|Titre||Sill evolution in marine inundated basins, Sachs Harbour, Banks Island, NWT|
|Auteur||Martin, B G; Bell, T; Smith, I R; Forbes, D L|
|Source||ArcticNet 2007, annual science meeting, programme/ArcticNet 2007, programme, réunion scientifique annuelle; 2007 p. 75|
|Liens||Poster - Affiche |
|Séries alt.||Secteur des sciences de la Terre, Contribution externe 20070456|
|Réunion||ArcticNet Annual Science Meeting; Collingwood, ON; CA; décembre 11-14, 2007|
|Media||papier; en ligne; numérique|
|Référence reliée||Cette publication est reliée Martin, B G; Bell,
T; Smith, I R; Forbes, D L; (2010). Sill stratigraphy and sedimentology in marine inundated basins, Sachs Harbour, Northwest Territories: implications for sea-level reconstruction, Commission géologique du Canada, Présentation scientifique no.
|Province||Territoires du Nord-Ouest|
|Lat/Long OENS||-125.0000 -124.5000 72.0000 71.7500|
|Sujets||milieu côtièr; érosion côtière; études côtières; érosion; littoraux; variations du littoral; changements du niveau de la mer; variations du niveau de la mer; filons-couches; géologie des dépôts
|Programme||Renforcer la résilience face aux changements
|Résumé||(disponible en anglais seulement)|
Realistic projections of future relative sea-level rise are critical for assessing future erosion and flooding impacts, and thus are necessary components of an
integrated regional impacts study (IRIS) involving coastal communities and habitats. One of the goals of ArcticNet Project 1.2 is to refine the record of past sea-level change and validate model projections for future change across the Canadian
Arctic. This presentation focuses on the interpretation of past sea-level records, specifically the process of marine inundation of former freshwater basins on coastal lowlands in the western Arctic, although it is broadly applicable to submerging
The inundation basin approach in sea-level studies relies on the accurate determination of the former height of the basin sill over which the marine water flooded, but this can be particularly challenging due to post-inundation
erosion and deposition altering sill morphology and elevation. Shallow seismic profiles and core samples of sills from marine-inundated basins at Sachs Harbour, Banks Island, are being used to identify key processes in the remodeling of sill
morphology following submergence and to define a range of attributes that may be used to characterize sill reworking.
The former glacial outwash plain that terminates at Sachs Harbour is dotted with kettle lakes that have gradually been inundated
by rising sea level. Basin sills (1.3-5.0 m depth) progressively shallow from west to east, reflecting the sequential inundation of higher basins. Sills have steep slopes and relatively flat tops, which in places are incised by channels that are
interpreted to be palaeo-basin outlets. The local Sachs River terminates in an estuarine basin 12 km farther east, but its drowned palaeo-channel can be traced to a submerged delta in front of the community.
Thirteen sediment cores, retrieved
through vibracoring and percussion coring from the sea-ice surface in 2006 and 2007, vary in length from 46 to176 cm. X-rays and textural analysis of the cores reveal pervasive fine to very fine laminated mud and fine sand. Three sedimentary units
have been identified across all cores, although their stratigraphic position and prominence may vary between cores. One unit consists mostly of mud with minor amounts of fine sand and appears to infill former outlet channels and the submerged Sachs
River channel. Organic carbon is generally highest in this unit, varying between 10 and 15% with a relatively low (3-5%) inorganic carbon content. Unit two is composed largely of fine to very fine sand with small amounts of mud and varying amounts of
medium to coarse sand. This unit is divided into three sub-units, one very finely laminated with a higher (5%+) mud content, one coarsely laminated, and the other more massive. Unit three is composed of medium to coarse sand and characterized by the
lowest organic and inorganic carbon content (as low as 2%) in the cores.
The next stages of the project are to correlate the acoustic and core stratigraphy to reconstruct the broad architecture of the sills and to formulate a depositional and
erosional history for the observed sedimentary sequences.