GEOSCAN, résultats de la recherche


TitreSediment dispersal patterns and their significance to mineral exploration in the East Arm area of Great Slave Lake
AuteurSharpe, D R; Cummings, D I; Kerr, D E; Kjarsgaard, B A; Knight, R D; Russell, H A J
SourceL'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 34, 2011 p. 1; 1 CD-ROM
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100429
Réunion2011 GAC-MAC-SEG-SGA Joint Annual Meeting; Ottawa; CA; mai 25-27, 2011
Documentpublication en série
Mediapapier; en ligne; numérique; CD-ROM
ProvinceTerritoires du Nord-Ouest
SNRC75K; 75L
Lat/Long OENS-112.0000 -108.0000 63.0000 62.0000
Sujetsgéochimie des dépôts glaciaires; exploration de dépôts glaciaires; dépôts glaciaires; dispersion des sédiments; tills; dépôts glaciaires; directions du transport de la glace; géologie des dépôts meubles/géomorphologie; géologie économique; Cénozoïque; Quaternaire
ProgrammeDiamands, GEM : La géocartographie de l'énergie et des minéraux
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
Field mapping, sampling and analysis of glaciogenic sediment in a ~250,000 km2 region near the East Arm of Great Slave was carried out to support regional mineral assessment (1 sample /~400 km2) in a proposed national park reserve. Glacial erosion features (e.g. striae) record an east to west flow with NW and SW radial divergence across the study area. Transport of glacial sediment, till, followed a similar divergent pattern based on 40-60 km wide, fan-shaped geometries for most dispersed indicators. Sediment transport ranges from a few kms to >200 kms, depending on the clast size and lithology reported, although transport distances from known sources within the study area range from ~1-80 kms. Dispersal in till appears to be aligned with ice flow direction. Glaciofluvial erosion (s-forms and till removal), transport and deposition, mainly expressed as esker sediment set within 0.25-3 km wide erosional corridors, show a similar divergent pattern as that of ice-flow (till) indicator distribution. This similarity in flow pattern suggests that meltwater and glacial events responded to similar directional gradients, potentially simplifying mineral tracing. The similarity in pattern, inferred close timing of events (late ice flow to meltwater flow), and lack of multiple flow phases may have contributed to the apparently simple dispersal pattern observed. Transport paths and dispersal of rock fragments and minerals is similar in till and glaciofluvial sediment, although transport distances appear to be greater (from 5 to 25 km) in some constituents in eskers and indicator minerals are more concentrated in esker sediment than in till. The fan-shaped geometry for most dispersed indicators is interpreted to relate to either broad source-rock areas or to expanding (point source?) flow patterns often observed in glacial erosion and dispersal trains. The 40-60 km wide East Arm patterns are in marked contrast to long, linear, parallel patterns found in nearby parts of the Slave such as Ranch Lake and Snap Lake. For example, the Ranch Lake diamond indicator dispersal train is pencil-shaped with sharply-defined lateral edges and a narrow width (500 m at source, 2 km at 30 km and <5km at 80 km down-flow). It is interpreted that these dramatically different geometries relate to either differing flow regimes, flow vectors, source dimensions or to different processes.