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TitlePost-accretionary fault deformation of the Intermontane region, Yukon and northern British Columbia, Canada
AuthorKellett, D AORCID logo; Banjan, M; Coutand, I; Ryan, J J; Zagorevski, AORCID logo; Colpron, M; Joyce, N
SourceThermo 2018: 16th International Conference on Thermochronology, conference abstracts; 2018 p. 105 Open Access logo Open Access
LinksOnline - En ligne (PDF, complete volume - volume complet, PDF, 9.72 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20190219
MeetingThermo 2018 - 16th International Conference on Thermochronology; Quedlinburg; DE; September 16-21, 2018
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 09 01
AbstractJurassic to Paleogene 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 their recessive nature, which can make the primary fault surfaces difficult to access. Low temperature multi-thermochronology and direct dating methods for fault-generated materials are well-suited to provide constraints on timing and kinematics of brittle faults, but have rarely been applied together.
Here we apply apatite and zircon (U-Th)/He and fission track dating 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 comparable depositional age. Detrital zircon U-Pb ages constrain depositional ages for Laberge Group samples from both structural positions. Zircon double dating results (U-Pb and (U-Th)/He ages from individual crystals) confirm a volcanic source for the zircon. Muscovite in footwall Laberge Group rocks preserve undisturbed Early Jurassic detrital ages. Thus footwall Laberge Group and older basement rocks were buried and heated to 400-170 °C during Late Jurassic (Oxfordian) to Early Cretaceous (Albian) while hanging wall Laberge Group rocks remained cooler than ~170 °C. Both footwall and hanging wall Laberge Group rocks exhibit cooling through ~40 °C at ca. 40 Ma suggesting a common Tertiary exhumation history. Temperature-time models resulting from this yet-evolving dataset 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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