terminology of the Subkommission Perm-Trias (2011) and the STG 2016 A. We here propose that numerous tuffs of the Glan Subgroup could originate from volcanic centres of the TW, whereas so far only source areas south of the SN were discussed: On the one hand, the tuff-rich time of the upper Jeckenbach Subformation - Odernheim Formation (= Glan units 7 and 8 = G7/G8) seems to correlate with the volcanogenic Oberhof time in the TW and, on the other hand, the tuff-poor time of the Wahnwegen Formation - middle Jeckenbach Subformation (G2/G6) seems to correlate with the upper Ilmenau, Manebach, Goldlauter and lowest Oberhof formations, which are devoid of volcanic rocks in the TW. Should causality exist here, an additional and also precise criterion for correlation would be established. At present there are two variants: On the one hand, volcanism in the Oberhof Formation, according to RIA (U-Pb CA-ID-TIMS on zircon), begins ≈ 1.8 Ma earlier and ends ≈ 0.8 Ma earlier than in the Donnersberg Formation (Ar-Ar, Rb- Sr recalculated). On the other hand, the conchostracan Lioestheria pseudotenella in the TW, if considered equivalent to L. cf. pseudotenella in the SN, the ecostratigraphic and lithofacial indications and the aquatic tetrapod D. pulcherrimus, point to for a similar age of these magmatites. The Sobernheim Lens (SN, Nahe units N4/N5) with its fossils so important for correlations is here assigned to the Jakobsweiler Member (N4, upper Donnersberg Formation), to the Quartzite-Conglomerate (N5, in literature often Wadern) and to the lowermost Standenbühl Formation (N4/N5). The youngest time indication Co13, the conchostracan Lioestheria arroyoensis sp. nov. correlates the upper Standenbühl Formation (N8, Martens 2020, where N8 may be extremely long), roughly with the Arroyo Formation in Texas (≈ early Kungurian). The here favoured age of the Tambach Formation of ≈ 294-292 Ma is significantly higher than the ≈ 286-283 Ma of STG 2016 A and the ≈ 284-281 Ma of STG 2016 B. It is based on RIA R25 (Table 9; lower Rotterode Formation, 295.8 ± 0.4 Ma; Lützner et al. 2021), which is the youngest CA-ID-TIMS RIA in the TW, and the duration estimate of the Rotterode - Tambach gap. In the SN, the youngest RIA R29 (Rb/Sr) is from the Donnersberg Formation (294.5 ± 2.2 Ma, this paper). From here on until ≈ 265 Ma (Illawarra Reversal), the numerical ages of all Rotliegend units and their connection to the Global Stratigraphic Scale (GSS) are uncertain and therefore correlations between Central Europe and the global reference section in the southern Ural area, partly biostratigraphically via North America, vary greatly. In this contect, the „series“ Wolfcampian and Leonardian (standard Permian units of the USA) played an important role. However, these lithostratigraphic units are at least unsuitabel as a reference system for large parts of North America, because they represent very variable time spans from region to region, similar with the "Lower Rotliegend" ("Autun") and "Upper Rotliegend" ("Saxon") of Central and Western Europe and therefore their assignement to the GSS is also very variable. This is due, among other things, to the fact that the Wolfcampian is often still understood as "lower Lower Permian", although considerable parts of it are now placed in the Carboniferous, because as a result of the introduction of the Global Stratigraphic Section and Point (GSSP) for the base of the Asselian Stage (= global base of the Permian in the southern Ural area), the conventional regional Carboniferous-Permian boundaries shifted to an higher stratigraphic level and thus to a younger age in the USA, China and the Donbass (Fig. 14). If the 57 sedimentary cycles in the Ottweiler and Glan subgroups (Königer & Stollhofen 2001: mean duration 245 ka each) in the SN are orbital-climatically induced, these cycles can only be 100 ka cycles (short eccentricity). This is also supported by the 6 cycles in units G7 and G8 that have been described in detail in the literature, which are consistent with the duration of the Glan Subgroup of 3 Ma and (preferred) 4 Ma, respectively. The total duration to be expected from 57 cycles à ≈ 100 ka is ≈ 5.7 Ma in contrast to the duration determined here according to RIA of ≤ 8 Ma. One reason for the difference could be that in the Ottweiler und Glan subgroups there are cycles that have not been recorded so far. The time span of ≤ 8 Ma is also an outcome of the new estimate for the duration of the Cantabrian Gap (early Stephanian) in the Saar-Nahe Basin of ≈ 3.6 Ma that is clearly longer than proposed in the STG 2002 and STG 2016. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geomechanics is the property of Journal of Geomechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Joggins Fossil Cliffs constitute an upper Carboniferous (Pennsylvanian) locality in Nova Scotia (Canada). This site, known for the rich record of fossils preserved in the palaeoenvironment in which they lived, sheds light on the late Carboniferous environment. More specifically, Joggins records one of the earliest Pennsylvanian ecosystems and is unique in preserving a rich diversity of terrestrial fauna compared with other Pennsylvanian communities, which mostly preserve aquatic fauna. For vertebrate palaeontology, the significance of Joggins lies in the discovery of the earliest amniotes (Hylonomus lyelli Dawson, Protoclepsydrops haplous Carroll, and Asaphestera platyris (Steen)) and the second earliest temnospondyl, Dendrerpeton (only Balanerpeton woodi Milner & Sequeira occurs earlier). Computed tomography of the most complete tetrapod specimen found at Joggins, the temnospondyl amphibian currently referred to Dendrysekos helogenes Steen, made accessible the internal anatomy and revealed previously obscured anatomical structures, including the stapes, scleral plates, and partial sphenethmoid. These newly accessible features enabled a redescription of this specimen. The resulting anatomical comparisons and phylogenetic analyses suggest that the genus Dendrysekos is a junior synonym of Dendrerpeton; the diagnostic characters previously distinguishing the two genera are considered to be instead a combination of ontogenetic and preservational parameters, and the two genera were not resolved as discrete. Additionally, the phylogenetic analyses show that the interrelationships between the main early temnospondyl groups (Edopoidea, Dvinosauria, Eryopoidea and Dissorophoidea) are neither robust nor well supported, due to the low number of shared derived characters. [ABSTRACT FROM AUTHOR]

Pleurotomariida have the longest fossil record among living gastropods and are diverse and abundant in the middle and upper Palaeozoic. Its traditional classification is based on adult shell characters. The early shell morphology has been largely unknown. We describe exceptionally well‐preserved Pleurotomariida from the Pennsylvanian marine shales of Texas, Oklahoma, Kansas and Ohio. In total, 38 species representing 19 genera are described, including 10 new species, one new genus and one new subgenus: Eirlysella buckhornensis gen. et sp. nov., Shansiella (Oklahomaella) globilineata subgen. et sp. nov., Phymatopleura girtyi, Phymatopleura conica, Worthenia (Yochelsonospira) kuesi, Dictyotomaria turrisbabel, Paragoniozona yanceyi, Spiroscala shwedagoniformis, Peruvispira oklahomaensis, Baylea tenera. Replacement names are Paragoniozona ornata nom. nov. (for Pleurotomaria aspera Girty), Spiroscala quasipulchra nom. nov. (for Euconospira pulchra Batten). The early ontogenetic shells including protoconchs and early teleoconchs are reported in detail for the first time for most taxa. Most species have a protoconch of one whorl as that of living Vetigastropoda. Planktotrophic protoconchs (multi‐whorled larval shells with sinusigera) are reported for Platyzona and Peruvispira; they are therefore placed in the family Goniasmatidae (Caenogastropoda). Repaired shell scars were found in juvenile Pleurotomariida specimens (c. 1 mm), suggesting exposure to predation from an early stage of ontogeny. Pleurotomariida are strongly dominant in surface samples of the Finis Shale (Texas) but in bulk samples using fine mesh‐sizes, dominance is much less pronounced, indicating a change in clade proportion depending on sampling method. The taxonomic richness and abundance of Pleurotomariida seen in these Carboniferous shales have not been reported from post‐Triassic formations. [ABSTRACT FROM AUTHOR]

In the Qaidam basin, Northwest China, karstic fissures and caves are developed in many places of the Lower Carboniferous Chengqianggou Fm. and Huaitoutala Fm. and the Upper Carboniferous Keluke Fm., in which are found typical karstic marks. Several suites of transgressive carbonate rocks formed during the Late Paleozoic epoch are preserved as reservoir properties in the Qaidam basin, with paleokarst‐related cave‐fractured diagenetic structures, which provided the basis for cave‐fractured development. Carbonate and clastic samples covering or infilling caves and fractures in Carboniferous strata were collected in the eastern Qaidam basin to focus on petrological and geochemical analyses of karst and infilling materials. Based on this study of the Caledonian diagenetic sequence, and bitumen‐infilled inclusion temperature and burial history, there existed a continuous atmospheric freshwater leaching process, which played a critical role in the construction of the Carboniferous supergene paleokarsts. Investigation and survey of the tectonic setting, plate paleolatitude and river development intensity also proves that there was abundant rainfall during the Indosinian period, after which the strata undergo a shallow burial process. Because Indosinian period is earlier than the key timing of hydrocarbon‐generation of the Carboniferous source rocks, this kind of karst reservoir has potential significance for oil‐gas resources in this area. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northeast Petroleum University is the property of Journal of Northeast Petroleum University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During the Palaeozoic Era, plants conquered the land and covered greater and greater areas from coastal lowlands to highlands. Palaeobotanical data based on macroremains from Polish Palaeozoic strata complete and enrich the picture of these processes. Knowledge about Polish Palaeozoic macrofloras developed significantly in the last hundred years but is very unevenly distributed among successive geological periods. Ordovician and Silurian macrofossils are single finds. Cores from deep boreholes provided significant material for recognition of Early Devonian plants. Carboniferous floras, especially from coal measures, are best known, as they are most numerous in taxa and specimens. Permian floras are very rare. Based on Devonian and Carboniferous fossils, many new, evolutionarily important taxa were proposed and have entered world science. [ABSTRACT FROM AUTHOR]

The Mahu Sag in the Junggar Basin, China, is a hydrocarbon-rich sag. Abundant hydrocarbon source rocks were developed in the late Paleozoic there across the Carboniferous–Permian boundary. However, studies of the source rocks have focused mainly on the lower Permian Fengcheng Formation. Here we compare the Fengcheng Formation with other Carboniferous rocks and those of the lower Permian Jiamuhe and middle Permian Lower-Wuerhe formations. Based on organic petrological and geochemical data, the organic matter precursors, sedimentary facies, and resource potential of these source rocks were investigated. The bio-precursors of Carboniferous, Jiamuhe, and Lower-Wuerhe Formations were dominantly estuarine higher plants, Nematothallus -higher plants, and spores, respectively. The bio-precursors of Fengcheng Formation were mainly bacteria and algae, and the organic matter is abundant, with a high hydrocarbon-generating capacity and significant shale oil potential. In contrast, the other three formations contain poor-quality source rocks, although the Lower-Wuerhe Formation has a higher organic matter abundance than the Jiamuhe Formation. The Carboniferous organic matter contains mainly type II kerogen, whereas the Jiamuhe and Lower-Wuerhe formations contain type III kerogen. The thermal maturities determined from Tmax values is larger than those indicated by biomarkers. The biomarkers show that the three studied formations contain a mixture of terrestrial higher plants and bacteria–algae, with the contribution of green algae being higher than that of bacteria in most samples. However, the ratio of algae to bacteria is lower than that of the Fengcheng Formation. The Fengcheng Formation was deposited in a strongly reducing, high-salinity, and water-stratified sedimentary environment. The other three formations were deposited in an oxidizing–reducing, low-salinity, and water-unstratified environment. They are characterized by the predominance of mudstone over carbonate rocks and the descending distribution type of tricyclic terpenes. Our results provide a basis for research on upper Paleozoic source rocks in western China, and useful information for oil and gas exploration in the Mahu Sag. [ABSTRACT FROM AUTHOR]

The Mississippian (Tournaisian–Visean) of the Jbel Asdaf area in the Tisdafine Basin (Eastern Anti-Atlas, Morocco) has been, for the first time, the subject of a palynological study. This work aims first to describe the lithological and the paleontological composition of the Aït Yalla and Tinerhir Formations, then to refine the age, reconstruct the paleoenvironment and assess the thermal maturity of the organic matter. The studied section is subdivided, from oldest to youngest, into three intervals, according to their lithological and paleontological compositions. Lithologically, the lower interval (lower part of the Aït Yalla Formation) and middle interval (upper part of the Aït Yalla Formation and basal part of the Tinerhir Formation) consist mostly of clay shales and green shales, respectively, both alternating with limestone or sandstone beds. The upper interval (upper part of the Tinerhir Formation) is dominated by sandstones, also alternating with pelitic-sandstone or limestone beds. The kerogen delivered by the analyzed samples is mostly of continental origin, composed mainly of opaque phytoclasts, while translucent phytoclasts and miospores are less represented. Marine fraction, consisting mainly of granular amorphous organic matter and some phytoplankton, are rare. Biostratigraphically, the late Visean Tripartites vetustus–Rotaspora fracta (VF) miospore Zone of the Western Europe biozonal scheme is recognized with some regards in the Tinerhir Formation, based on the first occurrence of the miospore Rotaspora cf. knoxi. Vallatisporites aff. ciliaris is another biostratigraphic marker taxon of the assemblage, whose the last occurrence marks the end of the VF Biozone at the top of the analyzed section. Qualitative and quantitative parameters of the different palynofacies constituents (e.g., shape, size, % of opaque and translucent phytoclasts) show, from the base to the top of the section, a gradual transition from a distal marine environment generally recognized in the Aït Yalla Formation towards an intermediate marine environment in the Tinerhir Formation, suggesting a sea-level fall. Optical analyses performed on the color of palynomorphs, mainly spores, suggest a thermal maturity, ranging from late mature to early post-mature stage for most of the analysed samples, with a burial depth and a temperature of at least 3300 m and 90 °C, respectively. [ABSTRACT FROM AUTHOR]

Abstract Stromatoporoid sponges were very abundant during the middle Palaeozoic Era and are thought to disappear at the end of the Devonian Period in the Hangenberg Crisis. However, there are records of organisms with stromatoporoid-type structure in Carboniferous strata, the subject of this study. The Viséan fossil Labechia carbonaria Smith 1932 has been discussed previously in literature and its affinity has not been confirmed. In this study, the type material of L. carbonaria collected from the middle part of the Frizington Limestone Formation (previously called Seventh Limestone), Holkerian Substage, stored in the Natural History Museum (London, UK) and British Geological Survey (Keyworth, UK) was re-examined. The Holkerian Substage, in which L. carbonaria was found, lies between ca 335–339 Ma, and the Frizington Limestone Formation ranges from topmost Arundian to upper Holkerian, so middle Frizington Limestone Formation is likely approximately 337 Ma. L. carbonaria comprises thick long pillars connected by thin curved cyst plates consistent with the structure of the stromatoporoid genus Labechia. However, a common opinion is that L. carbonaria fossils may be mistaken for fragments of rugose corals, but there are problems with assigning it to the Rugosa. In vertical section (VS) L. carbonaria could be mistaken for a transverse section (TS) of a Carboniferous rugose coral. However, in TS L. carbonaria shows the rounded cross sections of stromatoporoid pillars. If it was a coral, septal sheets of the VS of a coral should be seen. For a rugose affinity to still apply, a coral structure would have to be composed of free trabeculae, but these are not known after the middle of the Devonian Period; there are no corals of Early Carboniferous age with the structure of L. carbonaria. Another interpretation, that L. carbonaria is a chaetetid, is discounted because it lacks calicles and is very different in structure from chaetetids. We conclude that L. carbonaria is a stromatoporoid. Because the beginning of the Carboniferous Period was ca 359 Ma, stromatoporoids thus occur approximately 22 million years after their purported disappearance at the end-Devonian Hangenberg Crisis. L. carbonaria, together with other rare occurrences in Carboniferous strata of stromatoporoid-form sponges Newellia mira (Newell) in USA, and uncertain taxa Komia Korde and Palaeoaplysina Krottow that have been attributed to stromatoporoids by some authors, supports some published views that end-Devonian stromatoporoid extinction may not have been as final as is traditionally interpreted. Thus Mesozoic stromatoporoids may represent resurgence of sponge lineages that survived the late Palaeozoic, perhaps in uncalcified form. Palaeogeographically, during the Early Carboniferous, the UK was positioned in low latitudes and in a central location of global distribution of reefal buildups during the late Palaeozoic continental assembly towards Pangaea. Thus it is curious that L. carbonaria is found in only one place; future search may determine its true palaeographic distribution, with potential reconsideration of the extinction of stromatoporoids at the end of the Devonian Period.

Carboniferous carbonate reservoirs at the eastern edge of the Pre-Caspian Basin have undergone complex sedimentation, diagenesis and tectonism processes, and developed various reservoir space types of pores, cavities and fractures with complicated combination patterns which create intricate pore-throats structure. The complex pore-throat structure leads to the complex porosity-permeability relationship, bringing great challenges for classification and evaluation of reservoirs and efficient development. Based on the comprehensive analysis on cores, thin sections, SEM, mercury intrusion, routine core analysis and various tests, this paper systematically investigated the features and main controlling factors of pore-throats structure and its impact on the porosity-permeability relationship of the four reservoir types which were pore-cavity-fracture, pore-cavity, pore-fracture and pore, and three progresses are made. (1) A set of classification and descriptive approach for pore-throat structure of Carboniferous carbonate reservoirs applied to the eastern edge of the Pre-Caspian Basin was established. Four types of pore-throat structures were developed which were wide multimodal mode, wide bimodal mode, centralized unimodal mode and asymmetry bimodal mode, respectively. The discriminant index of pore-throat structure was proposed, realizing the quantitative characterization of pore-throat structure types. (2) The microscopic heterogeneity of pore reservoir was the strongest and four types of pore-throat structures were all developed. The pore-fracture and pore-cavity-fracture reservoirs took the second place, and the microscopic heterogeneity of pore-cavity reservoir was the weakest. It was revealed that the main controlling factor of pore-throat structure was the combination patterns of reservoir space types formed by sedimentation, diagenesis and tectonism. (3) It was revealed that the development of various pore-throat structure types was the important factor affecting poroperm relationship of reservoirs. The calculation accuracy of permeability of reservoirs can be improved remarkably by subdividing the pore-throat structure types. This study deepens the understanding of pore-throat structure of complicated carbonate reservoirs, and is conducive to classification and evaluation, establishment of precise porosity-permeability relationship and highly efficient development of carbonate reservoirs.

Research subject. This article focuses on the geological structure of the northern part of the Pai-Khoi carbonate parautochthone.Materials and methods. The study was based on the data obtained on the key sections of the North-Western Pai-Khoi. Research methods included lithological and facies analysis, subsidence curves, reconstruction of the thermal maturity of deposits based on conodont alteration indexes, X-ray microtomography for determining porosity values.Results. The Upper Devonian–Carboniferous succession (ca. 900 m thick) is composed of the terrigenous and carbonate Pyrkov Fm. (Frasnian), carbonate Lymbadyakha Fm. (Famennian-Tournaisian), Bolvanskii Fm. (Visean-Bashkirian), and Hoiponganase Fm. and Reef Chaika (Moskovian-Kasimovian). The early Frasnian part of the succession was deposited in a shallow-water environment. In the Middle–Late Frasnian, the Korotaikha paleodepression and an isolated carbonate platform was formed on the shelf edge. Filling of the paleodepression was completed at the end of the Early Visean. In the Late Visean–Late Carboniferous, a carbonate platform (ramp) formed. A Middle Paleozoic paleogeothermal gradient reconstructed on the basis of conodont alteration indexes is much higher in the Pai-Khoi carbonate parautochthone than in the most of Pechora Plate regions. This is likely to have been caused by the tectonic activity of the plate border in the Late Carboniferous–Mesozoic. A downward decrease in open porosity (from 6% to 0.1%) is likely to have been associated with increased compaction and recrystallization of the carbonates.Conclusions. Famennian-Tournaisian carbonate formations of the Pai-Khoi carbonate parautochthone were deposited under the conditions of isolated platform environment; however, the Visean–Late Carboniferous deposits were formed in the outer ramp environment. The Late Devonian–Middle Carboniferous carbonate deposits of the Pai-Khoi parautochthone demonstrate an extremely low open porosity and a high thermal maturity. These properties, along with the pronounced faulting and folding of the rocks, significantly decrease petroleum-bearing prospects of these deposits.

The impact of the late Devonian Hangenberg Event on ostracods is quantified for the first time from newly acquired data from the Blue Snake section, Guizhou Province, South China. Ninety–eight species belonging to 31 genera are identified and figured. Four new species are described: Clavofabella? lanshella sp. nov., Sansabella gelaohensis sp. nov., Cytherellina caerulea sp. nov., Sulcella baisuzhena sp. nov. The ostracod associations from the Blue Snake section document a significant drop in specific diversity as well as major changes in taxonomic composition through the Hangenberg Event. We here report the reduction of the proportion of Palaeocopida and the increase in that of Podocopida between the latest Famennian and the Tournaisian. The specific extinction and renewal rates are estimated at 44% and 62%, respectively. The main factor of the post–crisis renewal of ostracod faunas in the Blue Snake section appears to be the progressive diversification of the family Bairdiidae and was probably related to palaeoenvironmental changes. The characteristics of associations point to an increase of the water depth over the studied area, from a near–shore shallow environment during the latest Famennian to a deeper and more open offshore environment during the Tournaisian.

Polymetamorphic units are important constituents of continent–continent collisional orogens, and rift metamorphic assemblages are often overprinted by subsequent metamorphism during subduction and collision. This study reports the metamorphic conditions and evolution of the Dorud–Azna metamorphic units in the central part of the Sanandaj–Sirjan zone (SSZ), Iran. Here, new geothermobarometry results are integrated with 40Ar/39Ar mineral and Th–U–Pb monazite and thorite ages to provide new insight of polyphase metamorphism in the two different basement units of the SSZ, the lower Galeh-Doz orthogneiss and higher Amphibolite-Metagabbro units. In the Amphibolite-Metagabbro unit, staurolite micaschist underwent a prograde P–T evolution from 640 ± 20 °C/6.2 ± 0.8 kbar in garnet cores (M1) to 680 ± 20 °C/7.2 ± 1.0 kbar in garnet rims (M2). Three Th–U–Pb monazite ages of 306 ± 5 Ma, 322 ± 28 Ma and 336 ± 39 Ma from the garnet-micaschists testify the Carboniferous age of M1 metamorphism. In the same unit, the metagabbro records P–T conditions of 4.0 ± 0.8 kbar and 580 ± 50 °C in the (magmatic) amphibole core (Late Carboniferous intrusion) to 7.5 ± 0.7 kbar and 700 ± 20 °C in the amphibole rim indicating a prograde P–T path during subsequent burial (M1). New 40Ar/39Ar dating of white mica from the staurolite micaschist yielded a staircase pattern ranging from 36 ± 12 Ma to 170 ± 2 Ma. This implies polymetamorphism with a minimum Late Jurassic cooling age through the Ar retention temperature of ca. 425 ± 25 °C after M2 metamorphism and a Paleogene low-grade metamorphic overprint (M3), while 40Ar/39Ar white mica dating of garnet micaschist yielded a plateau age of 137.84 ± 0.65 Ma. We therefore interpret the amphibolite-grade metamorphism M2 to have predated 170 Ma and is likely between 180 and 200 Ma. Furthermore, it is overprinted at about 36 Ma under retrogressive low-grade M3 metamorphism (at temperatures of ~350–240 °C) during final shortening and exhumation. In the underlying Galeh-Doz unit, the Panafrican granitic orthogneiss intruded at P–T conditions of 3.2 ± 4 kbar and 700 ± 20 °C, then it was metamorphosed and deformed at 600 ± 50 °C and 2.0 ± 0.8 kbar (metamorphic stage M1) prior to Late Carboniferous intrusion of mafic dikes. 40Ar/39Ar dating of amphibole from the Galeh-Doz orthogneiss gave plateau-like steps between 260 and 270 Ma, representing the age of cooling through ca. 500 °C after the M1 metamorphic event. Interestingly, the results of this study demonstrate polyphase metamorphic histories in both the Galeh-Doz orthogneiss and Amphibolite-Metagabbro units at different P–T conditions and final thick-skinned Paleogene emplacement of these units over the underlying low-grade metamorphic June Complex. Our findings suggest that both units are affected by high-T/low-P Late Carboniferous orogenic metamorphism along with the bimodal magmatism, as result of rifting. We propose that the Early Jurassic amphibolite-grade M2 metamorphism of the SSZ is correlated with the initial subduction of the Neotethyan Ocean. Eventually, the investigated units reflect various stages of a Wilson cycle, from rifting to initiation of the subduction in final plate collision.

Changes in the nearshore pelagic ecosystems at the Devonian–Carboniferous boundary are considered. These changes are reconstructed based on conodont ecogeochemistry, carbon isotopic composition of marine carbonates, and abundance of the unilocular foraminifer Bisphaera. [ABSTRACT FROM AUTHOR]

The cladid crinoid Kholokholnyacrinus ilkhovskyi gen. et sp. nov. is described based on a very large cup from the Pennsylvanian (Kashirian Regional Substage, Smedva Formation) of the Rzhev–Staritsa Volga Region. The new taxon is characterized by a complex of morphological characters in the structure of the crown and arms, such as a disarticulated basal circlet, very low brachials in close contact with each other and with anal sac plates, fixed proximal arms, etc., by which it differs strongly from most other cladids. The uniqueness of the morphological characters indicates that the new genus should be assigned to a new family of cladid crinoids. Paleoecological aspects and systematics of the new crinoid genus are discussed. [ABSTRACT FROM AUTHOR]

Equisetales represents a diverse and abundant group of articulate plants with a wide geographical distribution that had their greatest development in late Palaeozoic and early Mesozoic times. The order is represented by 12 families, composed mostly by extinct families of late Palaeozoic age, with only a unique living family, the Equisetaceae. Here we describe the new equisetalean fossil-genus and species Iberisetum wegeneri gen. nov., sp. nov. from the lower Stephanian C (Gzhelian, Upper Pennsylvanian) of intramontane Douro Basin, in northwestern Portugal. This new fossil taxon represents another endemic species for the Douro Basin. Iberisetum wegeneri consists of a leafy articulated stem that shows a unique combination of macro-morphological features that are common in various fossil-genera of different equisetalean families, and that includes exclusive (autapomorphic) characters. The singular morphology of foliar sheaths of Iberisetum wegeneri represents an evolutionary novelty into the Equisetales and suggests a heliotropic organisation (heliotropism) of the plant during its lifetime. Such functional morphology is the result of an evolutionary adaptation to the climatic and ecological conditions restricted to intramontane environments of Douro Basin. [ABSTRACT FROM AUTHOR]

New archaeorthopterans Contracladus impar gen. nov. et sp. nov. (uncertain assignement), Paraspiculum brauckmannii gen. nov. et sp. nov. (Caloneurodea) and Piesbergopterum punctatum gen. nov. et sp. nov. (Cnemidolestodea) are described from the Moscovian of Piesberg quarry near Osnabrück (Lower Saxony, Germany). All new taxa display unique patterns of their forewing venations. The mosaic of characters found in C. impar with a particular lack of a free vein CuA demonstrates the limits of the current systematics for Archaeorthoptera. The evidence for a supposedly disruptive pattern of colouration is demonstrated on the forewing membrane of P. punctatum, which shows numerous spots in the distal part of the wing. Those are inside the cells delimited by the crossveins. The exceptionally preserved fossils found in Piesberg document fine structural details and complete our knowledge on the early history of this diverse group of polyneopteran insects. [ABSTRACT FROM AUTHOR]

The timing of regional deformation of the turbiditic Silurian–Devonian Hill End Trough in the northeastern Lachlan Orogen has been a contentious issue with one view ascribing the regional north–south folds and axial planar foliation to Middle Devonian basin inversion. Alternatively, it has been argued that given the low-angle discordance between Lower and Upper Devonian units on the Capertee and Molong highs, and the development of a dominant episode of folding mapped from the Hill End Trough into the adjoining highs, the major regional deformation is latest Devonian to early Carboniferous and predates intrusion of Bathurst-type granites at 358–314 Ma. We have approached the problem by analysing the gentle, upright, southeast-trending folds and deformation patterns in Devonian units of the northern Capertee High (Cudgegong area), drawing a cross-section across the Hill End Trough and reviewing the structure of two areas in the Molong High (west of Orange, and south of Wellington). Upper Devonian units on the highs are affected by fold patterns that extend into the underlying successions and have been interpreted as continuous into the central Hill End Trough, confirming the extent of the latest Devonian to early Carboniferous regional deformation in the northeastern Lachlan Orogen. Constraints from timing of deposition and radiometric ages are ambiguous and imply deformation was overlapping with sedimentation, as has also been inferred from sedimentary features of the Upper Devonian succession. Steeply dipping faults along the highs predated the Late Devonian and were probably formed in extension during formation of the Hill End Trough and were reactivated during basin inversion and potentially during Upper Devonian sedimentation. Our conclusion is that the simplest hypothesis is that the regional east–west shortening was of latest Devonian to early Carboniferous age, although poorly understood basin inversion occurred in the Middle to Late Devonian. The timing of the development of regional north–south folds in the northeastern Lachlan Orogen has been a contentious issue and is difficult to resolve, given the broad stratigraphic constraints and ambiguous radiometric ages. The simplest hypothesis remains that the regional deformation was of latest Devonian to early Carboniferous timing. Middle to Late Devonian deformation included reactivation of basin-forming steeply dipping faults during basin inversion and ongoing sedimentation. [ABSTRACT FROM AUTHOR]

A new crinoid species of the Order Cladida, Mooreocrinus liaoi Mao and Li sp. nov., is described from the Pennsylvanian (Upper Carboniferous) Outangdi Formation in Jiangshan, Zhejiang Province, representing the first record of Mooreocrinus Wright and Strimple, 1945 in China. The presence of Mooreocrinus in the South China Block extends the palaeogeographical record of this genus and indicates it to be a cosmopolitan taxon. Three other ancient tectonically separated areas that are now combined into the modern China mass (Sibumasu, Junggar, North China) do not contain any record of Mooreocrinus. Overall, there is low biodiversity of the Late Palaeozoic crinoid faunas in the South China Block. Our new materials provide further evidence for diversity assessment of crinoid faunas in peri‐Gondwana blocks. [ABSTRACT FROM AUTHOR]

As one of the pioneer palaeontologists, Professor Zhuoting Liao has contributed his lifetime to promoting palaeontological and stratigraphical research in China for 60 years, and he passed away in the field excursion in South China on June 20, 2020. In his palaeontological career, Liao has worked on Late Palaeozoic to Mesozoic palaeontology and stratigraphy of almost all regions across China, and his interests have also extended to the Permian–Triassic (P‐Tr) boundary and mass extinction. He has worked on palaeontology, palaeobiogeography, biostratigraphy, tectonostratigraphy, and their implications in mineral and oil‐gas industries. Liao has established 22 new genera and 172 new species of brachiopods, and, together with his colleagues, proposed 11 new genera and 25 new species of echinoderms. He dedicated his lifetime to work on Late Palaeozoic palaeontology and stratigraphy of the previously remote and tectonically complex Xinjiang and adjacent regions, north‐west China, and established integrated stratigraphical frameworks for the Carboniferous to Permian strata, providing fundamental basis for mineral and hydrocarbon exploration in the poorly understood Central Asian terranes. In addition, he has mentored many young palaeontologists and stratigraphers in various ways. This volume assembles 30 papers addressing the Late Palaeozoic to Mesozoic palaeontology and stratigraphy of China and adjacent regions, which pays tribute to the achievement of Professor Zhuoting Liao. [ABSTRACT FROM AUTHOR]

The Early Pennsylvanian land plant community is characterized by widespread forests consisting of lycopsids, ferns, and seeds fern in swampy wetlands. The contemporaneous palynological assemblages are mainly composed of spores of Lycospora spp., Densosporites spp., and Laevigatosporites spp. and monosaccate prepollen of Florinites spp. Taeniate bisaccate pollen appeared for the first time during the Early Pennsylvanian but never prevailed in the coeval palynological assemblages. Here, we report a taeniate bisaccate pollen‐dominated palynological assemblage from the Jiamuhe Formation of Well Ke 85 in the Zhongguai Uplift, northwestern Junggar Basin, Xinjiang. Nineteen miospore species belonging to 14 genera were identified from the assemblage. Based on their relative abundance, one assemblage is nominated informally as Calamospora breviradiata–Lunatisporites tersus (BT) assemblage. SIMS U–Pb geochronological analysis of zircons from two volcanic ash beds from the basal and upper parts of the formation yields weighted mean 206Pb/238U dates of 316.3 ± 2.2 Ma (MSWD = 1.2, n = 19) and 316.5 ± 2.8 Ma (MSWD = 0.85, n = 20) in an ascending order. A Bashkirian age is thus assigned to the BT assemblage. Our combined palynological and geochronological investigations reveal an early stage of the rise of conifers in the Kazakhstan Plate and offer a rare glimpse into the Early Pennsylvanian land vegetation in the subtropical area at the northern hemisphere. [ABSTRACT FROM AUTHOR]

Malayacyclus terengganuensis, a new genus and species of the Cyclida (Crustacea), is reported from the Early Carboniferous (Visean) of Terengganu, eastern Peninsular Malaysia (East Malaya Block). The new genus possesses diagnostic features of both families Cyclidae and Americlidae. Plus, it develops the trifurcate posterior spines: a unique morphology that was not previously known for any cyclidan genera. Based on the possession of an anterior rostrum and optic notches, it is tentatively included in the Americlidae. This represents the first find of the Cyclida from Southeast Asia and the second from the Carboniferous of Asia (eastern Tethys). [ABSTRACT FROM AUTHOR]

The vertebrate transition to land is one of the most consequential, yet poorly understood periods in tetrapod evolution. Despite the importance of the water–land transition in establishing modern ecosystems, we still know very little about the life histories of the earliest tetrapods. Bone histology provides an exceptional opportunity to study the biology of early tetrapods and has the potential to reveal new insights into their life histories. Here, we examine the femoral bone histology from an ontogenetic series of Greererpeton, an early tetrapod from the Middle‐Late Mississippian (early Carboniferous) of North America. Thin‐sections and micro‐CT data show a moderately paced rate of bone deposition with significant cortical thickening through development. An interruption to regular bone deposition, as indicated by a zone of avascular tissue and growth marks, is notable at the same late juvenile stage of development throughout our sample. This suggests that an inherent aspect to the life history of juvenile Greererpeton resulted in a temporary reduction in bone deposition. We review several possible life history correlates for this bony signature including metamorphosis, an extended juvenile phase, environmental stress, and movement (migration/dispersal) between habitats. We argue that given the anatomy of Greererpeton, it is unlikely that events related to polymorphism (metamorphosis, extended juvenile phase) can explain the bony signature observed in our sample. Furthermore, the ubiquity of this signal in our sample indicates a taxon‐level rather than a population‐level trait, which is expected for an environmental stress. We conclude that movement via dispersal represents a likely correlate, as such events are a common life history strategy of aquatically bound vertebrates. [ABSTRACT FROM AUTHOR]

Background. The megalichthyids are one of several clades of extinct tetrapodomorph fish that lived throughout the Devonian Permian periods. They are advanced "osteolepidid-grade" fishes that lived in freshwater swamp and lake environments, with some taxa growing to very large sizes. They bear cosmine-covered bones and a large premaxillary tusk that lies lingually to a row of small teeth. Diagnosis of the family remains controversial with various authors revising it several times in recent works. There are fewer than 10 genera known globally, and only one member definitively identified from Gondwana. Cladarosymblema narrienense Fox et al. 1995 was described from the Lower Carboniferous Raymond Formation in Queensland, Australia, on the basis of several well-preserved specimens. Despite this detailed work, several aspects of its anatomy remain undescribed. Methods. Two especially well-preserved 3D fossils of Cladarosymblema narrienense, including the holotype specimen, are scanned using synchrotron or micro-computed tomography (μCT), and 3D modelled using specialist segmentation and visualisation software. New anatomical detail, in particular internal anatomy, is revealed for the first time in this taxon. A novel phylogenetic matrix, adapted from other recent work on tetrapodomorphs, is used to clarify the interrelationships of the megalichthyids and confirm the phylogenetic position of C. narrienense. Results. Never before seen morphological details of the palate, hyoid arch, basibranchial skeleton, pectoral girdle and axial skeleton are revealed and described. Several additional features are confirmed or updated from the original description. Moreover, the first full, virtual cranial endocast of any tetrapodomorph fish is presented and described, giving insight into the early neural adaptations in this group. Phylogenetic analysis confirms the monophyly of the Megalichthyidae with seven genera included (Askerichthys, Cladarosymblema, Ectosteorhachis, Mahalalepis, Megalichthys, Palatinichthys, and Sen-goerichthys). The position of the megalichthyids as sister group to canowindrids, crownward of "osteolepidids" (e.g., Osteolepis and Gogonasus), but below "tristichopterids" such as Eusthenopteron is confirmed, but our findings suggest further work is required to resolve megalichthyid interrelationships. [ABSTRACT FROM AUTHOR]

Given the poor preservation potential of phloem in general (Smoot & Taylor, 1978), any specimen ostensibly exhibiting phloem fossilization - and particularly fossilization of secondary phloem - warrants particular attention. Keywords: cambium; Carboniferous; Lepidophloios; paleobotany; phloem; physiology; Stigmaria EN cambium Carboniferous Lepidophloios paleobotany phloem physiology Stigmaria 967 972 6 10/07/21 20211101 NES 211101 Introduction Consensus regarding arborescent lycopsid gross anatomy has not been reached in 150 years of study (Williamson, 1872; Walton, 1935; Pannell, 1942; Felix, 1952; Andrews & Murdy, 1958; Eggert, 1961; Bateman, 1994; Krings I et al i ., 2011; Boyce & DiMichele, 2016; Hetherington I et al i ., 2016; D'Antonio & Boyce, 2020; D'Antonio I et al i ., 2020; DiMichele & Bateman, 2020). Note, in both, the outward fanning of the ray into the secondary phloem similar to dilation growth in extant dicots (Lev-Yadun, 1996). red, wood; dark blue, secondary phloem; yellow, wood ray; light blue, sieve cells. Rather, the location of these sieve cells to the interior of the outer edge of the wood rays indicates secondary phloem. sp, secondary phloem; w, wood; r, ray. [Extracted from the article]

The distribution of forest cover alters Earth surface mass and energy exchange and is controlled by physiology, which determines plant environmental limits. Ancient plant physiology, therefore, likely affected vegetation-climate feedbacks. We combine climate modeling and ecosystem-process modeling to simulate arboreal vegetation in the late Paleozoic ice age. Using GENESIS V3 global climate model simulations, varying pCO2, pO2, and ice extent for the Pennsylvanian, and fossil-derived leaf C:N, maximum stomatal conductance, and specific conductivity for several major Carboniferous plant groups, we simulated global ecosystem processes at a 2° resolution with Paleo-BGC. Based on leaf water constraints, Pangaea could have supported widespread arboreal plant growth and forest cover. However, these models do not account for the impacts of freezing on plants. According to our interpretation, freezing would have affected plants in 59% of unglaciated land during peak glacial periods and 73% during interglacials, when more high-latitude land was unglaciated. Comparing forest cover, minimum temperatures, and paleo-locations of Pennsylvanianaged plant fossils from the Paleobiology Database supports restriction of forest extent due to freezing. Many genera were limited to unglaciated landwhere temperatures remained above -4 °C. Freezeintolerance of Pennsylvanian arboreal vegetation had the potential to alter surface runoff, silicate weathering, CO2 levels, and climate forcing. As a bounding case, we assume total plant mortality at -4 °C and estimate that contracting forest cover increased net global surface runoff by up to 6.1%. Repeated freezing likely influenced freeze- and drought-tolerance evolution in lineages like the coniferophytes, which became increasingly dominant in the Permian and early Mesozoic. [ABSTRACT FROM AUTHOR]

The new archaeorthopteran family Archaeogeraridae, based on Archaeogerarus schubneli gen. et sp. nov., is described from the Moscovian of Avion. It has several unique wing venation characters allowing to separate it from the other groups of this superorder, viz. a vein RP separating from RA very close to wing base and closely parallel to it; M shortly fused with RP; CuA+CuPa simple and straight; and CuPb branched. This last character is convergently present in a few Palaeozoic Panorthoptera, a feature of great interest for a future phylogenetic analysis of the whole superorder. Avionxixia gui gen. et sp. nov., second Cnemidolestidae from the Moscovian of Avion, is described and illustrated. It shares numerous characters with the Chinese Namurian genus Xixia and the European (Germany and France) Moscovian genus Piesbergopterum, suggesting possible phylogenetic affinities between these three genera. It is mainly separated from these two genera by the costal area much narrower than the subcostal one and the presence of only one posterior branch of the anterior branch of MP+CuA+CuPa. This new taxon confirms the high diversity of the Cnemidolestidae during the late Carboniferous. [ABSTRACT FROM AUTHOR]

Here we describe the postcranial skeleton and present the first full-body reconstruction of the early tetrapod Whatcheeria deltae from the Viséan of Iowa. The skeletal proportions, including an elongate neck and large limbs, are unlike those of other Devonian and Mississippian tetrapods. The robust limbs of Whatcheeria appear adapted for a walking gait, but the lateral lines of the cranium are fundamentally unsuited for sustained subaerial exposure. Thus, although Whatcheeria bears a general resemblance to certain terrestrially adapted Permian and Triassic members of crown tetrapod lineages, its unusual form signals a broader range of early amphibious morphologies and habits than previously considered. From the exceptionally rich collection it is evident that most Whatcheeria specimens represent immature individuals. Rare specimens suggest an adult body size of at least 2 m, over twice that of the holotype. Further comparison suggests that the Pederpes holotype might also be a juvenile and reveals a combination of hindlimb characters unique to Whatcheeria and Pederpes. These new data contribute to a revised diagnosis of the family Whatcheeriidae and a re-evaluation of fragmentary Devonian–Carboniferous fossils reported as 'whatcheeriid' but sharing no synapomorphies with the more precisely defined clade. [ABSTRACT FROM AUTHOR]

Abstract In view of the complex reservoir heterogeneities within weathered volcanic rocks, taking the Carboniferous volcanic weathered profile reservoir of the northwest Junggar Basin as an example, this study aims to characterize weathered volcanic rocks by the core, thin slice, log interpretation, and experimental test. The Carboniferous volcanic rocks are mainly composed of volcanic lava, volcanic breccia, and tuff, etc, which formed in a volcanic arc environment. As a result of the weathering and denudation, the weathered profile can be divided into four layers: weathered clay layer, intensive weathered zone, weak weathered zone, and unweathered compacted zone. The preserved void space mainly includes primary porosity (both vesicular and fractures), secondary pores, and fractures enhanced by weathering and structural processes. Among them, the volcanic facies control the first‐order properties of the reservoir. The degree of weathering‐leaching controls the thickness of the weathered part of the reservoir. The faults and fractures control the seepage/permeability capacity of weathered volcanic reservoir. On the plane, the weathered volcanic reservoirs mainly distributed along the fault zone, tectonic zone, and favorable lithofacies zone. On the longitudinal direction, they are always within the weathered profile toward the top of a certain depth range (20‐240 m).

The Karamaili ophiolite belt is an important tectonic unit in the East Junggar terrane, Xinjiang, China, and provides a material basis for the study of subduction, accretion and collision processes, regional tectonic evolution, and the exploration of oil (gas) reservoirs in the western part of the Central Asian Orogenic Belt (CAOB). In the late Paleozoic, an important tectonic transition from subduction to post–collisional extension occurred in the East Junggar terrane; however, the precise timing of the tectonic transition is still a matter of debate. The volcanic rocks in the Karamaili area, predominately rhyolite and basalt–andesite, are typical post–collisional volcanic rocks and thus provide important constraints on the tectonic setting of the East Junggar. Here, zircon U–Pb geochronology and He–Ne–Ar and Sr–Nd–Pb isotopic analyses were carried out on volcanic rocks from three localities in the Karamaili area. Four zircon U–Pb ages indicate that magmatism occurred in the Carboniferous at 335–310 Ma, which is interpreted as the age of post–collisional extension events. The 4He–3He/4He isotopic ratios of these samples are similar to those of the continental crust and show a weak contribution of mantle He, indicating the presence of mantle He in the orogenic belt. The 20Ne/22Ne, 21Ne/22Ne, and R/Ra–40Ar/36Ar ratios show that the air-like Ne and Ar are derived from dissolved atmospheric and continental crust sources in the subducted supracrustal rocks. Meanwhile, relatively low 87Sr/86Sr ratios of andesite and basalt (0.704–0.707) and high εNd(t) values (4.73–7.22) reveal the presence of depleted mantle components in their source regions. The heterogeneous isotopic signatures of the volcanic rocks in the East Junggar indicate that they formed via different processes or in multiphase settings, suggesting a significant tectonic transition from an island arc setting to a post-collisional extension regime during the Carboniferous period.

Colonies of the rugose corals Nemistium liardense sp. nov. and Heritschioides simplex sp. nov. were collected from limestone in the upper member of the Mattson Formation in the Liard Range in the Northwest Territories and are the only known identifiable coral species from the Mattson Fm. The Mattson Fm., deposited in the Liard Basin west of the syndepositional Bovie reverse fault, comprises sandstone with subordinate shale and carbonates deposited during several delta cycles. The close morphological similarity and identical mode of offsetting in N. liardense colonies from the Mattson Fm. and the allochthonous Stikine Terrane of British Columbia indicate they belong in the same species. This and the morphological similarity between H. simplex and the late Serpukhovian to early Bashkirian H. columbicum allow assignment of the coral-bearing part of the upper Mattson Fm. to Bashkirian Foraminiferal Biozone 20. Widespread occurrence of the genus Nemistium confirms open communication between the Liard Basin region and the western European and northern African seas.