On the onset of Central Atlantic Magmatic Province (CAMP) volcanism, and environmental and carbon-cycle change at the Triassic–Jurassic transition (Neuquén Basin, Argentina)

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThe Triassic–Jurassic transition is characterized by the end-Triassic mass extinction approximately synchronous with the onset of emplacement of the Central Atlantic Magmatic Province (CAMP), and associated with a major negative carbon-isotope excursion (CIE) affecting the ocean–atmosphere system. Here, we present new data (total organic carbon, pyrolysis analysis, carbon-isotopes from bulk organic matter, elemental mercury, and other elemental contents) from a southern-hemisphere Triassic–Jurassic boundary succession in the Neuquén Basin, Argentina. The end-Triassic mass extinction there coincides with a relatively small (2–3‰) negative CIE in bulk organic matter, and we present a model that suggests that extreme aridity across the western Pangaean landmass may have resulted in rather limited terrestrial organic-matter flux to the sedimentary realm in eastern Panthalassic marine basins, hypothetically reducing the magnitude of the observed negative CIE in δ13CTOC. Increased deposition of sedimentary Hg (and Hg/TOC and Hg/Zr) in the marine Neuquén Basin began stratigraphically before the negative CIE associated with the end-Triassic mass extinction, and thus before the commencement, in North America and Africa, of CAMP-related basaltic volcanism, but possibly coinciding with the early emplacement of CAMP-associated intrusives (dykes and sills). This relative chronology suggests thermal alteration of intruded country rocks and/or intrusive magmatic degassing of Hg as potential major sources of elevated Hg fluxes to the atmosphere at this time. The Neuquén Basin experienced the development of dysoxic–anoxic marine conditions across the Triassic–Jurassic transition, enabling increased preservation of organic matter. Simple mass-balance calculations show that enhanced carbon burial rates can explain the inferred evolution of the global exogenic carbon cycle across this time-interval.Natural Environment Research Council (NERC)University of OxfordShell International Exploration and Production BVCONICET (National Research Council of Argentina

New age constraints on the Lower Jurassic Pliensbachian-Toarcian Boundary at Chacay Melehue (Neuquén Basin, Argentina)

This is the final version. Available on open access from Nature Research via the DOI in this recordThe Pliensbachian-Toarcian boundary interval is characterized by a ~ 3‰ negative carbon-isotope excursion (CIE) in organic and inorganic marine and terrestrial archives from sections in Europe, such as Peniche (Portugal) and Hawsker Bottoms, Yorkshire (UK). A new high-resolution organic-carbon isotope record, illustrating the same chemostratigraphic feature, is presented from the Southern Hemisphere Arroyo Chacay Melehue section, Chos Malal, Argentina, corroborating the global significance of this disturbance to the carbon cycle. The negative carbon-isotope excursion, mercury and organic-matter enrichment are accompanied by high-resolution ammonite and nannofossil biostratigraphy together with U-Pb CA-ID-TIMS geochronology derived from intercalated volcanic ash beds. A new age of ~ 183.73 + 0.35/- 0.50 Ma for the Pliensbachian-Toarcian boundary, and 182.77 + 0.11/- 0.15 for the tenuicostatum-serpentinum zonal boundary, is assigned based on high-precision U-Pb zircon geochronology and a Bayesian Markov chain Monte Carlo (MCMC) stratigraphic age model.Scholarship Coordination Office, Abu Dhabi, United Arab EmiratesKhalifa UniversityShell International Exploration & Production B.V.Natural Environment Research Council (NERC)NIGFS

Cervical lymph node metastasis in adenoid cystic carcinoma of the larynx: a collective international review

Adenoid cystic carcinoma (AdCC) of the head and neck is a well-recognized pathologic entity that rarely occurs in the larynx. Although the 5-year locoregional control rates are high, distant metastasis has a tendency to appear more than 5 years post treatment. Because AdCC of the larynx is uncommon, it is difficult to standardize a treatment protocol. One of the controversial points is the decision whether or not to perform an elective neck dissection on these patients. Because there is contradictory information about this issue, we have critically reviewed the literature from 1912 to 2015 on all reported cases of AdCC of the larynx in order to clarify this issue. During the most recent period of our review (1991-2015) with a more exact diagnosis of the tumor histology, 142 cases were observed of AdCC of the larynx, of which 91 patients had data pertaining to lymph node status. Eleven of the 91 patients (12.1%) had nodal metastasis and, based on this low proportion of patients, routine elective neck dissection is therefore not recommended

Initial results of coring at Prees, Cheshire Basin, UK (ICDP JET project): towards an integrated stratigraphy, timescale, and Earth system understanding for the Early Jurassic

This is the final version. Available on open access from Copernicus Publications via the DOI in this recordData availability: Full core scan data (https://doi.org/10.5285/91392f09-25d4-454c-aece-56bde0dbf3ba, BGS Core Scanning Facility, 2022) will be available after 1 November 2024 via the Natural Environment Research Council (NERC) National Geoscience Data Centre (https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#, last access: 12 October 2023). Downhole logging data (https://doi.org/10.5880/ICDP.5065.001​​​​​​​, Wonik, 2023) will be made available via the ICDP (https://www.icdp-online.org/projects/by-continent/europe/jet-uk/, last access: 12 October 2023). The JET Operational Report is published as Hesselbo et al. (2023); full information about the operational dataset, the logging dataset, data availability and the explanatory remarks is available on the ICPD-JET project website: https://www.icdp-online.org/projects/by-continent/europe/jet-uk/ (last access: 12 October 2023). A subset of data, additional biostratigraphic tables, and vector graphics files for Figs. 3–5 are included as the Supplement. Supplementary Data File 1 tabulates the corrected depth scale for Prees 2C. Supplementary Data File 2 summarizes the ammonite-based chronostratigraphy of the Prees 2 cores (ammonite identifications by Kevin N. Page). Supplementary Data File 3 summarizes the ammonite-based chronostratigraphy for the Hettangian to Early Pliensbachian of the Llanbedr (Mochras Farm) borehole (updated by Kevin N. Page). Supplementary Data File 4 tabulates the organic carbon-isotope ratios, TOC, and carbonate content of low-resolution samples taken at the Prees drill site; TOC and carbonate data are calculated using calibration based on portable XRF (Supplementary Data File 5) and a gas source isotope ratio mass spectrometer (Supplementary Data File 6). Supplementary Data File 5 tabulates portable XRF results for bulk rock powders of low-resolution samples taken at the Prees drill site; uncertainties stated in the table are given for the fit to the raw data and do not reflect the true reproducibility of the data. Empty fields indicate values under the detection limit. Sample SSK116001 acted as a repeat sample which was measured 70 times over the course of the data acquisition to determine the repeatability and drift of the instrument. LE stands for “light elements”. Supplementary Data File 6 tabulates gas source isotope ratio mass spectrometry (GS-IRMS) data (oxygen- and carbon-isotope ratios of carbonate as well as carbonate content calculated as calcite) for a set of 24 samples covering the entire core length and reflecting a representative spread of carbonate content. Comparison of GS-IRMS data with p-XRF data was used to create a calibration curve to calculate the carbonate (and TOC) content of all low-resolution samples. Supplementary Data File 7 tabulates pyrolysis data (Rock-Eval 6) for Prees 1 well cuttings and Wilkesley borehole samples. Supplementary Data File 8 contains vector graphics files (.svg) for Figs. 3–5.Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian–Triassic half-graben system of the Cheshire Basin. The borehole is located to recover an expanded and complete succession to complement the legacy core from the Llanbedr (Mochras Farm) borehole drilled through 1967–1969 on the edge of the Cardigan Bay Basin, North Wales. The overall aim of the project is to construct an astronomically calibrated integrated timescale for the Early Jurassic and to provide insights into the operation of the Early Jurassic Earth system. Core of Quaternary age cover and Early Jurassic mudstone was obtained from two shallow partially cored geotechnical holes (Prees 2A to 32.2 m below surface (m b.s.) and Prees 2B to 37.0 m b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32 m (corrected core depth scale). Core recovery was 99.7 % for Prees 2C. The ages of the recovered stratigraphy range from the Late Triassic (probably Rhaetian) to the Early Jurassic, Early Pliensbachian (Ibex Ammonoid Chronozone). All ammonoid chronozones have been identified for the drilled Early Jurassic strata. The full lithological succession comprises the Branscombe Mudstone and Blue Anchor formations of the Mercia Mudstone Group, the Westbury and Lilstock formations of the Penarth Group, and the Redcar Mudstone Formation of the Lias Group. A distinct interval of siltstone is recognized within the Late Sinemurian of the Redcar Mudstone Formation, and the name “Prees Siltstone Member” is proposed. Depositional environments range from playa lake in the Late Triassic to distal offshore marine in the Early Jurassic. Initial datasets compiled from the core include radiography, natural gamma ray, density, magnetic susceptibility, and X-ray fluorescence (XRF). A full suite of downhole logs was also run. Intervals of organic carbon enrichment occur in the Rhaetian (Late Triassic) Westbury Formation and in the earliest Hettangian and earliest Pliensbachian strata of the Redcar Mudstone Formation, where up to 4 % total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1 % TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of ∼ 1 m, and these provide the basis for detailed correlation between the Prees 2 succession and adjacent boreholes and Global Stratotype Section and Point (GSSP) outcrops. Multiple complementary studies are currently underway and preliminary results promise an astronomically calibrated biostratigraphy, magnetostratigraphy, and chemostratigraphy for the combined Prees and Mochras successions as well as insights into the dynamics of background processes and major palaeo-environmental changes.ICDPNatural Environment Research Council (NERC)German Research FoundationHungarian Scientific Research FundNational Science Centre, PolandPolish Geological Institut

First record of the Early Toarcian Oceanic Anoxic Event from the Southern Hemisphere, Neuquen Basin, Argentina

The first record of the Early Toarcian Oceanic Anoxic Event (c. 183 Ma) from the Southern Hemisphere is described from the Neuquén Basin, Argentina, identified chemostratigraphically on the basis of a relative increase in marine organic carbon and a characteristic negative carbon-isotope excursion (δ13Corg) in bulk rock and fossil wood. The negative excursion of -6‰ in bulk organic carbon (falling to -31.3‰) crosses the boundary of the tenuicostatum-hoelderi Andean ammonite Zones, equivalent to the tenuicostatum-falciferum/serpentinum zones of Europe. These data indicate that the Early Toarcian Oceanic Anoxic Event was a global phenomenon. © 2010 Geological Society of London

On the onset of Central Atlantic Magmatic Province (CAMP) volcanism and environmental and carbon-cycle change at the Triassic–Jurassic transition (Neuquén Basin, Argentina)

The Triassic–Jurassic transition is characterized by the end-Triassic mass extinction approximately synchronous with the onset of emplacement of the Central Atlantic Magmatic Province (CAMP), and associated with a major negative carbon-isotope excursion (CIE) affecting the ocean–atmosphere system. Here, we present new data (total organic carbon, pyrolysis analysis, carbon-isotopes from bulk organic matter, elemental mercury, and other elemental contents) from a southern-hemisphere Triassic–Jurassic boundary succession in the Neuquén Basin, Argentina. The end-Triassic mass extinction there coincides with a relatively small (2–3‰) negative CIE in bulk organic matter, and we present a model that suggests that extreme aridity across the western Pangaean landmass may have resulted in rather limited terrestrial organic-matter flux to the sedimentary realm in eastern Panthalassic marine basins, hypothetically reducing the magnitude of the observed negative CIE in δ13CTOC. Increased deposition of sedimentary Hg (and Hg/TOC and Hg/Zr) in the marine Neuquén Basin began stratigraphically before the negative CIE associated with the end-Triassic mass extinction, and thus before the commencement, in North America and Africa, of CAMP-related basaltic volcanism, but possibly coinciding with the early emplacement of CAMP-associated intrusives (dykes and sills). This relative chronology suggests thermal alteration of intruded country rocks and/or intrusive magmatic degassing of Hg as potential major sources of elevated Hg fluxes to the atmosphere at this time. The Neuquén Basin experienced the development of dysoxic–anoxic marine conditions across the Triassic–Jurassic transition, enabling increased preservation of organic matter. Simple mass-balance calculations show that enhanced carbon burial rates can explain the inferred evolution of the global exogenic carbon cycle across this time-interval

Ecological signature of the end-Triassic biotic crisis: what do bivalves have to say?

In order to understand the causes underlying the Triassic-Jurassic (T/J) mass extinction, we tested different bivalve features for extinction selectivity, i.e. shell mineralogy, age at the Rhaetian and three main autoecologic traits (feeding mechanism, tiering and motility/attachment). Also, diversity and turnover rates throughout the Triassic and the Early Jurassic were analysed in detail. The dataset employed for this analysis was a precise database at genus level including data from Induan to Sinemurian times. Results point to a true mass extinction for bivalves around the T/J boundary. This extinction was not ageselective at the boundary. Certain analyses suggested that shell mineralogy was a character significantly increasing survival odds, but this relationship seems to reflect selectivity on autoecologic traits. There was no difference in extinction proportions between both feeding types (i.e. deposit feeders and filter feeders); among the other traits, deep burrowers, epifaunal-motile and endobyssate forms seem to have been favoured, while shallow burrowers (and probably reclined forms) were more heavily affected. This pattern suggests an environmental stress at the boundary with some particular issues affecting the different life modes. Models linking magmatism in the Central Atlantic Magmatic Province with the end- Triassic mass extinction are a plausible scenario for this kind of perturbation