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TitleReconnaissance of structural geology of the Atnarko metamorphic complex, southern Tweedsmuir Park, British Columbia
AuthorIsrael, S A; Kennedy, L A
SourceGeological Survey of Canada, Current Research (Online) no. 2002-A12, 2002, 8 pages,
PublisherNatural Resources Canada
Mediapaper; on-line; digital
RelatedThis publication is contained in Geological Survey of Canada; Geological Survey of Canada; (2002). Current Research 2002, winter release, Geological Survey of Canada, Current Research no. 2002
File formatpdf
ProvinceBritish Columbia
NTS93D/01; 93D/08; 93C/04; 93C/05; 92M/16; 92N/13
AreaBella Coola; Tweedsmuir Provincial Park; Ptarmigan Lake; Glacier Mountain; Pandemonium Pass
Lat/Long WENS-126.5000 -125.5000 52.5000 51.7500
Subjectsstructural geology; igneous and metamorphic petrology; bedrock geology; structural features; metamorphism; plutonic rocks; volcanic rocks; fracture zones; shear zones; folds; deformation; Atnarko Complex; Mesozoic; Cretaceous; Jurassic; Tertiary; Cenozoic
Illustrationssketch maps; photographs; stereonets
ProgramTargeted Geoscience Initiative (TGI-1), 2000-2003
Released2002 01 22
AbstractThe Atnarko metamorphic complex consists of polydeformed, Jurassic to Tertiary, intermediate plutonic and volcanic rocks. Northwest-striking fabrics dominate the southern portion of the complex, whereas northeast-striking fabrics dominate the northern portion of the complex. The central portion con-tains fabrics of both orientations. Large northwest- and north-striking, dextral, mylonite zones crosscut the main gneissic fabric, as do smaller sinistral and dextral, east-striking, ductile shear zones. At least three phases of folding are documented; F 1 and F 2 folds are tight to isoclinal with coplanar fold axes, and F 3 folds are open to closed with east- to southeast-plunging fold axes. Brittle deformation, expressed as large, north-striking, steeply dipping shear zones and discrete, randomly orientated fractures crosscut all other structures. Ages of deformation and the regional significance of these structures are not yet known and are the subject of ongoing research.