Play fairway analysis is essential for identifying hydrocarbon potential and assessing geological risks in datasparse frontier regions. Baffin Bay and Davis Strait are such provinces, with a complex tectonostratigraphic history shaped by Paleozoic platform development, Mesozoic-Cenozoic rifting, passive margin subsidence, seafloor spreading, and Paleogene volcanism. Stratigraphic analogues from West Greenland, hydrocarbon seeps, and geophysical data point to active petroleum systems, although direct evidence is limited. This study presents the first integrated play fairway analysis of the Canadian Baffin Bay-Davis Strait margin, based on 74,000 km of 2D seismic data, regional geology, one-dimensional burial history modelling, and analogues, focusing on conventional hydrocarbon resources. Six plays were defined: 1) lower Paleozoic, 2) Lower Cretaceous, 3) Upper Cretaceous-Danian, 4) lower Cenozoic, 5) upper Cenozoic, and 6) the Cenozoic Baffin Fan. Chance of success (COS) maps were developed for petroleum system elements for each play and combined into Technical COS maps through global scale factor calibration. Burial history modelling of source intervals (Upper Ordovician, Aptian(?)-Albian, Cenomanian-Turonian, and Eocene 'Azolla') suggests multiple phases of hydrocarbon generation since the Late Cretaceous, supported by geochemical data from Scott Inlet seep oils. Results highlight variable hydrocarbon potential. Highest prospectivity occurs in Cretaceous grabens along the shelf, while the northern Baffin Fan shows medium potential with seismic DHI support. Other areas exhibit low to very low potential due to thin, immature or overmature sediments. The play fairway framework provides a foundation for future offshore energy planning and regulatory processes in Canada's Arctic frontier.

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.

Geochemical data from sedimentary rocks are the primary source of information regarding Earth's surface evolution through time, including its air and water envelopes and interactions with life and deep Earth processes. The Sedimentary Geochemistry and Paleoenvironments Project (SGP) is a scientific consortium centered around open data and community-driven development of cyberinfrastructure tools and resources for sedimentary geochemistry and Earth history. Here we describe the SGP Phase 2 data release, which focused on incorporating Paleoproterozoic and Mesoproterozoic (2500–1000 million years ago) data and better accommodating carbonate data. This data release was built through the involvement of >200 researchers worldwide in academia, government, and industry, and provides the largest available public data resource for our user community in the academic fields of geochemistry, sedimentology, tectonics, paleontology, Earth history, and paleoclimate, as well as the petroleum and minerals industries. The dataset now encompasses 126,006 samples and 4,132,371 geochemical analyses. In addition to direct entry by SGP Team Members, we have ingested and incorporated datasets from the Geoscience Australia OZCHEM database, the Alberta Geological Survey, and the Deep-Time Marine Sedimentary Element Database (DM-SED) compilation. This paper details sampling in the Phase 2 dataset with respect to age, geography, lithology, and other geological characteristics, documents access via our search website and API, discusses possible issues and/or biases in the dataset that could impact analyses, describes plans for governance and stewardship of data from Indigenous lands, and serves as the citable reference paper for the data release.

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.

Solution-mined salt caverns are in versatile use for large-scale storage-withdrawal of petroleum products (collectively underground gas storage—UGS), as well as novel applications essential for transition to net zero carbon economy: hydrogen gas (UHS) and compressed air energy storage (CAES). We present the first comprehensive Canada-wide review of bedded and halokinetic halite formations suitable for cavern storage. Such halites occur at depths of ~200-2000 m in the industrially developed regions (Fig. 1): Western Canada sedimentary basin (WCSB) in the Prairie provinces; Salina Group in Ontario; and in the Maritimes sedimentary basin (the Gulf of St. Lawrence and onshore mostly in New Brunswick, Nova Scotia, and Newfoundland). The Devonian salt beds of WCSB are undeformed, and the size of caverns is limited by thickness of halite beds (40-100 m, maximum 200 m). There are 196 caverns in Alberta and Saskatchewan, most of them active. In Ontario, Salina Group halite beds are of variable thickness with complex, dissolution-controlled outlines. This region counts 142 active and historical caverns. The Maritimes Basin is a “saline giant” with thick Mississippian-age halites forming diapirs and walls. Several gas storage prospects were recently launched in the Maritimes, most notably in southern Newfoundland. Underexplored and untapped potential for salt caverns exists in frontier regions: the northern WCSB where Cambrian halites were partly involved in halokinesis to form walls and diapirs, in Hudson Bay depocenter (undeformed Devonian halites), and in the Canadian Arctic Archipelago where salt tectonics had formed domal structures potentially suitable for large (> 1 Mm3) caverns.

Abstract Recent high‐precision geochronological studies have delineated three main pulses of basaltic magmatism between ca. 130‐80 Ma in the Cretaceous High Arctic Large Igneous Province (HALIP) in northern Canada. Here we report new U‐Pb TIMS baddeleyite and zircon dates for samples from Axel Heiberg and Ellesmere Islands, which further support the duration and pulsed nature of the magmatism previously documented. We add new LA‐ICPMS U‐Pb zircon dates on samples analyzed in a previous study to help resolve age heterogeneity observed in some samples. We also report the first LA‐ICPMS zircon Lu‐Hf results from HALIP intrusives to better constrain the HALIP mantle source composition. Initial εHf zircon results for five HALIP basalts with minimal evidence for continental crustal contamination from the Canadian Arctic Islands range from +9.0 to +14.7, and indicate extraction from a depleted mantle source similar to plume‐derived oceanic plateaux such as Kerguelen.

Fifty-five resource assessments for northern Canada, completed between 1973 and 2023, were evaluated. Of these, 49 are considered to be relevant in that they contain quantitative resource assessments, and an additional six are prospectivity maps. Assessment areas match the major sedimentary basins, which in turn are controlled by the plate tectonic history. Lower Paleozoic basins formed following the breakup of Rodinia: Franklinian margin underlies the southern Arctic Islands; the Foxe Basin lies southwest of Baffin Island; and Hudson Bay Basin. Upper Paleozoic-Mesozoic basins formed following the Ellesmerian Orogeny: the Sverdrup Basin underlying the northern Canadian Arctic Archipelago; and the Lincoln Sea Basin that lies north of Ellesmere Island. Cretaceous-Recent margins developed after rifting of the Arctic Ocean and Baffin Bay: Beaufort-Mackenzie Delta region in the western Arctic; the deep water Canada Basin that occupies the floor of the Arctic Ocean; the Arctic Margin from Banks Island to northern Ellesmere Island; and the Baffin Margin that lies between Baffin-Devon-Ellesmere islands and Greenland. The assessed volumes in each basin have been standardized to recoverable barrels of oil equivalent (BOE) for those assessments reporting both oil and gas. After standardizing units, there is a pattern across basins of initial reported volumes being large, followed by significant drop-offs, mimicking the pattern seen in a ‘hype cycle’. P10:P90 ratios are a proxy for how much knowledge about petroleum systems exist in a basin, with well-explored areas having a P10:P90 ratio of less than 2, frontier areas have a ratio of 3–4, and areas with essentially no data having a ratio of 8 or more. There is evidence of anchoring (particularly phase ratio) in early reports where the estimates of phase ratio lagged what had been proven by drilling. Evolving geological knowledge and improvements to methodology and computing power mean that the volumes reported for the same assessment area will change over time. All the historical assessments reviewed in this report have at least some limitations that affect their accuracy.

The triple oxygen isotope composition of sulphate minerals has been used to constrain the evolution of Earth's surface environment (e.g., pO2, pCO2 and gross primary productivity) throughout the Proterozoic Eon. This approach presumes the incorporation of atmospheric O2 atoms into riverine sulphate via the oxidative weathering of pyrite. However, this is not borne out in recent geological or modern sulphate records, where an atmospheric signal is imperceptible and where terrestrial pyrite weathering occurs predominantly in bedrock fractures that are physically more removed from atmospheric O2. To better define the transition from a Proterozoic to a modern-like weathering regime, here we present new measurements from twelve marine evaporite basins spanning the Phanerozoic. These data display a step-like transition in the triple oxygen isotope composition of evaporite sulphate during the mid-Paleozoic (420 to 387.7 million years ago). We propose that the evolution of early root systems deepened the locus of pyrite oxidation and reduced the incorporation of O2 into sulphate. Further, the early Devonian proliferation of land plants increased terrestrial organic carbon burial, releasing free oxygen that fueled increased redox recycling of soil-bound iron and resulted in the final rise in pO2 to modern-like levels.

It has long been speculated that isolated Paleoproterozoic basins of northern Laurentia are remnants of a once contiguous sedimentary cover due to similarities in stratigraphy, paleocurrent directions, sediment provenance, and geochronological data. However, corroborating evidence for this 'superbasin hypothesis' has been lacking outside the footprints of the preserved basins. We present new zircon and apatite (U-Th)/He and fission-track thermochronology data and time-temperature inversions from metamorphic basement that support the previous existence of sedimentary cover over currently exposed shield regions, bridging the gap between preserved basin strata across a large expanse of northern Canada. Inversions also reveal a notably synchronous and relatively rapid cooling event consistent with deep erosional exhumation during supercontinent breakup and Snowball Earth glaciations. Our study provides a comprehensive dataset from the exposed craton in northern Canada that supports an originally more widespread Proterozoic basin and offers additional evidence of ~4.3 ± 1.1 km of Neoproterozoic erosional exhumation that played a role in the formation of the Great Unconformity surface across North America.

AbstractA causal mechanism for the Volgian Isotopic Carbon Excursion (VOICE) remains enigmatic. Elemental geochemical profiles of the Deer Bay Formation, Sverdrup Basin, Arctic Canada that record the VOICE and contemporaneous strata are herein examined to provide insight into depositional environments during Late Jurassic‐Early Cretaceous time. Silver (Ag) and Cadmium (Cd) are enriched across the VOICE at localities on Axel Heiberg Island, and in Tithonian (∼Volgian) strata of Ellef Ringnes Island. Other redox‐sensitive trace elements do not exhibit spatially or temporally consistent patterns and indicate oxic conditions. A lack of relationship across the VOICE between Ag and the quality, quantity, and isotopic composition of organic matter suggests that the negative isotope excursion and interval of Ag enrichment are not merely functions of changes in organic matter source or amount, while a lack of spatially consistent change in geochemical indices of weathering similarly excludes climate change and/or sediment provenance as a driver. Therefore, in a ventilated setting and without marked changes in organic matter content, Ag enrichment may be due to hydrothermal activity. Contemporaneous Ag enrichment in strata from Svalbard suggests that a source of hot fluid sufficient to produce Ag‐rich seawater may have been related to rifting in the adjacent proto‐Amerasia Basin. Hydrothermal activity may also have been a widespread source of isotopically depleted carbon. This work develops new geochemical fingerprints that may be used to trace the spatial extent of hydrothermal events that do not leave an extinction pattern but may nonetheless have a far‐reaching influence on biogeochemical systems.

A geologically rapid Neoproterozoic oxygenation event is commonly linked to the appearance of marine animal groups in the fossil record. However, there is still debate about what evidence from the sedimentary geochemical record—if any—provides strong support for a persistent shift in surface oxygen immediately preceding the rise of animals. We present statistical learning analyses of a large dataset of geochemical data and associated geological context from the Neoproterozoic and Palaeozoic sedimentary record and then use Earth system modelling to link trends in redox-sensitive trace metal and organic carbon concentrations to the oxygenation of Earth’s oceans and atmosphere. We do not find evidence for the wholesale oxygenation of Earth’s oceans in the late Neoproterozoic era. We do, however, reconstruct a moderate long-term increase in atmospheric oxygen and marine productivity. These changes to the Earth system would have increased dissolved oxygen and food supply in shallow-water habitats during the broad interval of geologic time in which the major animal groups first radiated. This approach provides some of the most direct evidence for potential physiological drivers of the Cambrian radiation, while highlighting the importance of later Palaeozoic oxygenation in the evolution of the modern Earth system. Oxygen in shallow shelf waters rose linearly with atmospheric oxygen in the Neoproterozoic era, potentially driving the first radiation of marine animals, but widespread ocean oxygenation came later, according to reconstructions of oxygen levels and marine productivity.

The Whitehorse Trough formed during early Mesozoic accretion of the Intermontane terranes to northwestern North America. Here we investigate its thermal history using detrital mineral thermochronology, including 171 single-crystal (U–Th)/He zircon (ZHe) ages from 35 samples, 158 single-crystal (U–Th)/He apatite (AHe) ages from 33 samples, and apatite fission track (AFT) ages from 12 samples. ZHe single crystal ages range from 222 to 42 Ma and define Triassic–Early Jurassic, Late Jurassic, and Cretaceous–Paleogene age groups. AFT central ages range from 95 to 30 Ma with a dominant age peak at ∼50 Ma, and AHe single crystal ages range from 228 to 13 Ma with a dominant age peak between 50 and 40 Ma. Forward and inverse models of thermochronological data are compatible with two regional burial/heating stages that variably reset He in zircon. Maximum temperatures of the Whitehorse Trough strata locally exceeded 150 °C during Early Jurassic burial and shortening into a fold and thrust belt. Following Middle to Late Jurassic exhumation-related cooling and development of a prominent unconformity, Whitehorse Trough strata were buried again. Temperatures locally exceeded 150 °C during the Cretaceous, suggesting maximum burial of between ∼4 and 7.5 km. Heating and cooling rates during the Early–Middle Jurassic were ∼10 °C/myr, coinciding with deposition, fold and thrust belt development, and regional crustal thickening during the final stages of Intermontane terrane accretion. Maximum heating rates during the Cretaceous were ∼4–7 °C/myr and likely correspond to regional crustal thickening of the northern Cordillera hinterland and establishment of an outboard, Andean-type continental arc system.

Abstract The Neoproterozoic–Devonian strata of the Canadian Arctic Islands record three Tectono-Sedimentary Elements (TSEs): (i) the Neoproterozoic Synrift TSE; (ii) the Neoproterozoic–Late Devonian Franklinian Margin TSE composed of Cambrian–Ordovician carbonate-dominated passive-margin strata and latest Ordovician, Silurian and Lower Devonian mixed carbonate and clastic strata deposited on an unstable margin; and (iii) Middle–Upper Devonian Foreland Basin TSE deposited in an expanding foreland basin. These three TSEs comprise the Franklinian Composite Tectono-Sedimentary Element (CTSE). In the southern parts of the Arctic Islands, strata are flat lying but there is localized faulting and folding in the central Arctic Islands and towards the northern end of the Franklinian CTSE. These strata of the Franklinian Margin and Foreland Basin TSEs were broadly folded over deeply seated reverse faults localized along Late Silurian–Early Devonian contractional uplifts or deformed by widespread Late Devonian thin-skin folds and thrusts related to the Ellesmerian Orogeny. The parts of the CTSE overprinted by Late Silurian–Early Devonian north–south-trending structures are grouped as Boothia Structural Domains, and the area of the CTSE overprinted by Ellesmerian structures is termed the Ellesmerian Structural Domain. The major hydrocarbon source rock is Upper Ordovician–Lower Silurian shale but maximum thermal maturity over much of the area was achieved by the Late Devonian, prior to the formation of large folds. The complex geological history of the area since the Late Devonian reduces the chances of hydrocarbon preservation.

Steroids and their derivatives are ubiquitous in the sedimentary rock record, where they are widely applied as biological or geochemical markers to determine organic facies as well as thermal maturation of bitumen and oils covering the diagenetic to catagenetic stages. The diagenetic continuum from early diagenesis into catagenesis of steroids has not been extensively studied despite the importance of these reactions in influencing the successive continuum of late diagenetic transformations.This study utilizes a stratigraphically constrained transect of 9 wells from the Upper Cretaceous Second White Specks and Belle Fourche formations of south-central Alberta, Canada ranging in thermal maturity from 0.2 %VRE to 0.8 %VRE. Biomarkers were examined from 69 samples from 8 wells and thermal matu-rity was determined from 87 samples from 9 wells using HAWK programmed pyrolysis analysis. Relative and absolute abundances of regular sterane, diasterene, diasterane, monoaromatic steroid, and triaro-matic steroid biomarkers and changes in the proportions of steroid compound classes were determined and evaluated for thermal maturity. Additionally, isomerization ratios within each of the compound classes were examined with increasing thermal maturation.Rearranged diasterenes initially dominate the steroidal hydrocarbons, followed by diasteranes in the late diagenetic and catagenetic stages and at peak oil maturity (0.8 %VRE) diasteranes were most abun-dant. The relative abundance of a steroid is initially controlled by its rate of production or isomerization from a biological precursor, but at higher thermal maturities selective catagenetic destruction alters the relative abundance of steroid classes, with aromatic steroids and regular steranes being degraded or expelled earliest. Thermal maturity parameters based on the isomerization of regular steranes, and the aromatization of monoaromatic steroids are effective thermal maturity indicators in specific but overlap-ping ranges beginning at 0.2 %VRE. This work represents a novel examination of a natural thermal matu-rity transect and helps to consolidate our understanding and application of the diagenetic transformations of steroid compounds.(c) 2022 Elsevier Ltd. All rights reserved.

Many continental large igneous provinces coincide with climate perturbations and mass extinctions. When basaltic plumbing systems traverse carbon-rich sedimentary rocks, large volumes of greenhouse gases may be generated. We document how intrusive sills of the Mesozoic High Arctic Large Igneous Province affected surrounding fine-grained, organic-rich siliciclastic rocks of the Sverdrup Basin in the Canadian Arctic Archipelago. Petrographic and X-ray diffraction data from samples located near sills show the presence of high-temperature metamorphic phases (diopside, andalusite, garnet, and cordierite). Raman thermometry on organic matter yields peak temperatures of 385−400 °C near sill contacts, tailing off to far-field temperatures of ≤230 °C. Samples located >20 m from sills show no systematic change in vitrinite reflectance and have a VRo eq% value of ∼2.5%, which indicates a temperature of ∼210 °C. The finite element thermal modeling tool SUTRAHEAT was applied to the 17-m-thick Hare Sill, emplaced at 3 km depth at 1105 °C. SUTRAHEAT results show that contact-proximal rocks attain temperatures of >700 °C for a brief period (∼1 year). By 5 years, the Hare Sill is completely solidified (<730 °C), and the temperature anomaly collapses rapidly thereafter as the thermal pulse propagates outward. By 10 years, all rocks within 10 m of the Hare Sill are between 450 °C and 400 °C, rocks at 20 m from the contact attain 200 °C, yet far-field temperatures (>50 m) have barely changed. When multiple sills are emplaced between 4 km and 6 km depth, all rocks between sills reach ∼250 °C after 100 years, showing that it is possible to raise regional-scale background temperatures by ∼150 °C for the observed High Arctic Large Igneous Province sill density. Vitrinite reflectance data and pyrolysis results, together with SILLi thermal modeling, indicate that much of the hydrocarbon-generating potential was eliminated by High Arctic Large Igneous Province intrusions. The SILLi model yields ∼20 tonnes/m2 of organic equivalent CO2 (all carbon gas is reported as CO2) from the Hare Sill alone when emplaced into Murray Harbour Formation rocks with 5.7 wt% organic carbon, and ∼226 tonnes/m2 by emplacement of multiple sills throughout the 2-km-thick Blaa Mountain Group with 3 wt% organic carbon. On a basin scale, this yields a total of ∼2550 Gt CO2 from the Hare Sill, with ∼13,000 Gt CO2 being generated by the multiple sill scenario, similar to estimates from other large igneous provinces. Much of the Blaa Mountain Group rocks now have organic carbon contents of <1 wt%, which is consistent with large volumes of carbon-species gas having been generated, likely a mixture of CO2, CH4, and other species. However, organic-rich Murray Harbour Formation rocks show no obvious reduction in organic carbon content toward the Hare Sill intrusive contacts, which suggests that not all of the carbon was lost from the sedimentary package hosting High Arctic Large Igneous Province magmas. We suggest that some of the gas generated by contact metamorphism failed to drain out for lack of high-permeability conduits, and then back-reacted to form calcite cements and pyrobitumen during cooling.

Abstract The Sverdrup Basin Composite Tectono-Sedimentary Element (CTSE) covers 210 000 km 2 in the Canadian Arctic Archipelago. The CTSE was initiated in the Early Carboniferous by rifting of highly deformed Early Paleozoic strata and contains a maximum of 15 km of Carboniferous–Eocene strata. Eight phases of basin development have been recognized, with each being characterized by a specific combination of tectonic and depositional regimes. The phases are separated by intervals of uplift and tectonic reorganization, and each resultant first-order sequence is regarded as a separate TSE. Carbonate sedimentation was dominant in the Late Carboniferous and Early Permian, with clastic sedimentation becoming more common in the Middle Permian. Source areas lay to the east, south and north. In the Triassic, clastic sedimentation rates increased; and by the end of the Triassic, the central basin was filled. A shallow seaway was present throughout the Jurassic. In the Early Cretaceous, subsidence rates and clastic supply increased significantly, and basic volcanism occurred over most of the CTSE. Subsidence rate, sediment supply and volcanism decreased in the Late Cretaceous. The basin was progressively deformed in the Paleogene (Eurekan Orogeny), with local foreland deposits reaching 3 km. Seventeen oil and gas fields have been discovered on salt-cored, Eurekan anticlines. A combination of stratigraphic and structural traps, involving Triassic–Jurassic strata, has the greatest potential for future hydrocarbon discoveries.

Constraints on the tectonic setting of the upper Triassic to lower Jurassic in the Sverdrup Basin can be elucidated from detrital-zircon U-Pb ages. During the Triassic, there was a dual provenance system into sedimentary basins along the western and northern margins of Laurentia. One of the sediment sources was from an extra-basinal igneous source of Permian-Triassic zircon while the other source was recycled sediment eroded from older sedimentary basins. The Heiberg Formation/Group was deposited during a period of significant siliciclastic sedimentation into the basin from the upper Triassic to the lower Jurassic and comprises three members: Romulus, Fosheim and Remus. Previous work has interpreted that the Carboniferous-Permian-Triassic detrital zircon had stopped reaching the northern part of the Sverdrup Basin by deposition of the upper Heiberg Formation (lower Jurassic). New detrital-zircon age analyses from samples along the northern part of the basin spanning different horizons in the Heiberg Formation show that the typical extra-basinal signature, with abundant Carboniferous-Permian-Triassic ages, was no longer recorded during the initial deposition of the Fosheim Member during the latest Triassic. Previously published basin analysis from the Sverdrup Basin interprets syn-Jurassic extensional faults and so we relate the provenance change to the onset of extension. It is interpreted that the Sverdrup Basin transitioned from a basin that received sediment from a northern extra-basinal igneous source during deposition of the Romulus Member to an extensional basin by the deposition of the Fosheim Member in the latest Triassic, as the northern sediment source was interrupted by intervening extensional basins of the proto-Amerasia Basin.