| Summary: | Micropaleontological and geochemical analyses of the Upper Cretaceous Smoking Hills and Mason River formations in the Anderson Basin, northern mainland coast of Arctic Canada, were used to evaluate the marine and terrestrial environmental conditions that prevailed in the southern extent of the Boreal Sea at the end of the Cretaceous. The radiolarian biozonation proposed in this study and its correlation with diatom, silicoflagellate and palynological biozones previously reported in the same area indicate a late Santonian-middle Campanian age for the Smoking Hills Formation and a middle Campanian-early Maastrichtian age for the Mason River Formation. The Smoking Hills Formation was deposited during marine transgression and water column stratification, and planktic communities were dominated by dinoflagellates, red algae, green algae and probably diatoms and silicoflagellates. Bottom waters were predominantly anoxic-euxinic during the deposition of this unit, with short intervals of ventilation as evidenced by the presence of benthic foraminifera. Terrigenous input increased considerably during the deposition of the Mason River Formation and fueled marine primary productivity. Marine planktic communities were dominated by diatoms, silicoflagellates, and probably red and green algae. Bottom waters were fully oxygenated and dominated by sponges. Total concentrations of polycyclic aromatic hydrocarbons indicate that angiosperms diversified during the early Maastrichtian and contributed considerably to the organic matter preserved in the Mason River Formation. These compounds also show evidence of increased wildfire activity and erosion rates in continental areas, increasing the amount of soil-derived organic matter in the marine basin. The integration of micropaleontological with elemental and organic geochemical data presented in this study provides new insight into the response of planktic communities to environmental perturbations in a Cretaceous Arctic shelf ecosystem. Additionally, the findings provided here, ...
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