Constraining fjord formation and isostatic uplift in Arctic Canada and Northeast Greenland using Pliocene-early Pleistocene sediment deposits

In Arctic Canada and Northeast Greenland, previous studies have found several high-elevation occurrences of marine and/or fluvial sediments of Pliocene-early Pleistocene age. In Arctic Canada, the deposits include the marine strata of the Hvitland beds on Ellesmere Island (up to ~130 m a.s.l.; Fyles et al., 1998), the marine deposits on Meighen Island (up to ~100 m a.s.l.; Fyles et al., 1991), as well as several sites with fluvial deposits, including the unconsolidated braided river deposits found on Banks Island (up to ~130 m a.s.l.; e.g., Fyles et al., 1994), Prince Patrick Island (up to ~200 m a.s.l.; Fyles, 1990), and on the high terraces of Ellesmere Island (up to ~600 m a.s.l.; Fyles, 1989) – all assumed to have be deposited prior to the carving of the deep fjord systems seen in the regions today. In Northeast Greenland, the sediment deposits include the marine Kap København (up to ~230 m; Funder et al., 1984) and Lodin Elv Formations (up to 62 m a.s.l.; Feyling-Hansen et al., 1983), assumed to have been deposited ca. 2-2.5 Ma. Previous work has studied these deposits in detail to constrain their fauna and age, their stratigraphic relationships, as well as their implications for past climates in the Arctic. However, particularly the current high elevation of the marine deposits can also put time constraints on surface uplift in these regions (e.g., Pedersen et al., 2019). Here we explore these constraints in the context of erosion driven flexural isostatic uplift associated with glacial erosion and fjord formation, allowing us to constrain the incision of the fjord systems in time, with the potential to also constrain the timing and rates of glacial erosion.

Feyling-Hanssen, R.W., Funder, S., Petersen, K.S., 1983, The Lodin Elv Formation: A Plio-Pleistocene occurrence in Greenland. Bulletin of the Geological Society of Denmark 31, 81-106.

Funder, S., Bennike, O., Mogensen, G.S., Noe-Nygaard, B., Pedersen, S.A.S., Petersen, K.S., 1984. The Kap København Formation, a late Cainozoic sedimentary sequence in North Greenland. Grønlands Geologiske Undersøgelse, 120, 9–18.

Fyles, J.G., 1989: High terrace sediments probably of Neogene age, west-central Ellesmere Island, Northwest Territories; in Current Research, Part D; Geological Survey of Canada, Paper 89-1 D, p. 101-104.

Fyles, J.G., 1990. Beaufort Formation (Late Tertiary) as seen from Prince Patrick Island, Arctic Canada. Arctic 43, 393-403.

Fyles, J.G., Marincovich, L., Jr., Matthews, J.V., Jr., Barendregt, R., 1991. Unique mollusc find in the Beaufort Formation (Pliocene) on Meighen Island, Arctic Canada; in Current Research, Part B; Geological Survey of Canada, Paper 91-1 B, 105-112.

Fyles, J.G., Hills, L.V., Matthews, J.V., Barendregt, R., Baker, J., Irving, E., Jetté, H., 1994. Ballast Brook and Beaufort Formations (late Tertiary) on Northern Banks Island, Arctic Canada. Quaternary International 22–23, 141-171.

Pedersen, V.K., Larsen, N.K., Egholm, D.L., 2019. The timing of fjord formation and early glaciations in North and Northeast Greenland. Geol­ogy 47, 682–686.