GEOSCAN, résultats de la recherche


TitreGlacial history and dispersal patterns north of Wager Bay, Nunavut
AuteurMcMartin, I; Campbell, J E; Dredge, L A; Corrigan, D; Huntley, D
Source40th Annual Yellowknife Geoscience Forum, abstracts of talks and posters; par Watson, D M (éd.); Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2012, 2012 p. 29 (Accès ouvert)
LiensOnline - En Ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120269
Réunion40th annual Yellowknife Geoscience Forum; Yellowknife; CA; Novembre 13-15, 2012
Documentpublication en série
SNRC56G; 56H
Lat/Long OENS-92.0000 -88.0000 66.0000 65.0000
Sujetsdépôts glaciaires; dépôts glaciaires; exploration de dépôts glaciaires; tills; échantillons de till; géochimie du till; géologie des dépôts meubles/géomorphologie; géologie économique; Cénozoïque; Quaternaire
ProgrammeGisements polymétalliques - Presqu'île Melville (Nunavut), GEM : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
New 1:100 000 scale surficial geological mapping across a large region (31 000 km2) north of Wager Bay, Nunavut, together with regional-scale till sampling (10-km spacing), provide new data and improved understanding of the glacial history in support of mineral exploration, sustainable resource development and land-use management. Conspicuous northward-trending crag-and-tail and other streamlined landforms over a large part of the study area indicate a prevailing northward direction of ice flow from a centre of outflow lying south of, or along Wager Bay. Prominent north-flowing meltwater corridors containing a succession of subglacial, supraglacial and proglacial sediments occur in the northern part of the study area and indicate southward ice retreat. Southwest of Repulse Bay, southeastward and eastward ice-flow indicators overprint the dominant northward flows and are associated with opening of Repulse Bay during deglaciation, followed by radial flow from a remnant ice mass. East-flowing meltwater corridors characterized by complex sediment-landform assemblages and eroded tills indicate a westward retreating ice margin in this area. Both the northward and eastward meltwater corridors have their heads close to topographic drainage divides (Committee Bay and Wager Bay) and are replaced farther inland (up-ice) by bedrock-controlled subglacial channels and esker sediments, nested ice-marginal meltwater channels, or continuous proglacial channels and small outwash pads. These late, more subtle channels and sediments formed as the ice mass receded and vanished into the highlands north of Wager Bay. A small area within these highlands shows evidence of pre-Late Wisconsinan relict, weathered till and bedrock surfaces, presumably reflecting cold-based conditions and preservation under a remnant ice mass. A late sequence of east-southeastward ice flows into Wager Bay is found along the northern shores of Wager Bay and reflects the opening of Roes Welcome Sound, drawdown into Wager Bay, and separation of remnant ice centres on either side of Wager Bay.
To date, 306 till samples have been collected for provenance, geochemistry, various indicator minerals and gold grain counts. A number of significant dispersal patterns are recognized from the 2010 and 2011 analytical results and 2012 field work. A major sand-sized fluorite grain anomaly forming a 20-km long fan-shaped dispersal train oriented NNE is found in the Stewart Lake area indicating a source within local intrusions of unknown age (Nueltin?). A multi-element geochemical signature (Al2O3-Co-Cr-Cr2O3-Cu-Fe2O3-Ga-Sc±Cd±Ni±Sn) is present in till (<63 ?m) collected in a large area southwest of Repulse Bay which may be associated with previously unknown slices of supracrustal rocks including metasediments and BIF found during 2012 joint bedrock and surficial mapping activities. Two ultramafic boulder dispersal trains and possible up-ice (south) sources were also identified in 2012. One of the boulder trains may be linked to a north-trending ultramafic geochemical dispersal train (Cr-Ni-Co) previously reported north of the study area within the Committee Bay TGI project area. Till pebble lithology analysis and results from 2012 sampling will further refine the characteristics and significance of glacial transport in the area. This research is part of the Wager Bay surficial mapping activity under the GEM Melville Peninsula Project.