ARCUS | Arctic Research Consortium of the United States

6th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Caroline Lavoie
Authors   Caroline Lavoie, M. Allard, and P.R. Hill
Category   Interdisciplinary Research
Title   Holocene deltaic sedimentation along an emerging coast: Nastapoka River Delta, eastern Hudson Bay, Québec
Affiliation   Centre d'études nordiques, Université Laval, Sainte-Foy, QC, Canada

Abstract

Eastern Hudson Bay is characterized by falling relative sea level as a result of postglacial isostatic rebound, which makes the region a natural laboratory for rapid forced regression, where the evolution of deltaic systems and offshore sedimentation patterns can be studied. A multidisciplinary approach involving air-photograph analysis, offshore geophysical surveys, sediment coring, and facies and diatom analyses was used in this study of the Nastapoka River delta. The delta has formed as a result of the fluvial erosion of emerged Quaternary sediments, but is mainly subaqueous. Offshore, in the prodelta zone, the oldest deposits are glaciomarine, laid down when the ice front of the receding Laurentide ice sheet stood on the Nastapoka hills some 7,700 - 6,800 years BP. Lateral equivalents of this glaciomarine unit are presently exposed on land. The shallow-water platform of the delta shows a thin surficial unit of wave-worked sand that overlies fine-grained, deeper-water deposits derived from erosion of clay soils in the river catchment a few centuries ago, probably during periods of intense thermokarst activity. As the isostatic uplift continues, the deltaic platform will gradually emerge and be incised by the river channel.