The end-Permian mass extinction (EPME) caused a severe decline in marine productivity, leading to a prolonged recovery. Extensive work has been conducted to reconstruct paleoenvironmental conditions during this time, often using numerous geochemical proxies in marine records without assessment of the nature of preservation. Despite Lower Triassic intervals being among the least productive hydrocarbon resources in the Phanerozoic, the Lower Triassic Montney Formation in the Western Canada Sedimentary Basin (WCSB) remains a prolific hydrocarbon system, even with low overall total organic carbon (TOC <= 1 wt%) content. We used this unit to investigate whether geochemical proxies in the Montney Formation preserve primary paleoenvironmental signals, as commonly assumed, or have been overprinted by post-depositional processes such as burial, hydrothermal diagenesis, organic matter thermal maturation, and hydrocarbon migration. We analyzed a 398 m core at similar to 1 m resolution using delta C-13(org), programmed pyrolysis, bulk elemental geochemistry, organic and scanning electron microscopy (SEM) petrography. The delta C-13(org) profile remain consistent with global Lower Triassic carbon isotope records, supporting - but not solely defining - the preservation of a primary signal. In contrast, elemental proxies commonly used for paleoredox and paleoproductivity reconstructions (e.g., Mo, U, V, Ni, Cu, Ba, Zn, P) appear significantly altered by diagenesis, hydrothermal alteration, and hydrocarbon migration. Although these alterations may partly reflect regional environmental variability, petrographic evidence and mineral paragenesis suggest that post-depositional alterations was a major control on elemental distribution. Among the redox proxies - Th/U, shows a good correlation with delta C-13(org) and may retain paleoenvironmental significance, despite known complexities in U mobility. Elevated Ti/Na ratios (>= 0.5) coincide with two negative delta C-13 excursions, and marcasite-replaced sponge spicules, near the Permian-Triassic boundary are consistent with enhanced terrestrial sediment influx and transient ocean acidification and anoxia. These results underscore the importance of integrating petrographic context with isotopic and elemental data to distinguish preserved depositional signals from diagenetic overprints in thermally mature systems.

Iridium (Ir) and mercury (Hg) enrichments at the Cretaceous-Paleogene (K-Pg) boundary are widely attributed to the Chicxulub impact and Deccan Traps volcanism, although their relative contributions remain debated. We present high-resolution analyses of Hg, Ir, coronene, and Hg isotopes from marine sediments in Haiti and Spain, representing proximal and distal settings relative to the impact site. Elevated Hg/TOC ratios at both sites indicate substantial atmospheric Hg input immediately before and after the impact. At the proximal site, impact-related turbidites are overlain by marl containing an Hg-Ir-enriched orange layer. Two Hg peaks are identified: one preceding the turbidites and another within the orange layer. The first peak shows low Ir and moderate coronene values, indicating a volcanic origin linked to Deccan Traps activity. The second peak is characterized by strongly correlated Hg and Ir concentrations (R = 0.97) and high coronene values, consistent with an impact origin. Similar patterns at the distal site support the global extent of these events. Hg isotope compositions (delta 202Hg and Delta 199Hg) converge during peak intervals, indicating mixing among volcanic, crustal, and hydrocarbon-derived sources. Mass balance calculations show that Hg enrichment in the Ir-rich layer can be explained by release from hydrocarbon-bearing impact target rocks. The second peak coincides with the extinction of Cretaceous planktonic foraminifera, suggesting the Chicxulub impact as the primary driver, with a possible contribution from volcanism. These results underscore the importance of integrating multiple geochemical proxies to resolve the complex interplay of volcanic and impact-related processes in Earth's history.

Abstract Remote northern communities of Canada generally rely on imported diesel and heating oil to meet energy needs. There is a strong interest in transitioning to a more renewable energy supply to reduce the carbon footprint as well as to enhance the energy sovereignty of communities. Here, we examine the geothermal energy potential of the second northernmost community in Canada, Resolute Bay (Qausuittuq) based on reassessment of historic data along with new data collection from cores and field work, as well as remote sensing-based measurements. We show that there are systematic errors in previously reported thermal gradients related to issues of drilling in regions of thick permafrost. Previous estimations as high as 39.4 °C/km are biased by transient thermal response to post-glacial rebound. We estimate the gradient to be 14.9 °C/km based on a continuous depth-temperature log but recognise it could be as high as 22 °C/km based on regional depth-temperature data. Aquifer potential is also limited except in areas where carbonate rocks are highly fractured, especially at intersecting folds related to two different periods of deformation. While previous studies overestimate the local potential, Resolute Bay could utilise some direct use heat or also develop a closed-loop system exploiting higher thermal conductivity evaporites, supplying heat for the community as well as nearby government installations.

Global superanoxia is widely accepted as one of the main drivers of the end–Permian Mass Extinction (EPME) alongside, oceanic acidification, productivity collapse, and toxification. However, modeling and paleontological studies suggest spatial heterogeneity, with parts of the Tethys Ocean remaining oxygenated. To assess water–column oxygenation in the central Tethys, we studied two shallow–marine Permian–Triassic sections in equatorial paleolatitudes of central Iran; one with terrestrial input, the other fully marine. Continuous sedimentation across the EPME enables reconstruction of the latest Permian environment. U, Th, Mo, and Mn concentration data indicate well–oxygenated conditions until the EPME horizon, followed by Mn concentration peaks in microbialite/black shale intervals that reflect fluctuating oxic–anoxic conditions across the EPME. Micronutrient decline preceding the extinction suggests reduced local productivity. Thus, oxic conditions in microbialite–bearing shallow–marine settings were likely sustained by photosynthetic O₂ production and/or wave agitation. Low productivity also implies limited oxygen demand for organic matter remineralization, minimizing redox stress in these environments. We highlight shallow–marine Tethyan settings as potential oxygenated habitat during deep–sea anoxia, although a fluctuating chemocline repeatedly introduced Mn into marine environments, restricting oxidized habitat to the surface layer in contact with the atmosphere and/or oxygen–producing microbial mats.

The Anisian Stage (Middle Triassic) marks a pivotal interval for biotic recovery following the Permian-Triassic mass extinction, yet its environmental drivers remain poorly understood. This study presents carbon isotopes, mercury (Hg) concentrations, and Hg isotope data from Anisian (mainly Pelsonian substage) marine and terrestrial sections across the Tethys. Our results reveal a widespread Hg enrichment event that is synchronous with the Pelsonian negative carbon isotope excursion (PENCIE). Hg isotopic compositions support an origin from enhanced regional volcanism, coupled with contemporaneous terrestrial input. New high-precision zircon U-Pb ages (244.200 ± 0.037 Ma and 243.451 ± 0.049 Ma), integrated with chemostratigraphic and biostratigraphic data, constrain the duration of the PENCIE to ∼0.5 Myr. This interval coincided with major biodiversification, revealing that recovery occurred alongside environmental perturbations rather than in stable conditions as traditionally thought. These global disturbances in carbon and mercury cycles, linked to volcanism and terrestrial input, likely accelerated Middle Triassic biotic recovery.

The Horn River Basin in northeastern British Columbia, Canada, hosts significant unconventional shale-gas resources and geothermal potential within the Devonian Horn River Group (HRG). The organic-rich HRG shale is highly heterogeneous due to complex mineralogy and matrix variability across the basin, posing challenges for accurate thermal conductivity (TC) prediction. This study presents an integrated approach to evaluate spatial TC variability by combining comprehensive petrophysical characterization with two-phase mixing models: the Voigt–Reuss–Hill (VRH) average approach and the geometric mean (GM) method. Machine learning techniques were applied to extensive mineralogical data to predict mineral compositions from well logs, while total organic carbon (TOC), porosity, and fluid saturation were quantified through core–log calibrations and statistical analysis. TC profiles were then calculated using the VRH and GM models, incorporating calculated component volumes and mineral TC values adjusted for in situ temperature and pressure conditions. Both measured and modeled results indicate that TC in the low-porosity shale is predominantly controlled by mineralogy/lithology, increasing with quartz and carbonate content and decreasing with higher clay volume. Notably, the VRH approach performs better for lower TC values (<2.5 W/m·K) associated with higher clay and lower quartz and carbonate contents, whereas the GM method is more accurate at higher TC values (≥2.5 W/m·K), corresponding to lower clay and higher quartz and carbonate contents. Given the heterogeneous mineralogy and high TOC content of the HRG shale, integrating both models effectively captures the full range of TC variability and enhances predictive accuracy.

Studies of critical geological boundaries and associated Earth system shifts are often limited by insufficient consideration of regional geological contexts, favouring correlations with purported global events over investigation of local geodynamic controls. The Devonian–Carboniferous Boundary (DCB) interval of western North America is an example. The margin underwent major depositional and environmental changes, including unconformities, collapse of warm-water carbonate platforms, clastic influx, anoxia, localized shallow-water extinctions, and warm- to cool-water carbonate turnover beginning at ∼364 Ma and lasting more than 10 Myr. New stratigraphic analyses of 10 DCB outcrops spanning 700 km in western Canada and the western United States, combined with new geochemical data and review of published sedimentological, and geochronological datasets, demonstrate that unconformities, clastic influx, anoxia, and carbonate facies distributions were largely controlled by tectonism along a convergent margin related to the DCB phase of the Antler Orogeny. This contrasts with previous interpretations that linked these changes to purported global events, including the Hangenberg Crisis (∼359 Ma), assuming western North America remained a passive margin.We propose a model whereby Antler-related geodynamic inversion transformed western Laurentia from a passive to a convergent margin, causing lithospheric loading, foreland basin development, restricted marine circulation, and diachronous uplift causing collapse of warm-water carbonates, shallow-water anoxia, clastic influx and unconformities development. A subsequent Early Carboniferous subsidence and deepening episode promoted the return of cool-water carbonate production across western Laurentia. We conclude that Earth system changes during the DCB in western Laurentia were primarily driven by regional tectonism rather than global mechanisms.

The widespread occurrence of highly phosphatic black shales in Middle Triassic strata reveals a major transition in paleo-environmental conditions and resultant biological productivity. To establish whether this phosphatic interval was linked to a recovery in productivity following the Permian-Triassic Mass Extinction, we examined geochemical records of trace metal concentrations in sediments deposited along NW Pangea exposed in the Ursula Creek section on the shore of Williston Lake, British Columbia, Canada. Profiles of trace element paleo-environmental proxies were normalized to sedimentation rates to account for distortion by shifts in sedimentation. Our results show that an increase in seawater oxygenation and productivity during the Induan to lower Olenekian was short-lived. However, enhanced productivity in the Anisian to Ladinian was likely linked to a re-established connection with nutrients that had been trapped in deep ocean waters during the Early Triassic, when hothouse conditions suppressed upwelling. The phosphatic interval at Ursula Creek thus marks the resumption of nutrient upwelling and a corresponding recovery in productivity during the Middle Triassic. These findings indicate that widespread phosphogenesis observed in Middle Triassic strata archived the return of continental margin productivity.

The Permian-Triassic mass extinction, the most severe biodiversity crisis of the Phanerozoic, is widely linked to Siberian Traps volcanism, yet mercury (Hg) isotope responses to eruptive phases remain poorly constrained. Here we identify a pronounced negative correlation between Δ199Hg and δ202Hg that occurs exclusively during three coupled volcanic-environmental-biotic crisis intervals ( ~ 150 kyr) and is absent under background conditions. Across multiple sections, crisis-interval samples converge between terrestrial, marine carbonate, and volcanic source fields, whereas background samples are more dispersed, indicating distinct isotopic behaviour. Hg/total organic carbon ratios normalized to background values strongly correlate with the Δ199Hg-δ202Hg relationship, linking Hg loading to isotopic systematics. These results reveal a previously unrecognized isotopic structure and suggest enhanced large-scale source control during crisis intervals, providing a framework for resolving eruptive pulses and tracing volcanism-driven environmental change.

The middle–late Cambrian witnessed recurrent biotic crises in the aftermath of the Cambrian explosion, exemplified by the late Cambrian end-Marjuman Biomere Extinction linked to major environmental perturbations across the Guzhangian–Paibian boundary. However, the precise mechanisms underlying this biodiversity collapse remain unclear. Mercury isotopes from two slope sections in South China reveal enhanced upwelling during the late Guzhangian, followed by photic zone euxinia in the early–middle Paibian, corresponding to the two extinction phases. This mercury record suggests that initial upwelling, followed by hydrogen sulfide toxicity in shallow oceans, drove the two-stage collapse of shallow marine shelf faunas in South China. Furthermore, this study strengthens the case that the coupled positive Δ199Hg (mass-independent isotope fractionation) and negative δ202Hg (mass-dependent isotope fractionation) shifts can serve as a tracer for upwelling in Precambrian–Cambrian oceans. Collectively, our mercury isotopes offer new insights into the dynamic interactions between ocean chemistry and early animal evolution in the middle–late Cambrian. The late Cambrian Marjuman extinction event in South China was triggered by enhanced upwelling and hydrogen sulfide toxicity in shallow oceans, according to analyses of Mercury isotope data from China.

Deploying shallow temperature probes to record temperature variation is one approach to identify anomalous zones of high ground heat-flux, and following data processing and analysis of the subsurface temperature time series is essential to interpretation. This study presents a different processing workflow to estimate thermal anomalies more accurately and reliably. In order to reduce the daily solar radiation effect, calculate the thermal variations with depth, and then estimate the near-surface relative thermal anomalies, a regularized conjugate gradient inversion algorithm with a Monte Carlo (MC) parameter generator was employed to solve the objective function and overcome the uncertainty related to variation of complex parameters. A physical model was created by assuming that the thermal conductivity and thermal diffusivity vary seasonally as a function of soil water content and density. An empirical equation was then employed to estimate variations in the thermal parameters. The workflow and code using the Python language were developed for the pre-processing and analysis of thermal datasets. Based on the processed transient temperature variations, the estimated long-term temperature trends at different depths were used to deduce deeper geothermal gradients. In a study with real data, the proposed inversion and simulation workflow was applied to calculate the temperature variations at 2.0 m depth. The results identified an anomalous zone of relatively high thermal flux in the south Mount Meager area. By comparing with previous results from shallow temperature wells, the proposed method for estimation of anomalous thermal fields provide a significant advantage for identifying variations in regional thermal gradient and could be a practical tool for different case studies.

The majority of geothermal energy is produced in tectonically active volcanic-arc regions due to their high geothermal gradients. Reservoirs in these settings are often stratified with smectite/kaolinite-, illite-, and chlorite-rich zones, in order of increasing depth and temperature. Eighteen andesitic core and surface samples were taken from five geothermal fields in the Lesser-Antilles and Cascade volcanic arcs. The collected samples have experienced various degrees of alteration and can be considered, in their ensemble, to be representative of the previously mentioned alteration zones. The influence of the alteration was assessed through biaxial rate-and-state friction experiments on prepared gouge. The samples were each tested at 10, 30, and 50 MPa normal stress in both nominally dry and nominally wet conditions. While significant water-induced frictional-strength reduction was observed, phyllosilicate content dominates frictional behavior, with increased phyllosilicate content reducing frictional strength, promoting velocity-strengthening behavior, and reducing frictional healing. Negative frictional healing is observed and likely related to the presence of expandable clays, leading to frictional weakness over long time periods. It is suggested that, by controlling frictional strength, phyllosilicate content influences the depth of onset of ductile shear zones, which often underlie these reservoirs and are critical for the horizontal advection and vertical sealing of geothermal fluid. Further, as these types of reservoirs are likely critically stressed, varying degrees of alteration within different reservoir zones can give rise to the formation of stress jumps. Overall, the frictional behavior depended to a first order on overall phyllosilicate content, potentially simplifying engineering studies.

Here we investigate Mesozoic and Paleozoic porous aquifer systems with different grades of temperature reservoirs to meet growing heat demand and sustain government infrastructure overlying The Western Canada Sedimentary Basin, Canada, where winters are cold (average daily temperature below -4 degrees C) and direct heat is an essential energy demand. Two stratigraphic intervals were modeled and simulated for geothermal heat production systems: conventional and closed loop. We estimated that 2.93 MWth and 6.9 MWth heat energy can be generated over 30 years of operation in the Mesozoic (300-500 m depth; 100 m thickness, 16 degrees C reservoir temperature, 1 D permeability, 0.3 porosity, 180 m3/h flow rate, 800 m well spacing) and Paleozoic (1400-1200 m depth, 100 m thickness, 35 degrees C reservoir temperature, 10 mD permeability, 0.1 porosity, a 180 m3/h flow rate, 400 m spacing) respectively. This study highlights the geothermal potential of the WCSB as a viable opportunity.

The late Paleozoic ice age (LPIA) was the longest-lived glaciation of the Phanerozoic, and its demise marks Earth's only recorded transition from an icehouse to a greenhouse state since the occurrence of vascular plants and complex terrestrial ecosystem. While global volcanism has been widely considered a key driver of carbon cycle during this period, limited high-resolution records have constrained our understanding. Here, we use high-resolution carbon isotope and mercury records from the North China Craton, spanning the late Gzhelian to early Kungurian stages, to evaluate the relationship between carbon cycle perturbation and volcanism. We identify two negative carbon isotope excursions during the late Gzhelian and early Asselian, both coinciding with climate warming. Our data reveal a variable relationship between carbon cycle disturbances and mercury records, suggesting volcanism was not the only trigger. Instead, they may result from the superimposition of multiple mechanisms, including tundra conditions, methane release, or orbitally-paced climate changes.

The (Basal) Choteč Event, first recognised in the 1980s in Czechia, is a globally widespread anoxic pulse associated with transgression and eutrophication just above the Emsian-Eifelian (Early-Middle Devonian) boundary (cycle 1c of the Johnson et al. [1985] Devonian eustatic sea-level curve). Despite being one of several anoxia-driven faunal turnovers during the Devonian, the Choteč Event remains poorly understood. The global reach, intensity, and duration of anoxia is not constrained and nor is it clear whether eutrophication had its “roots” in contemporary floral developments on land (as suggested for younger Devonian anoxic events).We present a geochemical (carbon isotopes; trace metals as proxies for redox and productivity; and major elements for the Chemical Index of Alteration [CIA] as a weathering proxy) and palynological study of the Cabonera section (León, Spain). This succession is part of an extensive Devonian sequence developed around isolated islands in the Armorican Terrane Assemblage that was located between the supercontinents Laurussia and Gondwana. Here, limestones of the Emsian-Eifelian Santa Lucia Formation are abruptly overlain by siltstones and shales belonging to the Eifelian Huergas Formation. This conodont- and brachiopod-constrained manifestation of the Choteč Event sees the onset of a gradual 4‰ negative δ13Ccarb excursion (CIE) consistent with records in other regions. The lower part of the Huergas Formation (Cabornera Bed) records a brief interval of anoxia (low Th/U, elevated V/Al and U/Al) at the same level that sees the onset of the negative CIE. This appears to have been accompanied by, or was perhaps driven by, greatly enhanced primary productivity, with enrichment factors (EFs) of Ba, and particularly Ni, Zn and P, all >>1. This brief burst of productivity and anoxia soon ended, with EFs falling

The mid-Capitanian (Middle Permian) extinction has been widely attributed to the eruption of the Emeishan large igneous province. Here, we investigate the nature and timing of this link by determining Hg concentrations and isotopic compositions of limestones from the Xiongjiachang section of southwestern China, where Emeishan basalts directly overlie sediments recording the mid-Capitanian extinction horizon. Results show an initial Hg-enrichment interval similar to 2.2 m below the mid-Capitanian extinction horizon. Positive 0199Hg values in the Hg- enrichment interval suggest enhanced volcanic Hg influx into the ocean via atmospheric Hg(II) deposition. The late stage of the midCapitanian extinction interval has lower 0199Hg values, which indicates enhanced input of terrestrial Hg due to ecosystem collapse and soil erosion. The results of this study provide evidence that the Emeishan large igneous province eruption occurred earlier than the mid-Capitanian extinction, and establish a more reasonable temporal link between Emeishan large igneous province volcanism and the mid-Capitanian extinction.

AbstractThe Early Permian witnessed the first icehouse‐to‐greenhouse turnover of the vegetated Earth, yet its climate dynamics remain enigmatic. Here, we used mercury (Hg) isotopes from pelagic and continental successions at low paleo‐latitudes to track the perturbations of the global carbon (C) cycle and the climatic impact. Our results indicate that small‐scale volcanism promoted marine organic C burial, and the concomitant extreme cooling triggered the waning of wetland ecosystems in North China block at ∼296.2 Ma. Subsequently, the mass‐independent fractionation of odd Hg isotopes (Δ199Hg) and C isotopes synchronously decline in the deep‐marine succession, likely supporting progressive oxidation of terrestrial biomass and airborne release of Hg and C. Lowered C sequestration (as coal swamps) on land and dampened continental weathering limited the drawdown of CO2 emissions from wildfires, initiating deglaciation. Our findings highlight that the climate forcing on terrestrial ecosystems could activate additional C reservoirs, driving Earth into a warmer state.

The Late Ordovician mass extinction (LOME, ca. 445 Ma), which occurred over two extinction intervals (LOMEI-1 and LOMEI-2), was the first “Big Five” biotic crises of the Phanerozoic. The ultimate trigger of this extinction remains debated, with glacially induced global cooling and volcanism-driven warming events separately suggested as the underlying cause. Here, we report anomalously high mercury (Hg) levels in two Ordovician-Silurian successions from a shelf-to-slope transect in South China, indicating abnormally high Hg loading to the ocean. Analyses of Hg isotopes through the successions reveal near-zero Δ199Hg from the late Katian to the earliest Hirnantian (LOMEI-1), suggesting that Hg was mainly derived from large-scale volcanism. Positive shifts in Δ199Hg are observed during the Hirnantian stage, coincident with global glaciation, suggesting enhanced Hg sequestration to sediments driven by subsidence of cold and dense surface seawater. Negative shifts in Δ199Hg values across the LOMEI-2 within the Hirnantian likely suggest enhanced terrestrial Hg and sulfate fluxes to the ocean due to volcanism-induced global warming, which promoted oceanic anoxic/euxinic conditions. This study provides novel evidences linking intensive volcanism to significant changes in the atmosphere-land-ocean system across the Ordovician-Silurian transition, particularly to the euxinic ocean conditions that triggered the LOME.

The global extent of the Late Cretaceous oceanic anoxic event 3 (OAE 3) remains uncertain. It is not considered to have extended into the Boreal Realm. To test this, we examined Late Cretaceous organic- and metal-rich black mudstones of the Smoking Hills Formation in Arctic Canada. New high-precision U-Pb zircon ages indicate that deposition of the Smoking Hills Formation (88.535-78.230 Ma) was temporally coincident with OAE 3, indicating a much broader global expression of this event than previously thought. OAE 3 was likely manifest throughout the proto-Arctic Ocean (now Arctic Canada). Abundant bentonite layers and cryptotephra within the Smoking Hills Formation have rare earth element (REE) patterns that are consistent with ash- fall derived from Cretaceous arc volcanism. Anomalously high organic matter content in the Smoking Hills Formation, as compared to underlying and overlying units, suggests that ocean fertilization led to enhanced productivity and metal drawdown. A peak in arc volcanism may have been a key driver of the OAE 3 event. We also explored the potential use of cadmium as a geochemical marker of volcanism and show that high volcanogenic metal loading could affect the use of Cd and other proxies for marine productivity (e.g., Zn, Cu).

Micropaleontological and geochemical analyses in samples from the Coniacian-Maastrichtian-aged Smoking Hills and Mason River formations in the Anderson Basin of the northern mainland coast of Arctic Canada provide a refined picture of the environmental conditions occurring in the incipient southern Arctic Ocean at the end of the Cretaceous. These units were deposited within a 22 myr time span in an outer shelf setting characterized by relatively stable tectonic conditions and low sedimentation rates. The Coniacian-middle Campanian Smoking Hills Formation was deposited during times of marine transgression and water column stratification. Surface waters were highly productive and dominated by dinoflagellates, red algae, green algae and likely diatoms and silicoflagellates. Bottom waters were predominantly anoxic-euxinic, but the presence of benthic foraminifera and variations of geochemical signatures in some intervals indicate episodic ventilation. The deposition of the Smoking Hills Formation is temporally consistent with the Oceanic Anoxic Event 3 (OAE3), but the duration of these anoxic conditions is much longer in the Anderson Basin. During the middle Campanian, relative sea level reached a highstand, fostering the expansion of planktic siliceous microorganisms, including diatoms, silicoflagellates and radiolarians. During the late Campanian to at least the Maastrichtian, sediments of the Mason River Formation were deposited during a regressive sedimentation phase characterized by high productivity fueled by river run-off and the proliferation of diatoms, red and green algae. Despite high productivity, bottom waters were oxygenated. This study highlights the importance of data integration to reconstruct the environmental conditions of the past as many, if not all, of the proxies utilized to this end are subjected to preservational and diagenetic bias.