Diatom Stratigraphy of the Gubik Formation, Arctic Alaska

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Pushkar V.S.

International Journal on Algae, 2022, 24(3): 283–298

ABSTRACT: Diatom assemblages of marine sediments from the Gubik Formation deposit of Arctic Alaska, were used for age determination and paleoclimatic reconstruction during the Late Pliocene-middle Pleistocene. Extinct diatoms during the Late Pliocene and Middle Pleistocene, as well as the first appearance of diatoms at the Plio − Pleistocene boundary exist within the sediment. The studied deposits of Nulavik, Killi Creek and the Tuapaktushak beds correspond to the middle part Neodenticula kamtschatica − N. koizumii Zone (3.4–3.1 Ma), lower part Thalassiosira convexa Zone (2.58−2.4 Ma) and to lower part Pyxidicula zabelinae Zone (2.2–2.0 Ma) respectively, as the Karmuk beds contain a species-index of the middle Proboscia barboi Zone (0.43–0.38 Ma). The moderately warm climates within the described zonal age were the effect of high sea-level events (transgressions) in the Arctic Ocean basin. The first penetration of Pacific diatoms to the Chukchi Sea was likely due to the opening of the Bering Strait at ~ 3.4 Ma, or the early Colvillian age. 

KEY WORDS: diatoms, Pliocene, Pleistocene, biostratigraphy, Gubik Formation, transgressions, Skull Cliff, Alaska