Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery

The end-Permian mass extinction, ~252 million years ago, is notable for a complex recovery period of ~5 Myr. Widespread euxinic (anoxic and sulfidic) oceanic conditions have been proposed as both extinction mechanism and explanation for the protracted recovery period, yet the vertical distribution of anoxia in the water column and its temporal dynamics through this time period are poorly constrained. Here we utilize Fe–S–C systematics integrated with palaeontological observations to reconstruct a complete ocean redox history for the Late Permian to Early Triassic, using multiple sections across a shelf-to-basin transect on the Arabian Margin (Neo-Tethyan Ocean). In contrast to elsewhere, we show that anoxic non-sulfidic (ferruginous), rather than euxinic, conditions were prevalent in the Neo-Tethys. The Arabian Margin record demonstrates the repeated expansion of ferruginous conditions with the distal slope being the focus of anoxia at these times, as well as short-lived episodes of oxia that supported diverse biota

Smithian (Early Triassic) ammonoid faunas from exotic blocks from Oman: taxonomy and biochronology

Ammonoid-rich exotic bocks of Hallstatt facies in Jebel Safra, in Wadi Musjah and at Baid (Oman Mountains) have yielded several well preserved and highly diversified Smithian (Early Triassic) ammonoid faunas (Baidites hermanni fauna, Rohillites omanensis fauna, Flemingites rursiradiatus fauna, Nammalites pilatoides fauna, Owenites koeneni fauna and Anasibirites multiformis fauna). The comparison of these assemblages with data from other Tethyan basins such as the Salt Range, Spiti, Tibet and South China shows that nearly all known Smithian ammonoid faunal assemblages are present in the exotic blocks from Oman. The new Oman data strengthens the remarkably uniform biogeographic distribution of the Smithian ammonoid faunas within the Tethys. One new ammonoid family (Galfettitidae), five new genera (Baidites, Goudemandites, Lucasites, Omanites, Safraites), and twelve new species (Baidites hermanni, Galfettites kyrae, G. omani, Goudemandites sinensis, Kashmirites baidi, Lucasites involutus, L. evolutus, Omanites musjahensis, Paranannites baudi, Pseudaspidites planus, Rohillites omanensis, Safraites simplex) are described. Additionally, a new early Spathian (late Early Triassic) species (Procolumbites safraensis) is described

New latest Permian foraminifers from Laren (Guangxi Province, South China): palaeobiogeographic implications

Microfacies analyses performed on the latest Permian Wujiaping Formation at Laren (Guangxi Province, South China) show that the bioclastic-rich limestones of Late Permian age contain a rich and well-diversified foraminiferal fauna. This fauna is here revised in order to be compared with time-equivalent levels of southern Iran and southern Turkey. Some new and unexpected phylogenetic trends are highlighted among the biseriamminoids. The new or poorly known genera Retroseptellina, Septoglobivalvulina, Paraglobivalvulinoides, Dagmarita?, Bidagmarita nov. gen., Louisettita, Paradagmaritopsis nov. gen. and Paradagmarita? are concerned. Nevertheless, these newly appeared biseriamminoids are subordinate to abundant Tetrataxis and Climacammina, ultimate survivors of the families Palaeotextulariidae and Tetrataxidae, appeared as old as the Early Carboniferous (“Mississippian”). Algae, miliolids, and nodosarioids are poorly represented. Two genera and four species are here newly described: Globivalvulina curiosa nov. sp., Louisettita ultima nov. sp., Bidagmarita nov. gen., Bidagmarita sinica nov. gen. nov. sp., Paradagmaritopsis nov. gen., Paradagmaritopsis kobayashii nov. gen. nov. sp. The palaeogeographic distribution of these foraminifers is interpreted to be typically of Neo-Tethyan regions, ranging from southern Turkey (Hazro) to South China (Laren) and up to Japan for some species (i.e., Paradagmaritopsis). At Laren, Late Permian strata are generally characterized by Reichelina ex gr. simplex Sheng. Isolated samples of packstones, collected in Tsoteng region (Guangxi Province, South China), contain Sphaerulina sp. together with various smaller foraminifers and numerous representatives of the new species G. curiosa nov. sp. In this study we demonstrate that the regions of Zagros (Iran), Taurus (Turkey), South China and even Japan shared similar foraminiferal assemblages and represented intermittently connected palaeobiogeographic provinces during Late Permian times. = Dans la région de Laren (Province du Guangxi, Chine du Sud), des microfaciès calcaires bioclastiques renferment jusqu’à la limite Permo-triasique (PTB) de riches faunes de foraminifères. Elles sont révisées taxonomiquement afin d’être comparées aux éléments des associations du Sud de l’Iran et du Sud de la Turquie. Des tendances évolutives insoupçonnées se révèlent, surtout parmi les bisériamminoïdes, avec des genres nouveaux ou peu connus : Retroseptellina, Septoglobivalvulina, Paraglobivalvulinoides, Bidagmarita nov. gen., Louisettita, Paradagmaritopsis nov. gen. et Paradagmarita ? Ces taxons inhabituels sont cependant subordonnés à d’abondants survivants d’autres superfamilles (Palaeotextularioidea et Tetrataxoidea) apparues dès le Carbonifère inférieur (« Mississippien »), tels que Tetrataxis et Climacammina. Algues, miliolides et nodosarioïdes sont peu représentés. Six nouveaux taxons sont décrits : Globivalvulina curiosa nov. sp., Louisettita ultima nov. sp., Bidagmarita nov. gen., Bidagmarita sinica nov. gen. nov. sp., Paradagmaritopsis nov. gen. et Paradagmaritopsis kobayashii nov. gen. nov. sp. La répartition paléogéographique de ces foraminifères est typiquement néo-téthysienne, du Sud de la Turquie (Hazro) au Sud de la Chine, voire jusqu’au Japon avec Paradagmaritopsis. Des échantillons isolés de packstones collectés dans une autre région (Tsoteng, Province du Guangxi, Chine du Sud) contiennent Sphaerulina sp. ainsi que de petits foraminifères variés et de nombreux spécimens de l’espèce nouvelle G. curiosa nov. sp. Dans cette étude, il est démontré qu’au cours du Permien supérieur, le Zagros (Iran), le Taurus (Turquie), la Chine du Sud (bassin de Nanpanjiang) et même le Japon partagent des associations de foraminifères similaires et que ces diverses provinces paléobiogéographiques étaient périodiquement interconnectées

Modeling of diffusion and premixed flame of AP/HTPB laminate propellant

Composite propellants feature a diffusion flame. The size of oxidizer particles leverage some combustion properties (mainly, burning rate and pressure sensitivity) along with flame structure. Macroscopic combustion features are strictly related to those events occurring inside the gas phase and close to the burning surface. The flame of nonaluminized composite energetic materials is considered and a simplified combustion model is tested for this case. Combustion of a laminate propellant with varying lamina size is simulated. The benchmark consists of some movies taken from ammonium perchlorate (AP) / hydroxyl-terminated polybutadiene (HTPB) propellant combustion with a high-speed video camera. Three different powder sizes are used in propellant manufacturing

Palynology of the Lower Triassic succession of Tulong, South Tibet — Evidence for early recovery of gymnosperms

The thermally altered but otherwise well preserved Early Triassic palynomorphs from the Tulong area (South Tibet) allowed for qualitative and quantitative analyses and the differentiation of two distinct palynofloras, a Smithian lycopod-dominated flora and a Spathian gymnosperm-dominated flora. This suggests that gymnosperm vegetation recovered about 2 Ma after the end-Permian event on the subtropical North Indian Margin. Together with previously described successions from Pakistan, Australia, and Norway the new palynofloral record suggests an earlier establishment of diverse, gymnosperm-rich plant communities after the end-Permian event than previously proposed. The observed change in the ratio of the two major plant groups (pteridophytes/gymnosperms) in these two assemblages supports the global extent of a major climate change near the Smithian–Spathian boundary. The observed palynofloral patterns are closely related to the changes in the carbon isotope record, which suggests that the floral recovery dynamics were linked to environmental conditions