The palynological record across the transition on Seymour Island, Antarctica

Unconsolidated, fine-grained (sandy silts), shallow marine sediments of the upper Lopez de Bertodano Formation include the Cretaceous/Tertiary boundary on Seymour Island, northeastern Antarctic Peninsula. These strata contain abundant palynomorphs and other micro- and macrofossils. The Cretaceous/Tertiary boundary is provisionally placed at a dinocyst zonal boundary that occurs within a laterally persistent glauconite-rich interval. This glauconite interval marks the highest, definitely in-place Maastrichtian macro- and microfossils. Strata above this interval are considered Danian, based on palynological evidence, in the absence of other age-diagnostic fossils. Association of Maastrichtian ammonites and microfossils with typically “Danian” dinocysts below the glauconite interval accentuates the transitional nature of the Cretaceous/Tertiary succession on Seymour Island. Changes in Cretaceous/Tertiary dinocyst assemblages may be related to local environmental change, including regression. Pollen and spore assemblages record little change and no evidence of an abrupt event for the land vegetation across the Cretaceous/Tertiary boundary. Instead, a longterm floral turnover is inferred from nonmarine species. This gradual change is consistent with climatic change, possibly cooling, through much of Maastrichtian and early Paleocene time.