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Leopold Krystyn - One of the best experts on this subject based on the ideXlab platform.
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Short" or "long" Rhaetian ? Astronomical calibration of Austrian key sections
Global and Planetary Change, 2020Co-Authors: Bruno Galbrun, Silvia Gardin, Leopold Krystyn, Sylvain Richoz, Annachiara Bartolini, Slah Boulila, Martin MasloAbstract:The establishment of the Late Triassic time scale has given rise to considerable controversy, particularly regarding the Rhaetian duration and the inferred absolute age models. In this respect the astronomical polarity time scale (APTS) established from the continental successions of the Newark Basin (eastern North America) is considered as a reference record, although its completeness is questioned. Numerous magnetostratigraphic correlation schemes have been proposed between the APTS and biostratigraphically well-constrained Tethyan marine sections. This has led to two main contrasting options: a "short" Rhaetian duration (about 4-5 myr), and a "long" one (about 8-9 myr). Astronomical calibration of the Tethyan Rhaetian and estimate of its duration is necessary to help advance this debate. We have undertaken a cyclostratigraphic analysis of a Rhaetian composite record built from four overlapping Austrian reference sections. Magnetic susceptibility variations of the 131.5 m thick record are astronomically paced by the precession and 405-kyr orbital eccentricity cycles. 405-kyr orbital tuning allows to establish a floating time scale, and thus to suggest a minimum duration of 6.69 myr of the Rhaetian stage. Given the well-established radioisotopic age of the Rhaetian-Hettangian boundary of 201.36 Ma, an age no younger than 208.05 Ma for the Norian-Rhaetian boundary can be proposed. This result will contribute to the refinement of the Late Triassic time scale, but it does not solve the long-standing debate on bio-magnetostratigraphic correlations between the continental Newark APTS and the Tethyan marine sections, nor the question of the completeness of the Rhaetian Newark Basin.
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short or long Rhaetian astronomical calibration of austrian key sections
Global and Planetary Change, 2020Co-Authors: Bruno Galbrun, Silvia Gardin, Leopold Krystyn, Sylvain Richoz, Annachiara Bartolini, Slah Boulila, Martin MasloAbstract:Abstract The establishment of the Late Triassic time scale has given rise to considerable controversy, particularly regarding the Rhaetian duration and the inferred absolute age models. In this respect the astronomical polarity time scale (APTS) established from the continental successions of the Newark Basin (eastern North America) is considered as a reference record, although its completeness is questioned. Numerous magnetostratigraphic correlation schemes have been proposed between the APTS and biostratigraphically well-constrained Tethyan marine sections. This has led to two main contrasting options: a “short” Rhaetian duration (about 4–5 myr), and a “long” one (about 8–9 myr). Astronomical calibration of the Tethyan Rhaetian and estimate of its duration is necessary to help advance this debate. We have undertaken a cyclostratigraphic analysis of a Rhaetian composite record built from four overlapping Austrian reference sections. Magnetic susceptibility variations of the 131.5 m thick record are astronomically paced by the precession and 405-kyr orbital eccentricity cycles. 405-kyr orbital tuning allows to establish a floating time scale, and thus to suggest a minimum duration of 6.69 myr of the Rhaetian stage. Given the well-established radioisotopic age of the Rhaetian-Hettangian boundary of 201.36 Ma, an age no younger than 208.05 Ma for the Norian-Rhaetian boundary can be proposed. This result will contribute to the refinement of the Late Triassic time scale, but it does not solve the long-standing debate on bio-magnetostratigraphic correlations between the continental Newark APTS and the Tethyan marine sections, nor the question of the completeness of the Rhaetian Newark Basin.
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Towards accurate numerical calibration of the Late Triassic: High- precision U-Pb geochronology constraints on the duration of the Rhaetian
Geology, 2014Co-Authors: Joern Frederik Wotzlaw, Christopher A. Mcroberts, Leopold Krystyn, Annachiara Bartolini, Jean Guex, Yves Gallet, David Taylor, Blair Schoene, Urs SchalteggerAbstract:Numerical calibration of the Late Triassic stages is arguably the most controversial issue in Mesozoic stratigraphy, despite its importance for assessing mechanisms of environmental perturbations and associated biologic consequences preceding the end-Triassic mass extinction. Here we report new chemical abrasion–isotope dilution– thermal ionization mass spectrometry zircon U-Pb dates for volcanic ash beds within the Aramachay Formation of the Pucara Group in northern Peru that place precise constraints on the age of the Norian- Rhaetian boundary (NRB) and the duration of the Rhaetian. The sampled ash bed–bearing interval is located just above the last occurrence of the bivalve Monotis subcircularis, placing this stratigraphic sequence in the uppermost Norian, perhaps ranging into the earliest Rhaetian. Zircon U-Pb dates of ash beds constrain the deposition age of this interval to be between 205.70 ± 0.15 Ma and 205.30 ± 0.14 Ma, providing precise constraints on the age of the NRB. Combined with previously published zircon U-Pb dates for ash beds bracketing the Triassic-Jurassic boundary, we estimate a duration of 4.14 ± 0.39 m.y. for the Rhaetian. This ends a prolonged controversy about the duration of this stage and has fundamental implications for the rates of paleoenvironmental deterioration that culminated in the end-Triassic mass extinction.
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Where and when the earliest coccolithophores?
Lethaia, 2012Co-Authors: Silvia Gardin, Leopold Krystyn, Sylvain Richoz, Annachiara Bartolini, Bruno GalbrunAbstract:New calcareous nannofossil analyses from the Northern Calcareous Alps of Austria are herein used to update and improve the state of knowledge about the oldest occurrence of coccolithophores reported in the literature. Previously reported Norian occurrences of coccoliths were based on an obsolete Triassic chronostratigraphy, in which the Rhaetian stage was subsumed into the Norian (‘Sevatian 2’). The oldest stratigraphical record of coccoliths spp. lies just below the Norian-Rhaetian boundary and the first coccolith species, Crucirhabdus minutus, is recorded from the base of Rhaetian stage. The latter bio-event is located just above the First Occurrence of the conodont Misikella posthersteni and the first occurrence of the ammonoid Paracochloceras suessi in the Steinbergkogel section (Austria), Global Stratotype Section and Point (GSSP) candidate for the Norian–Rhaetian boundary. The appearance of the coccolith Crucirhabdus minutus is seen as a robust biochronological datum that will provide useful constraints for Triassic biostratigraphy, palaeoclimatic modelling and phylogenetic reconstructions. The new calcareous nannofossil biochronology of Steinbergkogel that we present herein completes the existing biostratigraphic characterization of the Norian-Rhaetian transition based on conodonts and ammonoids and strengthens the position of Steinbergkogel as the best GSSP proposed section for the base of the Rhaetian. The record of coccolithophores across the Norian–Rhaetian boundary at Steinbergkogel takes place along with a discernible increase in abundance of Prinsiosphaera triassica, as well as the appearance of Euconusphaera zlambachensis, which are the two most important Rhaetian pelagic carbonate producers. This succession of bio-events is interpreted as the initiation of the pelagic carbonate production driven by the successful spreading of calcareous nannofossils in the Western Tethys during the Rhaetian.
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Rhaetian (LATE TRIASSIC) MONOTIS (BIVALVIA: PECTINOIDA) FROM THE EASTERN NORTHERN CALCAREOUS ALPS (AUSTRIA) AND THE END-NORIAN CRISIS IN PELAGIC FAUNAS
Palaeontology, 2008Co-Authors: Christopher A. Mcroberts, Leopold Krystyn, Adriel SheaAbstract:Species of marine bivalves of the pectinoid genus Monotis provide useful biochronologic indices for the Late Triassic (middle Norian-earliest Rhaetian). We report the succession of Monotis at Hernstein in Lower Austria where typical late Norian Monotis salinaria (Schlotheim) are overlain by strata with apparently the youngest Monotis known of demonstrable Rhaetian age: Monotis hoernesi Kittl and Monotis rhaetica sp. nov., a species closely related to M. rudis Gemmellaro. A Rhaetian (Sevatian 2) age is con- firmed by the co-occurrence of Monotis with the platform conodont Misikella posthernsteini and close association with the ammonoid Paracochloceras. A review of late Norian monotid species indicates that a profound extinction event occurred in the pelagic realm at or close to the Nori- an ⁄ Rhaetian boundary where c. 15 monotids (Monotis s.l. and Maorimonotis) became extinct. The surviving Monotis are dwarfed when compared to their Norian predecessors and may represent an ecological ⁄ phylogenetic response to the crisis.
Jean Besse - 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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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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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:International audienceThe 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 not, vert, similar 2 Myr, and not, vert, similar 4.5 Myr if the Sevatian 2 zone is included as part of the Rhaetian
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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: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 not, vert, similar 2 Myr, and not, vert, similar 4.5 Myr if the Sevatian 2 zone is included as part of the Rhaetian.
Yves Gallet - One of the best experts on this subject based on the ideXlab platform.
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Towards accurate numerical calibration of the Late Triassic: High- precision U-Pb geochronology constraints on the duration of the Rhaetian
Geology, 2014Co-Authors: Joern Frederik Wotzlaw, Christopher A. Mcroberts, Leopold Krystyn, Annachiara Bartolini, Jean Guex, Yves Gallet, David Taylor, Blair Schoene, Urs SchalteggerAbstract:Numerical calibration of the Late Triassic stages is arguably the most controversial issue in Mesozoic stratigraphy, despite its importance for assessing mechanisms of environmental perturbations and associated biologic consequences preceding the end-Triassic mass extinction. Here we report new chemical abrasion–isotope dilution– thermal ionization mass spectrometry zircon U-Pb dates for volcanic ash beds within the Aramachay Formation of the Pucara Group in northern Peru that place precise constraints on the age of the Norian- Rhaetian boundary (NRB) and the duration of the Rhaetian. The sampled ash bed–bearing interval is located just above the last occurrence of the bivalve Monotis subcircularis, placing this stratigraphic sequence in the uppermost Norian, perhaps ranging into the earliest Rhaetian. Zircon U-Pb dates of ash beds constrain the deposition age of this interval to be between 205.70 ± 0.15 Ma and 205.30 ± 0.14 Ma, providing precise constraints on the age of the NRB. Combined with previously published zircon U-Pb dates for ash beds bracketing the Triassic-Jurassic boundary, we estimate a duration of 4.14 ± 0.39 m.y. for the Rhaetian. This ends a prolonged controversy about the duration of this stage and has fundamental implications for the rates of paleoenvironmental deterioration that culminated in the end-Triassic mass extinction.
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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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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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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:International audienceThe 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 not, vert, similar 2 Myr, and not, vert, similar 4.5 Myr if the Sevatian 2 zone is included as part of the Rhaetian
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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: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 not, vert, similar 2 Myr, and not, vert, similar 4.5 Myr if the Sevatian 2 zone is included as part of the Rhaetian.
Christian Pott - One of the best experts on this subject based on the ideXlab platform.
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the Rhaetian flora of wustenwelsberg bavaria germany description of selected gymnosperms ginkgoales cycadales coniferales together with an ecological assessment of the locally prevailing vegetation
Review of Palaeobotany and Palynology, 2021Co-Authors: Johanna H A Van Konijnenburgvan Cittert, Günter Dütsch, Christian Pott, Stefan Schmeisner, Evelyn KustatscherAbstract:Abstract This paper describes the ginkgoaleans (Ginkgoites) and conifers (Palissya, Stachyotaxus, Schizolepis) of the Rhaetian flora from Wustenwelsberg, as well as a new species of the cycad Becklesia. The ginkgophyte leaf fragments are very abundant in certain levels (‘Blatterkohle‘) whereas conifers are common in the main fossiliferous bed. The Wustenwelsberg specimens extend the range for Ginkgoites taeniatus from the Hettangian to the Rhaetian and for the genus Becklesia from the Cretaceous to the Rhaetian. The other elements are typical for the Rhaetian floras of Bavaria and often also of the Northern Hemisphere. A comparison with other Northern Hemisphere plant assemblages demonstrates a high similarity with the Rhaetian floras from Jameson Land (Greenland) and Scania (Sweden) but significant differences to the Hettangian floras from adjacent areas in Franconia, especially at species and sometimes at generic level. A comparison with the microflora from the same sections shows a hidden diversity that is highest in small herbaceous plants (mosses, lycophytes, ferns) and by the conifers. Wustenwelsberg reflects, thus, an articulated landscape with a high water and nutrients availability (stagnant water bodies and/or river systems) covered by a complex and multi-storeyed vegetation shown, among others, by the general abundance in hygrophytic spores and high diversity among the various plant groups. This must have corresponded to one of the humid episodes that characterized the generally warm and arid climate of the Rhaetian of Europe.
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New data on Selaginellites coburgensis from the Rhaetian of Wüstenwelsberg (Upper Franconia, Germany)
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 2016Co-Authors: Christian Pott, Stefan Schmeissner, Günter Dütsch, Evelyn Kustatscher, Johanna H.a. Van Konijnenburg-van Cittert, Michael KringsAbstract:A branched shoot with several attached microsporangiate strobili of the Rhaetian (late Triassic) herbaceous lycophyte Selaginellites coburgensis is described from Wustenwelsberg near Coburg, German ...
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Bennettitales in the Rhaetian flora of Wüstenwelsberg, Bavaria, Germany
Review of Palaeobotany and Palynology, 2016Co-Authors: Christian Pott, Stefan Schmeissner, Günter Dütsch, Johanna H.a. Van Konijnenburg-van CittertAbstract:Abstract The diverse bennettitalean plant remains from the Rhaetian of Wustenwelsberg, Franconia, southern Germany, are described by means of macromorphological and epidermal anatomy; the study is part of the ongoing examination of this recently excavated and excellently preserved fossil flora. The taxa identified include four species of Pterophyllum , one species of Anomozamites , two species of Nilssoniopteris and one species of Wielandiella with sterile leaves, bracts and ovulate reproductive organs. In addition, an enigmatic type of bennettitalean microsporangiate organ has been obtained, remains of which from the Rhaetian of Greenland had been assigned to Bennettistemon . However, the material from Wustenwelsberg is much more complete and is assigned to a new genus, viz. Welsbergia gen. nov., with its type species Welsbergia bursigera (Harris) comb. nov., based on the organ's unique architecture. The microsporangiate organs are always exclusively associated with the sterile foliage Pterophyllum aequale . Comparison of the flora from Wustenwelsberg with adjacent Rhaetian floras revealed distinct local differences in the bennettitalean constitution, which are discussed in the light of palaeogeography and plant dispersal patterns.
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A Selaginellites from the Rhaetian of Wüstenwelsberg (Upper Franconia, Germany)
Neues Jahrbuch Fur Geologie Und Palaontologie-abhandlungen, 2014Co-Authors: J.h.a. Van Konijnenburg-van Cittert, Stefan Schmeissner, Günter Dütsch, Christian Pott, Kathleen Bauer, Evelyn Kustatscher, Michael KringsAbstract:Sterile shoots and a microsporangiate strobilus of a new herbaceous lycophyte, Selaginellites coburgensis nov. spec., are described from the Rhaetian (uppermost Triassic) of Wustenwelsberg near Cob ...
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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A new Rhaetian δ13Corg record: Carbon cycle disturbances, volcanism, End-Triassic mass Extinction (ETE)
Earth-Science Reviews, 2018Co-Authors: Mariachiara Zaffani, Flavio Jadoul, Manuel RigoAbstract:Abstract The links between large-scale volcanism, carbon cycle perturbations and the biotic crises at the End-Triassic Extinction event (ETE) are not well understood. The ETE seems to be marked by three carbon isotope excursions (CIEs) likely triggered by different eruptive phases of the Central Atlantic Magmatic Province (CAMP). These three CIEs appear to occur during the late Rhaetian, close to the Triassic/Jurassic boundary (TJB), but the relative timing connecting the volcanism, carbon perturbations and extinctions is still subject to debate resulting from: i) the difficulties in long-distance biostratigraphic correlations of Rhaetian successions due to the step-like extinction pattern characterizing the ETE, and to the lack of globally correlatable key-fossil group(s) across the system boundary; ii) the limit of coverage of available δ13C profiles to the system boundary interval, rather than the entire Rhaetian; iii) the inherent difficulties in correlating CIEs without clear biostratigraphic markers. Here we present a δ13Corg curve from the Lombardy Basin which covers for the first time the entire Rhaetian. Using this chemostratigraphy, we propose two possible correlations (option 1 and option 2) with other late Rhaetian to early Hettangian successions worldwide. These two possible correlations rely on a combination of paleontological (ammonoids, pollens, conodonts), lithostratigraphic and geochemical constraints. Option 2 in particular has important implications for the causality and geochronology of the ETE events by suggesting that the sharp negative peak usually considered to be the “initial” CIE in the Lombardy might represent a carbon perturbation within the negative trend of the “main” CIE. This implies that a reconsideration of the succession of biotic events occurring during this time interval is required.
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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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the pignola abriola section southern apennines italy a new gssp candidate for the base of the Rhaetian stage
Lethaia, 2016Co-Authors: Manuel Rigo, Matteo Maron, Angela Bertinelli, Miriam E Katz, Linda Godfrey, Giuseppe Concheri, Giovanni Gattolin, Paolo Mietto, Giovanni MuttoniAbstract:The base of the Rhaetian stage (Norian/Rhaetian boundary, NRB) is still awaiting formal designation by the International Commission on Stratigraphy. At present, only the 4.30-m-thick Steinbergkogel section (Austria) has been proposed as GSSP (Global Stratotype Section and Point) candidate for the base of the Rhaetian. Here we present data from the 63-m-thick Pignola-Abriola section (Southern Apennines, Italy) that we consider an alternative candidate for the Rhaetian GSSP. The Pignola-Abriola basinal section, represented by hemipelagic–pelagic carbonate successions belonging to the Lagonegro Basin, matches all the requirements for a GSSP: 1, it is well exposed with minimal structural deformation; 2, it is rich in age diagnostic fossils (e.g. conodonts and radiolarians); 3, it yields a geochemical record suitable for correlation (e.g. δ13Corg/carb); and 4, it has a robust magnetostratigraphy and is correlated with the Newark APTS for age approximation of the NRB and additional Rhaetian bioevents. In the Pignola-Abriola section, we opt to place the NRB at the 44.4 metre level, coincident with a prominent negative shift of ca. 6‰ of the δ13Corg. This level is located 50 cm below the FAD of conodont Misikella posthernsteini s.s within the radiolarian Proparvicingula moniliformis Zone. Both the negative δ13Corg shift and the FAD of Misikella posthernsteini occur within Pignola-Abriola magnetozone MPA-5r, at ~205.7 Ma, according to magnetostratigraphical correlation to the Newark APTS. We also illustrate the coeval Mt. Volturino stratigraphical section deposited below the calcite compensation depth (CCD) within the same Lagonegro Basin and characterized by a detailed radiolarian biostratigraphy and strong δ13Corg negative shift around the NRB.
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The Pignola‐Abriola section (southern Apennines, Italy): a new GSSP candidate for the base of the Rhaetian Stage
Lethaia, 2015Co-Authors: Manuel Rigo, Matteo Maron, Angela Bertinelli, Miriam E Katz, Linda Godfrey, Giovanni Muttoni, Giuseppe Concheri, Giovanni Gattolin, Paolo Mietto, Mario SprovieriAbstract:The base of the Rhaetian stage (Norian/Rhaetian boundary, NRB) is still awaiting formal designation by the International Commission on Stratigraphy. At present, only the 4.30-m-thick Steinbergkogel section (Austria) has been proposed as GSSP (Global Stratotype Section and Point) candidate for the base of the Rhaetian. Here we present data from the 63-m-thick Pignola-Abriola section (Southern Apennines, Italy) that we consider an alternative candidate for the Rhaetian GSSP. The Pignola-Abriola basinal section, represented by hemipelagic–pelagic carbonate successions belonging to the Lagonegro Basin, matches all the requirements for a GSSP: 1, it is well exposed with minimal structural deformation; 2, it is rich in age diagnostic fossils (e.g. conodonts and radiolarians); 3, it yields a geochemical record suitable for correlation (e.g. δ13Corg/carb); and 4, it has a robust magnetostratigraphy and is correlated with the Newark APTS for age approximation of the NRB and additional Rhaetian bioevents. In the Pignola-Abriola section, we opt to place the NRB at the 44.4 metre level, coincident with a prominent negative shift of ca. 6‰ of the δ13Corg. This level is located 50 cm below the FAD of conodont Misikella posthernsteini s.s within the radiolarian Proparvicingula moniliformis Zone. Both the negative δ13Corg shift and the FAD of Misikella posthernsteini occur within Pignola-Abriola magnetozone MPA-5r, at ~205.7 Ma, according to magnetostratigraphical correlation to the Newark APTS. We also illustrate the coeval Mt. Volturino stratigraphical section deposited below the calcite compensation depth (CCD) within the same Lagonegro Basin and characterized by a detailed radiolarian biostratigraphy and strong δ13Corg negative shift around the NRB.