Volcanism from large igneous provinces leads to increases in the Earth’s surface temperature and acidity, thus triggering mass extinction events. However, the dependence of acidity on latitudinal position has remained underexplored and is key to better understand, and react to, global environmental changes today. Here, we study biotic recovery after the catastrophic end-Permian mass extinction, in Early Triassic continental environments. We quantify strontium-rich hydrated aluminum phosphate-sulfate minerals in 179 samples from tropical to circumpolar paleolatitudes in both hemispheres. We provide evidence that latitude controls acidity and its impact on biotic recovery. Subequatorial latitudes concentrate volcanic aerosols through wind circulation patterns, enhancing the impact of acidity on the environment. In contrast, high latitudes provide refuge against environmental change, hosting accelerated recovery after the end-Permian biotic crisis.

Jamoytius kerwoodi, is a primitive, eel-like jawless vertebrate found uniquely in an Early Silurian (Llandovery epoch; 444–433 Ma) horizon near Lesmahagow, Scotland. This species is a rare component of a low-diversity dominantly nektonic detritus-feeding and herbivorous fauna living over an anoxic bottom and is found at the transition from a marine-influenced, probably brackish-water, deep-water basin to a shallower-water, less saline and likely freshwater basin. In the absence of true teeth, Jamoytius was probably a detritivore or herbivore feeding on Dictyocaris. Jamoytius may have a common ancestor with living lampreys, especially as their ectoparasitic mode of life might have evolved from ancestral detritivores or herbivores.

The Slate Islands (Ontario) is one of Canada's larger impact structures at 32 km in diameter and has been linked to the Ordovician meteorite event (OME). We report zircon U-Pb dates from two suevite and two syenite samples collected from the Slate Islands. Plagioclase 40Ar/39Ar dates were also obtained from one of the samples. The plagioclase and most zircon dates record pre-impact ages with links to known tectonic events, including those associated with the assembly of the Superior Craton at approximately 2700 Ma. However, Neoarchean zircon grains appear to be reset at 456.1 +/- 6.9 Ma (+/- 2 sigma) based on the lower intercept of discordia for all dated samples. The date overlaps its previously accepted age of 450 Ma and would be 2-19 million years following the parent asteroid breakup if related to the OME.

On Kerrera island, poorly dated braided stream conglomerates and sandstones are interbedded with finer lake siltstones and shales, with land plants, fish and arthropods, including 'millipedes'. Crystallization dates for minerals in the overlying Lorne Plateau Lave are older than 425 Ma (Upper Silurian Ludfordian), yet palynological data are supposed to give an early Devonian (419 Ma) age. Detrital zircon U/Pb dates of sediments enclosing the fish beds give two clusters of dates, one Proterozoic and the other Silurian. The most concordant youngest single grain date of 427.0 +/- 4.5 Ma (0% discordance) gives the maximum age of the Fish beds and is consistent that the radiometric dates of the overlying rapidly erupted lavas. This maximum age is slightly older than that of the 'millipede'-bearing Cowie fish bed with maximum age of 414.3 +/- 7.1 Ma, which make the Kerrera 'millipedes' the oldest so far dated.

The emergence of vascular plants, such as Cooksonia, had a profound impact on Earth's Early Paleozoic biogeochemical cycles (e.g. atmospheric oxygen, nitrogen and CO2), potentially triggering global environmental and biological changes. However, the timing of Cooksonia's terrestrial emergence remains elusive as phylogenetic models, microfossils and macrofossils provide different timings for land colonization by vascular plants. Here, hundreds of zircon grains from three siltstones were dated using Laser Ablation-Inductively Couple Plasma-Mass Spectrometry (LA-ICP-MS). The study presents detrital zircon U-Pb dates, which refine the current biostratigraphy ages assigned to Cooksonia macrofossils from the three oldest sites globally. Specifically, siltstones hosting Cooksonia macrofossils from Borrisnoe Mountain (Ireland) and Capel Horeb (Wales) yield Gorstian-Homerian maximum depositional ages (MDAs) of 426 +/- 2 Ma and 427 +/- 2 Ma, respectively. Additionally, Cwm Graig Ddu (Wales) yields a (Pridoli-Ludlow) maximum age of 423 +/- 3 Ma. The findings provide the first detrital zircon U-Pb dates for the oldest Cooksonia macrofossils globally and contribute crucial maximum ages. These maximum ages are instrumental in refining future calibrations of molecular clocks and improving phylogenetic models, thus contributing significantly to a better understanding of Cooksonia's evolutionary history, including its environmental and ecological impacts.

Jamoytius kerwoodi was a primitive, eel‐like jawless fish that lived in the Early Silurian period (444–433 myr) and lived over a stagnant bottom environment, at the transition from a marine‐influenced, probably brackish‐water, deep‐water basin to a shallower water, less saline and probably freshwater basin. Jamoytius lacked teeth and was most likely a free‐living herbivore grazing on floating plants, as were possibly many of its euphanaropid relatives. The palaeoenvironment in which it lived compares well with that of living lampreys, especially as their ectoparasitic mode of life may have evolved from ancestral grazers.

The pre-Hirnantian glaciation Katian Lower Hartfell siltstones were deposited in deep quiet water, comparable to those of the Ulleung basin of the Japan Sea, which suggests, together with the likely paleogeographic position, that Hartfell was on the landward side of a back arc basin. The major element/Al ratios do not vary much up the section and indicate a dominantly continental source, with predominantly physical weathering, but with chemical weathering during transport to the final site of deposition. The abundant quartz silt indicates significant eolian transport. Climate may have changed from hot and arid to hot and humid from the lower to the upper part of the Hartfell siltstones, with possibly an increase in surface water temperature from 25 o C to 50 o C. Salinity is assumed to be normal marine based on the fauna, despite the freshwater indicated by trace element ratios. Relative paleoproductivity changes suggest a slight fluctuating decrease in productivity from the wilsoni to the linearis zones. The actual productivity seems low compared with the Ulleung basin and very low compared with younger Hirnantian black shales. Overall, the redox sensitive trace elements and ratios suggest that the Hartfell sediments started oxic, became dysoxic to anoxic, and then returned to oxic.

The eastern Great Lakes Late Quaternary timescale is based on older thermoluminescence dates and on uncalibrated radiocarbon dates from extensive sections along the north shores of Lakes Erie and Ontario. New optically stimulated luminescence dates from Late Quaternary delta sediments from the north shores of Lake Erie at Sand Hills Park give consistent ages of 23.5 to 20.5 ka. This is 4 to 7 ka older than previously assigned based on lithologic correlation with 16.5 ka calibrated radiocarbon dated sediments 5 km to the west at Vanderven. On the existing eastern Great Lakes stratigraphy, it puts deposition of these Sand Hills Park sediments in the Erie interstadial and not in the fluctuating postglacial glacial retreat of the Mackinaw phase to which the Vanderven sediments belong. The Sand Hills delta and underlying diamicts must have been overridden by the Porty Bruce advance at 18 ka. IntCal20 calibration of existing radiocarbon ages suggests that the physical stratigraphic relations of the various Wisconsin units are accurate and that the existing timescale is simply too young.

AbstractSedimentary rocks exposed at Dob’s Linn, Scotland, have significantly influenced our understanding of how life evolved over the Ordovician to Early Silurian. The current interpreted chronostratigraphic boundary between the Ordovician and Silurian periods is a Global Boundary Stratotype Section and Point (GSSP), calibrated to 443.8 ± 1.5 Ma (Hirnatian–Rhuddanian age), based on biostratigraphic markers, radioisotopic dates and statistical modelling. However, challenges arise due to tectonic disturbances, complex correlation issues and the lack of systematic dating in Ordovician–Silurian stratigraphic sections. Here, hundreds of zircon grains from three metabentonite ash horizons were dated using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). A subset of the grains were re-analyzed using Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS). We present a high-precision CA-ID-TIMS 238U-206Pb weighted mean date of 440.44 ± 0.55/0.56/0.72 Ma (±analytical/with tracer/with U-decay constant) for the Coronagraptus cyphus biozone. However, the study reports younger, and in certain cases, older LA-ICP-MS zircon dates within the Coronagraptus cyphus, Akidograptus ascensus and Dicellograptus anceps zones, suspected as being influenced by Pb loss and LA-ICP-MS matrix mismatch. The study reports concerns about the suitability of Dob’s Linn as a GSSP section and examines various LA-ICP-MS maximum depositional age (MDA) approaches, suggesting the use of the TuffZirc date and the youngest mode weighted mean (YMWM) as suitable MDA calculations consistent with CA-ID-TIMS results.

AbstractThe Shyok Suture Zone is an oceanic remnant of the Neo-Tethyan ocean sandwiched between the Ladakh Batholiths to the south and Karakoram Batholith to the north. The Tirit granitoids in this suture are dark-coloured, relatively rich in ferromagnesian minerals and range from granodiorite–tonalite to gabbro–diorite in composition. Mafic igneous enclaves are quite common and they are intruded by NW–SE parallel doleritic and aplitic dykes. The Tirit granitoids have a wide range of major oxide compositions (SiO2 = 52.1–72.11 wt %, TiO2 = 0.21–1.23 wt %, Al2O3 = 11.42–13.52 wt %, MgO = 1.69–10.69 wt % and CaO = 3.24–9.31 wt %) and show calc-alkaline, metaluminous, I-type characteristics, transitional between primitive and mature arc continental plutons. Rare earth elements (REE) show considerable enrichment in light REE (LREE) as compared to the heavy REE (HREE). Late Cretaceous U/Pb dates (74–68 Ma) show that they formed during the pre-collision northward movement of India. The Tirit dykes are only slightly younger and probably part of the same episode.

Abstract The Permian–Triassic boundary sediments at Ursula Creek accumulated in a continental shelf basin, or on the continental slope of the western Canadian passive margin, at 30°N palaeolatitude along the eastern Panthalassic Ocean margin. The area lay within the cold northerly ocean currents at the junction of westerly and north‐easterly trade wind belts, the latter causing summer coastal upwelling. The shift from uppermost Permian grey radiolarian cherts and grey shales to lowermost Triassic grey and black shales and fine‐grained dolomites is typical of deep‐water Panthalassic sediments. The palaeogeographical situation and palaeoenvironments are comparable to those of the present Canadian north‐western Pacific margin. The Ursula Creek section reveals the progressive decline of seafloor oxygen values in the Changhsingian Stage), followed by the persistent development of euxinic conditions in the latest Changhsingian and throughout the Early Triassic; a transition that coincides with the disappearance of a siliceous sponge fauna and the loss of diverse radiolarian populations. Much of the detrital sediment was supplied by summer north‐east Trade winds from the deserts of western North America, although variable amounts may have come across the Panthalassic Ocean as dust from contemporary volcanic eruptions. Relative palaeoproductivity changes show no consistent change in productivity across the Permian–Triassic boundary producing results that are comparable with those from the similar Opal Creek section to the south‐east. The Ni/Co, Cu/Zn, U/Al and Th/U ratios indicate variable redox conditions in all sections, but with a tendency for oxic conditions to change to dysoxic across the Permian–Triassic boundary. The lack of consistent element geochemical changes across the boundary accompanied by significant isotopic changes, here and elsewhere, suggests that atmospheric and oceanic chemistry rather than physical changes, like provenance and sea‐level changes, drove Permian–Triassic environmental changes and extinctions.

The eastern Great Lakes late Quaternary time-scale is based on extensive sections along the north shores of Lake Erie and Ontario, and on older Optically Stimulated Luminescence (OSL) dates and on uncalibrated radiocarbon dates. New OSL dates from late Quaternary delta sands on Lake Erie give a consistent age of around 24 ka. This is 12 ka older than previously assigned based on lithological correlation with radiocarbon dated sediments 5 km to the west. On the existing eastern Great Lakes stratigraphy, it puts deposition of these delta sands in the early glacial advance of the Nissouri stadial and not in the fluctuating postglacial glacial retreat of the Mackinaw phase. IntCal20 calibration of existing radiocarbon dates and re-interpretation of exiting thermoluminescence dates, however, suggest that the stratigraphic relations of the various Quaternary units are accurate and that the existing time scale is simply too young. Our OSL dating also illustrates that inferring sediment ages from lithological correlations of dated Quaternary units with supposed equivalents is unsafe. Comprehensive OSL dating is needed to establish an accurate Quaternary stratigraphy for the classic large and extensive exposures along the north shores of lakes Erie and Ontario.

Dob’s Linn (Scotland) is a location that has significantly influenced our understanding of how life evolved over the Ordovician to early Silurian. The current chronostratigraphic boundary between the Ordovician and Silurian periods is a Global Boundary Stratotype Section and Point (GSSP) at Dob’s Linn calibrated to 443.8±1.5 Ma, partly based on biostratigraphic markers, radiometric ages, and statistical modeling. Graptolites are used here as relative dating markers. We dated hundreds of zircon grains extracted from defined metabentonites from six horizons exposed at Dob’s Linn using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Each zircon was imaged using cathodoluminescence, and most show igneous zoning with minimal alteration. Sample locations range from 42 meters above to 5 meters below the recognized GSSP for the Ordovician-Silurian. Samples were responsibly collected and analyzed for paleontology and geochemistry in other work. Overall, many 238U-206Pb zircon ages from the section are significantly younger than expected. The youngest zircon in sample DL7, located 5 meters below the GSSP, yielded a 238U-206Pb age of 402±12 Ma (±2s, 5% disc). Nineteen spots on zircons from this sample are younger than the presently assigned GSSP age, including more concordant results of 426±8 Ma (0.8% disc) and 435±5 Ma (0.2% disc). The youngest zircon in sample 19DL12, < 1 m below the GSSP, is 377±8 Ma (2% disc) with a more concordant age of 443±7 Ma (0.6% disc). A sample located directly on the GSSP (19DL09) yields 327±5 Ma (0.8% disc). Eight spots on zircons from this sample are also younger than the presently assigned GSSP age. We also dated two samples (DL24 and BRS23) 8 meters above the GSSP, and the youngest, most concordant zircon ages in these samples are 400±11 Ma (5% disc) and 421±9 Ma (0.4% disc), respectively. Overall, the U-Pb ages would re-assign the Dob’s Linn chronostratigraphic section to Silurian-Devonian. The young age results could be attributed to Pb loss due to hydrothermal alteration during the Acadian and Alleghenian orogenies. Future work will implement Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS) to obtain accurate U-Pb dating and evaluate the potential effects of Pb loss.

In contrast to the ‘propaganda’ of the currently dominant vertebrates (i.e. us), arthropods not amphibians were the first land animals. And like many another great advance, they first appeared in Scotland. The first land animals were ‘millipedes’, which evolved with the first true land plants at the edges of Scottish mountain lakes about 425 Ma. From then on, more elaborate and complex plant‐arthropod land communities evolved incredibly rapidly, and spread to lowland marshes, taking only 40 Myr to reach complex forest grade communities by 385 Ma. We recently dated some of the sediments enclosing these fossils to give a more precise age for the communities, a study still in progress, which indicates that the oldest land animal is a ‘millipede’ from Kerrera, Oban, Scotland.

In one of the most extended Permo-Triassic (PTr) boundary sections at Guryul Ravine (Kashmir), both carbon and oxygen isotopes show no marked trend across the boundary, but do show zigzag variations at a scale not seen above and below. These are interpreted as major short-term variations in biological storage of carbon (delta C-13(carb)), temperature (delta 18Ocarb), and land/ocean carbon mixing (delta C-13(org)) which also occur in other sections with the required detail of analysis. Oxygen isotopes, though probably altered show that relative sea surface temperatures fluctuated greatly at Guryul Ravine; if unaltered they fluctuated between 22 degrees C and 42 degrees C, using a salinity stratified model for the partially enclosed PTr Neotethys Ocean, about the same range as at Meishan and Shangsi in China at lower equatorial latitudes. Together with the carbonate isotopes, this suggests large fluctuations in climate and terrestrial biomass from the latest Permian event horizons to the fossil-defined base of the Triassic which lasted, on current estimates about 60 +/- 48 ka, and, by analogy with Quaternary studies, fit a 100kyr eccentricity cycle, with the main end Permian extinction occurring within the cycle. The lack of consistent element geochemical changes across the boundary accompanied by significant carbon, sulphur, and other isotopic changes, here and elsewhere, suggests that atmospheric and oceanic chemistry rather than physical changes, such as provenance and sea-level changes, drove the PTr environmental changes and extinctions at least on the mid-latitude Tethyan shelf of northern India.

Carbon and oxygen isotopes of both well-preserved articulate brachiopod Paucicrura rogata and cement in mid-Cincinnatian samples (Maysvillian to early Richmondian) on the eastern North American passive margin shelf in SW Ontario show no simple relationships. The delta C-13 trends of the brachiopods, organic matter and cements are little altered and vary little up section. The brachiopod delta C-13(brach) pattern is very close to the American mid-continent whole rock delta C-13(WRcarb) pattern across the Fairview excursions. The delta O-18(brach) variations, if primary, indicate fluctuating but generally slightly cooling temperatures upwards, though the actual temperatures depend on inferred salinities of the seawater. The temperature/ salinity relationships variations are compatible with the warm deep saline water hypothesis. The paleoceanography shows a change from a warm open passive carbonate margin to a fluctuating warmer/cooler enclosed clastic marginal basin with freshwater input, heralding the cold conditions of the Hirnantian ice age. The Milankovitch cyclicity determined from delta C-13(carb) patterns, is practically identical to that from determined from magnetic intensities on the contemporary Yangtse Shelf.

The Bálvány North Permian-Triassic boundary sediments were deposited on a carbonate platform in the tropical part of the western PaleoTethys ocean. The overall elemental geochemistry of the detailed two-metre-thick sec-tion across the boundary that we studied shows that the clastic content of the sediments came from dominantly silica-rich continental sources though with some more silica-poor inputs in the uppermost Permian and lowest Triassic limestones as shown by Ni/Al and Nb/Ta ratios. These inputs bracket, but do not coincide with, the main extinctions and associated C, O and S changes. Increased aridity at the Permian-Triassic boundary with in-creased wind abrasion of suitable Ti-bearing heavy minerals accounts for both the high Ti/Al and Ti/Zr ratios. Var-ious geochemical redox proxies suggest mainly oxic depositional conditions, with episodes of anoxia, but with little systematic variation across the Permian–Triassic extinction boundary. The lack of consistent element geo-chemical changes across the Permian-Triassic boundary occur not only in adjacent shallower-water marine sec-tions, and in other marine sections along the SW Tethys margin such as the Salt Range sections in Pakistan, but also in deeper shelf and oceanic sections, and in non-marine African and European continental sediments. In the absence of significant changes in physical environments, chemical changes in the atmosphere and oceans, reflected in various isotopic changes, drove the Permian–Triassic extinctions.

The Brsnina Permian–Triassic nearshore marine sediments were deposited on the Adria carbonate platform in tropical latitudes at the western end of the Neotethys Ocean. Continuous channel samples across the boundary show no consistent change in element or element/Al ratios, except that most element/Al ratios increase in the top 0.5 m of the Permian strata. Though there are sporadic higher values of some element/element ratios, such as Ti/Zr, Th/Sc, Zr/Sc, Cr/Ni, Y/Ni, Co/Th, Cu/Zn, and Nb/Ta, La/Sc, the overall geochemistry indicates that the sediments were derived from dominantly silica-rich continental rather than silica-poor sources though with some more silica-poor inputs at times. Sporadic high Ti/Zr ratios indicate periods of increased aridity, but no overall increase across the boundary. Various geochemical redox proxies suggest mainly oxic depositional conditions, with episodes of anoxia, but with little systematic variation across the boundary. Geochemical proxies for productivity indicate little change up the section with values two orders of magnitude less than elsewhere. The lack of consistent element geochemical changes across the boundary accompanied by significant C, S, and other isotopic changes suggests that atmospheric and oceanic chemical variations drove the Permian–Triassic boundary environmental changes at least on the sabkha environments of the tropical Adria platform.

The Ludlow Bone Bed (Welsh Basin) is a critical stratigraphic horizon and contains a rich assemblage of fish scales. Units above provide insights into the early evolution of animal and plant life. The bed has not yet been radioisotopically dated. Here, we report 207 secondary ion mass spectrometry (SIMS) ages from 102 zircon (ZrSiO 4 ) grains from the Ludlow ( n = 2) and stratigraphically higher Downton ( n = 1) bone beds. SIMS ages are middle Ordovician (471.6 ± 20.7 Ma) to late Devonian (375.7 ± 14.6 Ma, 238 U– 206 Pb, ±1σ analytical uncertainty). Cathodoluminescence images show that the youngest ages appear affected by alteration. Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U–Pb geochronology was utilized to improve precision. Detrital zircon grains from Downton yield 424.91 ± 0.34/0.42/0.63 Ma and from Ludlow 424.85 ± 0.32/0.41/0.62 Ma ( n = 5 each, 238 U– 206 Pb, ±2σ analytical, tracer or systematic uncertainty). These ages provide a maximum deposition age. Results overlap the basal Přídolí age (423.0 ± 2.3 Ma) in its stratotype (Požáry Section, Reporyje, Prague, Czech Republic). The Ludlow Bone Bed marks the base of the local Downton Group, which has previously been correlated with the base of the Přídolí Series. The CA-ID-TIMS ages are older than those for other land arthropod-bearing sediments, such as the Cowie Harbour Fish Bed and Rhynie Chert. Supplementary material: An Excel file containing detailed information on the SIMS analyses, a figure showing calibration curves for AS3 standards sputtered over sessions 1 and 2, and a figure showing CA-ID-TIMS U–Pb age data (concordia and weighted mean plots) are available at https://doi.org/10.6084/m9.figshare.c.5087031