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Emplacement of Large Igneous Provinces (LIPs) had a major effect on global climate, ocean chemistries as traced in sedimentary records and biotic turnovers. The linkage between LIPs and oceanic anoxic events has been documented with the Cenomanian/Turonian boundary event and Oceanic Anoxic Event 2 (OAE2). The Caribbean LIP and High Arctic Large Igneous Province (HALIP) are regarded as possible triggers. The pericratonic Arctic Sverdrup Basin is the partial location of the HALIP, where little is known about sedimentary, geochemical and biotic responses to the HALIP phases. Sedimentary strata at Glacier Fiord, Axel Heiberg Island, exhibit a dynamic Cretaceous polar carbon burial history within the lower to middle Cenomanian Bastion Ridge Formation and upper Cenomanian to Turonian part of the Kanguk Formation. We present the first initial 187 Os/ 188 Os (Os i) composition profile for a polar Cenomanian/Turonian boundary interval (~100-93.9 Ma) linked to recently dated magmatic phases of the Strand Fiord Formation, part of the HALIP. The carbon isotope record coupled with the Os i profile show two events in the upper Cenomanian interval marked by positive carbon perturbations and shifts to more non-radiogenic Os i compositions. The earlier short-lived event is interpreted as result of weathering of the surrounding Strand Fiord volcanics causing a local non-radiogenic Os i signal. Coinciding transgressive shorelines let to an increase in marine and terrestrially derived organic matter. Subsequently, injection of mantle-derived basalts into organic rich sediments is credited with causing the release of methane documented in a distinct negative carbon isotope excursion. We speculate that the methane release of the HALIP was an important contribution for rapid global warming caused by increasing atmospheric CO 2 levels associated with the OAE2 event likewise recognized in the Sverdrup Basin. As climate cooled in the middle and late Turonian, carbon burial decreased under increasingly oxygenated benthic conditions. Epifaunal 3 foraminiferal species, adapted to low oxygen conditions, persisted during the OAE2. Our Cenomanian to Turonian multiproxy record of the Sverdrup Basin distinguishes between local and global signals within a restricted High Arctic basin. Our results demonstrate the interplay between basin tectonism and sea-level change, increased weathering during transgressive phases, seafloor processes such as hydrothermal activity and methane release and biotic response to a complex paleoceanography. With future reliable dated frameworks this unique polar record will facilitate correlations to other polar basins and records of lower paleolatitudes.

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The Eagle Plain, located in the northeastern Yukon Territory, Canada, forms a northern segment of the Cretaceous Western Interior Sea. Its preserved mid-Cretaceous strata document an active structural regime with sea-level fluctuations and changing sediment supply areas. The mid-Cretaceous rocks are unconformably underlain by either Paleozoic or younger Mesozoic formations. Recent paleontological evidence, including pollen, foraminifera and macrofossils from outcrop sections in the Eagle Plain, suggested that Albian to Cenomanian aged strata are preserved. This package includes the Whitestone River, Parkin, Fishing Branch, Burnthill Creek and Cody Creek formations. This project tests new subsurface stratigraphy hypotheses by examining two continuous cores (Molar P-34 and Ellen C-24) and their benthic foraminiferal assemblages. It compares subsurface faunal changes with those obtained from outcrop samples by Haggart et al (2013) and integrates those to well log signatures that are used to establish the subsurface architecture. Three new biostratigraphic zones are recognized; the Early Albian Gaudryina tailleuri Zone in the lower Whitestone River Formation, the Middle to early Late Albian Gaudryina canadensis Zone in the Upper Whitestone River and sandstone member of the Parkin Formation, and the latest Albian Miliammina manitobensis Zone in the shale member of the Parkin Formation and lowermost Fishing Branch Formation. The biostratigraphic framework established in the subsurface correlates well with the fauna observed in outcrops. Foraminiferal assemblages are almost entirely dominated in both cores by agglutinated specimens that document a response to regionally recognized fluctuating sea-level changes during the Albian. Observations of foraminiferal morphogroups and their relative proportions allow for iii paleoenvironmental reconstruction, including oxygen and nutrient conditions. The Ellen C-24 well represents a fully marine, well oxygenated proximal shelf deposited during the lower to early Late Albian Whitestone River Formation. The Molar P-34 well represents a deep water, offshore setting with increased accommodation space marked by sediment slumping, demonstrating a northwestward deepening of the basin. This interpretation is supported by the presence of abundant tubular suspension feeders which are less common in the Ellen C-24 well. In both settings a marked lithological change from mudstone to sandstone occurs between the Whitestone River and Parkin formations, corresponding to a distinct faunal changeover from rich to impoverished fauna. The Whitestone River Formation documents Albian sea-level fluctuations of the Moosebar, Hulcross, Joli Fou and Mowry seas. These are distinguished from each other by faunal reductions that mark regressive phases and shifts in log signatures, and can be correlated to the northern Polar Sea and southern Western Interior Sea basins, as well as globally. The latest Albian disconformity is believed to occur in the terrestrial sandstones of the Fishing Branch Formation. Whi...