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TitleA juvenile Paleozoic ocean floor origin for eastern Stikinia, Canadian Cordillera
AuthorOotes, L; Milidragovic, DORCID logo; Friedman, R; Wall, C; Cordey, F; Luo, Y; Jones, G O; Pearson, D G; Bergen, A
SourceGeosphere 2022 p. 1-19, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210338
PublisherGeological Society of America
Mediapaper; digital; on-line
File formatpdf
ProvinceBritish Columbia
Lat/Long WENS-126.5000 -126.0000 56.5000 56.0000
Subjectsgeneral geology; detrital zone; detrital minerals; zircon; trace element analyses; trace elements; zircon dates; Stikinia; Canadian Cordillera; Paleozoic
Illustrationslocation maps; stratigraphic columns; photographs; photomicrographs; element distribution diagrams; plots; graphs
ProgramGSC Pacific Division
Released2022 05 12
AbstractThe Cordillera of Canada and Alaska is a type example of an accretionary orogen, but the origin of some terranes remains contentious (e.g., Stikinia of British Columbia and Yukon, Canada). Presented herein are igneous and detrital zircon U/Pb-Hf and trace- element data, as well as the first radiolarian ages from the Asitka Group, the basement to eastern Stikinia. The data are used to evaluate the role of juvenile and ancient crust in the evolution of Stikinia and the tectonic environment of magmatism. Two rhyolites are dated by U-Pb zircon at 288.64 ± 0.21 Ma and 293.89 ± 0.31 Ma, with EHf(t) = +10. Red chert contains radiolarians that are correlated with P. scalprata m. rhombothoracata + Ruzhencevispongus uralicus assemblages (Artinskian-Kungurian). Detrital zircon U/Pb-Hf from a rare Asitka Group sandstone have a mode at ca. 320 Ma and EHf(t) +10 to +16; the detrital zircon suite includes five Paleoproterozoic zircons (~5% of the population). Detrital zircons from a stratigraphically overlying Hazelton Group (Telkwa Formation) volcanic sandstone indicate deposition at ca. 196 Ma with zircon EHf(t) that are on a crustal evolution line anchored from the Asitka Group. Zircon trace-element data indicate that the Carboniferous detrital zircons formed in an ocean arc environment. The Proterozoic detrital zircons were derived from a peripheral landmass, but there is no zircon EHf(t) evidence that such a landmass played any role in the magmatic evolution of eastern Stikinia. The data support that eastern Stikinia formed on Paleozoic ocean floor during the Carboniferous to early Permian. Consistent with previous fossil modeling, zircon statistical comparisons demonstrate that Stikinia and Wrangellia were related terranes during the Carboniferous to Permian, and they evolved separately from Yukon- Tanana terrane and cratonic North America.
Summary(Plain Language Summary, not published)
The age and affinity of the basement to the exotic island arc terrane Stikinia is poorly known, but is speculated to derive from attenuated North American crust. Radiolarian fossils from the Asitka Group (Carboniferous) and isotopic (U/Pb and Hf) and trace element data from zircon and from the Asitka Group and the overlying Hazelton Group (Early Jurassic) constrain the ages of key volcano-sedimentary successions in eastern Stikinia, and indicate the evolution of source magmas in an arc environment with negligible involvement of evolved continental crust.

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