A new late-glacial sea-level record for St. George's Bay, Newfoundland
A new relative sea-level curve is presented for St. George's Bay, southwest Newfoundland, based on (i) a revised stratigraphic framework and depositional model for glacial and marine deposits exposed in coastal sections and (ii) 19 new radiocarbon dates on shells from emerged and submerged mari...
Published in: | Canadian Journal of Earth Sciences |
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Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
2003
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Subjects: | |
Online Access: | http://dx.doi.org/10.1139/e03-024 http://www.nrcresearchpress.com/doi/pdf/10.1139/e03-024 |
Summary: | A new relative sea-level curve is presented for St. George's Bay, southwest Newfoundland, based on (i) a revised stratigraphic framework and depositional model for glacial and marine deposits exposed in coastal sections and (ii) 19 new radiocarbon dates on shells from emerged and submerged marine deposits, including fossiliferous diamictons. The data produce a type B sea-level curve, falling steeply from an extrapolated marine limit of 105 m above sea level at 14.0 14 C ka BP, passing below modern sea level at ~10.6 14 C ka BP, to a lowstand of 25 m at ~9.4 14 C ka BP, and rising again close to modern sea level by 5.0 14 C ka BP. Marine limits in the northern part of the bay have lower elevations (2765 m) due to delayed ice retreat of up to 1.2 ka. Between 12.8 and at least 12.3 14 C ka BP, glaciofluvial outwash graded to falling sea levels between 27 and 17 m above present throughout the bay, whereas lowstand deltas were constructed in sheltered locations at the outlets of major river systems, when sea level was 25 m below present. Establishment of the sea-level lowstand at ~9.4 14 C ka BP is supported by new seismic data and radiocarbon dates from St. George's Bay and also from White Bear Bay on the south coast of Newfoundland. Short-term fluctuations in emergence rates of 12 m/century between 12.5 and 9.5 14 C ka BP are attributed to variable eustatic sea-level rise, superimposed on a declining local glacio-isostatic adjustment. |
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