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TitreGeophysical evidence for crustal thickness variations between the Denali and Tintina Fault Systems in west-central Yukon
AuteurLowe, C; Cassidy, J F
SourceTectonics vol. 14, no. 4, 1995 p. 909-917,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 910027
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC105B; 105C; 105D; 105E; 105FG; 105J; 105K; 105L; 105M; 105N; 105O; 106B; 106C; 106D; 115A; 115B; 115C/01; 115C/02; 115C/07; 115C/08; 115C/09; 115C/10; 115C/15; 115C/16; 115F/01; 115F/02; 115F/07; 115F/08; 115F/09; 115F/10; 115F/15; 115F/16; 115G; 115H; 115I; 115J; 115K/01; 115K/02; 115K/07; 115K/08; 115K/09; 115K/10; 115K/15; 115K/16; 115N/01; 115N/02; 115N/07; 115N/08; 115N/09; 115N/10; 115N/15; 115N/16; 115O; 115P; 116A; 116B; 116C01; 116C02; 116C07; 116C08; 116C09; 116C10; 116C15; 116C16
Lat/Long OENS-141.0000 -130.0000 65.0000 60.0000
Sujetstectonique de plaques; études de la croûte; mouvements de la croûte; épaisseur de la croûte; rangées sismiques; interpretations sismiques; levés sismiques; profils sismiques; données sismiques; croûte continentale; failles, extension; discontinuité de Mohorovicic; anomalies gravimétriques; interprétations de la pesanteur; Crétacé; Tertiaire
Illustrationslocation maps; gravity profiles; seismic profiles; seismic maps
Diffusé2010 07 26
Résumé(disponible en anglais seulement)
Analyses of receiver functions recorded at two broadband seismic stations in the northern Cordillera indicate that the crust is thinner beneath Dawson (-35 km) than Whitehorse (-39 km). A simple two-dimensional gravity model, constrained by the seismic results shows that this change in crustal thickness occurs at about 63øN, in a zone approximately 35 km wide, where the Moho dips at ---8 ø to the south. The Bouguer anomaly high associated with the thinner crust can be traced westward into east-central Alaska where crustal thinning and extension are well documented; therefore we propose that west-central Yukon (north of 63øN) has been extended also. On the basis of geological and other geophysical data we examine three likely time windows, in the Cretaceous, early Tertiary, and Present. We discuss data which indicate that early Tertiary and younger extension may be related to the transfer of motion from the Denali Fault System inboard to the Tintina Fault System. Earlier Cretaceous extension has been variously attributed to collision related back arc extension syncollisional processes, or gravitational collapse of an overthickened crustal section. The relative importance of extension in these periods remains nebulus; however, the correspondence between the transition in crustal thickness determined in this study and a mapped boundary between "lower" plate and "upper" plate rocks suggests mid-Cretaceous extension exerted a significant influence on current Moho depths.