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TitlePost-accretionary fault deformation of the Intermontane region, southern Yukon and northern British Columbia, Canadian Cordillera
AuthorKellett, D AORCID logo; Ryan, J J; Zagorevski, AORCID logo; Colpron, M; Joyce, N
SourceCordilleran Tectonic Workshop, 2018; 2018 p. 40 Open Access logo Open Access
LinksOnline - En ligne (PDF, complete volume - volume complet, PDF, 4.80 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20190220
MeetingCordilleran Tectonic Workshop; Whitehorse, YT; CA; March 2-4, 2018
Mediaon-line; digital
File formatpdf
ProvinceYukon; British Columbia
NTS104J; 104K; 104L; 104M; 104N; 104O; 105B; 105C; 105D; 105E; 105F; 105G; 105L; 115A; 115G; 115H; 115I; 115J
AreaWhitehorse; Atlin Lake; Dawson
Lat/Long WENS-139.5000 -130.0000 65.0000 58.5000
Subjectstectonics; structural geology; geochronology; Science and Technology; Nature and Environment; tectonic history; faulting; deformation; burial history; thermal history; volcanism; bedrock geology; basement geology; structural features; faults; plate motions; kinematic analysis; thermal analyses; temperature; radiometric dating; uranium lead dating; zircon dates; fission-track dates; argon argon dating; potassium argon dating; muscovite; modelling; models; illite; calcite; Paleogene; Intermontane Belt; Canadian Cordillera; King Salmon Fault; Laberge Group; Phanerozoic; Cenozoic; Tertiary; Mesozoic; Cretaceous; Jurassic
ProgramGEM2: Geo-mapping for Energy and Minerals Western Cordillera, Yukon Tectonic Evolution - late Mesozoic to Tertiary
Released2018 03 01
AbstractJurassic and later post-accretionary structures in the northern Canadian Cordillera generally lack absolute timing constraints and their kinematics are only broadly understood. This is largely due to the challenges in directly dating motion on brittle faults, as well as the recessive nature of brittle faults which often form linear topographic lows in the landscape. Low temperature multi-thermochronology can provide constraints on timing and kinematics of brittle faults. Apatite and zircon U-Th/He and fission track dating methods are used to develop footwall and hanging wall temperature-time models for Jurassic to Paleogene faults in the Intermontane region of southern Yukon and northern British Columbia.
Preliminary results, which also incorporate complementary detrital zircon U-Pb and detrital muscovite Ar/Ar age data, illustrate the potential of these methods for reconstructing the post-accretionary structural history of the Intermontane region. For example, multi-geo- and thermochronological results across the King Salmon fault in northern British Columbia demonstrate contrasting burial/heating and cooling histories for footwall and hanging wall Laberge Group units of the Whitehorse trough. Detrital zircon U-Pb data constrain comparable Pliensbachian to Toarcian depositional ages for Laberge Group samples from both structural positions and zircon double dating results (U-Pb and U-Th/He ages from individual crystals) confirm their volcanic source. Muscovite in footwall Laberge Group rocks preserve undisturbed Early Jurassic detrital ages, while zircon U-Th/He yields reset Early Cretaceous ages. Thus footwall Laberge Group and older basement rocks were buried and heated to between 400-180 °C during Late Jurassic (Oxfordian) to Early Cretaceous (Albian) while hanging wall Laberge Group rocks remained above ~180 °C. Both footwall and hanging wall Laberge Group rocks exhibit cooling through ~40 °C at ca. 40 Ma suggesting a common late exhumation history. These temperature-time models will be compared where possible against age constraints obtained by direct dating of fault materials: K-Ar dating of fault gouge illite and U-Pb dating of calcite slickenfibres.

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