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Titolo:
GEOPHYSICAL EVIDENCE FOR CRUSTAL THICKNESS VARIATIONS BETWEEN THE DENALI AND TINTINA FAULT SYSTEMS IN WEST-CENTRAL YUKON
Autore:
LOWE C; CASSIDY JF;
Indirizzi:
GEOL SURVEY CANADA,PACIFIC GEOSCI CTR,BOX 6000 SIDNEY BC V8L 4B2 CANADA
Titolo Testata:
Tectonics
fascicolo: 4, volume: 14, anno: 1995,
pagine: 909 - 917
SICI:
0278-7407(1995)14:4<909:GEFCTV>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
EAST-CENTRAL ALASKA; TANANA TERRANE; EXTENSIONAL TECTONICS; CORDILLERA; EVOLUTION; BENEATH;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
C. Lowe e J.F. Cassidy, "GEOPHYSICAL EVIDENCE FOR CRUSTAL THICKNESS VARIATIONS BETWEEN THE DENALI AND TINTINA FAULT SYSTEMS IN WEST-CENTRAL YUKON", Tectonics, 14(4), 1995, pp. 909-917

Abstract

Analyses of receiver functions recorded at two broadband seismic stations in the northern Cordillera indicate that the crust is thinner beneath Dawson (similar to 35 km) than Whitehorse (similar to 39 km). A simple two-dimensional gravity model, constrained by the seismic results, shows that this change in crustal thickness occurs at about 63 degrees N, in a zone approximately 35 km wide, where the Moho dips at similar to 8 degrees 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 63 degrees N) 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 are 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.

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Documento generato il 15/07/20 alle ore 14:43:53