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Early Triassic temperatures were some of the hottest of the Phanerozoic, sea‐surface temperatures approached 40°C, with profound consequences for both the sedimentology and faunal distributions in the oceans. However, the impact of these temperatures in terrestrial settings is unclear. This study examines shallow lacustrine sediments from the Lower Triassic succession of North China. These consist of diverse fluvial to shallow lacustrine sandstones and also spectacular, coarse conglomerates composed of diverse, intraformational clasts reworked from the interbedded sediments. The conglomerate beds can show inverse grading and high angle, flat‐pebble imbrication in their lower part and vertically orientated flat pebbles in their upper part. The cobbles include cemented and reworked conglomerate intraclasts and sandstone concentrically‐laminated concretions that record multi‐step histories of growth and reworking, pointing to rapid cementation of the sandy lake bed (likely facilitated by high temperatures). The conglomerates record frequent, high‐energy events that were capable of brecciating a lithified lake bed and transporting cobbles in wave‐influenced sediment‐gravity flows. Initially, powerful oscillatory flows brecciated and deflated the lake bed and subsequently helped to sustain turbulence during short‐distance lateral flow. It is possible that hurricanes, originating from the adjacent hyper‐warm, Palaeo‐Tethyan Ocean travelled into the major lakes of the North China continent during the Early Triassic. [ABSTRACT FROM AUTHOR]

Abstract Shallow carbonate platforms exhibit major changes in faunal composition and facies types during the latest Permian and earliest Triassic. Although the microbialites that developed following the latest Permian mass extinction (LPME) have attracted wide attention, temporal variations in shallow-platform facies and faunas prior to the LPME have been less thoroughly studied. Here, we analyze diversity patterns and variation in skeletal composition in three Upper Permian sections from isolated carbonate platforms of the Nanpanjiang Basin. In addition to the well-known transition from fossil-rich Upper Permian limestones to fossil-poor Permian-Triassic boundary (PTB) microbialites, these sections exhibit several distinct changes that predate the LPME. First, foram faunas show a shift from non-fusulinid-dominated to fusulinid-dominated communities in the <1-m interval below the LPME horizon of each section, reflecting a shallowing trend over ~20–30 kyr preceding the mass extinction. Second, a "foram gap" and concurrent "detrital event" are observed below the LPME in all three sections, recording a rapid influx of detrital siliciclastics that predated the mass extinction by <60 kyr. These features reflect a degree of marine environmental instability prior to the end-Permian mass extinction. The sudden influx of siliciclastics may represent an early perturbation to terrestrial ecosystems linked to incipient Siberian Traps magmatism, resulting in secondary effects in marine environments through increased sediment yields. Highlights • Analysis of carbonate microfacies and foraminifer abundances in three P-Tr sections (Wengna, Taiping, Lung Cam) • Environmental instability on carbonate platforms of Nanpanjiang Basin, South China up to 60 kyr preceding mass extinction • A discrete episode of detrital siliciclastic influx to carbonate platforms initiated major pre-extinction faunal changes. • Shift to fusulinid-dominated foram assemblages at ~20–30 kyr prior to mass extinction owing to platform shallowing • Pre-extinction perturbations possibly caused by terrestrial ecosystem deterioration and increased subaerial erosion. [ABSTRACT FROM AUTHOR]

Evidence for microbial mats has been reported repeatedly from marine Lower Triassic rocks, but scarcely mentioned in post-mass extinction terrestrial facies. Here, we report from the terrestrial Lower Triassic Liujiagou Formation in North China the presence of five kinds of microbially induced sedimentary structures (MISS) or sedimentary surface textures, including “old elephant skin” textures, wrinkle structures, palimpsest ripples, “ Manchuriophycus ” structures and sand cracks. Terrestrial microbial communities that produced these MISS adapted not only to periodically desiccated conditions, but also to the storm-dominated palaeoenvironments in the Liujiagou Formation. The Permian–Triassic mass extinction (PTME) in North China is marked by the die-off of plants, disappearance of coal beds, extinction of pareiasaurs among tetrapods, decreased bioturbation levels and a dramatic change of sedimentary systems through the Sunjiagou Formation. The Sunjiagou Formation recorded the turnover from an ever-wet to a progressively drier and hotter climate and it spans the PTME in North China. Following this mass extinction, MISS became much more common and widespread, suggesting that the mass extinction provided favourable biological and environmental conditions for the development of the MISS in terrestrial ecosystems, especially the decreased bioturbation intensity and grazing pressure associated with increased temperature and climatic drying. In the upper part of the Liujiagou Formation and overlying Heshanggou Formation, the disappearance of MISS coupled with increased bioturbation might indicate an improvement of terrestrial ecosystems and the beginning of the Triassic biotic recovery. However, as the investigation of MISS in space and time through the geological record is in its early stages, further geobiologic and geochemical studies, as well as high-precision isotopic dating from Permian–Triassic terrestrial successions, are needed to fully reveal the timing and pattern of the Early Triassic terrestrial ecosystem reconstruction. [ABSTRACT FROM AUTHOR]

The Lower Triassic Daye and Jialingjiang formations of the Three Gorges area (South China) record the recovery interval of benthic tracemaking invertebrates following the P–Tr mass extinction. A total of 17 ichnospecies in 14 ichnogenera are documented from Smithian and Spathian strata. Our trace fossil data, in combination with previously published studies, show that ichnodiversity in the Middle Yangtze region increased markedly in the early Spathian. Trace fossils in the Smithian are dominated by simple, small, horizontal burrows, including Didymaulichnus and Planolites , whereas Spathian trace fossils are diverse and abundant with moderate–high bioturbation levels and complex burrow networks, such as Thalassinoides . Both burrow sizes and penetration depths increased gradually from the early Spathian to the middle–late Spathian, implying a gradual recovery pattern for benthic ecosystems. Early Triassic ichnofossils are characterised by aspects of opportunistic behaviour (e.g., low-to-moderate ichnodiversity, low-to-moderate bioturbation, small burrow widths, and shallow tiering), suggesting stressed environmental conditions. The recovery tempo and pattern of ichnocoenoses in South China is likely structured by temporal and spatial changes of the refuge zone in the Early Triassic. [ABSTRACT FROM AUTHOR]

Widespread oceanic anoxia has been implicated as an important factor in the PTB (Permian Triassic boundary) mass extinction and the delayed recovery of Early Triassic marine ecosystems. An investigation of framboidal pyrite in the Bianyang section (Nanpanjiang Basin, South China) suggests that euxinia/dysoxia peaked during the Induan, late Smithian to earliest Spathian and late Spathian. These anoxic episodes show a relationship, albeit imperfect, to major episodes of climatic warming during the Early Triassic that were associated with intensified oceanic stratification, reduced marine productivity and organic carbon sinking fluxes, as well as diminished burial fluxes of organic carbon and reduced sulfur. In contrast, intervals of better-oxygenated marine conditions were associated with episodes of relative climatic cooling during the early to middle Smithian and mid-Spathian. The degree of ventilation of the thermocline region, in particular, had a profound effect on marine biotas, with intervals of improved ventilation resulting in increased global diversity among ammonoids and conodonts and increased local abundance of foraminifera in the Nanpanjiang Basin. These observations suggest that oceanic redox fluctuations played an important role in the delayed recovery of Early Triassic marine ecosystems, and, specifically, that episodic expansion of oceanic oxygen-minimum zones (OMZs) resulted in repeated setbacks to the recovery process, a pattern that persisted until the late Spathian. [ABSTRACT FROM AUTHOR]

Abstract: Unlike the high-abundance, low-diversity macrofaunas that characterize many Early Triassic benthic palaeocommunities, ichnofossils were relatively common in the aftermath of the end-Permian mass extinction worldwide. Ichnofossils therefore are a good proxy for ecosystem recovery after the end-Permian biotic crisis. This paper documents 14 ichnogenera and one problematic form from Lower Triassic successions exposed in the Lower Yangtze region, South China. Post-extinction ichnodiversity remained rather low throughout the Griesbachian–early Smithian period and abruptly increased in the late Smithian. However, several lines of evidence, including extent of bioturbation, burrow size, trace-fossil complexity, and tiering levels, indicate that diversification of ichnotaxa in the late Smithian did not signal full marine ecosystem recovery from the Permian/Triassic (P/Tr) mass extinction. Marine ichnocoenoses did not recover until the late Spathian in South China. The marginal sea provided hospitable habitats for tracemakers to proliferate in the aftermath of the end-Permian mass extinction. [ABSTRACT FROM AUTHOR]

Abstract: Paleontological, sedimentary and geochemical data obtained from the Lower Triassic strata of the Meishan section, South China, suggest that onset of biotic recovery coincided with amelioration of paleoceanographic conditions and an increase in ocean productivity. The Griesbachian Meishanorhynchia association from Meishan indicates biotic recovery between the recovery stages 1 and 2. Both the initial biotic recovery and palaeoceanic environmental amelioration occurred within 1–2 myr after the end-Permian mass extinction in the late Griesbachian. [Copyright &y& Elsevier]

Unitary Association Method (UAM) analyses of conodont faunas from 28 sections spanning the biggest Phanerozoic end-Permian mass extinction and significant global environmental and ecosystem perturbations during the succeeding Early Triassic are presented. Based on 72 conodont species, 26 Unitary Association Zones (UAZs) are established for the latest Permian to earliest Middle Triassic of South China. These UAZs provide quantitative high-resolution tools to correlate sequences in the Early Triassic of South China and to compare and test high-resolution conodont biostratigraphy based on interval conodont zones developed over the past three decades. Our quantitative analyses provide insights on ongoing debates relating to the First Appearance Datum (FAD) of the conodont Hindeodus parvus which is used to place and subsequently correlate the "Golden Spike" defining the base of the Triassic (Permian-Triassic Boundary) at the base of Bed 27c at the GSSP Meishan D Section. Previous proposals that suggested potential earlier occurrences of H. parvus below its FAD at Meishan section are not supported by our results. In deep water sections, the First Occurrence (FO) of H. parvus lies at the base of UAZ 5 at the Bianyang section while it lies within UAZ 6 at the Meishan section. This indicates that the earliest occurrence of H. parvus in South China is in the Bianyang section but this conclusion needs further testing due to the reliance on "spot" data by the UAM. Anomalously high occurrences of Hindeodus in the Mingtang section (close to the Bianyang section) further suggests that the Bianyang-Mingtang area may have provided a temporally extended habitable zone for anchignathodontid conodonts. Stage boundaries currently proposed or established using interval conodont zones locate within or between UAZs and are difficult to correlate with carbon isotope curves. UAZs are useful in helping to define GSSPs by recognizing which correlations are most robust and in the selection of the most appropriate species and level for GSSPs. [ABSTRACT FROM AUTHOR]

New 87 Sr/ 86 Sr data based on 127 well-preserved and well-dated conodont samples from South China were measured using a new technique (LA-MC-ICPMS) based on single conodont albid crown analysis. These reveal a spectacular climb in seawater 87 Sr/ 86 Sr ratios during the Early Triassic that was the most rapid of the Phanerozoic. The rapid increase began in Bed 25 of the Meishan section (GSSP of the Permian–Triassic boundary, PTB), and coincided closely with the latest Permian extinction. Modeling results indicate that the accelerated rise of 87 Sr/ 86 Sr ratios can be ascribed to a rapid increase (>2.8×) of riverine flux of Sr caused by intensified weathering. This phenomenon could in turn be related to an intensification of warming-driven runoff and vegetation die-off. Continued rise of 87 Sr/ 86 Sr ratios in the Early Triassic indicates that continental weathering rates were enhanced >1.9 times compared to those of the Late Permian. Continental weathering rates began to decline in the middle–late Spathian, which may have played a role in the decrease of oceanic anoxia and recovery of marine benthos. The 87 Sr/ 86 Sr values decline gradually into the Middle Triassic to an equilibrium values around 1.2 times those of the Late Permian level, suggesting that vegetation coverage did not attain pre-extinction levels thereby allowing higher runoff. [ABSTRACT FROM AUTHOR]

A precise global timescale for the Lower Triassic Series is essential to understand the sequence of events following the end-Permian mass extinction. A crucial step toward providing the necessary high-resolution chronostratigraphic framework for this interval is the final resolution of a long debated Global Stratotype Section and Point (GSSP) for the Induan-Olenekian boundary (IOB; Lower Triassic). Lower Triassic conodont biostratigraphy has been studied around the world in the past decades, with significant recent progress in the recognition of evolutionary lineages and new collections leading to a refined definition of the IOB. The worldwide distribution of Novispathodus waageni sensu lato has been proposed as the marker defining the IOB. This study recognized 15 or 9 unitary associations across the IOB interval worldwide depending on the taxa and sections that are utilized. The first analysis comprises 37 conodont species from 31 globally representative sections distributed around circum-Paleotethys and Panthalassic oceans, including South China, West Pakistan, northern India, North America and others. This analysis resulted in 15 unitary associations with the probable IOB being calibrated within UAZ-2. A second analysis involved only 31 taxa from 31 sections with species of four genera (Borinella , Scythogondolella , Paulella and Wapitiodus) removed. This analysis therefore was dominated by species of Neospathodus and Novispathodus that have wide distribution and normally are applied to define the IOB; this analysis only yielded 10 unitary associations with UAZ-2 including species normally considered for defining the IOB. Unitary association analyses are deterministic, providing a single result for a given dataset, but are also very conservative by defining zones based on maximal associations of taxa rather than taxonomic events. As such they cannot define a GSSP, although they can constrain a GSSP-bearing interval. Two sections are currently considered as the candidates for the base-Olenekian GSSP, including the West Pingdingshan section of Chaohu area, Anhui Province, South China and the Mud section near Spiti, northern India. This unitary association analysis indicates that the West Pingdingshan section is the most complete and reproducible site for the GSSP of the IOB based on the first appearances of Eurygnathodus costatus , Neospathodus posterolongatus , Novispathodus waageni eowaageni , and Nv. waageni waageni. They all co-occur in UAZ-2, which is calibrated to a 5 m interval from Beds 23–4 to 25–30 at the West Pingdingshan section, in which the primary markers Nv. waageni eowaageni and Nv. waageni waageni do not appear until upper Bed 24 and lower Bed 25. The same UAZ is confined to Beds 12b to 14a in the Mud section. In addition, two new species: Neospathodus yangtzeensis sp. nov. and Novispathodus shani sp. nov. are described, which will significantly refine the conodont zonations of early-middle Smithian and help to constrain the IOB interval. Owing to global distribution, the well-documented Ns. posterolongatus may serve as an auxiliary marker for the IOB by its first occurrence (FO), and Eurygnathodus costatus approximates the IOB in shallow-water settings. • Quantitative biochronology study of IOB conodonts using the UA method • Conodont data set for analysis is from 31 Lower Triassic sections around the world • The West Pingdingshan section is the most complete and reproducible site • Two newly described taxa (Ns. yangtzeensis and Nv. shani) will significantly help to restrict the IOB interval • A high precision time-frame for the IOB interval is proposed [ABSTRACT FROM AUTHOR]

Abstract Whether body size reduction (the Lilliput Effect) occurred in the Early Triassic invertebrates remains a matter of debate. Here, we investigate the size evolution of brachiopods spanning the Late Permian through the Early to Middle Triassic based on 3316 brachiopod specimens from South China. Our results show that the maximum and median size among species decreased dramatically from the latest Permian (Changhsingian) to the earliest Triassic (Griesbachian), and then increased during the Olenekian and Anisian. Our data support the Lilliput Effect on brachiopods during the Permian-Triassic mass extinction and its immediate aftermath. Size plots at species, genus, and family levels suggest that the earliest Triassic size reduction resulted from two factors: the preferential extinction of large brachiopod taxa (size-selective extinction), and the size reductions in the survivors. Persistent increases in brachiopod size in the Olenekian and Anisian are likely the result of the extinction of small survivors, the appearance of large-sized species and the Cope's rule that the new lineages tend to increase in body size over the early evolutionary time. The cause of the earliest Triassic size reduction of brachiopods might be environmental pressures such as global warming, oceanic anoxia, and increased water turbidity. Highlights • Brachiopod's sizes were smaller in the Early Triassic than nearby intervals. • Extinction of large taxa and size reduction of survivors are two key factors. • The results support the Lilliput effect on Early Triassic brachiopods. [ABSTRACT FROM AUTHOR]

The Early Triassic, following the end-Permian mass extinction, was an interval of severe low diversity. Increasing amounts of evidence demonstrate that variable environmental stresses were widespread and intense after the end-Permian mass extinction. Here we report biomarkers from lowest Triassic to lower Middle Triassic strata in South China (Qingyan and Chaohu sections), including biomarkers for environmental stress (2-methyl hopane index) and eukaryotic algae (steranes and C 21 n -alkylbenzene ratio). Using the 2-methyl hopane index, we detected the persistence of environmental stress during most of the Early Triassic. Using steranes and the C 21 n -alkylbenzene ratio, we found a gradual increase in the biomass of eukaryotic algae during the Early to early Middle Triassic. A decrease in environmental stress in the Qingyan section (Leidapo Member) during the early Middle Triassic was synchronous with the “explosion” of the Qingyan Biota, which is characterized by a high abundance and diversity of invertebrate marine animals. Because the environmental stresses revealed by the 2-methyl hopane index encompass various factors (e.g., pH and temperature), we cannot identify the exact stresses at that time; however, our results reflect the amelioration of harsh environments for life during the interval of complete biotic recovery. [ABSTRACT FROM AUTHOR]

We investigated the distribution of lipids in Lower Triassic sedimentary rocks (252–247 myr) from South China, including a shallow water microbialite in the uppermost section of the outcrop. Archaeal derived hydrocarbons were the major constituents of the microbialite from the latest Early Triassic. Among these, we detected (i) abundant C 40 acyclic and monocyclic biphytanes (possibly derived from glycerol dialkyl glycerol tetraether lipids) and their degradation products, C 30–39 pseudohomologues and (ii) a C 25 head-to-tail linked (regular) isoprenoid hydrocarbon [possibly derived from dialkyl glycerol diether lipids (DGDs)] and its degradation products, C 21–24 pseudohomologues and abundant pristane and phytane. Through combination of compound-specific stable carbon isotope analysis of isoprenoid hydrocarbons, which had average δ 13 C values of −35‰ to −30‰, and their molecular distribution, it was not possible to unambiguously define the archaeal source for the biphytanes in the microbialite. The δ 13 C values for pristane and phytane were similar to those for head-to-tail linked C 21–25 isoprenoids; potential source organisms for these compounds were halophilic archaea. Except for methane seep microbialites, no other ancient or recent phototrophic microbialites have been reported to contain predominantly archaeal isoprenoid hydrocarbons. Our findings suggest the presence of a new type of microbialite. [ABSTRACT FROM AUTHOR]

Abstract: Land–plant productivity was greatly reduced after the end-Permian mass extinction, causing a pronounced “coal gap” worldwide during the Early Triassic. Newly obtained organic geochemistry data from the Chaohu area, south China, indicated an abrupt and profound terrestrial vegetation change over the middle part of the Early Triassic Smithian–Spathian (S–S) interval. Herbaceous lycopsids and/or bryophytes dominated terrestrial vegetation from Griesbachian to Smithian times. The terrestrial ecosystem underwent an abrupt change, and woody conifers became dominant over the S–S interval. Several important biomarkers, namely retene, simonellite, and dehydroabietane (with multiple sources: conifer, lycopsid, and/or herbaceous bryophyte), were relatively abundant during Griesbachian, Dienerian, and Smithian times. The relatively low C/N ratio values during the Griesbachian–Smithian interval indicate that these biomarkers were likely sourced from herbaceous lycopsids and/or bryophytes. The extremely abundant conifer-sourced pimanthrene, combined with relatively high C/N ratio values, suggested the recovery of woody conifers after the S–S boundary. The new data revealed that the switch from herbaceous vegetation to woody coniferous vegetation marked a terrestrial plant recovery, which occurred globally within 3 million years after the end-Permian crisis rather than at a later date estimated in previous studies. In Chaohu, the S–S terrestrial event was marked by a reappearance of woody vegetation, while the S–S marine event was marked by an increase in ichnodiversity, trace complexity, burrow size, infaunal tiering level, and bioturbation level, and a possible intense upwelling event indicated by the extended tricyclic terpane ratios (ETR). Coeval vegetation changes with comparable patterns have also been documented in Europe and Pakistan based on palynologic studies. The S–S boundaries in Asia and Europe are associated with a positive δ13C excursion, the rebound of woody vegetation, a turnover of ammonoid faunas, and possible global climate cooling. This is the first study to document the S–S event using biomarkers and C/N ratios. [Copyright &y& Elsevier]

Abstract: A magnetostratigraphic study was performed on the lower 44 m of the West Pingdingshan section near Chaohu city, (Anhui province, China) in order to provide a magnetic polarity scale for the early Triassic. Data from 295 paleomagnetic samples are integrated with a detailed biostratigraphy and lithostratigraphy. The tilt-corrected mean direction from the West Pingdingshan section, passes the reversal and fold tests. The overall mean direction after tilt correction is D =299.9°, I =18.3° (κ =305.2, α 95 =1.9, N =19). The inferred paleolatitude of the sampling sites (31.6°N, 117.8°E) is about 9.4°, consistent with the stable South China block (SCB), though the declinations indicate some 101° counter-clockwise rotations with respect to the stable SCB since the Lower Triassic. Low-field anisotropy of magnetic susceptibility indicates evidence of weak strain. The lower part of the Yinkeng Formation is dominated by reversed polarity, with four normal polarity magnetozones (WP2n to WP5n), with evidence of some thinner (<0.5 m thick) normal magnetozones. The continuous magnetostratigraphy from the Yinkeng Formation, provides additional high-resolution details of the polarity pattern through the later parts of the Induan into the lowest Olenekian. The magnetostratigraphic and biostratigraphic data show that the conodont marker for the base of the Olenekian (first presence of Neospathodus waageni) is shortly prior to the base of normal magnetozone WP5n. This provides a secondary marker for mapping the base of the Olenekian into successions without conodonts. This section provides the only well-integrated study from a Tethyan section across this boundary, but problems remain in definitively relating this boundary into Boreal sections with magnetostratigraphy. [Copyright &y& Elsevier]