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Much of what we know about terrestrial life during the Carboniferous Period comes from Middle Pennsylvanian (~315–307 Mya) Coal Measures deposited in low-lying wetland environments1–5. We know relatively little about terrestrial ecosystems from the Early Pennsylvanian, which was a critical interval for the diversification of insects, arachnids, tetrapods, and seed plants6–10. Here we report a diverse Early Pennsylvanian trace and body fossil Lagerstätte (~320–318 Mya) from the Wamsutta Formation of eastern North America, distinct from coal-bearing deposits, preserved in clastic substrates within basin margin conglomerates. The exceptionally preserved trace fossils and body fossils document a range of vertebrates, invertebrates and plant taxa (n = 131), with 83 distinct foliage morphotypes. Plant-insect interactions include what may be the earliest evidence of insect oviposition. This site expands our knowledge of early terrestrial ecosystems and organismal interactions and provides ground truth for future phylogenetic reconstructions of key plant, arthropod, and vertebrate groups. Our knowledge of life in the Carboniferous Period is largely restricted to low-lying wetlands dated to 315–310 million years ago. Here, the authors present an older Lagerstätte on an alluvial fan 320–318 million years ago, preserving a diverse ecosystem of vertebrates, invertebrates, plants, and plant-insect interactions. [ABSTRACT FROM AUTHOR]

Applying BEAST v1.10.4, we constructed a Bayesian Inference tree comprising 322 taxa, primarily representing Paleoptera (Odonata and Ephemeroptera; Pterygota), Zygentoma and Archaeognatha (Apterygota; paraphyly), and Neoptera (Plecoptera; Pterygota), based on a 2685 bp sequence dataset. Our analyses revealed that robust dating required the incorporation of both Quaternary and pre‐Quaternary dates. To achieve this, our dating incorporated a 1.55 Ma (Quaternary) geological event (the formation of the Ryukyu Islands) and a set of chronologically well‐founded fossil dates, spanning from up to 400 Ma (Devonian) for the stem Archaeognatha, 320 Ma (Carboniferous) for the crown of Paleoptera, 300 Ma (Carboniferous) for the crown Ephemeroptera, and 280 Ma (Permian) for the crown Odonata, down to 1.76 Ma (Quaternary) for Calopteryx japonica, encompassing a total of 22 calibration points (events: 6, fossils: 16; Quaternary: 7, pre‐Quaternary: 15). The resulting dated tree aligns with previous research, albeit with some dates being overestimated. This overestimation was mainly due to the lack of Quaternary calibration and the exclusive dependence on pre‐Quaternary calibration, though the application of maximum age constraints also played a role. Our minimum age dating demonstrates that the molecular clock did not uniformly progress, rendering rate dating an inapplicable approach. We observed that the base substitution rate is time‐dependent, with an exponential increase evident from around 20 Ma (Miocene) to the present time, exceeding an order of magnitude. The extensive radiation and speciation of Insecta and Paleoptera, potentially resulting from the severe climatic changes associated with the Quaternary, including the commencement of glacial and interglacial cycles, may have significantly contributed to this increase in base substitution rates. Additionally, we identified a potential peak in base substitution rates during the Carboniferous period, around 320 million years ago, possibly corresponding to the Late Paleozoic Ice Age. [ABSTRACT FROM AUTHOR]

During the initial stages of Pangea amalgamation in the Carboniferous period, the Rheic Ocean basin experienced subduction prompted by the convergence between Gondwana and Laurasia, culminating in the basin's closure that preceded the paleocontinent collision. This tectonic episode promoted the Carboniferous (Mississippian and Pennsylvanian) tholeiitic to calc-alkaline magmatism, represented in the Colombian Andes through the tonalite and diorite-gabbro facies of the El Carmen Pluton. We investigate the two main facies (felsic and mafic facies) of the plutonic body, which crop out in the Central Cordillera of the Colombian Andes. U-Pb zircon crystallization ages are 326 ± 1 Ma for the mafic facies and 313 ± 1 Ma for the felsic facies. Positive ɛHf(i) isotopes ranging from +5.4 to +10.9 suggest mantle-derived magma with low crustal assimilation. The progressive increase in Eu anomaly (Eu × 0.64 to 1.15) and high LREE/HREE ratios underscore a continental magmatic arc formation in congruence with a subduction context. Thermobarometric analyses of mineral geochemistry across both facies reveal the magmatic emplacement at temperatures spanning 753–910°C, pressures between 3 and 4.65 kbar, and depths approximating 9–14 km. The simultaneous presence of two magmatic facies bearing tholeiitic and calc-alkaline characteristics, separated by ~13 Ma crystallization gap, infers a magmatic recharge episode. The results highlight a slightly thickened crust due to the arc maturity, or a transition from shallow-dipping to steep-angle subduction, consistent with tectonic slab-rollback mechanisms. The modest crustal thickening, indicative of low arc maturation between 326 and 313 Ma, is concomitant with the closure of the western part of the Rheic Ocean basin. [ABSTRACT FROM AUTHOR]

Based on the organic geochemical data and the molecular and stable carbon isotopic compositions of natural gas of the Lower Permian Fengcheng Formation in the western Central Depression of Junggar Basin, combined with sedimentary environment analysis and hydrocarbon-generating simulation, the gas-generating potential of the Fengcheng source rock is evaluated, the distribution of large-scale effective source kitchen is described, the genetic types of natural gas are clarified, and four types of favorable exploration targets are selected. The results show that: (1) The Fengcheng Formation is a set of oil-prone source rocks, and the retained liquid hydrocarbon is conducive to late cracking into gas, with characteristics of high gas-generating potential and late accumulation; (2) The maximum thickness of Fengcheng source rock reaches 900 m. The source rock has entered the main gas-generating stage in Penyijingxi and Shawan sags, and the area with gas-generating intensity greater than 20×108 m³/km2 is approximately 6 500 km². (3) Around the western Central Depression, highly mature oil-type gas with light carbon isotope composition was identified to be derived from the Fengcheng source rocks mainly, while the rest was coal-derived gas from the Carboniferous source rock; (4) Four types of favorable exploration targets with exploration potential were developed in the western Central Depression which are structural traps neighboring to the source, stratigraphic traps neighboring to the source, shale-gas type within the source, and structural traps within the source. Great attention should be paid to these targets. [ABSTRACT FROM AUTHOR]

The Cincinnati Museum Center has opened a new permanent exhibit called "Ancient Worlds Hiding in Plain Sight," which showcases the geologic riches of the Cincinnati region. The exhibit spans the majority of the Paleozoic Era, from the Ordovician Period to the Carboniferous Period, and features over 400 specimens, including fossils of trilobites, brachiopods, and corals. The gallery aims to connect the study of deep time with current issues such as climate change and evolution. The exhibit also includes interactive elements, such as hands-on displays and a life-sized image of an Ordovician hardground. The gallery is a collaboration between the Cincinnati Museum Center and local amateur collectors, and it aims to educate visitors, inspire future scientists, and foster a connection to the natural world. [Extracted from the article]

During the Carboniferous Period, the Qinghai-Tibetan Plateau and its surrounding areas were located in quite different paleogeographic positions with various sedimentary and biological types. It is important to systematically compile and summarize the Carboniferous strata and biotas of the Qinghai-Tibetan Plateau and its surrounding areas, to establish an integrated stratigraphic framework for correlation, and to reconstruct the paleogeography for correctly understanding the breakup of the Gondwana Continent and the evolution of the Paleo-Tethys Ocean in the Late Paleozoic. The Carboniferous of the Qinghai-Tibetan Plateau and its surrounding areas can be subdivided into the Gondwanan, Cimmerian, and Tethyan types. The Gondwanan-type Carboniferous are distributed in the North Himalayan, Kangmar-Lhunze, and Zanda-Zumba regions of the South Tibet Subprovince and northern India-Pakistan Area, where only the Mississippian is developed and the biota is of Gondwanan affinity. The Cimmerian-type Carboniferous, which are found in the Baoshan, Tengchong, Coqen-Xainza, Lhasa-Zayu, Nagqu-Biru, and South Qiangtang regions, as well as Shan-Thai and South Afghanistan-Pamir areas, also represent only the Mississippian strata, but their biota is characterized by mixed characters of European, South China, Australian, and North American types. The Tethyan-type Carboniferous are distributed in the Tanggula Mountains, Hoh Xil-Bayanhar, Chamdo-Hengduanshan, Tiekelike, West Kunlun, Karakorum, East Kunlun-Central Qinling, and Qilian regions, where the Carboniferous succession is well developed, and the biota is of warm-water Tethyan affinity. The biostratigraphical correlation of the Gond-wanan-type and Cimmerian-type Carboniferous is based mainly on conodonts and additionally on brachiopods and rugose corals. The Mississippian of the Tethyan-type Carboniferous is correlated mainly by using rugose corals and brachiopods, whereas in the Pennsylvanian foraminifera (fusuline) and conodonts are regarded as primary fossil groups, subordinated by rugose corals and brachiopods. Adhering to the International standard chronostratigraphy of the Carboniferous, we have reconstructed a framework of the litho- and biostratigraphic subdivision and correlation of the Qinghai-Tibetan Plateau and its surrounding areas. Further studies should focus on isotope geochronology, geochemistry, paleoclimates, and paleoenvironments of the Carboniferous in the Qinghai-Tibetan Plateau and its surrounding areas. [ABSTRACT FROM AUTHOR]

To explore the geological characteristics and exploration potential of the Carboniferous Benxi Formation coal rock gas in the Ordos Basin, this paper presents a systematic research on the coal rock distribution, coal rock reservoirs, coal rock quality, and coal rock gas features, resources and enrichment. Coal rock gas is a high-quality resource distinct from coalbed methane, and it has unique features in terms of burial depth, gas source, reservoir, gas content, and carbon isotopic composition. The Benxi Formation coal rocks cover an area of 16x104 km², with thicknesses ranging from 2 m to 25 m, primarily consisting of bright and semi-bright coals with primitive structures and low volatile and ash contents, indicating a good coal quality. The medium-to-high rank coal rocks have the total organic carbon (TOC) content ranging from 33.49% to 86.11%, averaging 75.16%. They have a high degree of thermal evolution (Ro of 1.2%-2.8%), and a high gas-generating capacity. They also have high stable carbon isotopic values (δ 13C1 of -37.6‰ to -16‰; δ 13C2 of -21.7‰ to -14.3‰). Deep coal rocks develop matrix pores such as gas bubble pores, organic pores, and inorganic mineral pores, which, together with cleats and fractures, form good reservoir spaces. The coal rock reservoirs exhibit the porosity of 0.54%-10.67% (averaging 5.42%) and the permeability of (0.001-14.600)x10-3 μm2 (averaging 2.32x10-3 μm2). Vertically, there are five types of coal rock gas accumulation and dissipation combinations, among which the coal rock-mudstone gas accumulation combination and the coal rock-limestone gas accumulation combination are the most important, with good sealing conditions and high peak values of total hydrocarbon in gas logging. A model of coal rock gas accumulation has been constructed, which includes widespread distribution of medium-to-high rank coal rocks continually generating gas, matrix pores and cleats/fractures in coal rocks acting as large-scale reservoir spaces, tight cap rocks providing sealing, source-reservoir integration, and five types of efficient enrichment patterns (lateral pinchout complex, lenses, low-amplitude structures, nose-like structures, and lithologically self-sealing). According to the geological characteristics of coal rock gas, the Benxi Formation is divided into 8 plays, and the estimated coal rock gas resources with a buried depth of more than 2 000 m are more than 12.33?1012 m3. The above understandings guide the deployment of risk exploration. Two wells drilled accordingly obtained an industrial gas flow, driving the further deployment of exploratory and appraisal wells. Substantial breakthroughs have been achieved, with the possible reserves over a trillion cubic meters and the proved reserves over a hundred billion cubic meters, which is of great significance for the reserves increase and efficient development of natural gas in China. [ABSTRACT FROM AUTHOR]

Based on core data, physical properties, well logging, gas testing, composition, and helium distribution from 13 newly drilled wells, in combination with regional tectonic evolution, depositional background, and typical gas reservoir profiles, helium-rich gas reservoirs geology characteristics and main controlling factors have been explored. The results show that three gas reservoirs formed from bottom to top, i.e., granite and metamorphite fractured reservoir in the basement, tight sandstone structural reservoirs in the Devonian, and huge continuous carbonate reservoirs in the Lower Carboniferous. Fractures developed on structural points control high-production, and gas is prominently displayed in low structural areas. The dry gas exhibits richness in helium, with decreasing helium content from the basement to the Carboniferous. The pre-Devonian large-scale granite and metamorphite basement serve as the primary helium source, while the high-gamma sandstones of the Devonian and the Carboniferous act as secondary sources. Fractures play a dual role, being filled up and conducting in two ways: gas from the Carboniferous source rocks migrates downward, and helium migrate upward. Thick interbedded gypsum-tight limestone on top of the Lower Carboniferous act as the regional caprock, effectively preserving the helium-rich gas reservoirs. [ABSTRACT FROM AUTHOR]

Through core observation, thin section identification, X-ray diffraction analysis, scanning electron microscopy, and low-temperature nitrogen adsorption and isothermal adsorption experiments, the lithology and pore characteristics of the Upper Carboniferous bauxite series in eastern Ordos Basin were analyzed to reveal the formation and evolution process of the bauxite reservoirs. A petrological nomenclature and classification scheme for bauxitic rocks based on three units (aluminum hydroxides, iron minerals and clay minerals) is proposed. It is found that bauxitic mudstone is in the form of dense massive and clastic structures, while the (clayey) bauxite is of dense massive, pisolite, oolite, porous soil and clastic structures. Both bauxitic mudstone and bauxite reservoirs develop dissolution pores, intercrystalline pores, and microfractures as the dominant gas storage space, with the porosity less than 10% and mesopores in dominance. The bauxite series in the North China Craton, which can be divided into five sections, i.e., ferrilite (Shanxi-style iron ore, section A), bauxitic mudstone (section B), bauxite (section C), bauxite mudstone (debris-containing, section D) and dark mudstone-coal section (section E). The burrow/funnel filling, lenticular, layered/massive bauxite deposits occur separately in the karst platforms, gentle slopes and low-lying areas. The karst platforms and gentle slopes are conducive to surface water leaching, with strong karstification, well-developed pores, large reservoir thickness and good physical properties, but poor strata continuity. The low-lying areas have poor physical properties but relatively continuous and stable reservoirs. The gas enrichment in bauxites is jointly controlled by source rock, reservoir rock and fractures. This recognition provides geological basis for the exploration and development of natural gas in the Upper Carboniferous in the study area and similar bauxite systems. [ABSTRACT FROM AUTHOR]

The eastern Qaidam Basin (EQB), along with its surrounding orogenic belts, witnessed complicated tectonic movements in the period from the late Paleozoic to the early Mesozoic. As strategic succeeding strata, the Carboniferous strata (CST) in the EQB have gradually become a research hotspot in recent years. However, the question of how tectonism controlled the tempo-spatial evolution of the CST has yet to be studied. To resolve these issues, we collated statistics related to unconformities, seismic interpretation, and basin modeling in this study. The results show that the structure of the CST was mostly controlled by NNE-striking faults, namely the Zongjia and Ainan Fault, in the period from the Carboniferous to the Triassic time. During the Carboniferous time, the sedimentation of the CST was controlled by medium-high angle potential normal faults. The CST experienced two stages of tectonic subsidence and subsequent burial: the highest average subsidence and burial rate of 45 m/Ma and 12 m/Ma occurred at 340~285 Ma, decreasing to 15 m/Ma and 7.5 m/Ma between 305 Ma and 250 Ma. However, the maximum burial (~5500 m) took place at ~250 Ma. From the end of the late Permian to the late Triassic (254~195 Ma), the overall exhumation rate of the CST has averaged 38.71 m/Ma, and 75 m/Ma in the southern margin of the Huobuxun Depression. The CST near the piedmont margins of the EQB suffered essential denudation at 254~195 Ma, resulting in small amounts of the residual CST. In these areas, the CST were deformed with a steepening dip during this time and were characterized by the combinations of syncline-anticlinal asymmetric folds with the high-angle interlimb. These findings indicated that the tempo-spatial evolution of the CST was possibly influenced by the sedimentary and tectonic transition, and was a combined response to Paleo-Tethys Ocean subduction, and arc-continental collisions since the late Paleozoic to early Mesozoic periods. [ABSTRACT FROM AUTHOR]

Lithospheric slices preserving pre-Alpine metamorphic imprints are widely described in the Alps. The Variscan parageneses recorded in continental, oceanic, and mantle rocks suggest a heterogeneous metamorphic evolution across the Alpine domains. In this contribution, we collect quantitative metamorphic imprints and ages of samples that document Variscan tectonometamorphic evolution from 420 to 290 Ma. Based on age distribution and metamorphic imprint, three main stages can be identified for the Variscan evolution of the Alpine region: Devonian (early Variscan), late Devonian–late Carboniferous (middle Variscan), and late Carboniferous–early Permian (late Variscan). The dominant metamorphic imprint during Devonian times was recorded under eclogite and HP granulite facies conditions in the Helvetic–Dauphinois–Provençal, Penninic, and eastern Austroalpine domains and under Ep-amphibolite facies conditions in the Southalpine domain. These metamorphic conditions correspond to a mean Franciscan-type metamorphic field gradient. During the late Devonian–late Carboniferous period, in the Helvetic–Dauphinois–Provençal and central Austroalpine domains, the dominant metamorphic imprint developed under eclogite and HP granulite facies conditions with a Franciscan field gradient. Amphibolite facies conditions dominated in the Penninic and Southalpine domains and corresponded to a Barrovian-type metamorphic field gradient. At the Carboniferous–Permian transition, the metamorphic imprints mainly developed under amphibolite-LP granulite facies conditions in all domains of the Alps, corresponding to a mean metamorphic field gradient at the transition between Barrovian and Abukuma (Buchan) types. This distribution of the metamorphic imprints suggests a pre-Alpine burial of oceanic and continental crust underneath a continental upper plate, in a scenario of single or multiple oceanic subductions preceding the continental collision. Both scenarios are discussed and revised considering the consistency of collected data and a comparison with numerical models. Finally, the distribution of Devonian to Triassic geothermal gradients agrees with a sequence of events that starts with subduction, continues with continental collision, and ends with the continental thinning announcing the Jurassic oceanization. [ABSTRACT FROM AUTHOR]

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Two diorite to monzodiorite sills are recently found among the Silurian sedimentary succession near to Asaritsa peak, West Stara Planina Mountain. Several levels with diagenetic metalliferous nodules occur within shale interval in the sediments. The magmatic rocks are affected by strong propylitic to sericitic alteration (chlorite, sericite, albite and quartz) and only relicts of the rock-forming minerals (feldspar, biotite and clinopyroxene) are observed. The bodies are crosscut by thin quartz veins and disseminated pyrite is observed. The chondrite normalized spidergrams show patterns similar to orogenic rocks, with very high peaks of Th and U and depletion in Sr and Ti. The zircon U-Pb geochronology reveals that the magmatic crystallization is during the Carboniferous period -- 326.4±3.2 Ma, with low content of xenocryst most probably from the sedimentary basement. The magmatic activity coincides with the Variscan orogeny formed during the late Paleozoic and most probabaly is related to the evolution of the alkaline Buhovo-Seslavtsi Pluton which is situated just to the south, at a direct proximity. The different composition of the pyrite from the sills and the diagenetic nodules from the sediments is most probably due to their different genesis. While the alterations of the nodules can be attributed to metasomatic processes related to the magmatic activity. [ABSTRACT FROM AUTHOR]

The study of coral fossils with clear growth lines inShiqiantan Formation (310 Ma) in China showed the growth line increments of a single coral growing in this area is related to the sunlight illumination time. Moreover, the daily increment of the growth line caused by calcium carbonate depositions has an unusual bimodal curve. The study of this bimodal curve indicated Shiqiantan had evident four-season changes in the Late Carboniferous period, and the climate at that time was similar to that of modern North China. The present paper updates the oldest existing record of climate analysis materials and provides important information for the study of Late Paleozoic climate, as well as the ancient obliquity of ecliptic. [ABSTRACT FROM AUTHOR]

The Carboniferous strata are widely distributed in the Hexi Corridor, Northwest China, with a complete stratigraphic sequence and abundant fossils. Four stratigraphic sections of the Carboniferous in the Hexi Corridor were selected for this study, which mainly examined foraminiferal assemblages. Based on the distribution of the foraminifera throughout these sections, four foraminiferal assemblages were established. In the ascending order, these assemblages are the Eostaffella proikensis–Koskinobigenerina (Aleksian, Late Visean), Climacammina simplex–Biseriella parva (Venevsky, Late Visean), Ozawainella guizhouensis (Middle to Late Bashkirian), and Nodosinelloides spp. (Kasimovian–Early Gzhelian). Foraminifer data indicate the direction of regression in the late Visean in the studied area was from east to west. During the Late Visean–Early Gzhelian, a comparison of recovered fauna with the paleobiogeographical affinities shows that the Hexi Corridor foraminiferal fauna maintains strong North Paleotethyan affinities. [ABSTRACT FROM AUTHOR]

This paper reports two types of basalt that have different ages (Carboniferous and Permian) but occur next to each other in the northern part of the Changning–Menglian accretionary wedge, southwestern China. We use the geochronology and geochemical data to evaluate the tectonic evolution of the Palaeo‐Tethys during this period. Zircon grains from the mafic‐ultramafic rocks associated with the Permian basalts in the Xiaomengtai area yield a U–Pb age of 281 Ma and εHf(t) values from +9.2 to +12.8. The Permian mafic‐ultramafic rocks and the associated basalts are all characterized by normal mid‐ocean ridge basalt (N‐MORB)‐like chondrite‐normalized rare earth elements patterns, moderately negative Nb‐Ta anomalies in the mantle‐normalized immobile incompatible trace element patterns, and positive εNd(t) values from +4.2 to +6.5, which are consistent with the geochemical characteristics of mafic‐ultramafic rocks in supra‐subduction zone (SSZ)‐type ophiolite. On the contrary, the Carboniferous basalts, which are associated with marine carbonates, are characterized by light REE enrichments, slightly positive Nb‐Ta anomalies, and εNd(t) values from +2.8 to +4.0. These features are similar to those of typical oceanic island basalts (OIBs) worldwide. Modelling results using REEs show that the parental magmas for the Carboniferous OIBs and the Permian basalts were likely derived from mantle peridotites at the depths of garnet and spinel stability, respectively, consistent with the formation depth of these two different types of basalt globally. The occurrence of these two different types of mafic‐ultramafic rocks with significantly different ages in the same area supports the view that they are the remnants of the accreted Palaeo‐Tethys oceanic crust. The Carboniferous OIBs are considered to be parts of an OIB‐carbonate seamount chain that originally formed in the southern part of the Palaeo‐Tethys. The Permian mafic‐ultramafic rocks are regarded as fragments of SSZ‐type ophiolites that were present in the northern part of the Palaeo‐Tethys. These different pieces of oceanic crust were accreted to the Simao–Indochina continental Block by subduction between the Late Permian and the Triassic. [ABSTRACT FROM AUTHOR]

The origin of crown Actinopterygii has been dated to near the Devonian-Carboniferous boundary, but poor phylogenetic signal occludes the origin of modern actinopterygian biodiversity. Scarcity of comparative endoskeletal anatomy from this period likely contributes to the uncertainty. For example, only a handful of neurocrania have been described from the Carboniferous period despite an abundance of fossil taxa. Here we present a new actinopterygian, Phoebeannaia mossae gen. et sp. nov. from the Bashkirian Coal Measures of Saddleworth, Greater Manchester, UK, represented by an exceptionally preserved neurocranium and associated dermal bones. Morphological similarities to the Virgilian Kansasiella eatoni prompted comparative study and construction of a new neurocranial character matrix. Subsequent systematic analysis enabled identification of a cluster of similar Late Palaeozoic neurocrania, exploration of trends in braincase evolution across time, and investigation of potential causes of cladistic instability. Our neurocranial dataset reliably places this new specimen on the neopterygian stem near Kansasiella , but it struggles to incorporate extant taxa such as Polypteriformes, leading to uncertainty in branching pattern and inferred neurocranial transformation series. This work triples the number of complete Carboniferous neurocrania described with modern microcomputed tomography and provides a framework for future testing of large-scale hypotheses regarding the diversification and origin of ray-finned fishes. [ABSTRACT FROM AUTHOR]

The article focuses on the taxonomic classification, carbon metabolic capabilities, and evolutionary history of Bathyarchaeia, a group of microorganisms that play important roles in the global carbon cycle. It mentions the study presents a comprehensive dataset of Bathyarchaeia genomes, reclassifies them into eight order-level units, and identifies highly diversified carbon metabolisms, including atypical C1 metabolic pathways.

Dark mudstones and shales of the Carboniferous Jiusi Formation are widely developed in northern Guizhou and Yunnan provinces, SW China. However, the distribution, reservoir characterization, and exploration potential of organic-rich shales in this area are yet to be quantified, thus limiting the prospect of shale gas in this area. This study investigates the basic geological conditions of Jiusi shale gas, using core data, well-logs, and some other test data, obtaining the following results. The organic-rich shales are mainly composed of deltaic-to-shallow-shelf deposits, with thickness ranging from 0 to 450 m, and above 350 m around the subsidence center. The organic matter is mainly type II kerogen with TOC content of mostly 1%e2%, indicating a moderate maturity. The argillaceous shale reservoirs are indicative of strong heterogeneity, high clay minerals content, low porosity, low permeability, high specific surface area, and relatively developed secondary porosity. The gas-log anomaly intervals obtained from the survey wells have a cumulative thickness that is apparently greater than 200 m, and a few shale intervals showing high desorbed and adsorbed gas contents. Due to complex structures in the study area, conditions responsible for shale gas occurrence and trapping are generally moderate. However, areas having wide and gentle folds with moderate depth of burial reveals relatively favorable conditions of hydrocarbon traps. In contrast with typical marine-continental transitional shales, the Jiusi shale have better geological conditions for shale gas preservation. The analysis of the geological framework and hydrocarbon potential of Carboniferous Jiusi Formation provide more insight for the exploration of Carboniferous shale gas in southern China. [ABSTRACT FROM AUTHOR]

Among ray‐finned fishes (Actinopterygii), the crushing, durophagous feeding strategy first evolved in the early Carboniferous period, with the †Eurynotiformes possessing dentitions with single layers of partially to fully fused blunt teeth. In the †'Platysomidae' (Permian), a new form of crushing dentition evolved (phyllodonty), in which multiple layers of superimposed crushing teeth developed intraosseously, within the jaw. The phyllodont durophagous dentition is also recovered from later‐occurring taxa originating mainly in the Mesozoic, such as the †Bobastraniiformes, the neopterygians †Pycnodontiformes and Ginglymodi, and in the teleost group †Phyllodonta. By comparison, †Kazanichthys viatkensis, an actinopterygian from the middle Permian of European Russia, is characterized by a third, putatively durophagous dentition, with anterior conical teeth and closely packed molariform teeth on the buccal dental plates (a potential similarity with eurynotiforms). Whereas the conical teeth are similar to those of basal actinopterygians, the molariform teeth superficially resemble teeth of some teleosts (Characiformes, Tetraodontiformes), but are unique among known fossil and living Actinopterygii in being crowned by anastomosing, sharp apical ridges. Teeth are ankylosed to the jaw and acrodont in implantation. There is neither evidence of plicidentine, nor cavities corresponding to intraosseous crypts. Most replacement teeth formed extraosseously, differing from the phyllodont dentition, but similar to several more phylogenetically basal actinopterygians. The dental system morphologically resembles recent Sparidae (Teleostei; Perciformes), possibly indicating a similar trophic adaptation. Based on these comparisons and patterns of wear, we propose that †K. viatkensis was a generalist durophagous feeder, with the ability to switch prey types with its unique and complex dentition. [ABSTRACT FROM AUTHOR]

China has focused on the exploration and development of shale gas resources to reduce its reliance on coal and shift to cleaner energy sources. While significant progress has been made in the Sichuan Basin, unlocking the shale gas potential in other regions of South China has proven challenging due to the complex geology and mountainous terrain. In 2021, Well QSD-1 was deployed in southwestern Guizhou and achieved a daily shale gas flow of 11,011 m3 in the Dawuba Formation, marking the first time an industrial gas flow had been obtained from shale gas drilling in the marine strata of the Upper Paleozoic in China. This breakthrough has deepened the understanding of the southern China Carboniferous marine strata and highlighted key aspects of the formation: (1) Sedimentation occurred in alternating platforms and basins, with most organic-rich shale developed in sloping and basin areas; (2) the formation exhibits favorable static indicators, with a relatively thick section (over 200 m), and an organic carbon content of approximately 1%; (3) the intercalation of argillaceous limestone and shale intervals is conducive to the preservation of shale gas within the formation. These results demonstrate the potential for the Upper Paleozoic in South China to become a significant shale gas producer, which could contribute significantly to China's energy security. Furthermore, exploring shale gas in the region may have positive economic and environmental impacts, including reducing China's dependence on coal and decreasing greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Karst reservoirs have always been a key field of oil and gas exploration. However, quantifying the process of meteoric transformation remains a persistent challenge that limits the accuracy of reservoir quality prediction. To explore the controlling factors of meteoric cementation on karst reservoirs, the Majiagou Formation of the Ordos Basin in China was selected as an example. The petrology; carbon, oxygen, and strontium isotopes; and in situ major, trace, and rare earth elements were used, types and origins of calcite cements were analyzed in detail. The results revealed five types of calcite cements (Cal-1~Cal-5), four types of cathodoluminescence (CL) intensities (dull, dull red, deep red, and bright red luminescence), and six types of rare earth element patterns (Pattern-1~Pattern-6). These five types of calcite cements developed in three periods. Cal-1 (transition CL) and Cal-2 (dull CL) were precipitated during the Early Pennsylvanian period, the meteoric freshwater was clean; Cal-3 (transition CL) and Cal-4 (bright red CL) were precipitated at the end of the Late Carboniferous period, the fluids had strong dissolution ability and were polluted by terrigenous debris; Cal-5 (transition CL) was deposited during the burial period, the fluid was pure pore water or groundwater. The control of the cement on the reservoir during the burial period was much weaker than that of meteoric cements. Therefore, explorations of karst reservoirs should be focused on weak cementation during the epigenetic period. [ABSTRACT FROM AUTHOR]

A well‐preserved remnant of the middle crust of the former Adriatic passive margin is exposed in the Southern Alps (Italy). The Dervio–Olgiasca Zone is located south of the Insubric Line along the northern part of Como Lake and, because of the lack of Alpine overprint, provides favourable conditions to investigate the pre‐Alpine (rift‐related) history. We reconstruct the P–T–t–d evolution of the Adria middle crust through petrological (petrography, mineral chemistry, thermobarometry and thermodynamic modelling) and geochronological (Lu/Hf in garnet and U–Pb in monazite) data from pegmatites and host micaschists. These data allow reconstruction of a complex tectono‐thermal evolution of the future proximal Adriatic margin at the onset of Alpine rifting. The amphibolite‐facies Carboniferous metamorphic basement (7.6–10 kbar and 610–660°C at 318–312 Ma) was affected by pervasive extensional deformation (5.1–7.6 kbar and 580–660°C) in the Middle‐ to Late‐Permian (257.5 ± 3.8 Ma). Pegmatite intruded at 249.8 ± 1.1 Ma in an extensional phase that re‐equilibrated rocks of the basement at 3.5–4.5 kbar and 560–600°C. During the Middle‐ to Late‐Triassic (241–235 Ma), the basement experienced static thermal recrystallization (T = 689 ± 41°C and ~5.0 kbar). This Late‐Anisian to Early‐Carnian thermal event was simultaneous with the emersion of carbonate platforms, volcanism and ore deposition in the future proximal Adriatic margin. The subsequent cooling of the middle crust was synchronous with large‐scale extensional detachments developed in the upper crust (e.g., the Lugano‐Val Grande Fault), which controlled the formation of the Monte Generoso Basin. This study reveals that the local post‐Carboniferous thinning and heating events recorded in the Adriatic middle crust were interconnected to other processes occurring at different crustal levels that were, in turn, induced by crustal stretching in the early stages of the Alpine rifting. [ABSTRACT FROM AUTHOR]

Detrital zircon populations of the South Qiangtang terrane (SQT) provide vital information for reconstructing the Tethyan evolution of the Tibetan Plateau but are obscured by the undefined affiliation of detrital zircon samples and the superimposition of multiple Tethyan tectonothermal events. We outlined the SQT based on geological mapping and collated Cambrian-Triassic detrital zircon samples to investigate representative detrital zircon populations. Although diachronous strata have distinctive detrital zircon age distributions, the Cambrian-Permian strata record similar ca. 2.50 Ga, 950 Ma, 800 Ma, and 550 Ma populations, which can be used in future detrital zircon studies as Palaeozoic indicators for the SQT. We analyse the above detrital zircon data and compare them to those from adjacent microcontinents (e.g. North Qiangtang terrane, NQT). We note that (1) the Cambrian-Late Ordovician detrital zircons from Upper Triassic strata yield positive εHf(t) values, suggesting juvenile arc-related magmatism in the NQT, and (2) the late Palaeozoic strata in the SQT and NQT both contain Late Devonian-early Carboniferous detrital zircons but have different detrital zircon populations. Together with previous studies on Tethyan evolution, we support that the southward subduction of the Proto-Tethys oceanic plate opened two diachronous back-arc basins between the NQT and SQT during the late Cambrian-Ordovician and Late Devonian-early Carboniferous. The former closed during the late Silurian; the latter evolved into the Palaeo-Tethys Ocean. Subsequently, the northward subduction of the Palaeo-Tethys oceanic plate produced early-middle Permian arc magmatism in the NQT, and the slab pull force from the subducting oceanic plate caused middle-late Permian intraplate magmatism on the opposite passive margin. [ABSTRACT FROM AUTHOR]

A tectonic switch from subduction to collision and/or arc–arc collision is a key issue for understanding accretionary orogenic processes. We present new U-Pb ages, geochemistry, whole-rock Nd and zircon Hf isotope data for a suite of late Carboniferous intrusive rocks along the Kalamaili suture zone of the southwestern Central Asian Orogenic Belt (CAOB) and demonstrate their petrogenesis and the transition of their tectonic settings. Zircon U-Pb dating for the gabbros, diorites, granodiorites, and monzogranites yields ages of 317–301 Ma. The gabbros (311 Ma) were likely derived from partial melting of a mixed source of depleted MORB-like asthenospheric mantle with minor old crustal material; the diorites (301 Ma) from the mixed depleted lithospheric mantle and crustal components; the granodiorites (303 Ma) from the mixed mantle- and crust-derived magmas; and the monzogranites (317 Ma) from melting of the newly underplated basaltic lower crust. Combined with previous data, we have grouped all the intrusive rocks along the Kalamaili suture zone into three phases: 350–340 Ma, 330–320 Ma, and 320–300 Ma. The first phase consists of tholeiitic and high-K calc-alkaline granites, the second phase is composed of high-K calc-alkaline I-type granites with strong deformation, and the third phase comprises voluminous and various rock types (mainly mafic and felsic, including many A-type granites), revealing a magmatic flare-up. The magmatic associations and evolution from the first to the third phase, together with regional geology, suggest a tectonic transition from subduction/accretion (350–340 Ma) through syn-collision (330–320 Ma) to post-collision (or post-accretionary, 320–300 Ma), respectively. This study provides new magmatic evidence for the switch from subduction to collision (arc-arc collision) along the Kalamaili suture zone in the southwestern CAOB. [ABSTRACT FROM AUTHOR]

In the Yili terrane at Awulale mountain, most shoshonitic lavas are related to post-collision extension and were extruded during the Late Carboniferous to Early Permian (310–280 Ma). Herein, we evaluate a small-volume occurrence of shoshonitic magmas in the southern Yili terrane formed c. 346 Ma ago. The high MgO (Mg#) and positive Hf isotope values of the shoshonitic magmas indicate the input of juvenile mantle-derived material. Still, their high Ba–Sr signatures were likely inherited from the partial melting of previously metasomatized lithospheric mantle. We argue the shoshonitic magmatic activity recorded a syn-subduction extensional history in the Yili terrane. This interpretation is consistent with the magmatic records from Early Carboniferous A-type granite and magnesian andesite found in the Zhaosu–Adentao–Dahalajunshan area of the southern Yili terrane. Combined with the geological development in this area, we propose that the emergence of the shoshonitic rocks records either the retreat of the trench or the rollback of the Junggar oceanic slab that occurred at or before the 346.1 ± 3.1 Ma age of the rocks. [ABSTRACT FROM AUTHOR]

Eumelanin, a macromolecule widespread in all the living world and long appreciated for its protective action against harmful UV radiation, is considered the beneficial component of the melanin family (ευ means good in ancient Greek). This initially limited picture has been rather recently extended and now includes a variety of key functions performed by eumelanin in order to support life also under extreme conditions. A lot of still unexplained aspects characterize this molecule that, in an evolutionary context, survived natural selection. This paper aims to emphasize the unique characteristics and the consequent unusual behaviors of a molecule that still holds the main chemical/physical features detected in fossils dating to the late Carboniferous. In this context, attention is drawn to the duality of roles played by eumelanin, which occasionally reverses its functional processes, switching from an anti-oxidant to a pro-oxidant behavior and implementing therefore harmful effects. [ABSTRACT FROM AUTHOR]

Whether the northern margin of the North China Craton (NCC) was a continental arc or in a lithospheric extensional setting during the Carboniferous is the primary divergence among different tectonic models about the terminal evolutionary history of the southeastern Central Asian Orogenic Belt (CAOB). The Alxa block is the western segment of the northern NCC and contiguous to the southeastern CAOB, and therefore the tectonic setting of the Carboniferous magmatic intrusions in this block can shed light on this controversy. In this contribution, new zircon U–Pb ages, elemental geochemistry, and Sr-Nd isotopes are presented for thirteen Late Carboniferous (~318–300 Ma) magmatic intrusions in the southwestern Alxa block. Among them, seven calc-alkaline I-type granites and one aluminous A2-type granite were probably generated by the partial melting and crystallization differentiation of various crustal sources (perhaps including earlier orogenic materials) under different temperature conditions. Four quartz diorites and one hornblende gabbro may be the partial melts of subduction-modified basaltic lower crust sources and sub-continental lithospheric mantle sources, respectively. According to the integration of the new results and regional geological correlations, the Alxa block and the southeastern CAOB were most likely in a uniform tectonic regime during the Carboniferous. At that time, this region was characterized by the lithospheric extension-related magmatic rock associations, the increasing mantle inputs over time, the clockwise P–T paths of high temperature-low pressure metamorphic rocks, and the transgression sedimentary sequences. All these lines of evidence suggest an intra-continental lithospheric extensional setting rather than a continental arc setting for the southeastern CAOB during the Carboniferous. [ABSTRACT FROM AUTHOR]

The discovery of Wytch Farm field in the Wessex Basin, and Kinsale Head field in the North Celtic Sea Basin in the early 1970s, led to exploration interest offshore in the Western Approaches Trough. Despite this activity, little evidence for prospective hydrocarbon resources has been found. To better understand the failures and analyse remaining hydrocarbon potential in this region, we make use of a large collection of new seismic reflection and well data to map Carboniferous to Neogene stratigraphy. The improved seismic imaging has allowed a better interpretation of the hitherto poorly understood, salt-related structures in the South Melville and the Plymouth Bay basins. The implications of the new interpretations for Carnian (Late Triassic), and Carboniferous stratigraphic and geodynamic evolution are assessed and contextualised with regional salt deposition in the Wessex, Bristol, and South Celtic Sea basins. From a petroleum system perspective, the Lias and Carboniferous source rocks are evaluated and modelled to analyse the maturity and evolution of the petroleum systems. We conclude that the Lias is an ineffective petroleum system due to timing and source maturation risk. However, the Triassic salt and associated subcropping faults have produced several possible pre-salt hydrocarbon traps. The traps may be charged from sporadic Mid-Late Carboniferous coal-bearing post-orogenic basins, a petroleum system previously overlooked. Thematic collection: This article is part of the New learning from exploration and development in the UKCS Atlantic Margin collection available at: https://www.lyellcollection.org/topic/collections/new-learning-from-exploration-and-development-in-the-ukcs-atlantic-margin Supplementary material: Appendix showing seismic, well data and petroleum systems boundary conditions. Burial history plots of the petroleum systems modelling scenarios used to generate source rock transformation ratio plots shown in Figures 9 & 10 are available at https://doi.org/10.6084/m9.figshare.c.6486999 [ABSTRACT FROM AUTHOR]

Results of a combined petrological, geochemical and geochronological study suggest that metasedimentary rock units in the Krndija region of the Slavonian Mountains, Croatia, were affected by at least three major tectonometamorphic imprints: during the Middle Ordovician (Sardic event), the early Carboniferous (Variscan event), and the Cretaceous (Alpine event). All three metamorphic phases are established by electron microprobe-based in-situ U–Th–Pb dating of monazite grains. The Sardic metamorphic event is additionally confirmed by a precise Lu–Hf garnet-whole-rock isochron age of 466.0 ± 2.3 Ma. Taken together, the data unveil a relatively large and well-preserved piece of the cryptic Sardic orogen in central Krndija, that we name the Kutjevo Zone. A Sardic subduction-related metamorphic event (ca. 540-580 ℃, 8–11 kbar) at ca. 466 Ma is manifested in the mineral paragenesis Ca-rich garnet plus rutile. A low degree of retrograde reequilibration suggests a subsequent fast exhumation. Low-Ca cores in some garnets and staurolite relics record a pre-HP metamorphic event that involves isobaric heating from 570 to 610 ℃ at ~ 7 kbar. We attribute this (so far undated) event to mid-crustal contact metamorphism caused by early Sardic magmatism. Southern parts of Krndija (the Gradište Zone) experienced an (additional?) clockwise PT evolution in Variscan times at ca. 350 Ma. Garnet formed with ilmenite during a PT increase from 580 ℃/5 kbar to 600 ℃/6 kbar and underwent later strong retrograde resorption. Slow Variscan exhumation resulted in andalusite formation at < 550 ℃/ < 3.8 kbar. Penetrative Alpine metamorphism was observed in low-grade phyllites in the north. The lithology and metamorphic history of the Kutjevo Zone is similar to what has been reported from the Sardic Strona-Ceneri Zone in the western Alps. Both areas expose metapelitic (metagreywacke) rocks with a pre-middle Ordovician formation age. These metasedimentary rocks are inter-layered with numerous small amphibolitic units as well as metagranitoids and were likely deposited along the active Gondwana margin, perhaps in a fore-arc position, prior to their subduction during the middle Ordovician. According to recent palaeogeographic reconstructions, both the Kutjevo Zone and the Strona-Ceneri Zone have once resided in an eastern sector of the northern Gondwana margin (i.e., in E-Armorica). We conclude that in the Middle Ordovician, important subduction activities took place in this E-Armorican segment of north Gondwana, which is today exposed in the Alps. The W-Armorican segment of north Gondwana (now exposed in the French, German, and Czech Variscides) had probably already mutated from a (Cadomian) subduction setting to an extensional (transtensional–transpressional) setting by the late Cambrian. [ABSTRACT FROM AUTHOR]

Significant iron (Fe) loss can occur during continental weathering and efflux to the ocean via runoff, historically affecting global Fe cycling and marine ecosystems. Here, we report extremely low Fe content in early Carboniferous (ca. 340 Ma) bauxites in southwestern China. These bauxites were formed by redeposition of terrestrial soils along the paleo‐continental margin of the western South China Plate in warm climates. The bauxites contain high δ56Fe (−0.17‰ to +1.15‰) values with a negative correlation between Fe2O3 and δ56Fe, indicating that a substantial amount of Fe(III) was reduced to isotopically light dissolved Fe(II) and effuxed to the ocean via reductive dissolution under anoxic conditions. The low Corg content and low FeHR/FeT, Mo/Al, U/Al, and V/Al ratios of bauxite suggest that this reduction process occurred during the pedogenic (continental weathering) rather than the depositional/diagenetic stage of karst bauxite formation. Most of the dissolved Fe(II) were rapidly re‐oxidized to Fe(III) and transported toward the paleo‐continental margin forming iron ores with δ56Fe values around zero (−0.13‰ to +0.16‰). The negative correlation between Al2O3 and Fe2O3 contents in global karst bauxites suggests common Fe loss processes during continental weathering in geological periods favoring karst bauxite formation, such as during the Carboniferous, Permian, and Cretaceous periods and the Cenozoic era. Karst bauxite may thus provide a record of Fe loss during continental weathering and act as an indicator of enhanced Fe flux to oceans. Plain Language Summary: Bauxite deposits are weathered residues enriched in aluminum (Al). They are of economic importance and record critical information concerning extensive weathering in geological history. Karst bauxite has extremely low iron (Fe) contents, and the mechanism of Fe loss is poorly understood. We observed high δ56Fe values in the early Carboniferous period (ca. 340 Ma) karst bauxite in southwestern China, suggesting the bauxite formation under water‐saturated anoxic conditions with extensive loss of isotopically light Fe(II). Our results indicate strong decoupling of Fe and Al during the formation of karst bauxite, which may thus act as an indicator of Fe loss during continental weathering. Key Points: Fe‐poor bauxite is enriched in heavy Fe isotopes due to the release of isotopically light dissolved Fe(II) during pedogenesisMost dissolved Fe(II) was rapidly oxidized to Fe(III) and transported toward the continental margin forming iron oresKarst bauxite in southwestern China may have recorded Fe loss during continental weathering [ABSTRACT FROM AUTHOR]

The now-extinct Palaeozoic to Mesozoic Mongol–Okhotsk Ocean is evidenced by the Mongol–Okhotsk suture, which stretches from central Mongolia to the Sea of Okhotsk. The geodynamics of southward subduction of the Mongol–Okhotsk Ocean remain enigmatic, especially whether the subduction began during the Carboniferous is highly debated. In this paper we present new zircon U–Pb ages and whole-rock geochemical data for the Carboniferous magmatic rocks in Northeast Mongolia. Zircon U–Pb dating indicates that the Adaatsag dacite, Northern Bayanjargalan gabbro-diorite and Bagannur pluton were emplaced at ca. 325 Ma, ca. 316 Ma, and ca. 305 Ma, respectively. Occurrences of these rocks together constitute a Carboniferous magmatic belt to the northwest of the Middle Gobi volcanic-plutonic belt. The ages of trapped zircon xenocrysts within the Bagannur pluton indicate that the basement of this magmatic belt is the Ereendavaa terrane. Geochemical analysis indicates that these magmatic rocks were formed in an Andean-type active margin, which provides robust evidence for southward subduction of the Mongol-Okhotsk Ocean during the Late Carboniferous. By combining all the available data, we argue that the onset of the Central Mongolia–Tsagaan Uul continental collision during the Late Carboniferous – Early Permian may have triggered the beginning of an active margin of the Mongol-Okhotsk Ocean along the northern coast of the Central Mongolia microcontinent. [ABSTRACT FROM AUTHOR]

U-Pb isotope ages from magmatic zircon grains are provided for different volcanic rocks of the NW Saxonian Volcanic Basin within the Rochlitz and Wurzen volcanic systems. Measurements were obtained with LA-ICP-MS and revealed late Pennsylvanian to early Cisuralian ages (301-299 Ma). For the Rochlitz Volcanic System supereruption, we present for the first time a radiometric age consistent with biostratigraphic evidence. We report geochemical data for the Gnandstein Andesitoid, the Dölitzsch, Rüdigsdorf, Rochlitz and Wolftitz tuffs and the Rochlitz-α Ignimbrite. The results yield a modified picture of the Kohren, Rochlitz and Oschatz formations as well as new insights into the understanding of the complex volcano-tectonic processes of the NW Saxonian Volcanic Basin, an area of the Saxo-Thuringian Zone of the European Variscides. [ABSTRACT FROM AUTHOR]

The Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province, located in the southwestern margin of the Yangtze Block, is the most intensively developed region of carbonate-hosted Pb-Zn deposits in China. Both the number of Pb-Zn deposits/spots (more than 500) and the amount of Pb and Zn metal reserves(more than 2000×104 t)play an important role in the Pb-Zn metallogenic regions/belts of China. Although the previous research has made fruitful theoretical understanding and prospecting achievements, there has been a dispute on the source of ore-forming materials of the Pb-Zn deposits in the study area. A systematic In-situ Pb isotope analysis of galena from nine Pb-Zn deposits hosted in the Sinian(Wusihe, Chipu, Yinchanggou and Maozu deposits), Devonian (Huodehong, Maoping and Maozachang deposits) and Carboniferous(Maoping, Huize, Liangyan and Maozachang deposits)carbonate rocks was carried out. The results show that ① the In-situ Pb isotopes of galena in all deposits have an obvious linear relationship, and their Pb-Pb isochron age is about 2.5 Ga ((2 574±30)Ma); it is suggested that the sources of ore-forming metals for these deposits are the same, and the Archean-Paleoproterozoic crystalline basement rocks are the most likely major metal source; ② in the age of ore-bearing strata, the Pb isotopes gradually increase from the old (Sinian) to the new (Carboniferous); in the space of ore-bearing horizon, the Pb isotopes gradually increase from Wusihe, Chipu deposits in N(W) to Maozachang, Liangyan deposits in S(E); it is indicated that they are the evolvement products of the same ore-forming fluids in different stages, and the crystalline basement-derived and/or flowed ore-forming fluids evolve and migrate from deep to shallow, and from N(W)to S(E)on a regional scale. [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. [ABSTRACT FROM AUTHOR]

Large-winged blattoids of the Middle to Late Pennsylvanian reveal a striking appearance, diversification, and decline in the fossil record. Among them, the families Necymylacridae Durden, 1969, and Gyroblattidae Durden, 1969, as well as the mylacrid genus Opsiomylacris exhibit, the largest pre-Cenozoic blattoids with forewing lengths up to 7.5 cm. As finds from coal-bearing sedimentary basins in Europe, North Africa, and North America indicate, these giant insects started to spread around the Bashkirian–Moscovian transition and experienced a diversification in late Moscovian and Kasimovian times, until they disappeared in the middle Gzhelian. Whereas necymylacrids are only patchily reported and still lack distributional patterns, we disclose the occurrence and particular habitat preference of gyroblattids. Although appearing first in some vast North American basins, they became successively widespread only in small-sized basins of the European Variscan interior. Frequently found associated with enigmatic gymnosperms, they may have lived in well-drained hinterland areas from where they immigrated into the ever-wet basin centers only with increasing seasonality. Gyroblattids apparently followed meso- to xerophilous plants and likely colonized spaces offering a broader spectrum of edaphic conditions that resulted from the closeness of erosional and depositional areas. The presented analysis and revision of all gyroblattids aim to facilitate future more realistic biodiversity estimations based on fossil taxa. [ABSTRACT FROM AUTHOR]

Although an extensive continental arc magmatism was recorded in the northern North China Craton (NCC) during the Carboniferous, a general geodynamic model has not been constructed, and associated crust–mantle processes are not fully understood. Here, we carried out systematic geochronological and geochemical investigations on the alkali‐feldspar granite pluton in the Zhaojinggou area, northern NCC. U–Pb dating of high‐U–Th zircons failed to obtain concordant ages due to severe metamictization, while apatite U–Pb dating yielded a perfect age of 327.6 ± 4.1 Ma, indicating the emplacement of granites in the Early Carboniferous. The granites have high SiO2 (74.99–76.88 wt%) and K2O (5.73–6.43 wt%) contents and exhibit enriched LREEs, K, Rb, Th, U, and Pb, and depleted Nb, Ta, P, and Ti contents, which are typical of highly fractionated, I‐type high‐K granites formed under a continental arc setting. Moreover, the high‐K granites show highly enriched Nd isotopic compositions (with whole‐rock and apatite εNd(t) of −33.6 to −16.3) that are distinctly lower than other Carboniferous continental arc rocks in the northern NCC (εNd(t) from −18.5 to −9.9). These geochemical characteristics indicate that the high‐K granites possibly originated by partial melting of the Archean TTG gneisses and mafic rocks in the lower crust. Involvement of mantle‐derived fluids is crucial to induce the low‐temperature melting, and sufficient fractional crystallization was reached during subsequent magmatic evolution. Previous studies suggest that the Carboniferous continental arc rocks in the northern NCC have mantle‐derived or crust–mantle mixed sources. Our study, however, indicates that there also exist coeval crust‐derived magmatic rocks in this area. In combination with previous work and this study, we support the hypothesis that the widespread Carboniferous continental arc magmatism in the northern NCC is related to the southward subduction of the Palaeo‐Asian Ocean (PAO), and the different magma sources and extensive crust–mantle interactions are responsible for the formation of diverse types of magmatic rocks with contrasting isotopic compositions. We also draw attention to the fact that phosphate minerals such as apatite may be a preferable chronometer relative to high‐U–Th zircon in a highly fractionated igneous system. [ABSTRACT FROM AUTHOR]

The earliest fossils of winged insects (Pterygota) are mid-Carboniferous (latest Mississippian, 328–324 Mya), but estimates of their age based on fossil-calibrated molecular phylogenetic studies place their origin at 440–370 Mya during the Silurian or Devonian. This discrepancy would require that winged insects evaded fossilization for at least the first ~50 Myr of their history. Here, we examine the plausibility of such a gap in the fossil record, and possible explanations for it, based on comparisons with the fossil records of other arthropod groups, the distribution of first occurrence dates of pterygote families, phylogenetically informed simulations of the fossilization of Palaeozoic insects, and re-analysis of data presented by Misof and colleagues using updated fossil calibrations under a variety of prior probability settings. We do not find support for the mechanisms previously suggested to account for such an extended gap in the pterygote fossil record, including sampling bias, preservation bias, and body size. We suggest that inference of an early origin of Pterygota long prior to their first appearance in the fossil record is probably an analytical artefact of taxon sampling and choice of fossil calibration points, possibly compounded by heterogeneity in rates of sequence evolution or speciation, including radiations or 'bursts' during their early history. [ABSTRACT FROM AUTHOR]

Hibbertopterus lamsdelli sp. nov., from the Late Carboniferous Kinney Quarry Lagerstätte of New Mexico (USA), is a large (ca. 1.1 m long) stylonurid eurypterid (sea-scorpion; Chelicerata), similar to H. scouleri from Scotland but with less serrate segment margins, a wider pretelson, shorter telson (tail-spine), and more parallel ventral keels. It is only the fourth, yet most reliable record of an American hibbertopterid. A taxonomic reassessment of Hibbertopterus regards Dunsopterus and Vernonopterus (but not Cyrtoctenus) as synonyms. Hibbertopterids were aquatic (benthic) scavengers and microphagous sweep-feeders, but their trackways indicate that they were capable of brief terrestrial, seasonal nuptial walks, despite their large size; Hibbertopterus had walking legs with spinose extensions at the base (Laden) to spread their load, and the ventral keels on their telson functioned like sled rails to reduce body drag. Hibbertopterids were interpreted as moving into freshwater during the Late Palaeozoic, but a trackway from the middle Permian Collingham Formation (Ecca Group) of South Africa may be from a marine setting, though further analysis is needed to fully evaluate this possibility. [ABSTRACT FROM AUTHOR]

Poroblattina anadiensis sp. nov., first record of the roachoid family Poroblattinidae from Portugal, is described from the upper Gzhelian Vale da Mó 'Formation' of Buçaco Carboniferous Basin. The genus Poroblattina was previously known by numerous records from the Moscovian and the Asselian (time range between 306.95 and 295.0 Ma) in Euramerica, showing a high forewing venation variability. The new species is most similar to the French Moscovian Poroblattina duffieuxi, but it differs from this species in having a larger forewing, more irregularly anterior pectinate RP, and more forked branches. Poroblattina anadiensis sp. nov. supports the links between the entomofaunas of North America and Western Europe during the late Carboniferous and early Permian. Despite the intense exploration of the Buçaco Carboniferous Basin units in the nineteen-century and mid-20th century, the new discovery highlights the potential of palaeontological studies now resumed in this region. [ABSTRACT FROM AUTHOR]

Plant adaptations to environmental and climatic changes in Pangaean intramontane basins are poorly understood. Here, we document a previously unknown primitive gymnosperm species, Lesleya ceriacoi sp. nov., from the Douro Carboniferous Basin (DCB; lower Gzhelian, Upper Pennsylvanian; NW Portugal) of the Variscan Iberian Massif (Iberia). This new species is described from a 303 million-years-old fossil rediscovered at the U.Porto's Herbarium PO, stored at the Museu de História Natural e da Ciência da Universidade do Porto (MHNC-UP; Portugal). L. ceriacoi sp. nov. displays an exquisite leaf shape with morphological traits adapted to specific ecological conditions of the DCB. These leaf morphological traits comprise toothed and dissected margins, which represent specialised adaptations to drier (xerophytic) conditions of the DCB during the Gzhelian (ca. 304–299 Ma), at the end of the Late Pennsylvanian. The xeromorphic traits of the new species represent an evolutionary novelty for the Pennsylvanian Euramerican dry-climate adapted floras, and are evidence of evolutionary adaptation to environmental and climatic change in intramontane basins like DCB within central tropical Pangaea. Such an adaptation occurred during an interval of wet to dry climate transition after the end of one late Palaeozoic Gondwana Ice Age (glaciation) in Gzhelian time. [ABSTRACT FROM AUTHOR]

During late Carboniferous time, the residual ocean basin gradually closed in West Junggar and only a small amount of seawater remained in the Hala'alat Mountain area, where discussions of provenance and tectonics are limited. In this study, LA-ICP-MS U–Pb dating and heavy mineral identification are conducted on the upper Carboniferous tuffaceous sandstones from the Hala'alat and Aladeyikesai formations in the Hala'alat Mountain area. The results reveal the low maturity of the clastic sediments, indicating proximal deposition. The Hala'alat Formation detrital zircons present a single peak (c. 330 Ma). Speculatively, the primary provenance is the Boshchekul–Chingiz Arc, and the secondary sources are the Darbut Tectono-Magmatic Belt and island arcs in the basin. The main peak and provenance of the Aladeyikesai Formation are similar to those of the Hala'alat Formation. Moreover, several age groups, namely, 370–344 Ma, 427–404 Ma and 478–476 Ma, potentially correspond to provenances of the Darbut Tectono-Magmatic Belt, the Boshchekul–Chingiz Arc and the Kujibai–Hongguleleng Ophiolitic Mélange Belt. In addition, the maximum depositional ages of the Hala'alat and Aladeyikesai formations calculated are 314.6 ± 1.54 Ma and 330.8 ± 0.61 Ma, respectively. Comprehensive analysis shows a relatively singular provenance of the Hala'alat Formation. While the provenance of the Aladeyikesai Formation shows inheritance, the provenance area extends northwards to the Kujibai–Hongguleleng Ophiolitic Mélange Belt. Furthermore, the closure of the Junggar Ocean during Carboniferous time caused the potential source region of the Hala'alat Mountain area to migrate northeastwards from Barleik Mountain to Xiemisitai Mountain. This study provides a basis for the analysis of regional geological evolution. [ABSTRACT FROM AUTHOR]

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In the Ennedi Plateau, northeastern Chad, Cambrian(?)-Ordovician to Carboniferous strata represent one of the most proximal succession of the north-facing Gondwana platform. This study presents preliminary results related to the c. 200 m-thick Lower Sandstones and overlying Bedo Formation, which essentially record Early to Middle Ordovician flooding events and the end-Ordovician glaciation and subsequent deglaciation. In the Lower Sandstones, fluvial-dominated deposits (prevailing cross-stratification, NW to NNE paleocurrent trends) include intervening high-frequency marine incursions (tidal deposits, ichnofacies including Cruziana and Arthrophycus). Above an erosional unconformity, the end-Ordovician glacial record consists of fluvioglacial conglomeratic deposits atop the Lower Sandstones, which are in turn superimposed by the fine-grained Bedo Formation. The latter interval, onlapping an exhumed erosion surface showing north-trending km-scale glacial lineations, shows glaciomarine deposits only at its base and possibly include Lower Silurian deposits in its upper part. [ABSTRACT FROM AUTHOR]

Mantis shrimps (Stomatopoda) are marine benthic predators well known for their raptorial claws that have, through time, evolved into unique structures with exceptional stunning, piercing or even dismembering functions. Known since the Carboniferous, Stomatopoda fossils have started providing insights into the rise of these predators, however, major gaps in the fossil record remain. In particular, neither Permian, nor Triassic specimens have ever been uncovered. Such a long hiatus strongly hinders our understanding of their evolutionary history, especially regarding the transition between Palaeozoic and Mesozoic forms. We here report two mantis shrimp specimens from the Early Triassic Paris Biota of Idaho, USA, formally described as Triassosculda ahyongi gen. et sp. nov., partially closing an over 100 myr gap in the fossil record. Despite being incomplete, these specimens present distinct and wellpreserved diagnostic characters on the posterior trunk and the tail fan. The telson shows a triangular shape closely resembling that of Palaeozoic mantis shrimps. The broadness of both the pleon and anterior rim of the telson, however, differs from that of most Palaeozoic forms, which have an overall narrow telson, and is more similar to that of modern representatives of Stomatopoda. Additionally, the uropodal exopods of Triassosculda ahyongi gen. et sp. nov. presents a considerable number of movable spines that are common among Jurassic and more recent taxa, but that have never been reported among Palaeozoic Stomatopoda. These features further support and above all, allow temporal refinement of previously suggested evolutionary scenarios. In the latter, and as for other major clades of crustaceans, Stomatopoda are assumed to have evolved from a shrimplike morphology with a narrow triangular telson to a more lobsterlike one with a broad and rather squareshaped telson. Triassosculda ahyongi gen. et sp. nov. indicates this transition was underway by the Early Triassic. [ABSTRACT FROM AUTHOR]

The Billefjorden Trough, a well studied onshore analogue to Carboniferous rift basins in the Ba-rents Sea, is bounded to the west by the Billefjorden Fault Zone. Structural field analysis of a megabreccia and adjacent strata of the Minkinfjellet Formation in the hanging wall of the Odellfjellet Fault segment of the Billefjorden Fault Zone suggests that slope failure occurred along the basin-bounding fault in the Middle Pennsylvanian during the "through-going fault zones" phase of extension, i.e., during decreasing tectonic activity. Structural field data acquired in the megabreccia adjacent to the Odellfjellet Fault using the scanline method show no relationship between fracture density and the presence and/or proximity to a major fault. In the early Cenozoic, mild reworking of Middle Pennsylvanian deposits, including plastic deformation within the megabreccia, reflects Eurekan strain partitioning and decoupling during reactivation of the Billefjorden Fault Zone. The study also reveals the occurrence of abundant WNW-ESE-striking faults in Middle Pennsylvanian sedimentary deposits, which probably formed parallel to the preexisting structural grain trending highly oblique to Grenvillian and Caledonian grains. [ABSTRACT FROM AUTHOR]