Latest Permian to Early Triassic basin-to-shelf anoxia in the Sverdrup Basin, Arctic Canada

A combined sequence stratigraphic and geochemical study of the Latest Permian Extinction event in NW Pangea provides new insight into the onset and extension of basin anoxia onto the adjacent shallow shelf. The Latest Permian transgression in the Sverdrup Basin of Arctic Canada initiated prior to onset of deep-water anoxia and continued past the Latest Permian Extinction event. Deep-water anoxia initiated after the shelf was flooded in mid to Late Changhsingian time, requiring a much more rapid, and much greater vertical, rise in the chemocline than that associated with relative sea level, supporting the chemocline upward excursion model. Our work also extends evidence of global euxinc conditions to NW Pangea. Euxinic conditions developed just prior to the main extinction event, and we suggest that this was associated with a significant pyrite rain-out event which stripped bio-essential nutrients from anoxic seawater prior to the main disruption of the global carbon cycle, as recorded by shifts in the carbon isotope record.