scholarly journals New constraints on Eocene extension within the Canadian Cordillera and identification of Phanerozoic protoliths for footwall gneisses of the Okanagan Valley shear zone

Lithosphere ◽  
2012 ◽  
Vol 4 (4) ◽  
pp. 354-377 ◽  
Author(s):  
S. R. Brown ◽  
H. D. Gibson ◽  
G. D. M. Andrews ◽  
D. J. Thorkelson ◽  
D. D. Marshall ◽  
...  
Keyword(s):  
Shear Zone ◽  
Canadian Cordillera ◽  
Okanagan Valley

U–Pb constraints on the thermotectonic evolution of the Vernon antiform and the age of the Aberdeen gneiss complex, southeastern Canadian Cordillera

2006 ◽  
Vol 43 (2) ◽  
pp. 213-244 ◽  
Author(s):  
P Glombick ◽  
R I Thompson ◽  
P Erdmer ◽  
L Heaman ◽  
R M Friedman ◽  
...  
Keyword(s):  
Shear Zone ◽  
Hanging Wall ◽  
Ductile Deformation ◽  
Granitic Rocks ◽  
Tectonic Activity ◽  
Canadian Cordillera ◽  
Metamorphic Complex ◽  
Seismic Reflection Data ◽  
Gneiss Complex ◽  
Shuswap Metamorphic Complex

The Aberdeen gneiss complex is composed of complexly deformed migmatitic orthogneiss and paragneiss situated within the core of the Vernon antiform, a structure defined by a series of subparallel reflectors visible at upper to middle crustal depths (6–18 km) in seismic reflection data from the Vernon area of the Shuswap metamorphic complex. The Vernon antiform and the Aberdeen gneiss complex lie within the footwall of the gently west dipping (top to the west) Kalamalka Lake shear zone. Migmatitic gneiss exposed within the antiform records evidence (recorded as age domains in complexly zoned zircon grains) of three metamorphic events, occurring at 155–150, 90, and 66–51 Ma. The timing of magmatic events within the antiform includes emplacement of diorite at ~232 Ma, tonalite at ~151 Ma, granodiorite at 102 Ma, and monzonite at 52 Ma. Middle to Late Jurassic metamorphism resulted in widespread migmatization. Early Tertiary metamorphism (66–51 Ma) was coeval with the emplacement of granitic rocks and exhumation typical of other areas of the Shuswap metamorphic complex. Highly deformed orthogneiss situated within the hanging wall of the Kalamalka Lake shear zone, comprising the superstructure, was emplaced at ~171 Ma. Ductile deformation had ceased by 162 Ma. The complex metamorphic and magmatic evolution of the Vernon antiform, which is similar to other areas of the southern Canadian Cordillera including the Nicola horst, Mount Lytton – Eagle plutonic complex, Cariboo Mountains, and Mica Creek area, may reflect episodic tectonic activity at the plate margin.

POLYPHASE DEFORMATION ALONG THE WANN RIVER SHEAR ZONE: IMPLICATIONS FOR THE EVOLUTION OF THE YUKON-TANANA TERRANE IN THE NORTHERN CANADIAN CORDILLERA

2020 ◽  
Author(s):  
Renaud Soucy La Roche ◽  
◽  
Alexandre Zagorevski ◽  
Alexandre Zagorevski ◽  
Nancy L. Joyce ◽  
...  
Keyword(s):  
Shear Zone ◽  
Canadian Cordillera ◽  
Polyphase Deformation

Kilometre-scale folding in the Teslin zone, northern Canadian Cordillera, and its tectonic implications for the accretion of the Yukon-Tanana terrane to North America

1999 ◽  
Vol 36 (3) ◽  
pp. 479-494 ◽  
Author(s):  
Martin de Keijzer ◽  
Paul F Williams ◽  
Richard L Brown
Keyword(s):  
North America ◽  
Shear Zone ◽  
North American ◽  
Root Zone ◽  
Fault System ◽  
Canadian Cordillera ◽  
The West ◽  
The North ◽  
South Central ◽  
North American Craton

The Teslin zone in south-central Yukon has previously been described as a discrete zone with a steep foliation unique to the zone. It includes the Anvil assemblage and the narrowest portion of the Yukon-Tanana terrane (the Nisutlin assemblage), and is defined by post-accretionary faults: the Big Salmon fault to the west and the d'Abbadie fault system to the east. The zone was interpreted as a lithospheric suture or a crustal-scale transpression zone, and as the root zone of klippen lying on the North American craton to the east. We demonstrate that deformation and metamorphism are the same inside and outside the zone. The steep transposition foliation in the zone, in contrast to adjacent rocks to the east, coincides with the steep limb of a regional F3 structure. This fold has a shallow limb in the easternmost part of the zone and immediately east of the zone. Thus we reject earlier interpretations. If a suture exists between the obducted Anvil and Yukon-Tanana Nisutlin assemblages and North America, it is a shear zone that occurs at the base of the obducted rocks, which has been folded by the F3 fold. However, evidence that this thrust boundary is a lithospheric suture is lacking. A consequence of our interpretation is that North American rocks pass under the eastern Teslin zone and outcrop to the west of the Nisutlin and Anvil assemblages. This geometry precludes the possibility of the Teslin zone being the root zone of the klippen.

The Monashee decollement of the southern Canadian Cordillera: a crustal-scale shear zone linking the Rocky Mountain Foreland belt to lower crust beneath accreted terranes

1992 ◽  
pp. 357-364 ◽  
Author(s):  
Richard L. Brown ◽  
Sharon D. Carr ◽  
Bradford J. Johnson ◽  
Vicki J. Coleman ◽  
Frederick A. Cook ◽  
...  
Keyword(s):  
Shear Zone ◽  
Lower Crust ◽  
Rocky Mountain ◽  
Canadian Cordillera ◽  
Accreted Terranes ◽  
Scale Shear

Metamorphism in the Clachnacudainn terrane and implications for tectonic setting in the southern Omineca Belt, Canadian Cordillera

1996 ◽  
Vol 33 (11) ◽  
pp. 1570-1582 ◽  
Author(s):  
J. L. Crowley ◽  
E. D. Ghent ◽  
R. L. Brown
Keyword(s):  
Shear Zone ◽  
Tectonic Setting ◽  
Regional Metamorphism ◽  
Contact Metamorphism ◽  
Canadian Cordillera ◽  
Metamorphic Complex ◽  
Shuswap Metamorphic Complex ◽  
Garnet Zone ◽  
Contact Aureoles ◽  
Upper Boundary

New and previously published metamorphic data suggest that the Clachnacudainn terrane of the southern Omineca Belt has tectonic affinities with the overlying Selkirk allochthon, rather than the underlying Shuswap metamorphic complex. This interpretation is based on relationships between metamorphic minerals and deformation phases, plutons, and the upper boundary of the terrane, the Standfast Creek fault. Regional kyanite and staurolite zones in the structurally lowest part of the terrane are overlain by a garnet zone that is continuous upward across the Standfast Creek fault into the Selkirk allochthon. This metamorphism is inferred to be Jurassic age based mainly on the continuity of these zones with those of known age in the allochthon. Textural relationships show that metamorphism occurred at different times relative to deformation across the terrane. Thermobarometry and a petrogenetic grid indicate that the terrane attained lower to middle amphibolitc facies conditions. Sillimanite and andalusite zones in the contact aureoles of posttectonic mid-Cretaceous plutons overprint the regional metamorphic zones and the Standfast Creek fault. Comparison of estimated pressures shows that approximately 5–10 km of exhumation occurred between regional and contact metamorphism. These metamorphic data are interpreted to indicate that the Standfast Creek fault had minor displacement after regional metamorphism and negligible displacement after contact metamorphism. Therefore, the fault cannot be an Eocene ductile to ductile–brittle shear zone that appressed or omitted metamorphic isograds and rapidly exhumed the Clachnacudainn terrane in its footwall, as was previously proposed.

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