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Manuel Rigo - One of the best experts on this subject based on the ideXlab platform.
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correlation between the warepan otapirian and the Norian rhaetian stage boundary implications of a global negative δ13corg perturbation
New Zealand Journal of Geology and Geophysics, 2021Co-Authors: Manuel Rigo, H J CampbellAbstract:The Norian/Rhaetian boundary interval (Late Triassic) is characterised by significant biotic turnover and severe climatic changes. However, this boundary still awaits formal definition. We have inv...
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the aftermath of the cpe and the carnian Norian transition in northwestern sichuan basin south china
Journal of the Geological Society, 2019Co-Authors: Manuel Rigo, Christopher A. Mcroberts, Xin Jin, Zhiqiang Shi, Paolo Mietto, Guido Roghi, Stefano Manfrin, Marco Franceschi, Nereo PretoAbstract:The northwestern Sichuan Basin (South China) was a portion of eastern Tethys where, during the Late Triassic, a sharp lithological transition from oolitic–bioclastic limestones and sponge reef mounds to dark grey terrigenous clays, siltstones and sandstones is visible in several localities. The timing and significance of this major facies transition is still unclear. Here we report new biostratigraphic and carbon stable isotope data from Hanwang and Jushui, northwestern Sichuan Basin. Sporomorphs, ammonoids, conodonts and halobiid bivalves show that the lithological change is Late Carnian to Early Norian in age. This amended age determination facilitates recalibration of the magnetostratigraphy in the area allowing correlation between the Late Triassic of the Sichuan Basin and the Astrochronostratigraphic Polarity Time Scale. A carbon stable isotopic perturbation across the Carnian–Norian Boundary (CNB) is missing in our sections, or it is concealed because of the mixed organic matter sources. Our findings pinpoint the position of the CNB to a short stratigraphic interval of c. 12 m thickness in the Sichuan Basin. The studied sections greatly extend the palaeogeographical documentation of the CNB and provide novel information on biostratigraphy and chemostratigraphy that should be considered in defining the best position of the Norian Global Stratotype Section and Point.
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The aftermath of the CPE and the Carnian–Norian transition in northwestern Sichuan Basin, South China
Journal of the Geological Society, 2018Co-Authors: Xin Jin, Manuel Rigo, Christopher A. Mcroberts, Zhiqiang Shi, Paolo Mietto, Guido Roghi, Stefano Manfrin, Marco Franceschi, Nereo PretoAbstract:The northwestern Sichuan Basin (South China) was a portion of eastern Tethys where, during the Late Triassic, a sharp lithological transition from oolitic–bioclastic limestones and sponge reef mounds to dark grey terrigenous clays, siltstones and sandstones is visible in several localities. The timing and significance of this major facies transition is still unclear. Here we report new biostratigraphic and carbon stable isotope data from Hanwang and Jushui, northwestern Sichuan Basin. Sporomorphs, ammonoids, conodonts and halobiid bivalves show that the lithological change is Late Carnian to Early Norian in age. This amended age determination facilitates recalibration of the magnetostratigraphy in the area allowing correlation between the Late Triassic of the Sichuan Basin and the Astrochronostratigraphic Polarity Time Scale. A carbon stable isotopic perturbation across the Carnian–Norian Boundary (CNB) is missing in our sections, or it is concealed because of the mixed organic matter sources. Our findings pinpoint the position of the CNB to a short stratigraphic interval of c. 12 m thickness in the Sichuan Basin. The studied sections greatly extend the palaeogeographical documentation of the CNB and provide novel information on biostratigraphy and chemostratigraphy that should be considered in defining the best position of the Norian Global Stratotype Section and Point.
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New Upper Triassic Conodont Biozonation of the Tethyan Realm
Topics in Geobiology, 2017Co-Authors: Manuel Rigo, Michele Mazza, Viktor Karádi, Alda NicoraAbstract:Conodonts are biostratigraphically very important microfossils in the Upper Triassic, occurring in different marine habitats, from deep-ocean to shallow-shelf waters. Because of their great abundance, worldwide distribution, strong resistance to rock metamorphism, and mineralogical composition that makes them reliable tools for biostratigraphic and geochemical studies, conodonts have proven to be important tools in defining the Geological Time Scale (GTS) and Global Stratotype Section and Points (GSSPs). We present here an original Upper Triassic conodont biozonation for the Tethyan Realm integrated, where possible, with ammonoid and radiolarian zones, providing also numerical ages for stages and substages. Based on the most recent conodont biostratigraphic and systematic studies, we propose a subdivision of the Upper Triassic interval into 22 conodont zones (nine for the Carnian, ten for the Norian, and three for the Rhaetian), correlated, where possible, with the most recent North American conodont zonations. Discussions on the most biostratigraphically important conodont taxa are also provided, in particular for the stratigraphic intervals around the base of the Norian and Rhaetian stages, the GSSPs of which have yet to be defined. In this view, we provide data supporting the validity of conodonts as reliable tools for global correlations, recommending two conodont biovents as possible primary biomarkers: the FAD (First Appearance Datum) of Metapolygnathus parvus for the base of the Norian and the FAD of Misikella posthernsteini for the base of the Rhaetian. The conodont species Norigondolella carlae n. sp. from the upper Tuvalian (Carnian) is also defined.
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magnetostratigraphy biostratigraphy and chemostratigraphy of the pignola abriola section new constraints for the Norian rhaetian boundary
Geological Society of America Bulletin, 2015Co-Authors: Matteo Maron, Manuel Rigo, Angela Bertinelli, Miriam E Katz, Linda Godfrey, Mariachiara Zaffani, Giovanni MuttoniAbstract:A detailed magnetostratigraphic investigation of the Pignola-Abriola section of Norian to Rhaetian age permits the identification of 22 magnetic polarity reversals grouped in 10 magnetozones. We correlate the magnetostratigraphy of the Pignola-Abriola section with the Newark astrochronological polarity time scale (APTS). In total, 19 correlation options were tested, and only one (option 7) yielded a statistically significant correlation that was consistent with the available information on the stratigraphic age of the Newark APTS. After some adjustments to minimize erratic variations in sediment accumulation rates, a final correlation (option 7.1) was used to generate an age model of sedimentation for the Pignola-Abriola section. The Pignola-Abriola section has been correlated with Rhaetian sections from the literature, notably the current global boundary stratotype section and point candidate for the base of the Rhaetian at Steinbergkogel, Austria, where the Norian-Rhaetian boundary is proposed to be placed at a stratigraphic level containing the first appearance datum (FAD) of conodont Misikella posthernsteini , traced on the Newark APTS to ca. 209–210 Ma. Issues regarding the taxonomy of M. posthernsteini , a species characterized by transitional forms with its ancestor Misikella hernsteini , lead us to propose the alternative option of placing the Norian-Rhaetian boundary at a prominent negative δ 13 C org spike observed in the Pignola-Abriola section at meter 44.5, 50 cm below the level containing the FAD of M. posthernsteini sensu stricto and close to the base of radiolarian Proparvicingula moniliformis zone. This level has been magnetostratigraphically correlated to Newark magnetozone E20r.2r at ca. 205.7 Ma. Assuming an age of ca. 201.3 Ma for the Triassic-Jurassic boundary, the Rhaetian Stage would have a duration of ~4.4 m.y.
Heinz W Kozur - One of the best experts on this subject based on the ideXlab platform.
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the late triassic timescale age and correlation of the carnian Norian boundary
Earth-Science Reviews, 2012Co-Authors: Spencer G. Lucas, Lawrence H Tanner, Heinz W Kozur, Robert E Weems, Andrew B HeckertAbstract:The Late Triassic timescale is poorly constrained due largely to the dearth of reliable radio-isotopic ages that can be related precisely to biostratigraphy combined with evident contradictions between bio-stratigraphic and magnetostratigraphic correlations. These problems are most apparent with regard to the age and correlation of the Carnian–Norian boundary (base of the Norian Stage). We review the available age data pertaining to the Carnian–Norian boundary and conclude that the “long Norian” in current use by many workers, which places the Carnian–Norian boundary at ~228 Ma, is incorrect. The evidence supports a Norian stage that is much shorter than proposed by these workers, so the Carnian–Norian boundary is considerably younger than this, close to 220 Ma in age. Critical to this conclusion is the correlation of the Carnian–Norian boundary in nonmarine strata of Europe and North America, and its integration with existing radioisotopic ages and magnet-ostratigraphy. Three bio-stratigraphic datasets (palynomorphs, conchostracans and tetra-pods) reliably identify the same position for the Carnian–Norian boundary (within normal limits of bio-stratigraphic resolution) in nonmarine strata of the Chinle Group (American Southwest), Newark Supergroup (eastern USA–Canada) and the German Keuper. These biostratigraphic datasets place the Carnian–Norian boundary at the base of the Warford Member of the lower Passaic Formation in the Newark Basin, and, as was widely accepted prior to 2002, this correlates the base of the Norian to a horizon within Newark magnet-ozone E13n. In recent years a correlation based solely on magnetostratigraphy has been proposed between the Pizzo Mondello section in Sicily and the Newark section. This correlation, which ignores robust biostrati-graphic data, places the Norian base much too low in the Newark Basin section (~at the base of the Lockatong Formation), correlative to a horizon near the base of Newark magnet-ozone E8. Despite the fact that this correlation is falsifiable on the basis of the bio-stratigraphic data, it still became the primary justification for placing the Carnian–Norian boundary at ~228 Ma (based on Newark cyclo-stratigraphy). The “long Norian” created thereby is unsupported by either bio-stratigraphic or reliable radioisotopic data and therefore must be abandoned. While few data can be presented to support a Carnian–Norian boundary as old as 228 Ma, existing radio-isotopic age data are consistent with a Norian base at ~220 Ma. Although this date is approximately correct, more reliable and precise radio-isotopic ages still are needed to firmly assign a precise age to the Carnian–Norian boundary.
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δ13c and δ18o values of triassic brachiopods and carbonate rocks as proxies for coeval seawater and palaeotemperature
Palaeogeography Palaeoclimatology Palaeoecology, 2005Co-Authors: Christoph Korte, Heinz W Kozur, Jan VeizerAbstract:Abstract A dataset of 160 isotope δ13C and δ18O values from Anisian, Ladinian, Carnian and Rhaetian articulate brachiopod shells, complemented by 158 carbon and oxygen isotope values from whole rock carbonates, define the first continuous stable isotope baseline trends for the Triassic seawater. The carbon isotope data suggest the existence of several short-term high amplitude excursions in the Early Triassic, followed by a predominance of values around 0.5 ± 1‰ during the Middle Triassic, a rise to ∼ 3.5‰ during the Carnian, plateau at this level during the Late Carnian to Early Norian, and a 1.5‰ decline in the Middle Norian to values around 2‰ during the Late Norian–Rhaetian interval. The causation scenarios for these rapid oscillations are at present equivocal, but may in part reflect a biological instability of the carbon cycle following the recovery from the end-Permian extinction event and/or an input of “mantle”-derived CO2 from enhanced volcanic activity. The δ18O values from well-preserved brachiopods from the Tethyan realm range from − 3.9 to − 0.6‰ V-PDB. These values require open marine Triassic seawater δ18O values close to 0‰ V-SMOW for the calculated temperatures to be within the range of tolerance of the coexisting reef-building corals. A 2‰ δ18O increase within the uppermost Cordevolian and early Julian suggests either a distinct temperature decline in the Southern Alps during that time interval, an increase in seawater salinity, or their combination. Oxygen isotope values for the Muschelkalk brachiopods range between − 6.2 and − 2.0‰ and likely reflect a strong influx of meteoric waters into the Germanic Basin that shifted the oxygen isotopes to more negative values.
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strontium isotope evolution of late permian and triassic seawater
Geochimica et Cosmochimica Acta, 2003Co-Authors: Christoph Korte, Heinz W Kozur, Jan Veizer, Peter BruckschenAbstract:The 87Sr/86Sr values based on brachiopods and conodonts define a nearly continuous record for the Late Permian and Triassic intervals. Minor gaps in measurements exist only for the uppermost Brahmanian, lower part of the Upper Olenekian, and Middle Norian, and only sparse data are available for the Late Permian. These 219 measurements include 67 brachiopods and 114 conodont samples from the Tethyan realm as well as 37 brachiopods and one conodont sample from the mid-European Middle Triassic Muschelkalk Sea. The Late Permian/Lower Triassic interval is characterized by a steep 1.3 × 10−3 rise, from 0.7070 at the base of the Dzhulfian to 0.7082 in the late Olenekian, a rate of change comparable to that in the Cenozoic. In the mid-Triassic (Anisian and Ladinian), the isotope values fall to 0.7075, followed again by a rise to 0.7081 in the Middle/Late Norian. The 87Sr/86Sr values decline again in the Late Norian (Sevatian) and Rhaetian to 0.7076. The sharp rise in the 87Sr/86Sr values during the Late Permian/Early Triassic was coincident with widespread clastic sedimentation. Because of the paucity of tectonic uplifts, the enhanced erosion may have been due to intermittent humid phases, during mainly an arid interval, coupled with the absence of a dense protective land plant cover following the mass extinction during the latest Permian. The apex of the 87Sr/86Sr curve at the Olenekian/Anisian boundary coincides with cessation of the large-scale clastic sedimentation and also marks the final recovery of land vegetation, as indicated by the renewed onset of coal formation in the Middle Triassic. The rising 87Sr/86Sr values from the Middle Carnian to the Late Norian coincide with the uplift and erosion of the Cimmeride-Indosinian orogens marking the closure of the Palaeotethys. The subsequent Rhaetian decline that continues into Jurassic (Pliensbachian/Toarcian boundary), on the other hand, coincides with the opening of the Vardar Ocean and its eastern continuation in the Izmir-Ankara Ophiolitic Belt. Samples from the Upper Muschelkalk are more radiogenic than the global trend. This may reflect separation of the basin from the open ocean. Due to strong meteoric influx from a large land mass in the north, the Germanic Basin became increasing brackish up section in the north and east, but because of the high evaporation rates, the salt content was not much reduced in the southern and central basin where a rich, but increasingly endemic, marine fauna survived.
Jean Marcoux - One of the best experts on this subject based on the ideXlab platform.
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new constraints on the end triassic upper Norian rhaetian magnetostratigraphy
Earth and Planetary Science Letters, 2007Co-Authors: Yves Gallet, Leopold Krystyn, Jean Marcoux, Jean BesseAbstract:Abstract The end-Triassic was marked by one of the five important Phanerozoic global mass extinctions. The construction of a detailed magnetic polarity time scale for this period, that would integrate data from marine and terrestrial realms, is thus of particular interest. We report new magnetostratigraphic data from the Oyuklu section located in southwestern Turkey, which allow one to propose a complete late Upper Norian (Sevatian 2) to Rhaetian magnetic polarity sequence. Two correlations are discussed between the new Tethyan marine sequence and the (continental) magnetic polarity record previously determined from the Newark basin in eastern North America. Both options suggest that the Rhaetian is at least partly missing in the Newark basin, which would reconcile most Late Triassic magnetostratigraphic results and biotic features obtained from marine and continental environments. Following our preferred correlation, the Rhaetian would have a duration as short as ∼ 2 Myr, and ∼ 4.5 Myr if the Sevatian 2 zone is included as part of the Rhaetian.
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Integrated Upper Carnian to Lower Norian biochronology and implications for the Upper Triassic magnetic polarity time scale
Earth and Planetary Science Letters, 2002Co-Authors: Leopold Krystyn, Yves Gallet, Jean Besse, Jean MarcouxAbstract:Abstract We summarize the ammonoid, conodont and halobiid biochronology of the Upper Carnian to Lower Norian, based on a discussion of data in the Alps, Sicily, Balkans, Turkey, Himalayas and Timor. With this integrated biostratigraphic scale, the Pizzo Mondello section (Sicily) can be recalibrated and the Carnian–Norian boundary more precisely located there. As a result, the magnetostratigraphy of this section is now in good agreement with previous results from Turkey, although the latter series are more condensed. Cross-correlation of available magnetostratigraphic data from marine Tethyan sections allow us to construct a composite Upper Carnian to Upper Norian geomagnetic polarity time scale (GPTS). This GPTS leads us to question previously proposed magnetobiostratigraphic and chronostratigraphic correlations within the Upper Triassic Newark non-marine sedimentary sequence.
Michele Mazza - One of the best experts on this subject based on the ideXlab platform.
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New Upper Triassic Conodont Biozonation of the Tethyan Realm
Topics in Geobiology, 2017Co-Authors: Manuel Rigo, Michele Mazza, Viktor Karádi, Alda NicoraAbstract:Conodonts are biostratigraphically very important microfossils in the Upper Triassic, occurring in different marine habitats, from deep-ocean to shallow-shelf waters. Because of their great abundance, worldwide distribution, strong resistance to rock metamorphism, and mineralogical composition that makes them reliable tools for biostratigraphic and geochemical studies, conodonts have proven to be important tools in defining the Geological Time Scale (GTS) and Global Stratotype Section and Points (GSSPs). We present here an original Upper Triassic conodont biozonation for the Tethyan Realm integrated, where possible, with ammonoid and radiolarian zones, providing also numerical ages for stages and substages. Based on the most recent conodont biostratigraphic and systematic studies, we propose a subdivision of the Upper Triassic interval into 22 conodont zones (nine for the Carnian, ten for the Norian, and three for the Rhaetian), correlated, where possible, with the most recent North American conodont zonations. Discussions on the most biostratigraphically important conodont taxa are also provided, in particular for the stratigraphic intervals around the base of the Norian and Rhaetian stages, the GSSPs of which have yet to be defined. In this view, we provide data supporting the validity of conodonts as reliable tools for global correlations, recommending two conodont biovents as possible primary biomarkers: the FAD (First Appearance Datum) of Metapolygnathus parvus for the base of the Norian and the FAD of Misikella posthernsteini for the base of the Rhaetian. The conodont species Norigondolella carlae n. sp. from the upper Tuvalian (Carnian) is also defined.
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application of numerical cladistic analyses to the carnian Norian conodonts a new approach for phylogenetic interpretations
Journal of Systematic Palaeontology, 2012Co-Authors: Michele Mazza, Andrea Cau, Manuel RigoAbstract:The high intraspecific variability of conodont platform elements in the upper Carnian–lower Norian interval and the proliferation of numerous species in this relatively short time have generated many problems for the understanding of Late Triassic conodont phylogeny, systematics and taxonomy. Since Late Triassic natural assemblages are still unknown, we have applied cladistic methodologies to investigate the evolution of Carnian–Norian conodont platforms and to infer more precise phylogenetic relationships among taxa. Numerical cladistic analysis was undertaken of species belonging to the five Late Triassic genera Paragondolella, Carnepigondolella, Metapolygnathus, Epigondolella and Norigondolella. A taxon–character data matrix describing the distribution of 64 characters amongst two outgroups and 31 ingroup taxa was compiled and processed using PAUP* 4.1. Our analyses show the evolutionary and systematic value of certain morphological characters, and lead to a reinterpretation of the phylogenetic positio...
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generic turnovers of carnian Norian conodonts climatic control or competition
Palaeogeography Palaeoclimatology Palaeoecology, 2010Co-Authors: Michele Mazza, Stefano Furin, Christoph Spotl, Manuel RigoAbstract:Abstract Pizzo Mondello section (western Sicily, Italy) yields a very rich conodont record, ranging from Late Carnian to Rhaetian in age, shedding new light into the evolution of conodonts across the Carnian/Norian boundary. Conodont biostratigraphy around the Carnian/Norian boundary is still problematic due to an inferred provincialism that affects most of the conodont species and to the occurrence of a great number of transitional forms, linked to the fast recovery of conodonts after the Middle Carnian crisis. The lower 144 m of the succession, Tuvalian to Lacian in age, were sampled in detail for a biostratigraphic and ecological study of five Upper Triassic conodont genera: Paragondolella , Carnepigondolella , Metapolygnathus , Epigondolella , and Norigondolella. After a taxonomic revision of the genera studied, meant to define the most significant morphological features for their classification, a statistical approach was applied to the study of conodont populations. Quantitative curves of the absolute abundances for each genus show potential ecological competition between Paragondolella – Carnepigondolella and later between Metapolygnathus – Epigondolella (and partially between Epigondolella – Norigondolella ). Recognition of morphoclines among species, integrated by a similar ecological behaviour, supports the phylogenetic derivation of Norigondolella and Metapolygnathus from Paragondolella and that of Epigondolella from Carnepigondolella . Furthermore, cross checks of the quantitative curves evidenced the presence of three major assemblage changes: at metre 64.76 (named event T1) Carnepigondolella is replaced by its descendant Epigondolella in an evolutionary step; at metre 80 (event T2) Epigondolella is substituted by the mass occurrence of Metapolygnathus and at metre 95 (event T3) Metapolygnathus is succeeded by advanced Epigondolellae species and by Norigondolella . In looking for environmental explanations to these biological events, the conodont assemblages are compared to coeval δ 18 O and δ 13 C isotopic curves, based on new data from Pizzo Mondello. From the comparison, a correspondence appears between higher 13 C/ 12 C ratios and the interval between events T2–T3, but not with event T1. This is in accordance with the interpretation of event T1 as an evolutionary turnover. In more detail, we observe the possible influence of environmental conditions on the absolute abundances of all the studied genera: while Epigondolella proliferate when seawater δ 13 C ranges between 2.1‰ and 2.5‰ , Carnepigondolella proliferate in the range between 1.6‰ and 2.1‰; Metapolygnathus instead appears to be limited to environmental conditions related to higher δ 13 C values in the seawater. We explain this behaviour by interpreting the genus Metapolygnathus as an opportunist taxon, exactly as its forerunner, the genus Paragondolella .
Yasuhiro Kato - One of the best experts on this subject based on the ideXlab platform.
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bolide impact triggered the late triassic extinction event in equatorial panthalassa
Scientific Reports, 2016Co-Authors: Tetsuji Onoue, Honami Sato, Daisuke Yamashita, Minoru Ikehara, Kazutaka Yasukawa, Koichiro Fujinaga, Yasuhiro KatoAbstract:Extinctions within major pelagic groups (e.g., radiolarians and conodonts) occurred in a stepwise fashion during the last 15 Myr of the Triassic. Although a marked decline in the diversity of pelagic faunas began at the end of the middle Norian, the cause of the middle Norian extinction is uncertain. Here we show a possible link between the end-middle Norian radiolarian extinction and a bolide impact. Two palaeoenvironmental events occurred during the initial phase of the radiolarian extinction interval: (1) a post-impact shutdown of primary and biogenic silica production within a time span of 10(4)-10(5) yr, and (2) a sustained reduction in the sinking flux of radiolarian silica for ~0.3 Myr after the impact. The catastrophic collapse of the pelagic ecosystem at this time was probably the dominant factor responsible for the end-middle Norian conodont extinction.
