GEOSCAN, résultats de la recherche


TitreEvolution of the ancestral Pacific margin, southern Canadian Cordillera: insights from new geologic maps
AuteurThompson, R I; Glombick, P; Erdmer, P; Heaman, L M; Lemieux, Y; Daughtry, K L
SourcePaleozoic evolution and metallogeny of pericratonic terranes at the Ancient Pacific Margin of North America, Canadian and Alaskan Cordillera; par Colrpon, M (éd.); Nelson, J L (éd.); Geological Association of Canada, Special Paper 45, 2006 p. 433-482
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20060158
ÉditeurAssociation géologique du Canada
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC82K; 82L; 92I; 82M
Lat/Long OENS-122.0000 -116.0000 52.0000 50.0000
Sujetscroûte continentale; accretion; marges continentales; schistes; gneiss; épaisseur de la croûte; formation de failles; plissement; bassins sédimentaires; terrains; géologie structurale; tectonique
Illustrationslocation maps; cross-sections, structural; geological sketch maps; photographs; geochemical plots; schematic diagrams; stratigraphic columns
ProgrammeProjet de l'ancienne marge du Pacifique du CARTNAT
ProgrammeCRSNG Conseil de recherches en sciences naturelles et en génie du Canada
Résumé(disponible en anglais seulement)
We postulate an ancestral margin that differs in three important respects from previous accretion models: (1) a block of North American continental crust at least 200 km wide and several hundred long, the Okanagan high, defined the outboard side of the ancestral continental margin during the Neoproterozoic and early Paleozoic; (2) upper Paleozoic and lower Mesozoic rocks comprising so-called accreted crust were stratigraphically rather than tectonically emplaced; and (3) Proterozoic North American continental crust is within approximately 5 km of the present day surface between Upper Arrow Lake and the Fraser fault. These postulates derive from recognition of Devonian-Mississippian stratigraphy that traverses from the "accreted" realm into the miogeoclinal realm, tying them together long before postulated mid-Jurassic accretion. Across the Vernon map area, few Meso- and Neoproterozoic rocks are present, implying profound stratigraphic omission, and subsequence structural thinning, between the Upper Paleozoic succession and underlying 1.5 Ga and older schist and gneiss. The search for terrane boundaries was complicated, first by Middle Jurassic to Late Cretaceous crustal thickening, and subsequently by Late Cretaceous to Early Eocene extensional flow. The weight of geological evidence supports stratigraphic rather than tectonic "terrane" emplacement, which is consistent with stratigraphic relations exposed farther east. The belt of intense folding and faulting along the Kootenay arc and western Selkirk fan is interpreted as inversion of a Proterozoic and Paleozoic sedimentary basin between the Okanagan high and the cratonic margin. The arcuate surface trace of this fold belt is thought to reflect the subsurface eastern face of the Okanagan high.