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TitleMiddle Jurassic to earliest Cretaceous mid-crustal tectono-metamorphism in the northern Canadian Cordillera: Recording foreland-directed migration of an orogenic front
 
AuthorStaples, R D; Murphy, D C; Gibson, H D; Colpron, M; Berman, R GORCID logo; Ryan, J J
SourceGeological Society of America Bulletin vol. 126, no. 11-12, 2014 p. 1511-1530, https://doi.org/10.1130/B31037.1 Open Access logo Open Access
Image
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20130498
PublisherGeological Society of America
Documentserial
Lang.English
Mediapaper; digital; on-line
File formatpdf
ProvinceYukon
NTS105A; 105B; 105C; 105D; 105E; 105F; 105G; 105H; 105J; 105K; 105L; 105M; 115G; 115H; 115I; 115J; 115K; 115N; 115O; 115P; 116B; 116C
AreaNorthern Cordilleran
Lat/Long WENS-141.0000 -128.0000 65.0000 60.0000
Subjectsgeochronology; general geology; thermobarometry; monazite; garnet; zoning; Yukon-Tanana terrane; garnet isopleth; Jurassic; Cretaceous; Triassic; Permian
Illustrationslocation maps; geological sketch maps; photomicrographs; profiles; phase diagrams; plots; diagrams
ProgramGEM: Geo-mapping for Energy and Minerals, Multiple Metals - NW Canadian Cordillera (Yukon, B.C.)
Released2014 06 23
AbstractIn situ sensitive high-resolution ion microprobe monazite geochronology and garnet isopleth thermobarometry reveal a previously unrecognized Middle Jurassic to earliest Cretaceous mid-crustal tectono-metamorphic event in the eastern part of the Yukon-Tanana terrane (Finlayson Lake district, southeast Yukon) in the northern Canadian Cordillera. Intersection of garnet end-member compositional isopleths applied to single-stage, growth-zoned garnet records progressive garnet growth from 550 °C and 6.1-6.6 kbar to 600 °C and 7.5 kbar. Monazite textures, chemical zoning, and in situ U-Pb ages record a single protracted episode of monazite growth from ca. 169 to 142 Ma coeval with the development of transposition fabrics and the late stages of garnet growth. This event post-dates widespread Early Jurassic exhumation of Yukon-Tanana terrane rocks west of the Tintina fault in west-central Yukon, which were previously ductily deformed and metamorphosed in the Permo-Triassic. The lack of evidence for Permo-Triassic ductile deformation and high-grade metamorphism within the Finlayson Lake district, and its position east of the Permian arc center and west of Permian blueschists and eclogites, suggests this eastern part of the terrane occupied the cool forearc at this time. These data indicate younger, more protracted mid-crustal orogenesis in the northern Cordillera than was previously recognized, with deformation and metamorphism migrating toward the foreland and downwards in the Middle Jurassic to Early Cretaceous, in part contemporaneous with and analogous to that in the southeastern Canadian Cordillera.
Summary(Plain Language Summary, not published)
Sophisticated dating techniques on rocks from the Finlayson Lake area of southeast Yukon reveal a previously unrecognized Middle Jurassic to earliest Cretaceous mountain building event that helps further unravel the tectonic evolution of the Canadian Cordilleran mountain chain by constraining the location of domains in the northern Cordillera at different geological times. The new ages allow correlation of deformation and metamorphism in the northern Cordillera with partly contemporaneous and analogous events recognized in the southeastern Canadian Cordillera.
GEOSCAN ID293753

 
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