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Titolo:
Three-dimensional structure of the Torngat Orogen (NE Canada) from active seismic tomography
Autore:
Funck, T; Louden, KE; Wardle, RJ; Hall, J; Hobro, JW; Salisbury, MH; Muzzatti, AM;
Indirizzi:
Dalhousie Univ, Dept Oceanog, Halifax, NS B4H 4J1, Canada Dalhousie Univ Halifax NS Canada B4H 4J1 nog, Halifax, NS B4H 4J1, Canada Mem Univ Newfoundland, Dept Earth Sci, Ctr Earth Resources Res, St Johns, NF A1B 3X5, Canada Mem Univ Newfoundland St Johns NF Canada A1B 3X5 ohns, NF A1B 3X5, Canada Univ Cambridge, Dept Earth Sci, Bullard Labs, Cambridge CB3 0EZ, England Univ Cambridge Cambridge England CB3 0EZ abs, Cambridge CB3 0EZ, England Dalhousie Univ, Dept Earth Sci, Halifax, NS B3H 3J5, Canada Dalhousie Univ Halifax NS Canada B3H 3J5 Sci, Halifax, NS B3H 3J5, Canada Geol Survey Canada, Bedford Inst Oceanog, Dartmouth, NS B2Y 4A2, Canada Geol Survey Canada Dartmouth NS Canada B2Y 4A2 tmouth, NS B2Y 4A2, Canada Newfoundland Dept Mines & Energy, Geol Survey, St Johns, NF A1B 4J6, Canada Newfoundland Dept Mines & Energy St Johns NF Canada A1B 4J6 B 4J6, Canada
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B10, volume: 105, anno: 2000,
pagine: 23403 - 23420
SICI:
0148-0227(20001010)105:B10<23403:TSOTTO>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
U-PB GEOCHRONOLOGY; RIVER MAP AREA; LABRADOR SEA; NORTHERN LABRADOR; NORTHEASTERN LAURENTIA; TECTONIC EVOLUTION; DEFORMATION; METAMORPHISM; TRANSECT; PROVINCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Funck, T Dalhousie Univ, Dept Oceanog, Halifax, NS B4H 4J1, Canada Dalhousie Univ Halifax NS Canada B4H 4J1 fax, NS B4H 4J1, Canada
Citazione:
T. Funck et al., "Three-dimensional structure of the Torngat Orogen (NE Canada) from active seismic tomography", J GEO R-SOL, 105(B10), 2000, pp. 23403-23420

Abstract

The crustal velocity structure and the Moho depth of the Proterozoic Torngat Orogen, NE Canada, is determined by active seismic tomography using travel times of crustal turning rays and Moho reflections. The orogen developedduring oblique convergence of the Archean Superior and Nain Provinces, which trapped an interior belt of Archean crust (Core Zone) between them, withthe Torngat Orogen evolving between the Core Zone and the Nain Province. Beneath the central orogen a crustal root is found with a preserved depth of>52 km and a width of similar to 100 km. To the north, the root shallows to <44 km and narrows to a width of similar to 45 km. The root correlates with a set of major, late orogenic shear zones that accommodated oblique convergence of the Superior and Nain Provinces. This correlation suggests that the transpressional shearing focused strain in the region of the root and contributed to the crustal thickening. Absence of postorogenic magmatic activity prevented reworking or thermal relaxation of the root. The lack of late magmatism is probably related to the depleted and refractory nature of the Archean lithosphere underlying the orogen. Upper crustal velocities are lowest in the Core Zone (similar to 5.7 km/s at the surface) and are compatible with laboratory measurements carried out on gneissic rock samples from that area. Higher velocities in the Nain Province (similar to 5.9 km/s) correlate with felsic gneiss and anorthosite rock samples. A high-velocity region immediately to the north of the crustal root is associated with a Moho uplift (similar to 34 km). This is explained by extension along the Ungava transform fault, and possibly in Hudson Strait, at similar to 55 Ma when rifting in the Labrador Sea was transferred into Baffin Bay.

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Documento generato il 29/03/20 alle ore 12:17:21