Our understanding of the greatest biologic catastrophe in Earth history, the Permian/Triassic mass extinction, is largely informed by extensive studies of highly fossiliferous sedimentary records from the Tethys Ocean. Deposited on the eastern equatorial margin of the Pangea supercontinent, Tethyan sediments record the dramatic devastation of ecosystems across the Permian/Triassic boundary, and the long, slow recovery that characterizes its aftermath. In contrast, the western margin of Pangea has a sparse fossil record, but it provides important insights into the dynamic changes in biogeochemical and nutrient cycles that occurred during the extinction. Here we examine chemostratigraphic and geochemical records from the northwestern margin of Pangea, with a focus on the type sections of the Griesbachian, Dienerian, Smithian, and Spathian (the four substages of the Lower Triassic), the sediments of which were deposited in the Sverdrup Basin which now lies in the Canadian Arctic Archipelago. We show that northwest Pangea, was under growing environmental stress prior to the mass extinction, where Boreal depositional systems were marked by the eradication of carbonate producers and progressive occupation of shallow shelf environments by siliceous sponges. The Siberian Traps erupted into this already stressed world driving shallow to deep water marine anoxia. Following the extinction, the Early Triassic was an interval of major perturbations in global biogeochemical cycles, defining several aborted recoveries including the Smithian hyperthermal event and subsequent Spathian negative carbon isotope excursion. Final stabilisation of marine environments occurred in the Middle Triassic, marked by massive carbon drawdown sequestered as marine algae.

The Strathearn Formation is a carbonate-dominated succession cropping out in Carlin Canyon, northern Nevada. The upper part of this unit is mid-upper Asselian (Lower Permian), as determined by conodont biostratigraphy including occurrences of Sweetognathus expansus, Streptognathodus constrictus, and Mesogondolella striata. At the study location, the Strathearn is fine-grained carbonate, dominated by a heterozoan assemblage of bryozoans, brachiopods and echinoderms that accumulated in a mid-ramp setting below a thermocline. The studied unit is highly fossiliferous with a silicified bryozoan assemblage dominated by ramose forms including trepostomids, cryptostomids, and cystoporids, and subordinate fenestrids. The matrix between bryozoan zoaria includes carbonate mud and peloids with some microbial fabric and minor quartz silt. Brachiopods are also found throughout, mostly in life-position. The assemblages include large productides as well as small ones, and small rhynchonellide and spriferinide taxa, suggesting sparse and limited food resources, as these conditions favour the growth of brachiopods with simple lophophores, which can attain large size as the productides Reticulatia huecoensis and Kochiproductus sp. They are mostly free-living semi-infaunal taxa indicating the occurrence of soft substrates, but some forms are pedicle-attached. Biotic relationships within the palaeocommunity were dominated by competition among suspension-feeders that collected food in different tiers at a depth between fair-weather and storm wave base. Some bryozoans lie horizontal to bedding, but others have a vertical life-position. Overall, the degree of relief suggests that this unit represents multiple incipient biostromes that were never fully developed, as determined by numerous storms that are recorded as graded tempestites downslope. The assemblage is compared to others along the western and northwestern margin of Pangea. Storms, increasing turbidity, and climate change may have locally inhibited and limited long-term development of this suspension-feeding community.“I'd like to be, under the sea, in a bryozoan's garden, in the shade” apologies to The Beatles.

The cyclic to non-cyclic Pennsylvanian-Lower Permian successions of the Robledo Mountains, New Mexico and the Carnic Alps, south Austria, record the acme and demise of the late Palaeozoic ice age (LPIA). Microfacies analyses of cyclic strata of the Pennsylvanian-Asselian Horquilla, Shalem Colony (New Mexico), and Schulterkofel (Carnic Alps) formations record glacioeustatic sea-level fluctuations of an amplitude on the order of 100 m. These fluctuations were the result of Milankovitch-driven eustatic sea-level shifts associated with the waxing and waning of ice sheets during the peak of the main phase of the LPIA. Microfacies analyses of the overlying upper Asselian cyclothems of the Community Pit, Robledo Mountains (New Mexico) and Zweikofel (Carnic Alps) formations record relatively moderate sea-level variations on the order of a few tens of metres (~ 30–40 m). This comparatively minor sea-level amplitude may be linked to the demise of ice sheets during the final stages of the LPIA and the limited input that shrinking ice sheets had on global sea-level fluctuations prior to their final collapse at the Asselian-Sakmarian boundary. The uppermost part of the Robledo Mountains and the Apache Dam (New Mexico) and Zottachkopf (Carnic Alps) formations are Sakmarian. These strata are interpreted as non-cyclic and represent sedimentation following the end of the LPIA.

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.

A thick succession of upper Paleozoic carbonate rocks and minor chert crops out north of the head of Otto Fiord (northwest [NW] Ellesmere Island, Nunavut) in the Canadian Arctic Archipelago. These rocks accumulated in a tectonic subbasin—the Otto Fiord Depression (OFD)—of the Sverdrup Basin that likely originated through rifting during late Early Carboniferous (Serpukhovian). Following a long interval of passive subsidence that allowed a thick succession of Moscovian–Kasimovian carbonate rocks to fill the OFD, tectonic activity resumed during the Gzhelian (Late Pennsylvanian). This resulted in rapid collapse of the depression along its axis and simultaneous uplifts of its margins, a style of tectonism in accord with the inferred basin-wide shift to a transpressional–transtensional stress regime at that time. Late Pennsylvanian–Early Permian sedimentation in the OFD led to the development of four long-term (second-order) transgressive–regressive sequences of early Gzhelian–middle Asselian (<1200 m), late Asselian–late Sakmarian (<380 m), latest Sakmarian–late Artinskian (<160 m) and latest Artinskian–late Kungurian (<60 m) age. These ages are supported by integration of biostratigraphic data from conodonts, fusulinaceans, and small foraminifers. The development of each sequence-bounding unconformity was associated with renewed tectonism in the OFD. Each sequence recorded the development of a depositional system characterized by high energy peripheral shoreface grainstones passing basinward across a gently dipping ramp into deep-water basinal calcareous and siliceous mudstone. The ramp portion of the early Gzhelian–middle Asselian system comprises both cool-heterozoan to warmphotozoan carbonates (Nansen Formation) suggesting a relatively shallow thermocline at that time. These rocks are arranged in a series of high-order cyclothems of glacio-eustatic origin. Cyclothemic sedimentation ended at the Asselian–Sakmarian boundary, simultaneous to a major depositional system shift to cool-water heterozoan sedimentation (Raanes Formation), a change presumably brought on by the closure of the Uralian seaway linking NW Pangea with the Tethyan Ocean. This event led to the destruction of the permanent thermocline, and disappearance of photozoan carbonates by the early Sakmarian despite rising temperatures globally. Cool-water heterozoan sedimentation, associated with relatively shallow outer-ramp to midramp spiculitic chert resumed in the Artinskian and then again in the Kungurian (Great Bear Cape Formation) when the OFD was filled up. The depression ceased to exist as a separate tectonic/subsidence entity with the widespread sub-Middle Permian unconformity, above which sediments were deposited during a passive subsidence regime across most of the Sverdrup Basin. The Pennsylvanian–Lower Permian succession that accumulated in the OFD along the clastic-free northern margin of the Sverdrup Basin is essentially identical, both in terms of tectonic evolution and stratigraphic development, with the coeval succession of Raanes Peninsula, southwest (SW) Ellesmere Island, the type area of the Raanes, Trappers Cove, and Great Bear Cape formations along the clastic-influenced southern margin.

Following the latest Permian extinction ∼252 million years ago, normal marine and terrestrial ecosystems did not recover for another 5-9 million years. The driver(s) for the Early Triassic biotic crisis, marked by high atmospheric CO 2 concentration, extreme ocean warming, and marine anoxia, remains unclear. Here we constrain the timing of authigenic K-bearing mineral formation extracted from supergene weathering profiles of NW-Pangea by Argon geochronology, to demonstrate that an accelerated hydrological cycle causing intense chemical alteration of the continents occurred between ∼254 and 248 Ma, and continued throughout the Triassic period. We show that enhanced ocean nutrient supply from this intense continental weathering did not trigger increased ocean productivity during the Early Triassic biotic crisis, due to strong thermal ocean stratification off NW Pangea. Nitrogen isotope constraints suggest, instead, that full recovery from ocean nutrient stress, despite some brief amelioration ∼1.5 million years after the latest Permian extinction, did not commence until climate cooling revitalized the global upwelling systems and ocean mixing ∼10 million years after the mass extinction.

The Gzhelian (Upper Pennsylvanian) to Kungurian (Lower Permian) succession around Carlin Canyon, northern Nevada, in the Basin and Range province of the western USA is a relatively undeformed wedge of fossiliferous marine carbonate and fine-grained calcareous and cherty clastic rocks that rests with profound angular unconformity on Mississippian to mid-Pennsylvanian sedimentary rocks that had been uplifted, faulted, folded, and eroded prior to the Late Pennsylvanian transgression. This wedge of sediments, which tapers over less than 2 km from 1341 m in the west to 588 m in the east, comprises the Strathearn, Buckskin Mountain, and lower part of the Beacon Flat formations. These units form a second-order sequence within which five third-order unconformity-bounded transgressive–regressive sequences are nested. These sequences are Gzhelian, early to late Asselian, latest Asselian to late Sakmarian, latest Sakmarian to late Artinskian, and latest Artinskian to late Kungurian in age based on the determination and biostratigraphic interpretation of 26 conodont taxa, including two new species (Adetognathus carlinensis n. sp. and Sweetognathus trexleri n. sp.). Each sequence records sedimentation on a westward-dipping ramp along which significant facies change occurs with inner-ramp coarse-grained algal and bioclastic photozoan grainstone to the east passing westward into mid- to outer-ramp heterozoan carbonate, and ultimately into deep-water fine-grained mixed clastic–carbonate facies with no fossils except sponge spicules, representing deep-water sedimentation in a basinal area that underwent repeated episodes of rapid subsidence associated with each sequence. Accommodation during sedimentation of Gzhelian–Kungurian sequences around Carlin Canyon was repeatedly created in response to flexural subsidence caused by tectonic loading west of the study area. Each sequence recorded the simultaneous foundering of the basinal area in the west and uplift of the basin margin in the east. Individual sequences overlap the underlying sequence to the east, while flexural subsidence from the Gzhelian to the earliest Artinskian led to a basin in the west that became deeper over time. A lull in tectonic activity associated with each sequence allowed carbonates to prograde from east to west, partially filling the basinal area until the early Artinskian, and completely filling it to sea level during the late Artinskian and then again in the late Kungurian. The Gzhelian–Kungurian carbonate succession of the Carlin Canyon area bears much resemblance with the coeval succession that occurs all along the northwest margin of Pangea, from Nevada in the south to the Canadian Arctic islands in the north, and down from the Barents Sea to the central Urals to the east. That broad area was affected by the same oceanographic events, the most significant of which was the earliest Sakmarian closure of the Uralian seaway, which prevented warm water from the Tethys Ocean from reaching the northwestern Pangea margin as it did before; this led to much cooler oceanic conditions all along western North America, even in the low tropical paleolatitudes where northern Nevada was located, in spite of a globally warming climate following the end of the late Paleozoic ice age.

The Devonian to Carboniferous (DC) transition coincided with a green-to-ice house climatic shift, anoxia, disappearance of lower latitude carbonate banks, and turnover from warm-to-cool water carbonate factories. In western Laurentia, the switch to carbonate factories dominated by cool-water biota was contemporaneous with a tectonically driven palaeogeographic change. To investigate this depositional shift and infer the relative impact of climate vs tectonics, a continental-scale sedimentological and geochemical study was conducted on twelve stratigraphic sections of DC strata from western Canada to southern Nevada (USA). The spatial–temporal distribution of microfacies records the turnover from [i] a Famennian lime mud-rich, shallow warm-water carbonate ramp with low sedimentation rates, mesotrophic conditions and tabular geometry to [ii] Tournaisian to Viséan lime mud-depleted and grainstone dominated cool-water carbonate ramp with anomalous high sedimentation rates, oligotrophic conditions and a pronounced slope. Positive excursions of δ18Ocarb (+ 2‰ V-PDB) and δ13Ccarb (+ 4‰ V-PDB) of Lower Mississippian carbonates likely correspond to the first cooling peak of the Carboniferous-Permian icehouse climate, following carbon withdrawal during black shale deposition during the late Famennian and early Tournaisian. However, late Tournaisian return of photozoan elements and their persistence throughout the Viséan suggests that warmer surface water existed, revealing a decoupling of the lower latitude ocean and the atmosphere. Shoaling of the thermocline was likely a result of cold-water upwelling along an open coast, as the Antler orogen no longer provided an oceanic obstruction to the west. This study shows that carbonate platforms are more susceptible to regional changes than global shifts.

The Late Devonian-Early Carboniferous (DC) Antler orogeny in southwestern Laurentia is contemporaneous with influx of clastic sediments, unconformities, and volcanism across much of western Laurentia (WL), suggesting the demise of the Paleozoic passive margin. However beyond the type Antler orogeny in southwestern Laurentia, the DC tectonic setting is still unclear. Westerly sediment provenance has been suggested as evidence of a convergent margin setting in a foreland basin. However, there is a gap in our understanding in central WL (Alberta and Montana) despite the fact that paleogeographic reconstructions place this area at the centre of WL. We provide detrital zircon (DZ) U-Pb geochronological data from strata in Alberta, Montana, and Nevada that are synchronous with the Antler orogeny to constrain sediment dispersal patterns and test the westerly sediment sourcing hypothesis. We show three DZ facies specific to particular geographic locations: DZ facies 1 in southern Nevada has a prominent subpopulation of early to mid-Mesoproterozoic (mode at 1430 Ma), DZ facies 2 in northeastern Nevada has a late Paleoproterozoic population (mode at 1823 Ma), and DZ facies 3 in Alberta and Montana displays Mesoproterozoic to Neoproterozoic (mode at 1036 Ma), mid-Paleozoic (mode at 411 Ma), and depositional (ca. 360-340 Ma) ages. North-south variation in DZ facies indicates that WL basins were locally sourced from various tectonic fragments having different signatures. Comparing our data with published data, we show that WL is dominated by DZ recycled from uplifted older strata with input from mid-Paleozoic arc terrane (s) to the west. Westerly sourcing is evidenced by the presence of near-depositional ages and affinities of this study's DZ facies with strata located to the west. Our results and geological evidence from other studies suggest that the Antler orogeny triggered a depositional shift and controlled sediments dispersal in WL, signaling the demise of the Paleozoic passive margin.

The end-Permian mass extinction (EPME) was the most severe extinction event in the past 540 million years, and the Siberian Traps large igneous province (STLIP) is widely hypothesized to have been the primary trigger for the environmental catastrophe. The killing mechanisms depend critically on the nature of volatiles ejected during STLIP eruptions, initiating about 300 kyr before the extinction event, because the atmosphere is the primary interface between magmatism and extinction. Here we report Ni isotopes for Permian-Triassic sedimentary rocks from Arctic Canada. The δ 60 Ni data range from −1.09‰ to 0.35‰, and exhibit the lightest δ 60 Ni compositions ever reported for sedimentary rocks. Our results provide strong evidence for global dispersion and loading of Ni-rich aerosol particles into the Panthalassic Ocean. Our data demonstrate that environmental degradation had begun well before the extinction event and provide a link between global dispersion of Ni-rich aerosols, ocean chemistry changes, and the EPME.

The upper Paleozoic succession along the northwest margin of the Canadian Arctic Sverdrup Basin is little studied and poorly understood yet has the potential to yield insights into the paleogeographic and tectonic evolution of the Arctic regions including Crockerland. Carboniferous and Permian drill cuttings were collected from five exploration wells on Brock, Mackenzie King, and Ellef Ringnes islands. Seven unconformity-bounded sequences were identified and correlated. Reflection seismic interpreted on Ellef Ringnes Island indicates that a major syn-sedimentary fault offsets the Mississippian succession bounding a down-to-the-north half-graben. Late Pennsylvanian (Gzhelian) fault reactivation, associated with the Melvillian Disturbance, created a depression that extended northward and was bordered to the south by a structural high. Episodic minor fault reactivation occurred until the Early–Middle Permian boundary. During the latest Early Permian (Kungurian), sand derived from Crockerland prograded southward onto the Sverdrup Basin’s northwest margin and continued into the Roadian. After a lull during the Wordian, clastic progradation resumed in the Capitanian. Detrital zircon U–Pb ages recovered from Kungurian and Roadian samples on Brock and Ellef Ringnes islands display Devonian Clastic Wedge (DCW) signatures. A Moscovian–Artinskian carbonate blanket likely covered Crockerland and sheltered DCW material from erosion, implying it was a subsiding, carbonate bank throughout most of the Pennsylvanian – Early Permian. Base level fall in the Kungurian, associated with a transition to a more humid climate, breached these carbonate rocks to allow erosion and transportation of DCW material. Recycling of the DCW started earlier (Artinskian) and peaked later (Wordian) along the southern margin of the basin.

The largest extinction in Earth history, in the latest Permian, was followed throughout most of the Early Triassic by a prolonged period of ecologic recovery. What factors delayed biotic recovery are still under debate and partly revolve around impacts of global warming on primary marine productivity. We examined N isotope records from the Festningen section on Spitsbergen, Arctic Norway, to examine changes in nutrient availability through the Early to Middle Triassic along the northern margin of Pangea. Our results show progressive decline in N availability throughout the Griesbachian, leading to severe nutrient limitations through the remainder of the Early Triassic, until returning to a highly productive continental margin in Middle Triassic time. These results are consistent with other studies from northern and western Pangea and thus show regional nutrient limitations occurred in what should have been the main zone of marine primary productivity. Such nutrient limitation likely stressed primary production and consequently contributed to prolonged marine recovery. We suggest this was driven by high ocean temperatures depressing the marine nutricline.

The goal of this study is to catalogue all the large scale, tectonically-generated sequence boundaries which punctuate the Phanerozoic stratigraphy of the North American Arctic and to determine the frequency and possible origin of the interpreted tectonic episodes which gave rise to the boundaries. This study is feasible because, over the last 40 years, the Phanerozoic succession of the North American Arctic, both on the surface and in the subsurface, has been intensely studied in various sedimentary basins with modern basin analysis techniques including sedimentology, sequence stratigraphy and biostratigraphy.

The unit previously mapped as the lower Upper Devonian Okse Bay Formation in the Yelverton Pass area of northern Ellesmere Island, considered indicative of syn-orogenic foreland (Devonian clastic wedge) basin deposition along the apex of the Ellesmerian Orogen, is in fact Early Carboniferous (Serpukhovian) in age and belongs to the Borup Fiord Formation of the successor Sverdrup Basin. The principal lines of evidence in favor of the original Okse Bay formational assignment were: (1) the presence of late Middle (Givetian) or early Late (Frasnian) Devonian palynomorphs; (2) a set of lithofacies presumably different from that of the Borup Fiord Formation; and (3) an angular unconformity between the so-called Okse Bay strata and overlying Pennsylvanian carbonates of the Nansen Formation. Here we demonstrate that the Devonian palynomorphs were eroded from the Devonian clastic wedge, transported for some distance, and deposited into the Sverdrup Basin in the Early Carboniferous. We also show that the units mapped as Okse Bay and Borup Fiord formations share the same clastic lithofacies assemblages, albeit in different proportions. We report the presence of Early Carboniferous palynomorphs in the uppermost part of a section assigned to the Okse Bay Formation, and show that detrital zircons contained in the middle part of the Okse Bay Formation yield dates as young as 358 Ma, thus demonstrating that the rocks that contain them are considerably younger than the assumed youngest age (Frasnian) based on palynology. We conclude that the Okse Bay Formation is the same unit as the Borup Fiord Formation and should be remapped as such. Both units are part of the same unconformity-bounded syn-rift Serpukhovian sequence that was rotated and differentially eroded prior to the widespread Pennsylvanian transgression. The Serpukhovian sequence comprises three lithofacies assemblages: meandering stream clastic, braided stream/alluvial fan clastic, and shallow marine carbonate. These lithofacies assemblages were deposited as part of a differentially subsiding rift system likely bounded to the south by one or more master listric faults and associated footwall uplift, and to the north by hanging wall ramp uplift. The Serpukhovian sequence comprises three fourth-order sequences, each interpreted as corresponding to a rift pulse. Relatively coarse terrigenous sediments derived from the erosion of the Franklinian basement (Laurentia margin) and the Devonian clastic wedge entered the rift basin at a high angle through broad alluvial fans and braided river systems. These streams fed into a NE-flowing basin-axial meandering system, which met a shallow sea to the northeast. An additional source of sediments is Crockerland to the north, including syn- to post-Ellesmerian intrusions that shed detrital zircons of latest Devonian age once sufficient unroofing of these had occurred during the Serpukhovian.

AbstractA new carbon isotope record for two high-latitude sedimentary successions that span the Jurassic–Cretaceous boundary interval in the Sverdrup Basin of Arctic Canada is presented. This study, combined with other published Arctic data, shows a large negative isotopic excursion of organic carbon (δ13Corg) of 4‰ (V-PDB) and to a minimum of −30.7‰ in the probable middle Volgian Stage. This is followed by a return to less negative values ofc. −27‰. A smaller positive excursion in the Valanginian Stage ofc. 2‰, reaching maximum values of −24.6‰, is related to the Weissert Event. The Volgian isotopic trends are consistent with other high-latitude records but do not appear in δ13Ccarbrecords of Tethyan Tithonian strata. In the absence of any obvious definitive cause for the depleted δ13Corganomaly, we suggest several possible contributing factors. The Sverdrup Basin and other Arctic areas may have experienced compositional evolution away from open-marine δ13C values during the Volgian Age due to low global or large-scale regional sea levels, and later become effectively coupled to global oceans by Valanginian time when sea level rose. A geologically sudden increase in volcanism may have caused the large negative δ13Corgvalues seen in the Arctic Volgian records but the lack of precise geochronological age control for the Jurassic–Cretaceous boundary precludes direct comparison with potentially coincident events, such as the Shatsky Rise. This study offers improved correlation constraints and a refined C-isotope curve for the Boreal region throughout latest Jurassic and earliest Cretaceous time.

John Utting, an esteemed late Palaeozoic to Triassic palynologist, passed away on 17 August 2018, at the age of 78. He is survived by his wife, Lindsay, their children, Sonia, Oliver, Daniel and Ni...

Two negative carbon isotope excursions (3.5–6.5‰) across the Wuchiapingian-Changhsingian boundary (WCB) are observed globally (sections in China, Canada, and Iran); however, the causative mechanism of these excursions is debated. Here, high-resolution osmium isotope (187Os/188Os or Osi) chemostratigraphy of four globally correlated WCB sections (3 in China - Meishan, Shangsi and Lianyuan and 1 in Canada - Buchanan Lake) show two separate Osi excursions to less radiogenic compositions that are coincident with the carbon isotope shifts for two of the South China sections (Lianyuan, Meishan). In contrast, only a single Osi excursion to less radiogenic compositions, coinciding with the earliest Changhsingian carbon isotope shift, is observed for the Shangsi and Buchanan Lake sections. The Osi shift is interpreted to reflect increased unradiogenic Os input from basaltic magmatism in South China, possibly related to the Emeishan large igneous province (LIP). However, 187Os/188Os data suggest that only the earliest Changhsingian volcanism had global impact on both the ocean and atmosphere. The lack of any evidence for a biotic event associated with the WCB therefore may have been due to the more regional rather than global impact of volcanism during the latest Wuchiapingian. In contrast, during the earliest Changhsingian, volcanism was sufficient to cause a more global signal in the ocean osmium record, but was inadequate, or too prolonged, to drive any significant environmental change. Volcanism, however, may have provided the isotopically light carbon that drove the negative carbon isotope excursions across the WCB.

The upper Paleozoic (Carboniferous to Permian) succession of the Sverdrup Basin in the Canadian Arctic Islands has the potential to contain significant hydrocarbon reserves, though it has never been a primary exploration target. To better constrain previous estimates and hydrocarbon play possibilities, this study completed evaluations of source rock quality and extent and thermal maturity. This study also incorporated new understandings of reservoir units and their stratigraphic relation to source rocks, trapping configurations and timing of hydrocarbon migration. Several hydrocarbon source units were identified within the upper Paleozoic formations of the Sverdrup Basin including the Emma Fiord, Trappers Cove, Antoinette, Assistance, Sabine Bay, van Hauen and Trold Fiord formations. The Emma Fiord and Trold Fiord formations are both found to be oil prone, with the remainder of the sources being gas prone. The upper Paleozoic succession is interpreted to be gas prone due to dominant kerogen types and high average thermal maturity. Many of the older concept plays put forth for the upper Paleozoic succession have been determined to be unviable. However, modern plays that implement new understandings of the basin have the potential to be viable. This study has found that the upper Paleozoic succession of the Sverdrup Basin is promising for gas discoveries with new plays such as salt diapirism plays, or plays similar to the Barents Sea Gohta play. New hydrocarbon rock source data also suggests the potential for a new oil and gas play on northern Prince Patrick Island. This new research could lead to significant resource discoveries that have been previously overlooked.