Late Early Permian Research Articles

Upper Paleozoic stratigraphy and detrital zircon geochronology along the northwest margin of the Sverdrup Basin, Arctic Canada: insight into the paleogeographic and tectonic evolution of Crockerland

The upper Paleozoic succession along the northwest margin of the Canadian Arctic Sverdrup Basin is little studied and poorly understood yet has the potential to yield insights into the paleogeographic and tectonic evolution of the Arctic regions including Crockerland. Carboniferous and Permian drill cuttings were collected from five exploration wells on Brock, Mackenzie King, and Ellef Ringnes islands. Seven unconformity-bounded sequences were identified and correlated. Reflection seismic interpreted on Ellef Ringnes Island indicates that a major syn-sedimentary fault offsets the Mississippian succession bounding a down-to-the-north half-graben. Late Pennsylvanian (Gzhelian) fault reactivation, associated with the Melvillian Disturbance, created a depression that extended northward and was bordered to the south by a structural high. Episodic minor fault reactivation occurred until the Early–Middle Permian boundary. During the latest Early Permian (Kungurian), sand derived from Crockerland prograded southward onto the Sverdrup Basin’s northwest margin and continued into the Roadian. After a lull during the Wordian, clastic progradation resumed in the Capitanian. Detrital zircon U–Pb ages recovered from Kungurian and Roadian samples on Brock and Ellef Ringnes islands display Devonian Clastic Wedge (DCW) signatures. A Moscovian–Artinskian carbonate blanket likely covered Crockerland and sheltered DCW material from erosion, implying it was a subsiding, carbonate bank throughout most of the Pennsylvanian – Early Permian. Base level fall in the Kungurian, associated with a transition to a more humid climate, breached these carbonate rocks to allow erosion and transportation of DCW material. Recycling of the DCW started earlier (Artinskian) and peaked later (Wordian) along the southern margin of the basin.

Male postabdomen reveals ancestral traits of Megasecoptera among winged insects

External male genitalia of insects are greatly diverse in form and frequently used in evolutionary context and taxonomy. Therefore, our proper recognition of homologous structures among various groups from Paleozoic and extant insect taxa is of crucial interest, allowing to understand the key steps in insect evolution. Here, we reveal structural details of two Late Carboniferous representatives of Megasecoptera (families Bardohymenidae and Brodiopteridae), such as the presence of separated coxal plates VIII and ventral expansions of coxal lobes IX. Together with the confirmed presence of abdominal styli in some other members of Palaeodictyopterida (Diaphanopterodea) this suggests that early pterygotes may have had traits more archaic than expected. Whether or not these traits point to a stem-group relationship of Palaeodictyopterida to all other Pterygota as suspected by earlier authors remains unclear at this stage. Furthermore, the present study provides an updated comparison of male postabdomen morphology among extant species of wingless Archaeognatha and representatives of early diverging groups of Pterygota from the Late Carboniferous and Early Permian, the Megasecoptera (Palaeodictyopterida), Permoplectoptera (Ephemeroptera) and Meganisoptera (Odonatoptera).

Tectonic relationship between the Kelameili range and the Dajing depression: Insights into the Carboniferous tectonic-sedimentary framework

Based on comprehensive analysis of typical outcrops, latest deep wells drilled and high resolution seismic profiles in the study area, we examined the geologic structure of the Kelameili range, and analyzed the structural relationship between the Kelameili range and the Dajing depression, and discussed the tectonic-sedimentary framework in different periods of Carboniferous by using axial surface analysis and balanced section techniques. Understandings in three aspects are achieved: (1) The study area experienced five stages of compressional tectonic movements, the Early Carboniferous, the Late Carboniferous, the Middle-Late Permian, Late Cretaceous and Paleogene, and three stages of extensional tectonic movements, the middle-late Early Carboniferous, the middle-late Late Carboniferous and Early Permian. At the end of the Early Permian and the Mid-Late Cretaceous, the tectonic wedges moved southward respectively. (2) The Kelameili range and Dajing depression had the first basin-range coupling during the early Early Carboniferous, basin-range decoupling in the following middle-late Early Carboniferous to the Early Permian, then basin-range strong recoupling in the Middle Permian, and the basin-range coupling had been inherited in the subsequent Indosinian, Yanshanian and Himalayan movements. (3) During the early Early Carboniferous, the study area was a foreland basin where the Dishuiquan Formation source rock developed; in mid-late Early Carboniferous, a series of NW- and NWW-trending half-garben fault basins developed, where the Songkaersu Formation volcanic reservoir formed. In late Early Carboniferous, the study area entered into depression basin stage after rifting, and the Shuangjingzi Formation source rock developed; in the mid-late Late Carboniferous, Batamayineishan fault basin emerged, and the Upper-Carboniferous volcanic reservoir was formed, affected by the tectonic compression during late Carboniferous and Mid-Permian, the Batamayineishan Formation suffered extensive erosion, and only partially remains in the piedmont depression zone.

Intra-continental deformation and tectonic evolution of the West Junggar Orogenic Belt, Central Asia: Evidence from remote sensing and structural geological analyses

The West Junggar Orogenic Belt (WJOB) in northwestern Xinjiang, China, is located in the core of the western part of the Central Asian Orogenic Belt (CAOB). It has suffered two stage tectonic evolutions in Phanerozoic, before and after the ocean–continental conversion in Late Paleozoic. The later on intracontinental deformation, characterized by the development of the NE-trending West Junggar sinistral strike-slip fault system (WJFS) since Late Carboniferous and Early Permian, and the NW-trending Chingiz-Junggar dextral strike-slip fault (CJF) in Mesozoic and Cenozoic, has an important significance for the tectonic evolution of the WJOB and the CAOB. In this paper, we conduct geometric and kinematic analyses of the WJOB, based on field geological survey and structural interpretation of remote sensing image data. Using some piercing points such as truncated plutons and anticlines, an average magnitude of ~73 ​km for the left-lateral strike-slip is calculated for the Darabut Fault, a major fault of the WJFS. Some partial of the displacement should be accommodated by strike-slip fault-related folds developed during the strike-slip faulting. Circular and curved faults, asymmetrical folds, and irregular contribution of ultramafic bodies, implies potential opposite vertical rotation of the Miao’ergou and the Akebasitao batholiths, resulted from the sinistral strike-slipping along the Darabut Fault. Due to conjugate shearing set of the sinistral WJFS and the dextral CJF since Early Mesozoic, superimposed folds formed with N–S convergence in southwestern part of the WJOB.

First Palynological Record from the Upper Carboniferous/Lower Permian Succession in West Beni Suef Basin, Egypt, with Paleoecological and Paleogeographical Implications

FOR THE FIRST time, a palynological assemblage was recovered from the Safi Formation in the west Beni Suef Basin of the Western Desert in Egypt. A total of 65 miospore taxa were recognized; they included 31 species of pteridophyte spores (related to 20 genera) and 34 species of gymnosperm pollen (related to 14 genera). The dominance of monosaccate pollen confirms an age not older than Westphalian (Late Carboniferous) as documented in various Gondwanan basins. Besides the restricted presence and limited counts of typical guide taeniate bisaccate and non-taeniate bisaccate pollen in the present assemblage constrain and limit the age to the Asselian (Early Permian) and not younger. The paleovegetation of the studied palynoassemblage is reconstructed based on the paleobotanical affinities of the identified miospores, which are generally consistent with other macrofloral fossil records obtained from Egyptian outcrops during the Late Carboniferous and Early Permian. The paleoecological significance of the reconstructed paleovegetation enabled the recognition of two paleofloral communities: A lowland paleoflora represented by a cold climate wetland fern community associated with Lycopsida and Sphenopsida and an upland paleoflora dominated by a primitive group of gymnospermic plants with a unique moisture-independent reproduction strategy developed under the influence of a glacial climate. The high representation of the bilaterally or radially symmetrical monosaccate pollen genera, which are typical Late Paleozoic Gondwanan gymnospermic vegetation, in the present material supports the hypothesis that Egypt’s Western Desert was part of the Gondwanan floral province during the Late Carboniferous/Early Permian.

Late Early Permian Fusulines along Gongendani, South of Mt. Ryozen, Shiga Prefecture, Central Japan

Twenty species of fusulines and ten species of non-fusuline foraminifers have been identified from 20 limestone samples along Gongendani, a valley south of Mt. Ryozen, Shiga Prefecture, Japan. They are dominated by Pseudofusulina norikurensis, Ps. isomie, and Acervoschwagerina gongendaniensis, and considered to be late Cisuralian (late early Permian) based on their coexistence with five subordinate species reported from the Yakhtashian (Artinskian) and the Bolorian (lower Kungurian) in the southeast Pamir and other Tethyan regions. Taxonomic composition of the schwagerinids of Gongendani and other faunas in the Mino Terrane is considerably different from that of coeval faunas in the Permian Akiyoshi Terrane. It is highly probable that Acervoschwagerina is Yakhtashian and possibly ranging up to Bolorian. Thirteen species of fusulines including two new species, Acervoschwagerina gongendaniensis Kobayashi and Cuniculinella omiensis Kobayashi are described systematically.

Floral diversity and environment during the early Permian: a case study from Jarangdih Colliery, East Bokaro Coalfield, Damodar Basin, India

Macro and miofloral analyses of coal-bearing sequences of the Jarangdih coal mine, Damodar Basin, were carried out to infer the floral diversity, age assessment, and the palaeoenvironment during the deposition of the Barakar Formation in this area. Damodar Basin, one of the five major Gondwana basins in India, is considered as the reference basin for inter-basinal age correlations. The Barakar strata of this colliery have yielded a diverse macroflora consisting of the groups Glossopteridales (Glossopteris, Vertebraria, Gangamopteris, fructifications, and stem casts) and Equisetales (Phyllotheca indica, Schizoneura gondwanensis, and Paracalamites sp.). The genus Glossopteris dominates the assemblage with 16 species viz. G. arberi, G. communis, G. churiensis, G. giridihensis, G. indica, G. intermedia, G. intermittens, G. leptoneura, G. linearis, G. mohudaensis, G. recurva, G. searsolensis, G. stenoneura, G. taenensis, G. tenuifolia, and G. tenuinervis. The leaves of Glossopteris leptoneura have impressions of male sporangia adhered on them. The groups Lycopodiales, Coniferales, Sphenophyllales, and Filicales are not represented as macrofloral remains; however, their presence is recorded in the palynoassemblage. The palynological analysis has revealed only one palynoassemblage characterised by the dominance of striate bisaccate palynomorphs mainly Faunipollenites and non-striate bisaccate pollen—Scheuringipollenites. The other stratigraphically significant palynotaxa are Striatopodocarpites, Verticipollenites, Crescentipollenites, Striatites, and Arcuatipollenites. The recovered palyno- and megafloral assemblages suggest the late early Permian (Kungurian) age to the Barakar strata of Jarangdih coal mine and prevalence of moderately warm climate during their deposition.

Chapter 7 Patuki and Croisilles melanges in South Island, New Zealand: genesis related to Permian subduction–accretion processes

Abstract The late Early Permian ( c. 278–270 Ma) supra-subduction zone (SSZ) Dun Mountain ophiolite is bordered to the east by the Pataki Melange and to the NE by the Croisilles Melange. In the south, the ophiolite passes into a dismembered incipient oceanic arc (Otama Complex). The above units represent an oceanic forearc generated above a west-dipping subduction zone. Terrigenous sediment reached the subduction trench after the Mid-Permian(?) docking of the oceanic forearc with the long-lived SE Gondwana active continental margin. Mixed terrigenous–volcaniclastic turbidites accumulated in the trench prior to and during melange accretion. Fragments of the overriding oceanic forearc (and incipient arc, locally) detached and mixed to form melange and broken formation. Despite some individual features (e.g. of the basalt chemistry), the Patuki and Croisilles melanges are interpreted as originally representing a single Permian trench–accretionary complex. The more distal (easterly) part was sliced into the adjacent accretionary complex of the Caples Terrane to form the Croisilles Melange (and equivalent Greenstone Melange) probably after the Triassic. The South Island melanges exemplify accretionary processes in which igneous and sedimentary rocks were detached from the overriding plate by subduction–erosion, together with accretion, including seamount material from the subducting oceanic plate, with implications for melanges elsewhere.

Reef Construction in the Second Half of the Permian and Biotic Crisis at the Permian–Triassic Boundary

The Middle–Late Permian reefs were formed in two paleogeographic realms: North Pangaea and Tethyan Realm. The basic reef builders in the first realm were representatives of Calcispongiae and Bryozoa; in the second realm, sphinctozoans, corals, and stromatoporoids. In these realms, various algae and cyanobacteria communities were of importance. Reef construction in the first realm associated with arid climatic conditions, isolation of water basins, and accumulation of salt-bearing sequences came to the end in the early Late Permian. Reef construction in the Tethyan Realm occurred in the Late Permian up to the Permian–Triassic boundary. The termination of reef construction was due to features of the reef ecosystem, which turned out to be unstable against the background of variations in the conditions and mass extinction at the Permian–Triassic boundary and dissociated before the termination of this extinction.

Tectonic setting for Tsunemori Formation in the Permian accretionary complex of the Akiyoshi Belt, Southwest Japan

The purpose of this study is to reexamine the age, depositional environment, and tectonic setting of the Tsunemori Formation. This study provides a new tectonic model on the formation of Tsunemori Formation, which is a key formation to understand the Late Permian subduction and accretionary processes in Japan. The sedimentation age of the Tsunemori Formation is late Middle Permian to early Late Permian, based on radiolarians, such as Follicucullus cf. scholasticus Ormiston and Babcock reported in this study. This paper disproves the previous theory of atoll carbonates collapse at the trench for the Akiyoshi Limestone. Most of sedimentary rocks of the Tsunemori Formation is not pervasively sheared, are less deformed compared with sedimentary rocks of the typical accretionary complexes. There is no layer parallel or sub-parallel thrusting in the turbidite sequences of the Tsunemori Formation. Mudstone of turbidite and pebbly mudstone is lack of fissility and scaly cleavages. The styles of deformation, occurrence of reworked fossils, presence of calcarenite and limestone breccia suggest that the Tsunemori Formation was not a part of accretionary wedges, but possibly was fore arc or slope basin deposits. Presence of reworked fossils, calcarenite, limestone breccia suggest that a part of the provenance of Tsunemori Formation are limestone exposed at the arc trench gap, which was moved upward to reach the arc trench gap where the Akiyoshi Limestone provides its fragments and blocks into forearc and/or slope basins. Therefore, Tsunemori Formation is a deposit in the forearc basin and/or slope basin rather than trench deposits.

Mississippian–Permian evolution and paleogeographic distribution of the Cromyocrinidae and Pirasocrinidae (Crinoidea, Dendrocrinida)

Late Paleozoic macroevolutionary crinoid faunas were dominated by dendrocrinids, replacing most of the camerata crinoids that had dominated the Early and Middle Paleozoic macroevolutionary crinoid faunas. Two dendrocrinid taxa, the Cromyocrinidae and Pirasocrinidae, first recognized in the Mississippian (Visean), attained their greatest generic diversity in the late Moscovian to early Kasimovian, declined in the Late Pennsylvanian and Early Permian, and became extinct in the Late Permian or end-Permian extinction event. The paleontologic record of the Cromyocrinindae and Pirasocrinidae is best documented from the Midcontinent of the United States and both are recognized worldwide in the Late Paleozoic. Their diversity in the latest Pennsylvanian and Early Permian is probably greater than currently recognized because disarticulated ossicles that are ascribed to one or the other of the two families in described faunas are commonly not recognizable at the genus level. Both families show individual evolutionary trends while following the general evolutionary trends of the dendrocrinids.

Early Permian Sunidyouqi suprasubduction-zone ophiolites in the central Solonker suture zone (Inner Mongolia, China)

Different final closing ages have been proposed for the evolution of the Paleo-Asian Ocean (PAO), including Late Silurian, pre-Late Devonian, Early Permian, Late-Permian and Late Permian–Early Triassic. Ophiolites represent fragments of ancient oceanic crust and play an important role in identifying the suture zone and unveiling the evolutionary history of fossil oceans. Our detailed geological, geochemical and geochronological investigations argue for the existence of Early Permian (297 Ma) SSZ type ophiolites in the Sunidyouqi area of central Inner Mongolia, China. The gabbros and basalts show LREE depleted REE patterns and left-leaning primitive mantle-normalized spider diagrams with variable negative Nb-Ta anomalies (Nb* = 0.24–1.28 and 0.29–0.55, respectively). The Sunidyouqi ophiolites were generated in a mature back-arc basin. The Sunidyouqi ophiolites share the same petrological, geochemical and geochronological characteristics with the other ophiolites along the Solonker suture zone, delineating a Late Paleozoic ocean and arc-trench system. This Late Paleozoic ocean and arc-trench system coincides with a Permian paleobiogeographical boundary, i.e. the boundary between the northern cold climate (Boreal faunal–Angaraland floral realm), and a southern warm climate (Tethys faunal–Cathaysian floral realm). A tectonic scenario was proposed at last for the closure of the SE PAO involving (1) Late Ordovician to Middle Permian continuous southward subduction beneath the northern margin of North China; (2) Carboniferous to Middle Permian continuous northward subduction the forming the Northern Accretionary Orogen; (3) Late Permian final closure of the SE PAO.

Scale effect and value criterion of the permeability of the interlayer staggered zones in the basalt of Jinsha River basin, China

The hydrogeological characteristics of structural planes are different to those of the associated bedrock. The permeability, and therefore hydraulic conductivity (K), of a structural plane can be significantly different at different scales. The interlayer staggered zones in the Emeishan Basalt of early Late Permian were studied; this formation is located in the Baihetan hydropower project area in Jinsha River Basin, China. The seepage flow distribution of a solid model and two generalized models (A and B) were computed using COMSOL. The K values of the interlayer staggered zones for all three models were calculated by both simulation and analytical methods. The results show that the calculated K results of the generalized models can reflect the variation trend of permeability in each section of the solid model, and the approximate analytical calculation of K can be taken into account in the calculation of K in the generalized models instead of that found by simulation. Further studies are needed to investigate permeability variation in the interlayer staggered zones under the condition of different scales, considering the scaling variation in each section of an interlayer staggered zone. The permeability of each section of an interlayer staggered zone presents a certain degree of dispersivity at small scales; however, the permeability values tends to converge to a similar value as the scale of each section increases. The regularity of each section of the interlayer staggered zones under the condition of different scales can provide a scientific basis for reasonable selection of different engineering options.

Abiotic and biotic responses to Milankovitch-forced megamonsoon and glacial cycles recorded in South China at the end of the Late Paleozoic Ice Age

Abstract At the end of the Late Paleozoic Ice Age (LPIA) from late Early Permian to early Late Permian, the global climate was impacted by a prevailing megamonsoon and Gondwanan deglaciation. To better understand the abiotic and biotic responses to Milankovitch-forced climate changes during this time period, multi-element X-ray fluorescence (XRF) geochemistry analyses were conducted on 948 samples from the late Early−late Middle Permian Maokou Formation at Shangsi, South China. The Fe/Ti, S/Ti, Ba/Ti and Ca time series, which were calibrated with an existing “floating” astronomical time scale (ATS), show the entire suite of Milankovitch rhythms including 405 kyr long eccentricity, 128 and 95 kyr short eccentricity, 33 kyr obliquity and 20 kyr precession. Spectral coherency and cross-phase analysis reveals that chemical weathering (monitored by Fe/Ti) and upwelling (captured by S/Ti and Ba/Ti) are nearly antiphase in the precession band, which suggests a contrast between summer and winter monsoon intensities. Strong obliquity signal in the Ba/Ti series is proposed to derive from changes in thermohaline circulation intensity from glaciation dynamics in southern Gondwana. The abundance of foraminifer, brachiopod and ostracod faunas within the Maokou Formation were mainly controlled by the ~1.1 Myr obliquity modulation cycle. The obliquity-forced high-nutrient and oxygen-depleted conditions generally produced a benthic foraminifer bloom, but threatened the brachiopod and ostracod faunas.

Re–Os Dating of Bitumen from Paleo–Oil Reservoir in the Qinglong Antimony Deposit, Guizhou Province, China and Its Geological Significance

AbstractAbundant organic inclusions are present in the Qinglong antimony deposit. However, the source rocks of these organic matters have not been reliably identified. Recently, a paleo‐oil reservoir was found in the Qinglong antimony deposit. In view of similar components of gaseous hydrocarbon, we propose that the organic matters observed in inclusions in Qinglong antimony deposit would come from this paleo‐oil reservoir. We used the Re‐Os dating method to determine the age of the bitumen from this paleo‐oil reservoir, and obtained an isochron age of 254.3±2.8 Ma. The age indicates that the oil‐generation from source rock occurred in the early Late Permian, earlier than the Sb mineralization age (∼148±8.5 Ma) in the Qinglong antimony deposit area. After oil generation from Devonian source rock, first and secondary migration, the crude oil have probably entered into the fractures and pores of volcanic rocks and limestone and formed a paleo‐oil reservoir in the western wing of Dachang anticline. As burial process deepened, the crude oil has turned into natural gas, migrates into the core of Dachang anticline and formed a paleo‐gas reservoir. The hydrocarbons (including CH4) in the reservoirs can serve as reducing agent to provide the sulfur required for Sb mineralization through thermal chemical reduction of sulfates. Therefore, the formation of oil‐gas in the area is a prerequisite for the Sb mineralization in the Qinglong antimony deposit.

New whaitsioids (Therapsida: Therocephalia) from the Teekloof Formation of South Africa and therocephalian diversity during the end-Guadalupian extinction.

Two new species of therocephalian therapsids are described from the upper Permian Teekloof Formation of the Karoo Basin, South Africa. They include two specimens of a whaitsiid, Microwhaitsia mendrezi gen. et sp. nov., and a single, small whaitsioid Ophidostoma tatarinovi gen. et sp. nov., which preserves a combination of primitive and apomorphic features. A phylogenetic analysis of 56 therapsid taxa and 136 craniodental and postcranial characters places the new taxa within the monophyletic sister group of baurioids—Whaitsioidea—with Microwhaitsia as a basal whaitsiid and Ophidostoma as an aberrant whaitsioid just outside the hofmeyriid+whaitsiid subclade. The new records support that whaitsioids were diverse during the early-late Permian (Wuchiapingian) and that the dichotomy between whaitsiid-line and baurioid-line eutherocephalians was established early on. The oldest Gondwanan whaitsiid Microwhaitsia and additional records from the lower strata of the Teekloof Formation suggest that whaitsioids had diversified by the early Wuchiapingian and no later than Pristerognathus Assemblage Zone times. Prior extinction estimates based on species counts are reflected in an analysis of origination/extinction rates, which imply increasing faunal turnover from Guadalupian to Lopingian (late Permian) times. The new records support a growing body of evidence that some key Lopingian synapsid clades originated near or prior to the Guadalupian-Lopingian boundary ca. 260–259 million years ago, but only radiated following the end-Guadalupian extinction of dinocephalians and basal therocephalian predators (long-fuse model). Ongoing collecting in older portions of the Teekloof Formation (e.g., Pristerognathus Assemblage Zone) will shed further light on early eutherocephalians during this murky but critical time in their evolutionary diversification.

Permian Tetrapod Footprints from Tunisia

ABSTRACTTetrapod footprints have long been known from Permian outcrops of the Cheguimi Sandstone in southern Tunisia, but never described in detail. The only recovered specimen preserves vertebrate tracks of two different biospecies. Ichnomorphotype 1 shows affinity with mid-Permian tetrapod tracks from France (Merifontichnus Gand et al., 2000) and South Africa (unnamed tracks); ichnomorphotype 2 is most similar to Middle to Late Permian tracks of France (Planipes Gand et al., 1995) and Italy (Dicynodontipus Rühle von Lilienstern, 1944), respectively. Both kinds of the Tunisian tetrapod tracks can be referred to non-mammalian therapsid trackmakers. The ichnoassemblage is in agreement with the supposed late Middle to early Late Permian (∼Capitanian to Wuchiapingian) age of the Cheguimi Sandstone, although additional finds are necessary to obtain a more precise age control.

Distribution, Enrichment and Modes of Occurrence of Arsenic in Chinese Coals

Arsenic is one of the toxic trace elements in coals, which is harmful to both the ecological environment and human health. Based on published literature and the data obtained by our research group, a total of 5314 As concentrations of Chinese coals were analyzed. The arithmetic mean of arsenic content in Chinese coals is 6.97 mg/kg. Choosing the percentage of provincial coal resources in national coal resources as the weighting factor, the weighted average of arsenic content in Chinese coals is 5.33 mg/kg. The content of arsenic in Chinese coals increases from the north to the south. High arsenic content in coal primarily occurs in southwestern Yunnan and certain coalfields in the Guizhou Province. Additionally, arsenic is enriched in the coals from some regions, i.e., the western Yunnan, Guangxi, Tibet, southwestern Liaoning, Jilin, and Henan. The arsenic content in coals of different coal-forming periods shows an overall regularity: Paleogene and Neogene > Late Triassic > Late Permian > Late Jurassic and Early Cretaceous > Early and Middle Jurassic > Late Carboniferous and Early Permian. The modes of occurrence of arsenic in coals include sulfide-association, organic-association, arsenate-association, silicate-association, and soluble- and exchangeable-association. Generally, arsenic in Chinese coals exists predominantly in arsenic-bearing pyrite. Meanwhile, the organic arsenic content is relatively high in coal samples with a lower (<5.5 mg/kg) arsenic content and a low or medium ash yield (<30%).

Late Paleozoic anorogenic magmatism in Southern Mongolia: Evolutionary stages and structural control

Geochronological studies of anorogenic magmatic complexes in the South Mongolian Hercinide have been carried out. Series of the massifs composed of alkaline and subalkaline granitoids with some monzonite formed during the interval of 318–316 Ma have been found. Taking into account previously obtained data, two groups of Late Paleozoic A-type granitoids different in age have been identified in the region: Late Carboniferous and Early Permian. These two occupy different structural positions. The location the early magmatic massifs is controlled by the extended Trans–Altai fault zone of northwest strike: the massifs cluster in areas of the fault intersection with boundaries of structural blocks formed by the pull-apart mechanism. The later Early Permian igneous complexes are associated with the Gobi–Tienshan rift zone of sublatitudinal strike.

Sedimentary response to the paleogeographic and tectonic evolution of the southern North China Craton during the late Paleozoic and Mesozoic

With the aim of constraining the influence of the surrounding plates on the Late Paleozoic–Mesozoic paleogeographic and tectonic evolution of the southern North China Craton (NCC), we undertook new U–Pb and Hf isotope data for detrital zircons obtained from ten samples of upper Paleozoic to Mesozoic sediments in the Luoyang Basin and Dengfeng area. Samples of upper Paleozoic to Mesozoic strata were obtained from the Taiyuan, Xiashihezi, Shangshihezi, Shiqianfeng, Ermaying, Shangyoufangzhuang, Upper Jurassic unnamed, and Lower Cretaceous unnamed formations (from oldest to youngest). On the basis of the youngest zircon ages, combined with the age-diagnostic fossils, and volcanic interlayer, we propose that the Taiyuan Formation (youngest zircon age of 439Ma) formed during the Late Carboniferous and Early Permian, the Xiashihezi Formation (276Ma) during the Early Permian, the Shangshihezi (376Ma) and Shiqianfeng (279Ma) formations during the Middle–Late Permian, the Ermaying Group (232Ma) and Shangyoufangzhuang Formation (230 and 210Ma) during the Late Triassic, the Jurassic unnamed formation (154Ma) during the Late Jurassic, and the Cretaceous unnamed formation (158Ma) during the Early Cretaceous. These results, together with previously published data, indicate that: (1) Upper Carboniferous–Lower Permian sandstones were sourced from the Northern Qinling Orogen (NQO); (2) Lower Permian sandstones were formed mainly from material derived from the Yinshan–Yanshan Orogenic Belt (YYOB) on the northern margin of the NCC with only minor material from the NQO; (3) Middle–Upper Permian sandstones were derived primarily from the NQO, with only a small contribution from the YYOB; (4) Upper Triassic sandstones were sourced mainly from the YYOB and contain only minor amounts of material from the NQO; (5) Upper Jurassic sandstones were derived from material sourced from the NQO; and (6) Lower Cretaceous conglomerate was formed mainly from recycled earlier detritus.The provenance shift in the Upper Carboniferous–Mesozoic sediments within the study area indicates that the YYOB was strongly uplifted twice, first in relation to subduction of the Paleo-Asian Ocean Plate beneath the northern margin of the NCC during the Early Permian, and subsequently in relation to collision between the southern Mongolian Plate and the northern margin of the NCC during the Late Triassic. The three episodes of tectonic uplift of the NQO were probably related to collision between the North and South Qinling terranes, northward subduction of the Mianlue Ocean Plate, and collision between the Yangtze Craton and the southern margin of the NCC during the Late Carboniferous–Early Permian, Middle–Late Permian, and Late Jurassic, respectively. The southern margin of the central NCC was rapidly uplifted and eroded during the Early Cretaceous.