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Titolo:
NEW GEOPHYSICAL-DATA FROM THE NORTHERN CORDILLERA - PRELIMINARY INTERPRETATIONS AND IMPLICATIONS FOR THE TECTONICS AND DEEP GEOLOGY
Autore:
LOWE C; HORNER RB; MORTENSEN JK; JOHNSTON ST; ROOTS CF;
Indirizzi:
GEOL SURVEY CANADA,PACIFIC GEOSCI CTR SIDNEY V8L 4B2 BC CANADA UNIV BRITISH COLUMBIA,DEPT GEOL SCI VANCOUVER V6T 1Z4 BC CANADA CANADA YUKON GEOSCI OFF,DEPT ECON DEV WHITEHORSE Y1A 2C6 YT CANADA
Titolo Testata:
Canadian journal of earth sciences
fascicolo: 6, volume: 31, anno: 1994,
pagine: 891 - 904
SICI:
0008-4077(1994)31:6<891:NGFTNC>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
YUKON-TANANA TERRANE; ALASKA CRUSTAL TRANSECT; EAST-CENTRAL ALASKA; COPPER RIVER BASIN; BRITISH-COLUMBIA; NORTHWESTERN CANADA; NAHANNI EARTHQUAKES; CHUGACH MOUNTAINS; SOUTHERN ALASKA; DENALI FAULT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
71
Recensione:
Indirizzi per estratti:
Citazione:
C. Lowe et al., "NEW GEOPHYSICAL-DATA FROM THE NORTHERN CORDILLERA - PRELIMINARY INTERPRETATIONS AND IMPLICATIONS FOR THE TECTONICS AND DEEP GEOLOGY", Canadian journal of earth sciences, 31(6), 1994, pp. 891-904

Abstract

In this paper we analyze recently acquired geophysical data from the northern Cordillera and their relation to the mapped geology. A prominent gravity high (> -45 mGal (1 Gal = 1 cm/s(2))) coincides with a magnetic low and an aseismic region in west-central Yukon where the underlying geology is dominated by quartzo-feldspathic rocks having moderate densities. Extension (similar to 15%), magmatic underplating, and accretion of the anomalous region onto oceanic crust are three possible explanations. Magnetic, gravity, and seismicity data all show significant differences in the physical state of the crust on either side of the Tintina Fault and, together with geological data indicating large offset, suggest it was once a major crustal-scale strike-slip fault. The new gravity data also delineate an arcuate zone of steep gradients (up to 1.4 mGal/km) in the miogeocline, which may correlate with a west-dipping Proterozoic basement ramp mapped on deep seismic sections farther to the north and a transition,from thin (east) to thick sediment cover (west). Seismicity data show that current tectonic activity is concentrated dong the Pacific - North America plate margin in southwestern Yukon and adjacent Alaska and, although there is a marked decreasein activity inland of this margin, notable concentrations occur dong the Denali Fault System and in the eastern miogeocline. There is a distinct absence of earthquakes in parts of the Selwyn Basin and in the northern Yukon-Tanana Terrane. Limited field studies suggest activity is confined to the upper 10-15 km of the crust.

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Documento generato il 08/07/20 alle ore 06:40:46