Abstract
Here we present results from the first continuous core that extends through the upper 150 m of section on Sable Island. This core was positioned in the centre of a 400 m deep buried channel that runs underneath Sable Island. We believe the channel to be analogous with subglacial tunnel valleys observed in northern Europe.
Peat layers from platform borings and a vibracore, just offshore, provide some of the deepest and oldest postglacial sea-level points ever recovered on the North American margin: from -48.8 m (11 kybp) to -35.3 m (8.1 kybp). Combining these points with previous sea-level data, a rate of relative sea-level (RSL) rise of 62 cm/100 yrs is calculated between 8.1 kybp and 4.5 kybp with a decrease of RSL rise to 30 cm/100 yrs from 4.5 kybp to the present. If the faster rate is extrapolated back to 15,000 ybp, we obtain a maximum sea-level lowering of about 78 m in the late Wisconsinan.
The Holocene section of sand is underlain by a series of glacial and glacial-marine clays and sands. Beneath these (at 65–80 m) is what appears to be an interglacial (or interstadial?) sand that is similar to the Holocene sand body. The lowest 60 m of the section is composed of thick, dense clay, which contains a glacial-marine microfossil assemblage. The sediment character and microfossil content are similar to the glacial-marine Emerald Silt observed in most intra-shelf basins inshore of Sable Island. Although we have no samples below 150 m, seismic reflectors in the 150–400 m section of the channel fill suggest chaotic cut and fill deposits, characteristic of the first stage of tunnel-valley filling. The 60 m clay unit may represent the last stage of channel fill (the “quiet phase”) toward the end of the glacial interval. The position of the deposits above suggests that this major glacial cutting event occurred not during the isotope stage 2 world-wide Wisconsinan, but during an earlier (perhaps stage 4) glacial.
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Scott, D.B. et al. (1989). Holocene Relative Sea-Level Changes and Quaternary Glacial Events on a Continental Shelf Edge: Sable Island Bank. In: Scott, D.B., Pirazzoli, P.A., Honig, C.A. (eds) Late Quaternary Sea-Level Correlation and Applications. NATO ASI Series, vol 256. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0873-4_6
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DOI: https://doi.org/10.1007/978-94-009-0873-4_6
Publisher Name: Springer, Dordrecht
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