In setting up the Global Boundary Stratotype and Section (GSSP) for the Jurassic–Cretaceous boundary (JKB), the Berriasian Working Group (BWG) of the International Subcommission on Cretaceous Stratigraphy recommends to shift down the JKB to an interval between the paleomaginetic M20n1r and the base of M19r. The BWG is discussing markers defining the JKB. Radiolarians are one of ideal candidates for defining the JKB because they are wide spread and can be found in both shallow and deep marine sedimentary facies worldwide. The JKB lies around the base of the Unitary Association Zone (UAZ) 13 and within the Pseudodictyomitra carpatica Zone. Our radiolarian biostratigraphic research around the JKB in two Itarian sections, Torre de’Busi (Lombardian Basin) and Bosso Valley (central Apennines), and at ODP Site 801 in the western Pacific enables to correlate these sections by means of radiolarians.The Torre de’Busi and Bosso Valley sections are strong GSSP candidates in the Alpine Tethys. The Maiolica Formation, which includes the JKB at the lowermost part, is characterized by whitish beige to gray colored, well-bedded micritic limestones with abundant black to gray chert layers and nodules. Integrated calcareous nannofossil, calpionellid, magnetostratigraphic, and cyclostratigraphic investigations provide a reliable stratigraphic framework for the Torre de’Busi section. Calpionellid biostratigaraphic and magnetostratigraphic study was conducted in the Bosso Valley section. A total of 49 samples in the Torre de’Busi section and 47 samples in the Bosso Valley section have been collected for our radiolarian biostratigraphic study across the JKB. In the Torre de’Busi section only horizons corresponding to the lower part of M20 contain moderately preserved radiolarians. In the Bosso Valley section several horizons corresponding to the interval between the M20n1r and the base of M19r yielded moderately to well preserved radiolarians.Radiolarian biostratigraphy accross the JKB in the western Pacific was studied at ODP Site 801. The Pseudodictyomitra carpatica Zone is recognized in a radiolarite sequence from Core 15 to Core 20 at the site. Radiolarian markers for delimimating the JKB can be selected among taxa of which first occurrence is recorded in the UAZ 13. The result of a radiolarian biostratigraphic correlation between Alpine Tethys sections and western Pacific sections is presented. Candidates of radiolarian markers for the JKB are discussed. They are included in the genera Cinguloturris, Hemicryptocapsa, Hsuum, Loopus, Pantanellium, Vallupus, and Zhamoidellum.

ABSTRACT A clean, well‐organized and comprehensive dataset developed in accordance with the FAIR principles (Findable, Accessible, Interoperable and Reusable), provides a solid foundation for a new research initiative and supports open science. In this context, also legacy, deep boreholes data represent a valuable and unrepeatable source of geological and geophysical information to recover. This article presents the digitalization of legacy well documentation originally available only as scanned images, resulting in a dataset of 30 files, derived by an accurate digitalization workflow carried out on exploration boreholes documentation. The latter was collected across the offshore area between Pesaro‐Fano in the Adriatic Sea, a region that has experienced significant seismic activity, including the 9 November 2022 Mw 5.5 Fano‐Pesaro earthquake sequence. Such data were originally gathered as scanned images extracted from vintage raster files (PDF format), publicly available on the Italian ViDEPI Project website (www.videpi.com). Despite their findability and accessibility are straightforward, their interoperability and reusability are severely limited, due to variable image quality, non‐editable contents and obsolete stratigraphic nomenclature. Such wells are named from northwest to southeast as follows: Boheme 01, Tamara 01, Pesaro Mare 03, Pesaro Mare 04, Malachite 01, Cornelia 01 and Elga 01. The digitalization was carried out at high fidelity with respect to the original data, reassessing the relevant well stratigraphy by taking into account all the handwritten comments found inside the original images. Only minor reinterpretations based on lithology, depositional environment and age, were made. Some local formation names were updated, aligned and thus correlated with modern and officially recognized regional stratigraphic units. The digitalization also includes spontaneous potential, resistivity and sonic logs of the Tamara 01 and Boheme 01 wells. Such digitized data were successively stored in open and standard formats (CSV and LAS). Nowadays, these datasets are freely accessible and carry substantial significance as a foundation of earthquake studies, for enhancing geological and geophysical models, depicting the stratigraphic, structural and geophysical characteristics of the study area. Notable potential use includes, among others, seismotectonic studies, gas and CO2 storage, basinal analysis, stratigraphic and paleogeographic investigations within the region. Digitizing such legacy data reduces the risk of data loss, improves modernization and accessibility, supports interoperability and collaboration. It also enables easier quality control and facilitates future reuse, especially when integrated with other data sources such as seismic surveys, production data and reservoir models.

The conservation of the architectural heritage is a primary concern for the preservation of the cultural identity of a community. To this end, the choice of appropriate materials focusing on the economic and ecological compatibility with the existent ones is the main objective of scientific research in building materials for restoration and strengthening activities. Lime mortar is one of the main components of the heritage architecture, used as joints between bricks or stones, plasters or binders inside multi-leaf walls and in most cases is the component most prone to degradation. During the Roman era, above all, there were several improvements in theories, techniques and additives to be used in the mortar mix. Vitruvio was one of the most important architecture’s theorist and he proposed several recipes to be followed for different situations in order to obtain specific mechanical and physical properties. This study explores a novel biocomposite material compatible with the structural strengthening and restoration of ancient masonry buildings constructed with lime mortar, following a recipe attributed to Vitruvius. The mortar was mixed with Spanish broom and hemp fibers. The first phase involved mechanical characterization through three-point bending and uniaxial compression tests. The second phase assessed the effects of thermal and humidity-induced stress on the mixture and its mechanical properties.

The Norian/Rhaetian boundary (NRB) is marked by faunal turnover and global carbon cycle perturbation. Several possible causes of the environmental perturbation across the NRB have been proposed, including the volcanic activity from the Angayucham Terrane and an impact event related to the Rochechouart crater. Evaluating these proposed causes requires high-resolution biostratigraphy and accurate interregional correlation of carbon isotope curves. However, such comparisons remain challenging due to the limited resolution and inconsistent calibration of radiolarian and conodont biostratigraphic frameworks. Here, we present integrated, high-resolution radiolarian and conodont biostratigraphy and organic carbon isotope (S13Corg) data from an Upper Triassic pelagic sequence in the Sasso di Castalda section of the Lagonegro Basin, southern Italy. Our biostratigraphic analyses reveal two radiolarian assemblages, the Betraccium deweveri and Proparvicingula moniliformis zones, indicating an age from uppermost Norian to lowermost Rhaetian. The first occurrence of the conodont Misikella posthernsteini s.s. (sensu stricto) constrains the base of the Rhaetian. The S13Corg profile in the latest Norian exhibits an overall negative shift characterized by positive and negative fluctuations that correspond to the globally recognized carbon isotope excursion at this boundary. Furthermore, based on our conodont biostratigraphic data, the deposition of the platinum group elements-enriched layer reported in the studied section is constrained to the latest Norian, suggesting a correlation with the Rochechouart impact. Since this layer corresponds to the onset of the negative S13Corg shift, our new S13Corg record, integrated with highresolution biostratigraphy, could contribute to understanding the cause of extinction across the NRB.

The Late Triassic was a time of complex and rapid carbon cycle perturbations, which can be better understood through global carbon-isotope correlations. This study presents an integrated biostratigraphic, geochronological, and carbon isotope chemostratigraphic analysis across the Norian-Rhaetian boundary (NRB) and End-Triassic Mass Extinction (ETME) intervals from the Tela section in Southern Tibet. Four conodont biozones are identified, Mockina bidentata Zone, Parvigondolella andrusovi-Misikella hernsteini Zone, Misikella posthernsteini Zone, and Misikella ultima Zone, indicating a continuous succession from the Sevatian (upper Norian) to the upper Rhaetian. Globolaxtorum tozeri, one of the most indicative upper Rhaetian radiolarian taxa, was found within the M. ultima Zone. Zircon U-Pb dating of three volcanic detritus-bearing limestone samples from the lower part of the section yields ages of 217.0 +/- 1.4 Ma, 214.5 +/- 1.9 Ma, and 214.4 +/- 1.4 Ma, aligning with the Mo. bidentata Zone further refining the biostratigraphy. Carbon and oxygen isotope data (S13Ccarb and S18Ocarb) are subdivided into a lower (0-54 m) and an upper (70-120 m) interval. Four carbon isotope excursions (CIEs) are here documented. Three negative excursions (CIE1, CIE2, CIE3) occur in the Sevatian, each visible in both S13Ccarb and S13Corg curves. The fourth carbon excursion of S13Corg, the Initial-CIE (-5.24 parts per thousand), coinciding with the appearance of radiolarians G. tozeri and spans the M. posthernsteini and M. ultima zones, linking it to the ETME. While the cause of the Initial-CIE is generally attributed to Central Atlantic Magmatic Province, the drivers behind the three Sevatian CIEs and around the NRB remain uncertain. Volcanogenic materials from the Tela section suggest that prolonged volcanic activity-likely associated with seafloor spreading in the Neo-Tethys Ocean and the rifting of the Lhasa Block from eastern Gondwana may have contributed to global carbon cycle disruptions from the Sevatian through the NRB interval.

Norian time interval is a crucial period in Earth’s evolutionary history, characterized by several organic carbon-isotope perturbations in the carbon cycle that are closely related to global environmental change and biotic turnover (Zaffani et al., 2017). Among them, the Norian “chaotic carbon episode” has been recently reported globally in North America, Italy, and Japan, from shallow to pelagic environments (Whiteside and Ward, 2011; Zaffani et al., 2017; Jin et al., 2022; Sato et al., 2023). However, the mechanisms and timing of these events are poorly understood, especially in the eastern Tethys. In this study, we have investigated the carbon isotope profiles and conodont assemblage changes from the middle to upper Norian bedded carbonate rock succession in the Sanhedong section, Southwest China, to provide new insights into the Norian carbon cycle perturbation and its impact on marine biodiversity. We thus collected several samples for conodont biostratigraphic investigations and organic and carbonate carbon isotope (δ13Corg, δ13Ccarb) and oxygen isotope data (δ18Ocarb) along the study section. We identified various conodont genera, including some typical Norian Arcyrogondolella, Norigondollela, Mockina, and Primatella, and established detailed conodont biostratigraphy that indicates a middle to upper Norian age for the Sanhedong section. Furthermore, we detected a significant negative carbon isotope excursion (NCIE) across the middle/upper Norian, which can be globally correlated with the NCIE events reported from North America, the central Panthalassa Ocean, and the Tethys Ocean. We have also observed changes in conodont diversity and abundance associated with the NCIE.Our study provides an accurate age and a high-resolution carbon isotope record for the Sanhedong section, revealing the global nature of the Norian carbon cycle perturbation and its impact on the biosphere in the eastern Tethys. Our preliminary results suggest that also the carbon isotope perturbation in Eastern Tethys may be associated to the middle-late Norian carbon-cycle perturbations, which were triggered by the emplacement of the Angayucham Large Igneous Province (Alaska). Further studies are needed to constrain the timing and magnitude of Norian volcanic activity.Keywords: Norian, conodont biostratigraphy, carbon isotope perturbation, Eastern Tethys Reference:Jin, X., Du, Y., Bertinelli, A., Shi, Z., Preto, N., Zou, H., Ogg, J.G., Han, L., Wu, Q. and Rigo, M., 2022. Carbon-isotope excursions in the Norian stage (Upper Triassic) of the Baoshan terrane, western Yunnan, China. Journal of Asian Earth Sciences, 230, p.105215.Sato, H., Nozaki, T., Onoue, T., Ishikawa, A., Soda, K., Yasukawa, K., Kimura, J.I., Chang, Q., Kato, Y. and Rigo, M., 2023. Rhenium-osmium isotope evidence for the onset of volcanism in the central Panthalassa Ocean during the Norian “chaotic carbon episode”. Global and Planetary Change, 229, p.104239.Whiteside, J.H. and Ward, P.D., 2011. Ammonoid diversity and disparity track episodes of chaotic carbon cycling during the early Mesozoic. Geology, 39(2), pp.99-102.Zaffani, M., Agnini, C., Concheri, G., Godfrey, L., Katz, M., Maron, M. and Rigo, M., 2017. The Norian “chaotic carbon interval”: new clues from the δ13Corg record of the Lagonegro Basin (southern Italy). Geosphere, 13(4), pp.1133-1148.

The contribution to Tethyan and global Triassic studies from the Australian sector of southeastern Tethys is limited relative to that from the Himalayan sector. Whilst many of the Triassic successions from the Australian sector are located offshore, one succession is exposed on the island of Timor. This marine succession, dismembered during collision between the Australian continent and the volcanic Banda Arc, has been investigated for over 100 years but has also made limited modern contributions to Tethyan and global Triassic studies. To address this a new integrated Triassic biostratigraphic microfossil database (conodonts, palynomorphs and radiolarians) from Timor-Leste is presented here that compliments published foraminiferal data. This integrated data set 1) supports application in Timor of the endemic palynomorph zonal scheme from the North West Shelf of Australia whilst providing additional ties for this to the Geological Time Scale (GTS), 2) provides paleobiogeographic support for accumulation of the Timor-Leste Triassic succession within a southeast Tethyan Gondwanan basin and informs discussions about Tethyan paleobiogeography, 3) calibrates over 300 outcrops to the GTS enabling an improved reconstruction of the dismembered succession that will facilitate enhanced regional and local paleogeographic and tectonostratigraphic assessments, and 4) provides independent GTS calibration for published basinal foraminiferal assemblages which will assist understanding the biostratigraphic utility of these assemblages. This database identifies key outcrops, such as the first outcropping Permian -Triassic Boundary section from this sector of southeastern Tethys, that will facilitate targeted studies addressing a range of Tethyan and global Triassic issues unlocking insights from an under -sampled Gondwanan sector of Tethys.

The Triassic was a critical period for a significant increase in the generic diversity of radiolarians after the disappearance of >80% of radiolarian genera during the Permian-Triassic mass extinction. In particular, the Upper Triassic radiolarian fauna is rich and has been documented in several world regions, such as North America, Western Europe, the Mediterranean area, Japan, the Philippines, Timor, and Far East Russia. In this study, a well-preserved and high-diversity fauna from a continuous pelagic-hemipelagic section deposited in western Tethys (Sicily, Italy) provides one of the most detailed radiolarian records of the Carnian-Norian boundary interval, which can be correlated worldwide, from high to low-latitude, from both sides of the Pangea and both Hemispheres. The 99 species belonging to 50 genera from this time interval have been collected from the Pizzo Mondello section (Sicanian Basin, Western Sicily), the selected GSSP for the base of the Norian stage, and then compared to the radiolarian associations documented in other coeval regions. Based on the occurrences of characteristic radiolarian species, we defined and proposed a new radiolarian biozonation across the Carnian-Norian boundary, which consists of five new assemblages (PM assemblage 1–5) that are correlated and calibrated to the already well-defined biozonation of bivalves, ammonoids, and conodonts.

The latest Triassic was characterised by protracted biotic extinctions concluding in the End-Triassic Extinction (~ 200 Ma) and a global carbon cycle perturbation. The onset of declining diversity is closely related to reducing conditions that spread globally from upper Sevatian (uppermost Norian) to across the Norian-Rhaetian boundary, likely triggered by unusually high volcanic activity. We correlate significant organic carbon cycle perturbations to an increase of CO2 in the ocean–atmosphere system, likely outgassed by the Angayucham igneous province, the onset of which is indicated by the initiation of a rapid decline in 87Sr/86Sr and 188Os/187Os seawater values. A possible causal mechanism involves elevated CO2 levels causing global warming and accelerating chemical weathering, which increased nutrient discharge to the oceans and greatly increased biological productivity. Higher export production and oxidation of organic matter led to a global O2 decrease in marine water across the Norian/Rhaetian boundary (NRB). Biotic consequences of dysoxia/anoxia include worldwide extinctions in some fossil groups, such as bivalves, ammonoids, conodonts, radiolarians.

The Norian “chaotic carbon episode” stands out as a compelling carbon cycle perturbation event within the Late Triassic period. This episode has been documented in marine stratigraphic sections across North America, Italy, Japan, and China. However, limited Norian chronostratigraphy available in the eastern Tethys inhibited the identification of this event in this broad area, and thus the possible global response to this carbon cycle perturbation. To address this issue, we analyzed the conodonts and carbon-isotope of the Norian Sanhedong (SHD) section in the Simao terrane, Southwest China. The identification of the Alaunian Epigondolella spiculata Zone has well documented the base of the Alaunian stage. Moreover, a conodont faunal turnover can be recognized at the base of the Alaunian, with the evolution of Mockina from Ancyrogondolella and Epigondolella, and it is characterized by a gradual decrease in specimen size. The E. spiculata conodont Zone from the SHD section correlates well with the homonymous conodont Zones documented in both the Tethys and the Panthalassa Oceans. Two carbon-isotope negative excursions (CIE1 and CIE2) have also been recorded in the Lacian to Alaunian of the SHD section that can be compared with coeval global sections.

Microfossils are important components of sedimentary rocks used for palaeontological, biostratigraphic, palaeoenvironmental and palaeoclimatic investigations. They are usually extracted from rocks using an acid solution, which might vary depending on the embedding rock lithology. Here we propose a new method using common NaOH (sodium hydroxide; soda) to digest cherts (micro‐ and cryptocrystalline quartz) instead of the standard technique based on HF (hydrofluoric acid). This new method allows the collection of undamaged specimens of different kinds of microfossils, such as conodonts, radiolarians, teeth and dermal scales, the minerology of which is still preserved (e.g. biogenic apatite in conodonts). The use of soda is thus recommended, as it is less dangerous, less expensive, and it better preserves the extracted microfossils both in shape and mineralogy.

ABSTRACT The reduced Jurassic sedimentary sequences deposited on a structural high in the Umbria-Marche Apennines, as well their relationships with adjacent expanded basinal sequences, have been reconstructed through detailed, interdisciplinary study of the Sasso di Pale and Monte Serrone areas near Foligno, Italy. The physiographic features of the basin originated in the Early Jurassic (latest early Pliensbachian), when extensional tectonic activity broke up a shallow water platform where the Calcare Massiccio had been deposited, and the area evolved from an edge-stepped structural high to a distally steepened ramp. The biostratigraphic framework of this paper is mainly based on calcareous nannofossils, which are a useful tool for dating condensed Jurassic successions. Although the sections studied have limited thickness and much lateral facies variation, the sedimentary evolution can be traced and interpreted within a wider Jurassic environmental perspective. In the upper Pliensbachian–lower Bajocian interval, local sea-level variations are compatible with the global sea-level curve. Furthermore, some of the characteristic events—such as the Pliensbachian–Toarcian crisis, the Early Toarcian Jenkyns Event, and the Middle Jurassic carbonate crisis—can be recognized. The present study shows how the reconstruction of local paleogeography can fit into a more general framework and how regional and global signals can be recognized even in a small structural high such as the one we have investigated.

The biostratigraphy and carbon stable isotopes of the Norian Stage (Upper Triassic) are well studied in the western Tethys, but little information is available from the eastern Tethys. Therefore, we studied the Hongyan-B (HYB) section in the Baoshan terrane, western Yunnan Province, SW China, which was located in the eastern Tethys during the Late Triassic. The HYB section was investigated for conodonts, radiolarians, total organic carbon, carbonate carbon and oxygen stable isotopes (delta C-13(carb) and delta O-18(carb)), and carbon isotopes of organic matter (delta C-13(org)). The Mockina slovakensis and Mockina bidentata conodont biozones proposed in the HYB section are associated with two radiolarian zones of the Sevatian substage, the Praemesosaturnalis multidentatus and Praemesosaturnalis pseudokahleri zones (TR8A and TR8B Sugiyama zones). This biostratigraphy places the Alaunian-Sevatian substage boundary (middle-upper Norian) at meter 23 of the HYB section. Unfortunately, the delta C-13(carb) and delta O-18(carb) values suggest that they might have been influenced by diagenesis. However, the delta C-13(org) record preserves multiple carbon-isotope excursions across the Alaunian-Sevatian boundary that can be correlated with other coeval global sections. The carbon-isotope excursions registered at this middle-upper Norian boundary are perhaps related to the major outgassing of light carbon during the emplacement of Angayucham flood basalts.

The application of Ground Penetrating Radar (GPR) prospecting to the search of fossil structures, particularly using advanced techniques like Finite-difference time-domain (FDTD) modelling and GPR attribute analysis, is currently poorly exploited in paleontology. Here, we promote the use of such a GPR workflow at Bargiano (Umbria, central Italy), a unique paleontological site known for the discovery of cetacean skeletons, dolomitized sperm-whale cololites (Ambergrisichnu salleronae), and layered fossil assemblages. The study site is characterized by a very uneven topography shaping highly conductive clayey deposits, representing not exactly ideal conditions for GPR surveying. After generating models encompassing a real topography and variable electrical properties of media, we simulated buried fossil structures at variable depth with different size and geometry, using different operative frequencies. After obtaining information on the characteristics of reflections, investigation depth, and detectability, we provide a comparison with experimental data, also used to compute instantaneous amplitude and phase attributes. Upon depicting a peculiar GPR signature for our targets, we discuss the results in light of ground-truthing performed through trenching. Our workflow allowed us to restrict the excavation areas, extending the surface information in depth in a non-invasive way, and optimizing the field operations, necessary for the preservation of the study site.

Two significant stratigraphical microfossils, conodonts and radiolarians, are usually used for the Upper Triassic chronostratigraphy. The Baoshan Block was located in eastern Tethys during the Late Triassic where the biostratigraphical data of Upper Triassic are still poorly known. We collected new samples from the Hongyan section (HY) for biostratigraphical study. This 24-m-thick section in Dabaozi Village, Baoshan City, is mainly composed of thin-layered limestones, sandstone and siltstone. The conodont fauna is referred to Sevatian 1 (late Norian), in which the speciesMockina englandi,Mockina carinata and Mockina mosherimorphotype B are first recognized in the Baoshan Block, and thus eastern Tethys. The Norian radiolarian associations are first reported in the Baoshan Block, which correlate with the biozonation of North America and also that proposed for Central Japan. The radiolarian assemblages found in the analysed samples in HY section can be referred to the SevatianBetraccium deweveriZone. The Baoshan Block is a key area for conodont and radiolarian-based correlations between the Tethys, Japan and North American domains.

The Global Boundary Stratotype Section and Point (GSSP) of the Jurassic–Cretaceous boundary (JKB) is the last among the GSSPs in the Phanerozoic to be chosen. The Berriasian Working Group of the International Subcommission on Cretaceous Stratigraphy decided in 2016 to use the base of the Calpionella alpina Subzone as the primary marker for the formal definition of the JKB. This definition is satisfactorily applicable for near continent, shallow offshore deposits within the Western Tethys, North Atlantic and central-south America. Unfortunately, the primary marker taxon cannot be found in the Pacific and circum-Pacific regions since the distribution of calpionellids is limited to the Western Tethys and neighboring regions. Radiolarians are good candidates for defining the JKB, because they are widespread and can be found both in shallow and deep pelagic sedimentary facies worldwide. We carried out detailed field observations and careful sample collections in a 5-m thick interval around the JKB in the Bosso Valley section (Northern Apennines), which is one of potential candidates for GSSP of the JKB. The Maiolica Formation, which includes the JKB, is characterized by white to light gray, well-bedded micritic limestones with abundant light gray to black chert layers and nodules. In this study, after selection of samples acid-etched in the field, we observed the etched surface with a scanning electron microscope in the laboratory. Our detailed observations revealed that both micritic limestone and chert generally contain abundant radiolarian tests. Most of them in limestones are replaced by calcite, so that it is impossible to isolate radiolarian tests from rock samples with acid treatment. On the other hand, radiolarian tests within chert layers or nodules are too recrystallized to preserve their original surface ornamentation. The best preserved radiolarian tests are included in micritic limestone near chert layer or nodules. Careful and systematic sampling enabled us to get enough material to establish phylogenetic analysis on radiolarians.

Comparison of radiolarian assemblages from marls in the Gorgo a Cerbara section in the Umbria-Marche Basin in central Italy and a siliceous sequence (BB1 section) near Babazhadong in southern Tibet indicates similar faunas comparable to those in the Aurisaturnalis carinatus zone and the Turbocapsula costata zone. Several significant species, Archaeodictyomitra lacrimula (Foreman), A. excellens (Tan Sin Hok), Dictyomitra communis (Squinabol), and Aurisaturnalis carinatus perforatus Dumitrica and Dumitrica-Jud, which are common in older strata, make their last occurrences near the base of the Turbocapsula costata zone in these two areas. Comparison with the Gorgo a Cerbara section provides an accurate age constraint for the siliceous succession in southern Tibet, which contains no fossils other than radiolarians. The comparison indicates a close connection between the western and eastern Tethys during the Barremian to early Aptian. The correlation testifies that the radiolarian zonation in southern Tibet is applicable for the whole Tethys. The siliceous succession in BB1 section encompasses the early Aptian Oceanic Anoxic Event 1a (OAE 1a). The early Aptian OAE 1a is located in the upper part of the Aurisaturnalis carinatus perforatus subzone. The first occurrence biohorizon of the genus Turbocapsula and the evolutionary first appearance biohorizon of T. costata costata (Wu) are useful markers for constraining the OAE 1a in the Tethys. (C) 2019 Elsevier Ltd. All rights reserved.

The latest Triassic was an interval of prolonged biotic extinction culminating in the end-Triassic Extinction (ETE). The ETE is now associated with a perturbation of the global carbon cycle just before the end of the Triassic that has been attributed to the extensive volcanism of the Circum-Atlantic Magmatic Province (CAMP). However, we attribute the onset of declining latest Triassic diversity to an older perturbation of the carbon cycle (δ13Corg) of global extent at or very close to the Norian/Rhaetian boundary (NRB). The NRB appears to be the culmination of stepwise biotic turnovers that characterize the latest Triassic and includes global extinctions of significant marine and terrestrial fossil groups. These biotic events across the NRB have been largely under-appreciated, yet together with a coeval disturbance of the carbon cycle were pivotal in the history of the Late Triassic. Here, we present new and published δ13Corg data from widespread sections (Italy, Greece, ODP, Australia, New Zealand, USA, Canada). These sections document a previously unknown perturbation in the carbon cycle of global extent that spanned the NRB. The disturbance extended across the Panthalassa Ocean to both sides of the Pangaean supercontinent and is recorded in both the Northern and Southern Hemispheres. The onset of stepwise Late Triassic extinctions coincides with carbon perturbation (δ13Corg) at the NRB, indicating that a combination of climatic and environmental changes impacted the biota at a global scale. The NRB event may have been triggered either by gas emissions from the eruption of a large igneous province pre-dating the NRB, by a bolide impact of significant size or by some alternative source of greenhouse gas emissions. As yet, it has not been possible to clearly determine which of these trigger scenarios was responsible; the evidence is insufficient to decisively identify the causal mechanism and merits further study.