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1
Song, Haijun, Jinnan Tong, Z. Q. Chen, Hao Yang, and Yongbiao Wang. "End-Permian mass extinction of foraminifers in the Nanpanjiang basin, South China." Journal of Paleontology 83, no. 5 (September 2009): 718–38. http://dx.doi.org/10.1666/08-175.1.
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Newly obtained foraminifer faunas from the Permian-Triassic (P-Tr) transition at the Dajiang and Bianyang sections in the Nanpanjiang Basin, South China, comprise 61 species in 40 genera. They belong to thePalaeofusulina sinensisZone, the youngest Permian foraminifer zone in South China. Quantitative analysis reveals that the last occurrences of more than a half of species (28/54) fall into a 60-cm-interval at the uppermost Changhsingian skeletal packstone unit and thus calibrate the end-Permian extinction to the skeletal packstonecalcimicrobial framestone boundary. About 93% (54/58) of species of the latest Permian assemblage became extinct in the P-Tr crisis. Four major foraminiferal groups, the Miliolida, Fusulinida, Lagenida, and Textulariina, have extinction rates up to 100%, 96%, 92%, and 50%, respectively, and thus experienced selective extinctions. BothHemigordius longusand ?Globivalvulina bulloidestemporarily survived the end-Permian extinction event and extended into the earliest Triassic but became extinct soon after. The post-extinction foraminifer assemblage is characterized by the presence of both disaster taxa and Lazarus taxa. Foraminifer distribution near the P-Tr boundary also reveals that the irregular contact surface at the uppermost Permian may be created by a massive submarine dissolution event, which may be coeval with the end-Permian mass extinction. A new species,Rectostipulina hexamerata,is described here.
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Wignall, P. B., H. Kozur, and A. Hallam. "On the timing of palaeoenvironmental changes at the Permo‐Triassic (P/TR) boundary using conodont biostratigraphy." Historical Biology 12, no. 1 (August 1996): 39–62. http://dx.doi.org/10.1080/08912969609386553.
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Dolenec, Tadej, Sonja Lojen, and Matej Dolenec. "The Permian-Triassic boundary in the Idrijca Valley (Western Slovenia): isotopic fractionation between carbonate and organic carbon at the P/Tr transition." Geologija 42, no. 1 (December 30, 1999): 165–70. http://dx.doi.org/10.5474/geologija.1999.011.
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Vijaya and R. S. Tiwari. "Morpho-evolutionary biohorizon stratigraphy and cladistics in saccate pollen through Gondwana Sequence of India." Journal of Palaeosciences 40 (December 31, 1991): 157–93. http://dx.doi.org/10.54991/jop.1991.1772.
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The morphographic characters of fossil saccate pollen and their evolutionary sequence through the span of Gondwana formations play a vital role in the biohorizon stratigraphy. Based on evolutionary changes in the morphology of the pollen group, their FADs (First Appearance Datums) and LADs (Last Appearance Datum) and the cluster levels, eleven biohorizons and ten inter-biohorizon Zones (Interval-zones) have been identified. The model of alliance among the prime morphographies has been acquired through simple character state analysis. By extrapolation of lineages, four unique monosaccate and one simple disaccate organizations could be identified to have their origin in the early Upper Carboniferous stock of Australia, which, in turn, were related with the Devonian progymnospermopsida complex. The five outgroup stocks continued as such into the late Early Asselian Talchir Formation of India and sprouted in the subsequent Permian time. A gap in the sequence has been identified during Upper Carboniferous of Australia and the lowermost Permian in India. The sixth major lineage of striate pollen branched off from the simple disaccate pollen lineage to appear in the Late Asselian. Cladistic analysis supports the applicability of the proposed biohorizons as important stratigraphic parameter. The congruence of derived and ancestral states of internally compatible and persimonically harmonious characters in pollen organizations has been used in drawing relationship trees. Thus, the cladograms and stralograms (nested diagrams of stratigraphic occurrences) together depict the maximum diversification at the lower Upper Talchir and the P/Tr boundary. The major extinction of monosaccates at the Lower Permian-Upper Permian boundary and that of the striate-disaccates in the basal Triassic have also been brought to light. The reasons of such a behaviour is attributed to environmental stresses caused by massive glaciations during Early Permian Talchir Formation, climatic changes towards warmer-drier situation at Lower/Upper Permian passage and global cooling and regression at the permo-Triassic level. Pollen features, like striations, taeniae, girdling monosaccus, clefts and remnant of germinal marks, etc. of the Permian and Triassic have perished completely by the end of Triassic. Most of the Jurassic palyno-assemblages contain the fag-end organizations of simple disaccate lineages; the experimentation seems to have attained a more simple state in the morphography of saccate pollen which continued thereafter.
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Dolenec, Tadej, and Sonja Lojen. "Ce anomaly at the Permian-Triassic boundary in the Idrijca Valley as evidence of changing redox conditions at the P/Tr transition in the western Tethys (Slovenia)." Geologija 43, no. 1 (June 30, 2000): 103–7. http://dx.doi.org/10.5474/geologija.2000.009.
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Bonis, Nina R., and Wolfram M. Kürschner. "Vegetation history, diversity patterns, and climate change across the Triassic/Jurassic boundary." Paleobiology 38, no. 2 (2012): 240–64. http://dx.doi.org/10.1666/09071.1.
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High-resolution palynological data sets from shallow marine Triassic-Jurassic (Tr/J) boundary beds of two principal sections in Europe (Hochalplgraben in Austria and St. Audrie's Bay in the United Kingdom) were analyzed to reconstruct changes in vegetation, biodiversity, and climate. In Hochalplgraben, a hardwood gymnosperm forest with conifers and seed ferns is replaced by vegetation with dominant ferns, club mosses and liverworts, which concurs with an increased diversification of spore types during the latest Rhaetian. Multivariate statistical analysis reveals a trend to warmer and wetter conditions across the Tr/J boundary in Hochalplgraben. The vegetation changes in St. Audrie's Bay are markedly different. Here, a mixed gymnosperm forest is replaced by monotonous vegetation consisting mainly of Cheirolepidiaceae (80–100%). This change is caused by a transition to a warmer and more arid climate. The observed diversity decrease in St. Audrie's Bay affirms this interpretation. Although both sections show major vegetation changes, neither of them demonstrates a distinctive floral mass extinction. A compilation of Tr/J boundary sections across the world demonstrates the presence of Cheirolepidiaceae-dominated forests in the Pangaean interior and increases in abundance of spore-producing plants adjacent to the Tethys Ocean. We propose that the non-uniform vegetation changes reflected in the Tr/J palynological records are the result of environmental changes caused by Central Atlantic Magmatic Province volcanism. The increase in greenhouse gases caused a warmer climate and an enhanced thermal contrast between the continent and the seas. Consequently, the monsoon system got stronger and induced a drier continental interior and more intensive rainfall near the margins of the Tethys Ocean.
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Tripathi, Archana. "Palynological expression about Permian-Triassic transition in the Talcher Coalfield, Orissa, India." Journal of Palaeosciences 50, no. (1-3) (December 31, 2001): 247–53. http://dx.doi.org/10.54991/jop.2001.1826.
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A Permian-Triassic palynofloral transition is recorded in Borehole TP-8, Talcher Coalfield, Orissa, India. The change of palynoflora from Late Permian to Early Triassic is gradual and not abrupt. The variation in the pattern of changeover of the palynomorph distribution at P/Tr transition in Talcher Coalfield, Mahanadi Basin and Raniganj Coalfield, Damodar Basin is discussed.
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Guo, Zhen, Zhong-Qiang Chen, and David A. T. Harper. "Phylogenetic and ecomorphologic diversifications of spiriferinid brachiopods after the end-Permian extinction." Paleobiology 46, no. 4 (September 8, 2020): 495–510. http://dx.doi.org/10.1017/pab.2020.34.
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AbstractThe Order Spiriferinida spanning the latest Ordovician to Early Jurassic is a small group of brachiopods overshadowed by other taxon-rich clades during the Paleozoic. It diversified significantly after the end-Permian extinction and became one of the four major clades of Triassic brachiopods. However, the phylogeny and recovery dynamics of this clade during the Triassic still remain unknown. Here, we present a higher-level parsimony-based phylogenetic analysis of Mesozoic spiriferinids to reveal their evolutionary relationships. Ecologically related characters are analyzed to indicate the variances in ecomorphospace occupation and disparity of spiriferinids through the Permian–Triassic (P-Tr) transition. For comparison with potential competitors of the spiriferinids, the pre-extinction spiriferids are also included in the analysis. Phylogenetic trees demonstrate that about half of the Mesozoic families appeared during the Anisian, indicating the greatest phylogenetic diversification at that time. Triassic spiriferinids reoccupied a large part of the ecomorphospace released by its competitor spiriferids during the end-Permian extinction; they also fully exploited the cyrtiniform region and developed novel lifestyles. Ecomorphologic disparity of the spiriferinids dropped greatly in the Early Triassic, but it rebounded rapidly and reached the level attained by the pre-extinction spiriferids in the Late Triassic. The replacement in ecomorphospace occupation between spiriferids and spiriferinids during the P-Tr transition clearly indicates that the empty ecomorphospace released by the extinction of Permian spiriferids was one of the important drivers for the diversification of the Triassic spiriferinids. The Spiriferinida took over the empty ecomorphospace and had the opportunity to flourish.
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Nabbefeld, Birgit, Kliti Grice, Arndt Schimmelmann, Peter E. Sauer, Michael E. Böttcher, and Richard Twitchett. "Significance of δDkerogen, δ13Ckerogen and δ34Spyrite from several Permian/Triassic (P/Tr) sections." Earth and Planetary Science Letters 295, no. 1-2 (June 2010): 21–29. http://dx.doi.org/10.1016/j.epsl.2010.03.015.
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Parker, William G., and Jeffrey W. Martz. "The Late Triassic (Norian) Adamanian–Revueltian tetrapod faunal transition in the Chinle Formation of Petrified Forest National Park, Arizona." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 101, no. 3-4 (September 2010): 231–60. http://dx.doi.org/10.1017/s1755691011020020.
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ABSTRACTRecent stratigraphic revisions of the Upper Triassic Chinle Formation of Petrified Forest National Park, in conjunction with precise and accurate documentation of fossil tetrapod occurrences, clarified the local biostratigraphy, with regional and global implications. A significant overlap between Adamanian and Revueltian faunas is rejected, as is the validity of the Lamyan sub-land vertebrate faunachron. The Adamanian–Revueltian boundary can be precisely placed within the lower Jim Camp Wash beds of the Sonsela Member and thus does not occur at the hypothesised Tr-4 unconformity. This mid-Norian faunal turnover, may coincide with a floral turnover, based on palynology studies and also on sedimentological evidence of increasing aridity. Available age constraints bracketing the turnover horizon are consistent with the age of the Manicouagan impact event. The rise of dinosaurs in western North America did not correspond to the Adamanian–Revueltian transition, and overall dinosauromorph diversity seems to have remained at a constant level across it. The paucity of detailed Late Triassic vertebrate biostratigraphic data and radioisotopic dates makes it currently impossible to either support or reject the existence of globally synchronous Late Triassic extinctions for tetrapods.
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Jewuła, Karol, Wiesław Trela, and Anna Fijałkowska-Mader. "The Permian–Triassic boundary in continental sedimentary succession at the SE margin of the Central European Basin (Holy Cross Mountains, Poland)." Geological Magazine 157, no. 11 (March 27, 2020): 1767–80. http://dx.doi.org/10.1017/s0016756820000047.
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AbstractWe studied the upper Permian and Lower Triassic deposits from the northern and northwestern marginal part of the Holy Cross Mountains (SE part of the Central European Basin or CEB, Poland) to examine stratigraphic continuity between these two systems, and to revise the currently existing stratigraphic framework. A previously existing informal lithostratigraphic scheme has been revisited and placed in a broader chronostratigraphic and palaeoenvironmental context. Sedimentary continuity across the Permian–Triassic (P/T) boundary has been confirmed by the presence of Lueckisporites virkkiae Bc morphological norm and Lundbladispora obsoleta–Protohaploxypinus pantii palynomorphs. Facies development reflects an interplay between climatic variations and tectonism during late Permian – Early Triassic time. The P/T boundary was placed between the Siodła Formation and overlying Szczukowice and Jaworzna formations, which coincides with the classical Zechstein–Buntsandstein boundary in the SE part of the CEB. The facies changes recorded in the studied terrestrial succession of the P/T boundary shed light on the environmental dynamic prior, during and after one of the biggest biotic crises in Earth’s history.
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Mogutcheva, N. K. "Evolutionary stages of Triassic flora in Siberia (Angarida)." Journal of Palaeosciences 45 (December 31, 1996): 329–33. http://dx.doi.org/10.54991/jop.1996.1252.
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The Triassic flora of Siberia has been studied from three series of Triassic system in continuous sections. Therefore, its successive alterations and stages in the evolution throughout Triassic from the P/T boundary may be traced. Due to alternation of floristic complexes and marine deposits, the age of floristic complex may be precisely determined. The most ancient complex is studied from Induan deposits. In a single section Permian cordaitean flora is replaced.
In Siberia, the Early Triassic flora is heterogeneous. Two major floras, occupying different ecological niches, are distinguished: the lycopod flora (dominated by Tomiostrobus and Pleuromeia) being confined to marine plain, and the conifer fern (Korvunchanskaya) flora is distributed within intracontinental areas where intense volcanism had occurred at that time. The Middle Triassic flora is scanty in Siberia. The Early Ladinian flora differs from both the Early Triassic and Late Triassic ones, while the Late Ladinian flora is closely related to the Late Triassic flora.
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Kelly, Richard S., Andrew J. Ross, and Edmund A. Jarzembowski. "Earwigs (Dermaptera) from the Mesozoic of England and Australia, described from isolated tegmina, including the first species to be named from the Triassic." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 107, no. 2-3 (June 2016): 129–43. http://dx.doi.org/10.1017/s1755691017000329.
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ABSTRACTDermaptera (earwigs) are described from the Triassic of Australia and England, and from the Jurassic and Cretaceous of England. Phanerogramma heeri (Giebel) is transferred from Coleoptera and it and Brevicula gradus Whalley are re-described. Seven new taxa are named based on tegmina: Phanerogramma australis sp. nov. and P. dunstani sp. nov. from the Late Triassic of Australia; P. gouldsbroughi sp. nov. from the Triassic/Jurassic of England; Brevicula maculata sp. nov. and Trivenapteron moorei gen. et sp. nov. from the Early Jurassic of England; and Dimapteron corami gen et sp. nov. and Valdopteron woodi gen. et sp. nov. from the Early Cretaceous of England. Phanerogramma, Dimapteron and Valdopteron are tentatively placed in the family Dermapteridae, and Trivenapteron is incertae sedis. Most of the specimens of Phanerogramma heeri are from the Brodie Collection and labelled ‘Lower Lias'; however, some were collected from the underlying Penarth Group, thus this species spans the Triassic/Jurassic boundary. The palaeobiogeography of the Late Triassic and Early Jurassic of England is discussed.
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Ketchum, Hilary F., and Paul M. Barrett. "New reptile material from the Lower Triassic of Madagascar: implications for the PermianTriassic extinction event." Canadian Journal of Earth Sciences 41, no. 1 (January 1, 2004): 1–8. http://dx.doi.org/10.1139/e03-084.
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Recently discovered reptile specimens from the "Eotriassic" deposits of Madagascar (Lower Triassic) are reported, adding valuable information to our knowledge of Malagasy faunas and providing additional data on tetrapod survivorship across the PermianTriassic (PT) boundary. Four specimens are attributable to the terrestrial procolophonoid Barasaurus besairiei Piveteau 1955, whereas the remainder are referable to the aquatic younginiform family Tangasauridae, including some individuals identifiable as Hovasaurus boulei Piveteau 1926. These specimens represent the geologically youngest tangasaurid and Barasaurus specimens to be described from Madagascar and suggest that these small reptiles passed unaffected through the end Permian mass extinction event, when ~78% of amniote families disappeared.
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Wardlaw, Bruce R., Merlynd K. Nestell, Galina P. Nestell, Brooks B. Ellwood, and Luu Thi Phuong Lan. "Conodont biostratigraphy of the Permian-Triassic boundary sequence at Lung Cam, Vietnam." Micropaleontology 61, no. 4-5 (2015): 313–34. http://dx.doi.org/10.47894/mpal.61.4.05.
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The occurrences of a few specimens of Clarkina and many specimens of Hindeodus at the Permian-Triassic boundary section at Lung Cam, Vietnam allow accurate graphic correlation to the P-T boundary stratotype at Meishan, China. One species of Clarkina, ten species and two subspecies of Hindeodus, and the apparatuses of Hindeodus latidentatus and Merrillina ultima are described and illustrated.
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Sashida, Katsuo, Hisayoshi Igo, Shuko Adachi, Katsumi Ueno, Yoshimichi Kajiwara, Nikorn Nakornsri, and Apsorn Sardsud. "Late Permian to Middle Triassic radiolarian faunas from northern Thailand." Journal of Paleontology 74, no. 5 (September 2000): 789–811. http://dx.doi.org/10.1017/s0022336000033011.
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Moderately well-preserved Late Permian to Middle Triassic radiolarians are identified in chert beds that occur in the Shan-Thai Block of northern Thailand. These radiolarians are identical to the faunas of the Late Permian Neoalbaillella ornithoformis and N. optima Assemblage Zones and the Triassic Parentactinia nakatsugawaensis and Triassocampe coronata Assemblage Zones reported in chert sequences of Japan. We discovered the radiolarian faunas, apparently indicating Late Permian and Early Triassic ages, in almost continuous sequences of chert and shale exposed in the north of Chiang Mai. The occurrence of these radiolarian faunas provides important data to solve the P/T (Permian/Triassic) boundary in pelagic sequences. Our present discovery also furnishes significant data to reconstruct the paleobiogeography of Mainland Thailand during Late Permian to Middle Triassic times. Fifty species belonging to 35 genera, including three unidentified genera, are investigated taxonomically. Four new species Pseudospongoprunum? chiangdaoensis, Cenosphaera igoi, Cenosphaera? rugosa, and Tlecerina? apsornae are described.
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徐, 丽琼. "Coupling of Permian-Triassic Volcanic Activity in Dashanbao with P-T Boundary Mass Biotic Extinction." Open Journal of Nature Science 06, no. 01 (2018): 97–104. http://dx.doi.org/10.12677/ojns.2018.61015.
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Pace, D. W., R. A. Gastaldo, and J. Neveling. "Early Triassic Aggradational and Degradational Landscapes of the Karoo Basin and Evidence for Climate Oscillation Following the P-Tr Event." Journal of Sedimentary Research 79, no. 5 (May 1, 2009): 316–31. http://dx.doi.org/10.2110/jsr.2009.036.
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FENTON, S., K. GRICE, R. TWITCHETT, M. BOTTCHER, C. LOOY, and B. NABBEFELD. "Changes in biomarker abundances and sulfur isotopes of pyrite across the Permian–Triassic (P/Tr) Schuchert Dal section (East Greenland)." Earth and Planetary Science Letters 262, no. 1-2 (October 15, 2007): 230–39. http://dx.doi.org/10.1016/j.epsl.2007.07.033.
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Gautam, Saurabh, Ram-Awatar, Rajni Tewari, and Shreerup Goswami. "Permian-Triassic palynofloral transition in Sohagpur Coalfield, South Rewa Gondwana Basin, Madhya Pradesh, India." Journal of Palaeosciences 65, no. (1-2) (December 31, 2016): 109–29. http://dx.doi.org/10.54991/jop.2016.303.
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A 1300 m thick sedimentary sequence in borehole SNB–1 around Jaisinghnagar area in the western part of the South Rewa Basin has been lithologically designated as the Pali Formation. However, palynological investigation reveals presence of three distinct palynoassemblage zones belonging to late Permian, early and late Triassic ages in ascending order. Palynoassemblage I (Striatopodocarpites magnificus–Crescentipollenites fuscus) recorded between a depth of 1213.40–1164.10 m showing dominance of striate bisaccate pollen taxa chiefly―Striatopodocarpites ovatus, Faunipollenites varius and Crescentipollenites fuscus in association with Alisporites ovalis, Lunatisporites pellucidus, Densipollenites indicus and Lahirites rarus is late Permian (Raniganj) in age. Palynoassemblage II (Lundbladispora densispinosa–Densoisporites playfordii) recorded between a depth of 1054.30–956.00 m and showing dominance of cavate/cingulate spores, like Lundbladispora microconata, Densoisporites complicatus along with Kraeuselisporites rallus, Lapposisporites lapposus, Playfordiaspora crenulata, Goubinispora indica, Klausipollenites schaubergeri, Limatulasporites fossulatus and Reduviasporonites chalastus indicates an early Triassic age. Palynoassemblage III (Aulisporites astigmosus–Falcisporites nuthallensis) recorded between a depth of 404.40–53.60 m and characterized by the dominance of Aulisporites astigmosus along with Falcisporites nuthallensis, Tikisporites balmei, Dubrajisporites unicus, Enzonalasporites densus, Leschikisporites aduncus, Lunatisporites rhaeticus, Lueckisporites virkkiae, Playfordiaspora vellata, Polycingulatisporites crenulatus, Cingulizonates indicus, Neoraistrickia taylori and Aratrisporites fischeri is equated with late Triassic (Supra–Panchet) age.
The Permian–Triassic boundary is delineated at the contact of coal/shale bearing upper part of the Middle Member and lower part of the Upper Member of the Pali Formation (between 1164.10–1075.15 m depth). At the P/T boundary, the abrupt change of the palynoflora is marked by the disappearance of the striate bisaccate pollen grains and appearance of non–striate bisaccate grains in association with cingulate–cavate/zonate trilete spores. The Permian/Triassic palynofloras recorded in South Rewa Basin show close similarities with those of the uppermost Bainmedart Coal Measures (McKinnon Member) and Flagstone Bench Formation of east Antarctica.
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Foster, C. B., G. A. Logan, R. E. Summons, J. D. Gorter, and D. S. Edwards. "CARBON ISOTOPES, KEROGEN TYPES AND THE PERMIAN-TRIASSIC BOUNDARY IN AUSTRALIA: IMPLICATIONS FOR EXPLORATION." APPEA Journal 37, no. 1 (1997): 472. http://dx.doi.org/10.1071/aj96028.
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A global stratotype section for the boundary between the Permian and Triassic Systems is yet to be agreed internationally. However, in many parts of the world, there is evidence of massive extinction of marine fauna at or near the P-T boundary. In the absence of marine fauna, as is the case in most of Australia, changes in plant microfossils, in carbon isotopic signatures, and radiometric dates using SHRIMP, have been used to mark the boundary. The leading questions which arise from this are whether these events are synchronous and how they affect exploration.In eastern Australia, the top of the coal measures has been used as the top of the Permian, although presently only plant microfossils can be used to determine if the youngest seam is present. This has important economic consequences for determination of volumes of effective source rock and for estimates of coal-bed methane. It has been suggested that changes in the carbon isotopic signatures (δ13C) of either organic matter (δ13Corg) or carbonates (δ13Ccarb) can be used to delimit the P-T boundary. From studies of (δ13Ccarb data, Scholle (1995) concluded that 'the establishment of a secular variation curve which has enough detail and reliability to be used as a chemostratigraphic tool still lies in the future'. We concur, and demonstrate for organic carbon that, while there is evidence for secular change, the 13C signature is complicated and overprinted by contributions from different parent plant types; wood-dominated organics are typically −24 %o, while non-woody matter is significantly lighter (−30 %o). There is no simple relationship of δ13Corg to geological age. The consistency of our data, from both the east and west of Australia, allows us to construct a model to predict probable depositional and organic facies using either carbon isotopes (from kerogen or oil) or quantitative estimates of organic matter from standard palynlogical slides. This offers a novel and usefl predictive tool for hydrocarbon exploration.
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GALE, ANDREW S. "A new comb-star (Asteroidea, Astropectinidae) from the Upper Triassic (Carnian) of China." Zootaxa 4861, no. 1 (October 15, 2020): 139–44. http://dx.doi.org/10.11646/zootaxa.4861.1.10.
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A new astropectinid asteroid, Eoastropecten sechuanensis gen. et sp. nov. is described from the Upper Triassic (Carnian) of Sechuan Province, China, based upon marginal ossicles. This occurrence extends the known fossil record of the family Astropectinidae back by 50 myr from the Lower Jurassic, and indicates that a significant part of the radiation of the neoasteroids probably took place around 240 Ma, only 12 myr after the P–T boundary extinction.
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Nishizono, Yukihisa, Hidekazu Yoshida, and Masafumi Murata. "The siliceous rock facies near the Permo-Triassic (P/T) boundary in the Southern Chichibu Terrane, Kyushu." Journal of the Geological Society of Japan 102, no. 7 (1996): 591–608. http://dx.doi.org/10.5575/geosoc.102.591.
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Kraus, S. H., S. Siegert, W. Mette, U. Struck, and C. Korte. "Stratigraphic significance of carbon isotope variations in the shallow-marine Seis/Siusi Permian–Triassic boundary section (Southern Alps, Italy)." Fossil Record 12, no. 2 (August 1, 2009): 197–205. http://dx.doi.org/10.5194/fr-12-197-2009.
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Carbonate carbon-isotope values from the Permian–Triassic (P–T) boundary section at Seis/Siusi (Southern Alps, Italy) show a trend similar to that in numerous other P–T boundary sections worldwide. Values decrease from 3.2‰ (V-PDB) in the upper <i>Bellerophon</i> Limestone Formation (Late Permian) to a minimum of –1.7‰ in the lower Mazzin Member. This minimum may represent the P–T boundary. The overall declining carbon-isotope trend is interrupted by a ca. 1‰ positive excursion in the higher Tesero Oolite Horizon. This positive peak is located at a higher lithostratigraphic level than a comparable peak in the adjacent Pufels section, which suggests that the Tesero Oolite Horizon in the Seis section is stratigraphically slightly older than in the Pufels section, and this is also suggested by palaeomagnetic correlation. It is therefore concluded that the base of the Tesero Oolite Horizon does not reflect a synchronous "current event" but is slightly diachronous, a result that was previously shown by biostratigraphic correlation. Nevertheless, this suggestion should be verified by further detailed litho-, magneto- and chemostratigraphic analysis of other P–T sections in the Southern Alps. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200900007" target="_blank">10.1002/mmng.200900007</a>
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Zheng, Wei, Xin Xu, Yongan Qi, Zhifeng Xing, Yunlong Liu, Xiaoyan Li, and Baibing Chen. "Characteristic and paleoenvironment significance of microbially induced sedimentary structures (MISS) in terrestrial facies across P-T boundary in Western Henan Province, North China." Open Geosciences 13, no. 1 (January 1, 2021): 917–31. http://dx.doi.org/10.1515/geo-2020-0285.
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Abstract We report varied microbially induced sedimentary structures (MISS), and other sedimentary surface textures, from the Induan (Early Triassic) Sunjiagou Formation and Liujiagou Formation in the Xingyang, Dengfeng, Jiyuan and Yiyang areas, western Henan Province, North China. Microanalysis shows that these MISS are characterized by a U-shaped structure, thin clayey laminae, and discontinuous mica sheet that are arranged parallel to the bedding plane, as well as directionally oriented quartz grains floating in lamina, which are indicative of a biogenic origin. The MISS of the studied area were probably affected by four main factors, including the end-Permian mass extinction, the megamonsoon, the adapted sedimentary environment, and the sediment supply, and they possess significant stratigraphic correlation. Abundant microbial-related sedimentary structures from the study area indicate that continental ecosystems were severely devastated in the aftermath of the Permian-Triassic biocrisis. These sedimentary structure assemblages, including MISS, red beds, conglomerate layers, and calcareous concretions in the western Henan Province, show a specific, post-extinction continental ecosystem that was characterized by microflora dominance, monotonous and rare fossils, extreme hot climate, soil ecosystem devastation, and poor vegetation.
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Nourry, Cédric, Fabien Deruelle, Claudine Fabre, Georges Baquet, Frédéric Bart, Jean-Marie Grosbois, Serge Berthoin, and Patrick Mucci. "Exercise flow-volume loops in prepubescent aerobically trained children." Journal of Applied Physiology 99, no. 5 (November 2005): 1912–21. http://dx.doi.org/10.1152/japplphysiol.00323.2005.
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We studied mechanical ventilatory constraints in 13 aerobically trained (Tr) and 11 untrained (UT) prepubescent children by plotting the exercise flow-volume (F-V) loops within the maximal F-V loop (MFVL) measured at rest. The MFVL allowed to determine forced vital capacity (FVC) and maximal expiratory flows. Expiratory and inspiratory reserve volumes relative to FVC (ERV/FVC and IRV/FVC, respectively) were measured during a progressive exercise test until exhaustion. Breathing reserve (BR) and expiratory flow limitation (expFL), expressed in percentage of tidal volume (Vt) and defined as the part of the tidal breath meeting the boundary of the MFVL, were measured. Higher FVC and maximal expiratory flows were found in Tr than UT ( P < 0.05) at rest. Our results have shown that during exercise, excepting one subject, all Tr regulated their Vt within FVC similarly during exercise, by breathing at low lung volume at the beginning of exercise followed breathing at high lung volume at strenuous exercise. In UT, ERV/FVC and IRV/FVC were regulated during exercise in many ways. The proportion of children who presented an expFL was nearly the same in both groups (∼70% with a range of 14 to 65% of Vt), and no significant difference was found during exercise concerning expFL. However, higher ventilation (V̇e), ERV/FVC, and dyspnea associated with lower BR, IRV/FVC, and SaO2 were reported at peak power in Tr than UT ( P < 0.05). These results suggest that, because of their higher V̇e level, trained children presented higher ventilatory constraints than untrained. These may influence negatively the SaO2 level and dyspnea during strenuous exercise.
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Radley, J. D., and A. Swift. "‘Sedimentology of the Triassic-Jurassic boundary beds in Pinhay Bay(Devon, SW England)’ by P. B. Wignall: comment." Proceedings of the Geologists' Association 113, no. 3 (January 2002): 271–72. http://dx.doi.org/10.1016/s0016-7878(02)80029-3.
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Dolenec, Matej, and Bojan Ogorelec. "Organic carbon isotope variability across the P/Tr boundary in the Idrijca valley section (Slovenia): A high resolution study." Geologija 44, no. 2 (December 30, 2001): 331–40. http://dx.doi.org/10.5474/geologija.2001.025.
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Sues, Hans-Dieter, and Paul Eric Olsen. "Stratigraphic and temporal context and faunal diversity of Permian-Jurassic continental tetrapod assemblages from the Fundy rift basin, eastern Canada." Atlantic Geology 51, no. 1 (April 7, 2015): 139. http://dx.doi.org/10.4138/atlgeol.2015.006.
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<p style="margin: 1em 0px; line-height: 200%; text-indent: 0.5in;"><span style="font-family: 'Minion Pro','serif'; mso-bidi-font-family: 'Times New Roman'; mso-ansi-language: EN-CA;"><span style="font-size: medium;">The Fundy basin in Nova Scotia and New Brunswick is the largest exposed rift basin of the Newark Supergroup and also extends beneath the Bay of Fundy. Its strata can be divided into four tectonostratigraphic sequences (TS). TS I is represented by the probably Permian Honeycomb Point Formation and possibly the Lepreau Formation. TS II includes the Wolfville Formation with the probably Middle Triassic Economy Member and the early Late Triassic Evangeline Member. These members have yielded markedly different assemblages of continental tetrapods. TS III comprises most of the Blomidon Formation, which is Norian to Rhaetian in age. The Blomidon Formation has yielded few skeletal remains of tetrapods to date but many tetrapod tracks. TS IV includes the late Rhaetian top of the Blomidon Formation and the McCoy Brook Formation, which overlies the North Mountain Basalt and is latest Rhaetian and earliest Jurassic (Hettangian) in age. The McCoy Brook Formation has yielded a diversity of continental tetrapods and lacks any of the characteristic Late Triassic forms. Recent work has correlated the Global Boundary Stratotype Section and Point (GSSP) for the base of the Jurassic (Hettangian) to a level well above the North Mountain Basalt. Thus most of the tetrapod fossils from the McCoy Brook Formation are latest Rhaetian in age, but the higher horizon with skeletal remains of sauropodomorph dinosaurs may be earliest Hettangian in age. The Fundy basin preserves the only known, stratigraphically tightly constrained record of the profound biotic changes in continental ecosystems across the Triassic-Jurassic transition.</span></span></p>
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Grice, K., S. Fenton, M. E. Bőttcher, R. J. Twitchett, R. E. Summons, and E. Grosjean. "The biogeochemical cycling of sulfur, carbon and nitrogen across the Permian-Triassic (P-Tr) Hovea-3 borehole (Western Australia) and Schuchert Dal Section (Eastern Greenland)." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A218. http://dx.doi.org/10.1016/j.gca.2006.06.438.
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Badgujar, Chetan M., Daniel Flippo, Edwin Brokesh, and Stephen Welch. "Experimental Investigation on Traction, Mobility, and Energy Usage of a Tracked Autonomous Ground Vehicle on a Sloped Soil Bin." Journal of the ASABE 65, no. 4 (2022): 835–47. http://dx.doi.org/10.13031/ja.14860.
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HighlightsLaying the groundwork for AGV mobility models for high slope terrain operations.AGV drawbar pull performance was evaluated on a level terrain, uphill, and downhill slopes up to 18° on a soil bin.AGV generates the optimum power efficiency with enough drawbar pull to perform a range of agricultural operations on uphill and downhill slopes up to 18°.Explored the suitability and established the boundary conditions of small size ground vehicles on the high slope farming.Generated sloped traction data would empower the multi-AGV system on sloped terrain.Abstract. Excessive steepness of grasslands, hills, or uneven terrain presents difficulties for farming with large conventional equipment. Therefore, a fleet of Autonomous Ground Vehicles (AGV) is proposed to perform primary agricultural operations on high sloped hills or terrain. However, it is imperative to understand how an individual AGV functions on sloping terrain under varying load and speed. Hence, this study aims to investigate the traction, mobility, and energy consumption characteristics of AGV on a sloped soil bin environment. A drawbar pull performance of the prototype AGV was evaluated on a level terrain and variable slope of 10° and 18°, both uphill and downhill, at varying drawbar pull (P) and AGV speed. The AGV’s performance metrics include power efficiency (PE), travel reduction (TR), and power number (PN) which relates to AGV’s traction, mobility, and energy usage, respectively. The AGV generated drawbar pull equivalent to its weight only on downhill run for reduced PE. On a level terrain (0°), the peak PE was 0.20 and was found to be 108.3% and 328.6% higher on 10° and 18° downhill run than uphill with 55.5% and 133% increase in drawbar pull, respectively. Both applied drawbar pull and uphill operation caused the AGV’s TR. The TR, corresponding to a peak PE, increased from 10% to 30%, respectively, on 0° and both 10° and 18° uphill. The optimum values of power number ranged from 2 to 4. The AGV delivers the optimum PE and generates enough drawbar pull with an optimum TR to perform a range of agricultural operations on a slope up to 18°. This study explored the suitability and established the boundary conditions of small size ground vehicles for high-sloped farming. Besides this, the study also aims to generate an AGV’s slope traction database to optimize its control variables, design optimization, and develop a mobility model for sloped terrain. Keywords: Drawbar pull, Ground vehicle, Multi-AGV fleet, Power efficiency, Slope, Travel reduction.
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Xu, Guang-Hui. "The oldest species of Peltoperleidus (Louwoichthyiformes, Neopterygii) from the Middle Triassic (Anisian) of China, with phylogenetic and biogeographic implications." PeerJ 9 (September 29, 2021): e12225. http://dx.doi.org/10.7717/peerj.12225.
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The previously alleged ‘perleidid’ genus Peltoperleidus is a stem-neopterygian fish taxon with two or three horizontal rows of notably deepened flank scales. Until recently, members of this genus were known only from the Ladinian (late Middle Triassic) or near the Anisian/Ladinian boundary (~242 Ma) in southern Switzerland and northern Italy. Here, I report the discovery of a new species of the genus, Peltoperleidus asiaticus sp. nov., based on three well-preserved specimens from the Anisian (early Middle Triassic, ~244 Ma) of Luoping, eastern Yunnan, China. The discovery extends the geological range of Peltoperleidus by approximately two million years and documents the first record of the genus in Asia. Similar to its relatives (represented by P. macrodontus) from Europe, P. asiaticus sp. nov. is likely a small-sized durophagous predator with dentition combining grasping and crushing morphologies. Results of a cladistic analysis unite four species of Peltoperleidus as a monophyletic group within the Louwoichthyiformes, and suggest that the presence of two horizontal rows of notably deepened scales was independently evolved in Peltoperleidus and another stem-neopterygian taxon Altisolepis. P. asiaticus sp. nov. is nested at the base of Peltoperleidus, and a new family Peltoperleididae is proposed for the genus, contrasting the previous placement of Peltoperleidus in the poorly defined, paraphyletic ‘Perleididae’. Comparative studies of the basal peltoperleidid from China with its younger relatives from Europe provide new insights into the evolutionary origin and paleogeographic distribution of this clade.
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Garcia-Artigas, Ruben, Ramon Mercedes-Martín, Joan Cartanyà, Arnau Bolet, Marc Riccetto, and Josep Fortuny. "Faunal composition and paleoenvironmental reconstruction of a Middle–Late Triassic boundary assemblage in the Pyrenean basin (Catalonia, NE Spain)." Journal of Paleontology 96, no. 2 (November 8, 2021): 412–27. http://dx.doi.org/10.1017/jpa.2021.99.
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AbstractThe Ladinian–Carnian transition in the Tethys domain was accompanied by an important environmental change representing a milestone in the climate evolution of the Triassic. However, estimations on paleodiversity composition and paleoenvironmental conditions across this interval are scarce in marine settings due to the lack of fossil-bearing successions. In this work, a refined paleontological and sedimentological study has allowed us to better characterize a well-preserved marine ?Ladinian–Carnian carbonate succession in the South Central Pyrenees (Odèn site, Catalonia, NE Spain). Vertebrate faunas include numerous actinopterygian specimens, forming an assemblage composed of at least four taxa: Peltopleurus cf. P. nuptialis Lombardo, 1999, Saurichthys sp., Colobodus giganteus (Beltan, 1972), and an indeterminate halecomorph. Specimens belonging to the genus Peltopleurus are dominant; the long-snouted Saurichthys, the halecomorph, and the large-bodied Colobodus giganteus are less abundant. Tetrapod remains are scarcely present and are assigned to sauropterygians. Invertebrate faunas include bivalves (Pseudocorbula gregaria [Münster in Goldfuss, 1838]) and brachiopods (Lingula sp.). The fossil assemblage was recovered from organic-rich laminated silty mudstone layers. Sedimentological and textural analyses suggest that fossil biotas were deposited below the fair-weather wave base in shallow subtidal coastal settings. These environments were sporadically sourced by silt/clay. The age of the Odèn site, on the basis of the recovered fauna, is assigned to the ?late Ladinian–middle Carnian (Middle–Late Triassic), which is in agreement with previously published ages based on palynomorph data.The refined integration of paleontological, sedimentological, and biostratigraphic data from the Odèn site and other vertebrate-bearing localities in the Tethys domain can help better constrain the paleoenvironmental conditions and paleogeographical configuration impacting ecosystem diversity during the late Ladinian–Carnian interval.
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Hirsch, Francis. "Patterns of evolution before extinction of Triassic conodonts." Paleontological Society Special Publications 6 (1992): 129. http://dx.doi.org/10.1017/s2475262200006894.
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After surviving the notorious Permian-Triassic boundary-events, the conodont-bearing animals underwent a number of crisis at the end of Induan, Olenekian, Ladinian, Early Carnian and during Middle Norian to Rhaetian times, before their final extinction at the end of the Triassic. The causes responsible for speciation, radiation and extinction seem possibly related to global sea-level changes, although the Norian-Rhaetian speciations and final extinction of conodonts may have been controlled by competitional pressure at the trophic and reproductive level, possibly by newly appeared taxa, e.g. bonefishes.Families, defined herein by their multielement-apparatus, are three in number (4 genera, 1 being new) in Induan, two (8 genera, 6 new) in Olenekian, one (2 subfamilies, 5 genera, 3 new) in Anisian, Ladinian and Early Carnian before the Carnian crisis, and one (1 subfamily, 2 genera, 1 new genus) in Late Carnian, Norian and Early Rhaetian, until extinction of the last conodont taxon at the end of the Rhaetian.Palaeogeographic distribution of Induan Anchignathodus, Induan - Olenekian Ellisonia and Neospathodus, Induan - Early Rhaetian Neogondolella and Olenekian Plativillosus are boreal to equatorial. Olenekian Furnishius, Parachirognathus, Hadrodontina and Pachycladina are found in cratonic cordilleran and Werfen facies. Latest Olenekian, respectively Anisian to Early Carnian Gladi- and Paragondolella define low-latitude mesopelagic Tethys. Ladinian Sephardiella extends from shallow Tethys to Boreal realms, whereas Neogondolella and Pseudofurnishius dwelled respectively in restricted Anisian to Early Ladinian Germanic and semi-open Ladinian Sephardic provinces. The specialization of post-Induan taxa into environmental niches became first reduced from the generic to specific level and disappeared entirely in Late Norian and Rhaetian. Latest Carnian - Latest Rhaetian Epigondolella species extended from low (Tethyan) to high (Boreal) latitudes, in pelagic and cratonic facies. Norian species of Paragondolella had a pan-thallassic, including Notal, distribution.Triassic P-elements always show similar patterns of evolution of the platform and basal cavity as appearance of denticles on platform -edges, development of a free blade and splitting of basal cavity, causing broadening of platform. These characters are lost or abandoned in highly critical periods. Instead, ancestral morphs with reduced platforms, often without apparatus, or early ontogenetic stages, re-appear, from which evolution restarts. Norian-Rhaetian taxa, however, seem to play that scenario backwards, a process reminding of neoteny or paedomorphism. This process is accompanied by the irreversible reduction in the number of species of Late Rhaetian conodonts.
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Sanduzzi Zamparelli, Marco, Ana Matilla, Jose Luis Lledó, Sergio Muñoz Martínez, Maria Varela, Mercedes Iñarrairaegui, Christie Perelló, et al. "Early nivolumab addition to regorafenib in patients with hepatocellular carcinoma progressing under first-line therapy (GOING trial), interim analysis and safety profile." Journal of Clinical Oncology 40, no. 4_suppl (February 1, 2022): 428. http://dx.doi.org/10.1200/jco.2022.40.4_suppl.428.
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428 Background: Regorafenib (Rego) improves survival in patients with hepatocellular carcinoma (HCC) (RESORCE trial) while nivolumab (Nivo) is also safe and active in terms of radiologic response (15-20% objective response) in second-line. The GOING trial (NCT04170556) is an investigator-initiated phase I/IIa study assessing the safety of Rego plus Nivo in HCC patients who progress and tolerate sorafenib (Cohort A) or who discontinue atezolizumab plus bevacizumab (Cohort B). Methods: Patients from cohort A receive Rego as monotherapy for the first 2 cycles (starting dose 160 mg/day, 3 weeks on/1 week off and adjusted for adverse events [AEs]) and Nivo is added at day 1 of cycle 3 (the first 10 patients at 3 mg/kg; since they did not present serious-AE (SAE), the final dose is 240 mg every two weeks). Treatment continues until unacceptable AEs, symptomatic tumor progression, patient decision or death. Safety is measured by the rate of AEs, rate of treatment related-AEs (Tr-AE), rate of AEs leading to treatment discontinuation and rate of death. Severity of AEs are evaluated according to CTCAE v.5.0. A futility analysis using the non-binding Lan & DeMets beta-spending functions with a boundary of p=0.814 is mandated when 32.8% of cohort A has data of tumor assessment at least at week 16 by RECIST 1.1. Results: Fifty-one patients have been enrolled in cohort A as of May 15, 2021. The first 30 (BCLC-C 73%) were considered in this safety analysis. All patients developed at least one AE, 29 (96.7%) had Tr-AEs of any grade and 10 (33.3%) had grade 3 (no grades 4 or 5 have been reported). Ten (33.3%) patients had a Rego-related AE, 4 (13.3%) Nivo-related, and 4 (13.3%) Tr-AE grade 3 of special interest. The table describes the profile Tr-AE occurring in > 10% of patients. Only 4 (13.3%) patients developed Tr-SAE, 3 (10 %) Rego-related and 3 (10 %) Nivo-related. Four patients discontinued the study due to physician decision, 2 for progression, and 2 for AEs (one related to study treatment). One patient had surgical resection after treatment discontinuation and a complete necrosis was observed at pathology. Conclusions: The sequential combination of Rego-Nivo has a manageable safety profile. Less than one third of the patients developed grade 3/4 Tr-AE and there was no treatment-related death. Futility analysis allowed to continuing recruitment. Clinical trial information: NCT04170556. [Table: see text]
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GASTALDO, ROBERT A., and MARCY W. ROLERSON. "KATBERGIA GEN. NOV., A NEW TRACE FOSSIL FROM UPPER PERMIAN AND LOWER TRIASSIC ROCKS OF THE KAROO BASIN: IMPLICATIONS FOR PALAEOENVIRONMENTAL CONDITIONS AT THE P/TR EXTINCTION EVENT." Palaeontology 51, no. 1 (January 17, 2008): 215–29. http://dx.doi.org/10.1111/j.1475-4983.2007.00743.x.
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Saunders, W. B., Emily Greenfest-Allen, David M. Work, and S. V. Nikolaeva. "Morphologic and taxonomic history of Paleozoic ammonoids in time and morphospace." Paleobiology 34, no. 1 (2008): 128–54. http://dx.doi.org/10.1666/07053.1.
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Principal components analysis (PCA) of 21 shell parameters (geometry, sculpture, aperture shape, and suture complexity) in 597 L. Devonian to L. Triassic ammonoid genera (spanning ~166 Myr) shows that eight basic morphotypes appeared within ~20 Myr of the first appearance of ammonoids. With one exception, these morphotypes persisted throughout the Paleozoic, occurring in ~75% of the ~5-Myr time bins used in this study. Morphotypes were not exclusive to particular lineages. Their persistence was not just a product of phylogenetic constraints or longevity, and multiple iterations of the same morphotypes occurred at different times and in different groups. Although mass extinction events severely condensed the range of morphologic variation and taxonomic diversity, the effects were short lived and most extinct morphotypes were usually iterated within 5 Myr. The most important effect of mass extinctions on ammonoid evolutionary history seems to have been their role in large scale taxonomic turnovers; they effectively eliminated previously dominant orders at the Frasnian/Famennian (F/F) (Agoniatitida), the Devonian/Mississippian (D/M) (Clymeniida), and the Permian/Triassic (P/T) (Goniatitida and Prolecanitida) extinctions. Survivors varied from two (P/T) to four (D/M) and five genera (F/F). These events generated sharp reductions in morphologic disparity at the D/M (58%) and at the P/T (59%), but there was a net increase at the F/F (38%). There was no obvious survival bias for particular morphotypes, but 64% are interpreted to have beenNautilus-like nektobenthic. The recurrence of particular combinations of morphology and their strong independence of phylogeny are strong arguments for functional constraint. Intervals between mass extinctions seem to have been relatively static in terms of morphotype numbers, in contrast to numbers of genera. Significant decreases in genus diversity (54%) and morphologic disparity (33%) commenced in the mid-Permian (Wordian/Capitanian boundary), well before the final P/T event.
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DAVYDOV, V. I., J. L. CROWLEY, M. D. SCHMITZ, and W. S. SNYDER. "New U–Pb constraints identify the end-Guadalupian and possibly end-Lopingian extinction events conceivably preserved in the passive margin of North America: implication for regional tectonics." Geological Magazine 155, no. 1 (October 25, 2016): 119–31. http://dx.doi.org/10.1017/s0016756816000959.
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AbstractThe discovery and dating of a volcanic ash bed within the upper Phosphoria Formation in SE Idaho, USA, is reported. The ash occurs 11 m below the top of the phosphatic Meade Peak Member and yielded a 206Pb/238U date of 260.57 ± 0.07 / 0.14 / 0.31 Ma, i.e. latest Capitanian, Guadalupian. The stratigraphic position of this ash near the top of the Meade Peak phosphatic Member of Phosphoria Formation indicates plausible completeness of the sedimentation within the Guadalupian–Lopingian and probably at the Permo-Triassic (P-T) transitions. The new radiometric age reveals that the regional biostratigraphy and palaeontology of Phosphoria and Park City formations requires serious reconsideration, particularly in cool water conodonts, bryozoans and brachiopods. The new age proposes that the Guadalupian–Lopingian boundary (GLB) coincides with the Meade Peak – Rex contact and consequently with the end-Guadalupian extinction event. The lack of a major unconformity at the P-T transition suggests that the effects of the Sonoma orogeny were not as extensive as has been assumed.
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Saunders, W. Bruce, and David M. Work. "Evolution of shell morphology and suture complexity in Paleozoic prolecanitids, the rootstock of Mesozoic ammonoids." Paleobiology 23, no. 3 (1997): 301–25. http://dx.doi.org/10.1017/s0094837300019709.
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The ammonoid order Prolecanitida constitutes a relatively small (43 genera, ~250 species) but long-ranging lineage (Lower Carboniferous—Triassic, ~108 m.y.), which narrowly survived the P/Tr extinctions and provided the stock from which were derived all later Mesozoic ammonoids. Prolecanitids were a minority among Late Paleozoic ammonoids, which were dominated by the Goniatitida, and showed many features that set them far apart from their contemporaries, including (1) long-term, gradual changes in shell geometry (W-D-S); (2) the most strongly constrained morphospace of any Paleozoic ammonids examined to date; (3) an eight-fold increase in mean suture complexity (three times that of Pennsylvanian goniatitids); (4) high correlations between shell geometry, shell and septal thickness, and suture complexity; (5) short body chambers and, as a consequence, high aperture orientations; (6) indications that cameral liquid may have been used for buoyancy control; and (7) a genus longevity that averaged 14.7 m.y. compared with 5.7 m.y. in Upper Carboniferous goniatitids, and that appears to have been unrelated to suture complexity. Prolecanitids showed a pervasive tendency to increase suture complexity (in the clade as a whole as well as within subclades and in more than 90 percent of ancestor-descendant genera), thus arguing a case for a driven complexity trend. The uniqueness of the prolecanitids calls into question whether they and their Mesozoic descendants, ceratites and ammonites, were strictly analogous to Paleozoic goniatites.
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Ghaderi, A., L. Leda, M. Schobben, D. Korn, and A. R. Ashouri. "High-resolution stratigraphy of the Changhsingian (Late Permian) successions of NW Iran and the Transcaucasus based on lithological features, conodonts and ammonoids." Fossil Record 17, no. 1 (March 7, 2014): 41–57. http://dx.doi.org/10.5194/fr-17-41-2014.
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Abstract. The Permian–Triassic boundary sections in north-western Iran belong to the most complete successions, in which the largest mass extinction event in the history of the Earth can be studied. We investigated the Changhsingian stage in six sections in the area of Julfa (Aras Valley) for their lithology, conodonts and ammonoids. Revision of the biostratigraphy led to the separation of 10 conodont zones (from bottom to top Clarkina orientalis–C. subcarinata interval zone, C. subcarinata, C. changxingensis, C. bachmanni, C. nodosa, C. yini, C. abadehensis, C. hauschkei, Hindeodus praeparvus–H. changxingensis and Merrilina ultima–Stepanovites ?mostleri zones) and 8 ammonoid zones (from bottom to top Iranites transcaucasius–Phisonites triangulus, Dzhulfites nodosus, Shevyrevites shevyrevi, Paratirolites trapezoidalis, P. waageni, Stoyanowites dieneri, Abichites stoyanowi and Arasella minuta zones). The new ammonoid genera Stoyanowites and Arasella are described.
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Wiita, Paul J., and Alexander Rosen. "Interactions of Jets with Interstellar and Intergalactic Media." Symposium - International Astronomical Union 134 (1989): 467–68. http://dx.doi.org/10.1017/s0074180900141671.
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Jets emanating from AGN propagate first through an isothermal, but roughly power-law in density, galactic halo and then into a hotter, less dense, and uniform intergalactic medium (IGM) or intracluster medium (ICM). We use a three-dimensional boundary-following code (Mitteldorf & Wiita 1988), altered to allow for a two-phase external medium. We vary the beam power, P, the redshift, z, the radius of the galactic halo/IGM interface, Rh, the steepness of the power-law fall-off within the halo, n, and the temperature ratio of the IGM (or ICM) to the halo, Tr to estimate the average linear sizes of extragalactic radio galaxies (RGs). Good agreement is obtained with regard to the relationships between the overall linear size of such radio sources and both the total radio power (at fixed redshift) and the cosmological redshift (at fixed power). These numerical models tend to support recent analytical models (Gopal–Krishna & Wiita [GW] 1987, 1988).
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Horacek, Micha, Rainer Brandner, and Rainer Abart. "Carbon isotope record of the P/T boundary and the Lower Triassic in the Southern Alps: Evidence for rapid changes in storage of organic carbon." Palaeogeography, Palaeoclimatology, Palaeoecology 252, no. 1-2 (August 2007): 347–54. http://dx.doi.org/10.1016/j.palaeo.2006.11.049.
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Lan, Luu Thi Phuong, Ellwood Brooks B., Tomkin Jonathan H., Nestell Galina P., Nestell Merlynd K., Ratcliffe Kenneth T., Rowe Harry, et al. "Correlation and high-resolution timing for Paleo-tethys Permian-Triassic boundary exposures in Vietnam and Slovenia using geochemical, geophysical and biostratigraphic data sets." VIETNAM JOURNAL OF EARTH SCIENCES 40, no. 3 (June 4, 2018): 253–70. http://dx.doi.org/10.15625/0866-7187/40/3/12617.
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Two Permian-Triassic boundary (PTB) successions, Lung Cam in Vietnam, and Lukač in Slovenia, have been sampled for high-resolution magnetic susceptibility, stable isotope and elemental chemistry, and biostratigraphic analyses. These successions are located on the eastern (Lung Cam section) and western margins (Lukač section) of the Paleo-Tethys Ocean during PTB time. Lung Cam, lying along the eastern margin of the Paleo-Tethys Ocean provides an excellent proxy for correlation back to the GSSP and out to other Paleo-Tethyan successions. This proxy is tested herein by correlating the Lung Cam section in Vietnam to the Lukač section in Slovenia, which was deposited along the western margin of the Paleo-Tethys Ocean during the PTB interval. It is shown herein that both the Lung Cam and Lukač sections can be correlated and exhibit similar characteristics through the PTB interval. Using time-series analysis of magnetic susceptibility data, high-resolution ages are obtained for both successions, thus allowing relative ages, relative to the PTB age at ~252 Ma, to be assigned. Evaluation of climate variability along the western and eastern margins of the Paleo-Tethys Ocean through the PTB interval, using d18O values indicates generally cooler climate in the west, below the PTB, changing to generally warmer climates above the boundary. A unique Black Carbon layer (elemental carbon present by agglutinated foraminifers in their test) below the boundary exhibits colder temperatures in the eastern and warmer temperatures in the western Paleo-Tethys Ocean.ReferencesBalsam W., Arimoto R., Ji J., Shen Z, 2007. Aeolian dust in sediment: a re-examination of methods for identification and dispersal assessed by diffuse reflectance spectrophotometry. International Journal of Environment and Health, 1, 374-402.Balsam W.L., Otto-Bliesner B.L., Deaton B.C., 1995. 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Nedosekova, I. L., V. A. Koroteev, T. B. Bayanova, P. A. Serov, V. I. Popova, and M. V. Chervyakovskaya. "On the age of pyrochlore carbonatites from the Ilmeno-Vishnevogorsky Alkaline Complex, the Southern Urals (insights from Rb-Sr and Sm-Nd isotopic data)." LITHOSPHERE (Russia) 20, no. 4 (August 31, 2020): 486–98. http://dx.doi.org/10.24930/1681-9004-2020-20-4-486-498.
Full textAbstract:
Research subject. In this research, we carried out Sm-Nd- и Rb-Sr-dating of pyrochlore carbonatite from the Vishnevogorsky niobium deposit, Ilmeno-Vishnevogorsky Alkaline Complex, Southern Urals. IVC is located in the Ural fold region and is a carbonatite complex of the linear type. Rare metal (Nb-Zr-TR) deposits and occurrences are related to IVC. The age and the duration of IVC deposits formation remains a matter of debate. To determine the age of IVC carbonatites and related niobium ore, we measured Sm-Nd and Rb-Sr isotopic compositions and concentrations of the elements in the minerals (pyrochlore, calcite, apatite, biotite) and bulk sample of pyrochlore carbonatite. Materials and methods. The Sm and Nd isotopic compositions and concentrations were determined on a Finnigan MAT-262L (RPQ) seven-collector mass spectrometer in the static regime at the Geological Institute of the Kola Scientific Center, Apatity, Russia. The Sr and Rb isotopic compositions and concentrations were determined on thermos-ionization mass spectrometer Triton Plus (“Geoanalitik”, IGG UD RAN, Ekaterinburg, Russia). Results. Age of pyrochlore carbonatites from ore zone 140 (Vishnevogorsky deposit, IVC) defined by Sm-Nd and Rb-Sr isotopic methods. Mineral Sm-Nd-isochron (5 points) indicated age 229 ± 16 Ma, mineral Rb-Sr-isochron (5 points) showed similar age 250.5 ± 1.2 Ma. Conclusions. Results Sm-Nd и Rb-Sr dating indicate that the pyrochlore сarbonatites of ore zone 140 crystallized ≈ 250 Ma ago, at the stage of the postcollisional extension, possibly, in connection with exhumation complex, which was accompanied by decompression, partial melting of rocks, involving fluids, dissolution and precipitation of Ordovician-Silurian alkaline-carbonatitе complex. Thus, the formation of the IVC carbonatites and related Nb-ore, which began in Silurian (S), continued in Permian (P) and Triassic (T1-2) and was associated with the post-collision stage of tectonic activity in the Ural Fold Belt.
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Sizova, Elena, Christoph Hauzenberger, Harald Fritz, Shah Wali Faryad, and Taras Gerya. "Late Orogenic Heating of (Ultra)High Pressure Rocks: Slab Rollback vs. Slab Breakoff." Geosciences 9, no. 12 (November 27, 2019): 499. http://dx.doi.org/10.3390/geosciences9120499.
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Some (ultra)high-pressure metamorphic rocks that formed during continental collision preserve relict minerals, indicating a two-stage evolution: first, subduction to mantle depths and exhumation to the lower-crustal level (with simultaneous cooling), followed by intensive heating that can be characterized by a β-shaped pressure–temperature–time (P–T–t) path. Based on a two-dimensional (2D) coupled petrological–thermomechanical tectono-magmatic numerical model, we propose a possible sequence of tectonic stages that could lead to these overprinting metamorphic events along an orogenic β-shaped P–T–t path: the subduction and exhumation of continental crust, followed by slab retreat that leads to extension and subsequent asthenospheric upwelling. During the last stage, the exhumed crustal material at the crust–mantle boundary undergoes heating from the underlying hot asthenospheric mantle. This slab rollback scenario is further compared numerically with the classical continental collision scenario associated with slab breakoff, which is often used to explain the late heating impulse in the collisional orogens. The mantle upwelling occurring in the experiments with slab breakoff, which is responsible for the heating of the exhumed crustal material, is not related to the slab breakoff but can be caused either by slab bending before slab breakoff or by post-breakoff exhumation of the subducted crust. Our numerical modeling predictions align well with a variety of orogenic P–T–t paths that have been reported from many Phanerozoic collisional orogens, such as the Variscan Bohemian Massif, the Triassic Dabie Shan, the Cenozoic Northwest Himalaya, and some metamorphic complexes in the Alps.
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Tian, Mao-Jun, Huan Li, Landry Soh Tamehe, and Zhen Xi. "Geochronology and Geochemistry of the Zengudi and Tuobake Granite Porphyries in the Sanjiang Region, SW China: Petrogenesis and Tectonic Significance." Minerals 11, no. 4 (April 12, 2021): 404. http://dx.doi.org/10.3390/min11040404.
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The boundary between the Gondwana and Yangtze plate is still controversial. In southwest China, the Sanjiang region marks the collision zone which accreted several blocks coming from the northern Gondwana margin. In this region, subduction of the Paleo-Tethys Ocean and associated continental blocks during the Triassic Period led to the formation of an N–S trending complex involving intrusive and volcanic rocks. The intrusive rocks are important for constraining the evolution of the Paleo-Tethyan in southwestern China. This study presents new geochronological, geochemical, and Sr-Nd-Hf isotopic data of granite porphyries from northern Lancangjiang, in order to discuss the origin of these granites and their tectonic significance. Representative samples of the Zengudi and the Tuobake granite porphyries from the Yezhi area yielded weighted mean 206Pb/238U ages of 247–254 Ma and 246 Ma, respectively. The Zengudi granite porphyries display zircon ԐHf(t) values of −12.94 to −2.63, ԐNd(t) values of −14.5 to −9.35, and initial 87Sr/86Sr ratios of 0.708 to 0.716. The Tuobake granite porphyries have zircon ԐHf(t) values of −14.06 to −6.55, ԐNd(t) values of −10.9 to −9.41, and initial 87Sr/86Sr ratios of 0.716 to 0.731. Both the Zengudi and Tuobake granite porphyries exhibit strongly peraluminous signatures with high A/CNK nAl2O3/(K2O + Na2O + K2O) ratios (1.07–1.86 and 0.83–1.33, respectively). These granites are enriched in Rb and Th, and depleted in Ti, Nb, Ta, Sr, and P, with negative Eu anomalies (Eu/Eu* < 0.61). These geochemical and isotopic data indicate that the primary magma of the granite porphyries originated from partial melting of ancient continental crust as a result of basaltic magma underplating and underwent fractionation crystallization during their emplacement. We propose that the Triassic subduction of the Paleo-Tethys Ocean led to crust shortening and thickening in the Sanjiang region, while the northern Lancangjiang area was involved in the continental collision after the subduction of the Paleo-Tethys Ocean before 254 Ma.
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Zhou, Guoyun, Chia-Yun Chen, Liyi Li, Zhihua Tao, Wei He, and C. P. Wong. "Effects of MnSO4 on microstructure and electrical resistance properties of electroless Ni−P thin-films and its application in embedded resistor inside PCB." Circuit World 40, no. 2 (April 29, 2014): 45–52. http://dx.doi.org/10.1108/cw-08-2013-0030.
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Purpose – Nickel phosphorus (Ni−P) thin-films have been electrolessly deposited in an acid-plating bath with the addition of manganese sulfate monohydrate (MSM) to achieve higher resistance for the application of embedded resistor with value beyond 10 KΩ. As this material is being used for fabricating embedded resistors under the addition of MSM, its resistance properties including effects of MSM concentration and plating time on resistances, temperature coefficient of resistance (TCR), and resistance tolerance of embedded resistor were investigated. The paper aims to discuss these issues. Design/methodology/approach – The structure of fabricated Ni−P film was detected by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The properties of substrate, including the surface morphologies, glass transition process and boundary of copper pad and substrate surface, were performed by SEM, dynamic mechanical analysis and optical microscope, respectively. The resistance tolerances of embedded resistors were elaborated from the cases of Ni−P thin-film resistance tolerance and the size effects of resistors, respectively. Findings – The fabricated film was found to be constructed with numerous Ni−P amorphous nanoparticles, which was believed to be the reason of increasing thin-film resistance. The Ni−P thin-films presented over one magnitude order of resistance increasing in the case of MSM concentration varied from 0 to 40 g/L. For the case of TCRs, Ni−P thin-films deposited with 20 g/L MSM exhibited low TCRs of within ±100 ppm/°C Before TR at temperature elevating from 40 to 160°C, indicating that this Ni−P thin-film belongs to the constant TCR materials according to the military standard. For the tolerance of embedded resistor, the tolerance contributed by Ni−P thin-film was obtained to be 9.8 percent, whereas the geometry tolerances were in the range of 0-20 percent according to the geometries of embedded resistor. Originality/value – For Ni−P thin-film without MSM, its low resistance with around 100 ohm/sq. limit the values of resistor few KΩ and restricted its widespread application of embedded resistor with higher resistance beyond 10 KΩ. The authors introduced MnSO4 in Ni−P electroless plating process to improve the low resistance of Ni−P thin-film. The resistance was increased over one order of magnitude after added with 40 g/L MnSO4. Due to the specific structure, as this material is being used for fabricating embedded resistors, the electrical properties and its application properties to verify its appliance in embedded resistor were systematically investigated by means of SEM, TEM, XRD characterizations, TCRs, resistance tolerance analysis, respectively.
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Lachhab, Ahmed, El Mehdi Benyassine, Mohamed Rouai, Abdelilah Dekayir, Jean C. Parisot, and Mustapha Boujamaoui. "Integration of Multi-geophysical Approaches to Identify Potential Pathways of Heavy Metals Contamination - A Case Study in Zeida, Morocco." Journal of Environmental and Engineering Geophysics 25, no. 3 (September 2020): 415–23. http://dx.doi.org/10.32389/jeeg9-067.
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The tailings of Zeida's abandoned mine are found near the city of Midelt, in the middle of the high Moulouya watershed between the Middle and the High Atlas of Morocco. The tailings occupy an area of about 100 ha and are stored either in large mining pit lakes with clay-marl substratum or directly on a heavily fractured granite bedrock. The high contents of lead and arsenic in these tailings have transformed them into sources of pollution that disperse by wind, runoff, and seepage to the aquifer through faults and fractures. In this work, the main goal is to identify the pathways of contaminated water with heavy metals and arsenic to the local aquifers, water ponds, and Moulouya River. For this reason, geophysical surveys including electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and very low-frequency electromagnetic (VLF-EM) methods were carried out over the tailings, and directly on the substratum outside the tailings. The result obtained from combining these methods has shown that pollutants were funneled through fractures, faults, and subsurface paleochannels and contaminated the hydrological system connecting groundwater, ponds, and the river. The ERT profiles have successfully shown the location of fractures, some of which extend throughout the upper formation to depths reaching the granite. The ERT was not successful in identifying fractures directly beneath the tailings due to their low resistivity which inhibits electrical current from propagating deeper. The seismic refraction surveys have provided valuable details on the local geology, and clearly identified the thickness of the tailings and explicitly marked the boundary between the Triassic formation and the granite. It also aided in the identification of paleochannels. The tailings materials were easily identified by both their low resistivity and low P-wave velocity values. Also, both resistivity and seismic velocity values rapidly increased beneath the tailings due to the compaction of the material and lack of moisture and have proven to be effective in identifying the upper limit of the granite. Faults were found to lie along the bottom of paleochannels, which suggest that the locations of these channels were caused by these same faults. The VLF-EM surveys have shown tilt angle anomalies over fractured areas which were also evinced by low resistivity area in ERT profiles. Finally, this study showed that the three geophysical methods were complementary and in good agreement in revealing the pathways of contamination from the tailings to the local aquifer, nearby ponds and Moulouya River.
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H., Findlay R. "Geometry, kinematics and regional significance of faulting and related lamprophyric intrusion in the mineralised zone at the Pu Sam Cap complex, Northwest Vietnam." VIETNAM JOURNAL OF EARTH SCIENCES 40, no. 4 (September 18, 2018): 320–40. http://dx.doi.org/10.15625/0866-7187/40/4/13102.
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The alkali volcanics and intrusive rocks, dated at around 35-33Ma, are cut by mineralised northeast and east trending faults showing predominant evidence for strike-slip. Mineralisation includes haematite-Au-Cu and is accompanied by iron-rich alteration of the volcanic rocks. Detailed assessment of the geometry of the fault system at Pu Sam Cap suggests that the faults formed as a Riedel shear system during left-lateral slip within the Song Hong-Song Chay shear zone and the numerous contemporaneous northwest trending faults to the south; the northeast trending faults are interpreted as dextral “book-end’’ faults between major northwest trending faults enclosing the Pu Sam Cap massif. As mineralisation is hosted within these faults and is also associated with lamprohyric dykes it confirms a thermal event younger than the alkaline volcanics and syenitic intrusives at Pu Sam Cap, suggesting a hidden, young porphyry system. The age of faulting, and thus the maximum age for this young intrusive event, is attributed to the 23-21Ma period of late-stage left-lateral strike-slip motion across northwest Vietnam.ReferencesAnczkiewicz R., Viola G., Muntener O., Thrirlwall M., Quong N.Q., 2007. Structure and shearing conditions in the Day Nui Con Voi massif: implications for the evolution of the Red River Fault. Tectonics 26: TC2002.Cao Shunyun, Liu Junlai, Leis B., Zhao Chunquiang 2010. New zircon U/Pb geochronology of the post-kinematic granitic plutons in Diancang Shan Massif along the Ailao-Shan-Red River Shear Zone and its geological implications. Acta Geologica Sinica (English Edition), 84, 1474-1487.Chung S.-L., Lee T., Lo C., et al., 1997. Intraplate extension prior to continental extrusion along the Ailao Shan-Red River shear zone.Geology, 25, 311-314.Cloos H., 1928. Experimentezurinnern Tektonik. Zentralblatt fur Mineralogie und Palaeontologie, 1928, 609-621.Findlay R.H., Phan Trong Trinh 1997. The structural setting of the Song Ma region, Vietnam, and the Indochina-South China plate boundary problem. Gondwana Research, 1, 11-33.Jolivet L., Beysasac O., Goffe B., Avigad D., Leprevrier C., Maluski H., Ta Trong Thang, 2001. Oligo-Miocene midcrustal subhorizontal shear in Indochina. Tectonics, 20, 46-57.Khuong The Hung 2010. The complex tectonic events and their influence on formation of mineral deposits in northwest Vietnam. Unpublished PhD Thesis, University of Science and Technology, Cracow, 167p.Leloup P.H., N. Arnau, R. Lacassin, J.R. Kienast, T.M. Harrison, P.T. Trinh, A. Replumaz and P. Tapponnier, 2001. New constraints on the structure, thermochronology and timing of the Ailao Shan - Red river shear zone, SE Asia, J. G. R., 106, 6657-6671.Leloup PH.., R. Lacassin, P. Tapponnier, U. Scharer, Zhong Dalai, Liu Xaohan, Zhangshan, Ji Shaocheng and PT.Trinh, 1995. The Ailao Shan - Red river shear zone (Yunnan, China), Tertiary transform boundary of Indochina, Tectonophysics, 251, 3-84. Leprevier C., Maluski H., Nguyen Van Vuong, Roques D., Axente V., Rangin C., 1996. Indosinian NW-trending shear zones within the Truong Son belt, Vietnam: 40Ar-39Ar Triassic ages and Cretaceous to Cenozoic overprints. Tectonophysics, 283, 105-107.Lien-Sheng Zhang, Scharer U. 1999. Age and origin of magmatism along the Cenozoic Red River shear belt, China. Contributions to Mineralogy and Petrology, 134, 67-85.Nagy E.A., Scharer U., Minh N.T., 2000. Oligo-Miocene granitic magmatismin central Vietnam and implications for continental deformation in Indochina. Terra Nova, 12, 67-76.Nguyen Thi Bich Thuy, 2016. Isotop dating U-Pb Zircon of Syenit Formation, Pu Sam Cap. Journal of Geology, A Serie, 356, 30-36. (In Vietnamese).Pei-Long Wang, Ching-Hua Lo, Tung-Yi Lee, Sun-ling Chun, Ching-Yan Lan, Nguyen Trong Yem 1998. Thermochronological evidence for the movement of the Ailo Shan-Red River shear zone, a perspective from Vietnam. Geology, 26, 887-890.Phan Trong Trinh, Nguyen Trong Yem, Herve L.P., Tapponnier P., 1994. Late Cenozoic stress fields in North Vietnam from microtectonic measurements. Proceedings of the International Workshop on Seismotectonics and Seismic Hazard in Southeast Asia. Geological Survey of SR Vietnam, Hanoi, 182-186.Riedel W., 1929. Zur Mechanikgreologischer Brucherscheinungen. Zentralblatt fur Mineralogie und Palaeontologie, Abhandlung B, 354-368.Scharer U., Tapponnier P., Lacassin R., Leloup P.H., Dalai Z., Shaosheng J., 1990. Intraplate tectonics in Asia: a precise age for large-scale Miocene movement along the Ailao Shan-Red River shear zone, China. Earth and Planetary Science Letters, 97, 65-77.Scharer U., Zhang L.S., Tapponnier P., 1994. Duration of strike-slip movements in large shear zones: the Red River belt, China. Earth and Planetary Science Letters, 126, 379-397.Searle M.P., 2006. Role of the Red River Shear zone, Yunnan and Vietnam, in the continental extrusion of SE Asia. Journal of the Geological Society, London, 163, 1025-1036.Searle M.P., Meng-Wan Yeh, Te-Hsien Lin, Sun-Lin Chung, 2010. Structural constraints on the timing of left-lateral shear along the Red River shear zone in the Ailao Shan and Diancang Shan Ranges, Yunnan, SW China. Geosphere, 6, 316-338.Tapponnier P., Lacassin R., Leloup H., Scharer U., Zhong Dalai, Wu Hawei, Liu Ziaohan, Ji Shaocheng, Zhang Lianshang, Zong Jiayou, 1990. The Ailao Shan/ Red River metamorphic belt: Tertiary left-lateral shear between Indochina and south China. Nature, 342, 431-437.Tchalenko J.S., 1970. Similarities between shear zones of different magnitudes. Bulletin of the Geological Society of America, 81, 1625-1640.Viola G., Anczkiewicz R. 2009. Exhumation history of the Red River shear zone in northern Vietnam: new insights from zircon and apatite fission-track analysis. Journal of Asian Earth Sciences, 33, 78-90.Yang Yiseng, Hong Qun, Hu Huan-ting, Hieu Pham Trung, Nguyen Thi Bich Thuy, Chen Fu-kun, 2013. Geochemical characteristics and genesis of the Cenozoic porphyry in the Laizhou area, northwestern Vietnam. Acta Petrologica Sinica, 29(3), 899-911. (In Chinese with English abstract, full English version through Google Translate).
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Thanh, Nguyen Trung, Paul Jing Liu, Mai Duc Dong, Dang Hoai Nhon, Do Huy Cuong, Bui Viet Dung, Phung Van Phach, Tran Duc Thanh, Duong Quoc Hung, and Ngo Thanh Nga. "Late Pleistocene-Holocene sequence stratigraphy of the subaqueous Red River delta and the adjacent shelf." VIETNAM JOURNAL OF EARTH SCIENCES 40, no. 3 (June 4, 2018): 271–87. http://dx.doi.org/10.15625/0866-7187/40/3/12618.
Full textAbstract:
The model of Late Pleistocene-Holocene sequence stratigraphy of the subaqueous Red River delta and the adjacent shelf is proposed by interpretation of high-resolution seismic documents and comparison with previous research results on Holocene sedimentary evolution on the delta plain. Four units (U1, U2, U3, and U4) and four sequence stratigraphic surfaces (SB1, TS, TRS and MFS) were determined. The formation of these units and surfaces is related to the global sea-level change in Late Pleistocene-Holocene. SB1, defined as the sequence boundary, was generated by subaerial processes during the Late Pleistocene regression and could be remolded partially or significantly by transgressive ravinement processes subsequently. The basal unit U1 (fluvial formations) within incised valleys is arranged into the lowstand systems tract (LST) formed in the early slow sea-level rise ~19-14.5 cal.kyr BP, the U2 unit is arranged into the early transgressive systems tract (E-TST) deposited mainly within incised-valleys under the tide-influenced river to estuarine conditions in the rapid sea-level rise ~14.5-9 cal.kyr BP, the U3 unit is arranged into the late transgressive systems tract (L-TST) deposited widely on the continental shelf in the fully marine condition during the late sea-level rise ~9-7 cal.kyr BP, and the U4 unit represents for the highstand systems tract (HST) with clinoform structure surrounding the modern delta coast, extending to the water depth of 25-30 m, developed by sediments from the Red River system in ~3-0 cal.kyr BP.ReferencesBadley M.E., 1985. Practical Seismic Interpretation. International Human Resources Development Corporation, Boston, 266p.Bergh G.D. 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