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TitreRefined ice-flow directions of the Cordilleran Ice Sheet and implications for mineral exploration
AuteurLevson, V; Plouffe, A; Ferbey, T; Bond, J D
SourceGeological Society of America, Abstracts With Programs vol. 46, no. 6, 2014 p. 655
LiensOnline - En ligne
LiensHandout (PDF, 5.8 MB)
Année2014
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140206
ÉditeurGeological Society of America
RéunionGeological Society of America; Vancouver; CA; Oct. 19-22, 2014
Documentpublication en série
Lang.anglais
Mediaen ligne; numérique
Formatshtml
ProvinceYukon; Colombie-Britannique
SNRC82; 92; 93; 94; 95; 102; 103; 104; 105; 114; 115
Lat/Long OENS-141.0000 -114.0000 64.0000 48.0000
Sujetsdirections des mouvements de la glace; tills; cuivre; profils de dispersion; dépôts glaciolacustres; analyses stratigraphiques; glaciation; géologie des dépôts meubles/géomorphologie; Quaternaire
ProgrammeÉtude des gîtes porphyriques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
In the past 15 years, advancements in our understanding of changing flow directions within the Cordilleran Ice Sheet (CIS) during the last glaciation have followed numerous field-based geological survey surficial mapping campaigns. Reconstructed ice-flow histories have formed the basis for the interpretation of till composition studies which have direct application to mineral exploration. At the onset of the last glaciation in the southern CIS, ice from the Cariboo and Coast mountains advanced into the Interior Plateau, with Cariboo ice reaching the Fraser River. At the glacial maximum, an east-west oriented ice divide formed around 52° north latitude from which ice flowed north and south. The different phases of ice flow in this region produced palimpsest dispersal patterns in subglacial tills. In central CIS, outcrop-scale erosional landforms reveal that at the glacial maximum ice flowed outward across both the Coast and Rocky mountains. In the Houston area, for example, an ice divide originally located over the Coast Mountains at the onset of the last glaciation, migrated into the Interior Plateau at glacial maximum reversing flow to the west over the Coast Mountains. During deglaciation, this ice divide re-established over the Coast Mountains. The resulting ice flow reversals greatly impacted glacial transport as identified at Huckleberry Mine where till geochemistry in stratigraphic sections is interpreted in the context of the shifting ice divide. In the northern CIS in Yukon, the interior mountain ranges that hosted alpine glaciers during the onset of the last glaciation were subsequently overridden by the CIS at glacial maximum. This caused a reversal of ice flow in valleys such as those on the south side of the Pelly Mountains (e.g. Seagull Creek) where mineralized float was transported up-valley. Reconstruction of ice-flow histories not only allows for an understanding of the behaviour of past ice sheets but provides the transport vectors essential for tracing mineralized debris in glacial sediments to their bedrock sources. This is increasingly important in Canada as discoveries of surface-exposed mineralization are less common and vast areas with high mineral potential are covered by glacial sediments.
Résumé(Résumé en langage clair et simple, non publié)
L'Initiative géoscientifique ciblée (IGC-4) est un programme géoscientifique fédéral de collaboration qui fournit à l'industrie les connaissances géoscientifiques et les techniques novatrices de prochaine génération dont elle a besoin pour mieux détecter les gîtes minéraux enfouis, réduisant ainsi certains risques liés à l'exploration. Dans les dernières 15 années, d'importants avancemens ont été réalisés dans notre compréhension des directions d'écoulement glaciaire dans la Cordillère canadienne. Comprendre la direction d'écoulement des glaciers est important parce que lorsqu'un glacier s'avance il peut éroder des roches avec des minéraux d'intérêts économiques (par exemple, des roches avec de l'or) et les transporter dans la direction de son mouvement. Lorsque ces roches sont trouvées en surface, les géologues qui essaient de trouver des mines essaient de déterminer d'où les roches proviennent. Évidemment, comprendre la direction des écoulements glaciaires est essentiel pour trouver la source de ces roches.
GEOSCAN ID295170