Late Quaternary marine, deltaic and fluvial deposits, Kanairiktok Valley, coastal central Labrador

Awadallah, Sherif Abdel Monem (1992) Late Quaternary marine, deltaic and fluvial deposits, Kanairiktok Valley, coastal central Labrador. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (17MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The Kanairiktok River Valley, central coastal Labrador, extends more than 100 km inland at about 54°45'N latitude. Three of the five sedimentary units in the bluffs of the modern river were deposited in a marine embayment that occupied the isostatically depressed area during the Late Quaternary. The lateral relationships between the units are poorly known due to limited chronological control. The oldest units (units A and B) were deposited from surface sediment plumes originating from several points of fresh water input into the marine fjord, and from a variety of density currents. Unit B contains rare shells that have been dated at 7950 ± 95 yr B.P. (Beta-28885). Evidence for marine conditions comes from the local occurrence of (a) a periglacial shell community including Portlandia arctica and Mya arenaria, (b) benthic foraminifera including Elphidium excavatum f. clavata, Cassidulina reniforme and Islandiella helenae, and (c) marine dinocysts (Brigantedinium). Density currents became progressively more dominant as fjord-head and side-entry deltas prograded. Due to rapid rates of emergence, marine conditions existed for less than 2000 years in the thesis area (from about 8-6 ka), and perhaps for only a few hundred years in the western part of the area nearest the ice margin. Proximal deltaic sediments were deposited from fjord-head and side-entry deltas as the middle and eastern parts of the study area were emerging (upper part of Unit B and parts of Unit C). The marine and deltaic sediments are overlain by either local aeolian sands of Unit C or fluvial deposits of Unit D. The fluvial system truncated and reworked part of the underlying deltaic and marine sediments. A glacial re-advance may have occurred after the western part of the area became emergent, depositing ice-contact glaciofluvial sediments of units C and D and possibly till (Unit E) over marine muds. Alternatively, some Unit E deposits may have been deposited by debris flows of glaciogenic sediments. -- The main contributions of the thesis are: (1) description and interpretation of the postglacial sedimentary record of the Kanairiktok Valley area, (2) a local chronology of deglaciation and sea level, (3) the first sedimentological, micropalaeontological and process link between marine studies (Labrador Shelf and modern bays) and the land record of Quaternary events in coastal Labrador.

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