Glacial geology and Quaternary marine stratigraphy of the Robeson Channel area, northeastern Ellesmere Island, Northwest Territories

Abstract

Glacial and marine deposits associated with two phases of glaciation are exposed along a 60 km corridor on Ellesmere Island that borders Robeson Channel. The oldest sediments, tentatively dated at ≥ 70 000 BP, were deposited during a major advance of the northwest Greenland ice sheet across Robeson Channel. During subsequent retreat of this ice mass, glaciomarine sediments containing a High Arctic macro- and microfauna were deposited in the isostatic downwarp on Ellesmere Island. This marine unit was radiocarbon dated at 31 300 ± 900 and > 32 000 BP; mean aIle/Ile ratios are 0.218 ± 0.03 for the free fraction and 0.063 ± 0.011 for the total acid hydrolysate.The last ice advance (late Wisconsin – early Holocene) did not extend into the field area from either interior Ellesmere Island or northwest Greenland. The ice-marginal sea transgressed to the marine limit (~116 m) and overlapped the deposits of the previous maximum Greenland advance. Local plateau ice caps did, however, spill over into one major valley and delayed the establishment of the marine limit in this location. Radiocarbon dates on the Holocene marine limit shorelines indicate initial emergence between 8000 and 8600 BP. A mean aIle/Ile ratio of 0.037 was found for the total acid hydrolysate; aIle was undetectable in the free fraction of the Holocene shells.The Holocene and pre-Holocene glacial and marine chronologies in the Robeson Channel area are similar to chronologies demonstrated from other locations in Arctic regions. Tentative correlations based upon aminostratigraphy suggest that the field area has remained, for the most part, ice free since at least 70 000 BP.