Latest Triassic-Early Jurassic Stikine-Yukon- Tanana terrane collision and the onset of accretion in the Canadian Cordillera: Insights from Hazelton Group detrital zircon provenance and arc-back-arc configuration

The Hazelton Group is a Rhaetian-Bajocian (uppermost Triassic-Middle Jurassic) volcano-sedimentary sequence that represents both the last pre-accretionary arc volcanic cycle of Stikinia and its early synaccretionary aftermath. Hazelton magmatism of central Stikinia succeeded the Late Triassic (mainly Carnian-Norian) Stuhini arc, which ceased activity as a result of end-on collision with the pericratonic Yukon-Tanana ter-rane. The Hazelton volcanic belt lies to the south along strike with the coeval Whitehorse trough, the synorogenic clastic basin that developed on top of the Stikinia-Yukon- Tanana collision zone. Whereas the sources of voluminous clastic sedi-ments in the Whitehorse trough were its rapidly exhuming shoulders, the thin clastic intervals in the Hazelton Group in northwestern British Colum-bia were derived from local to subregional block uplifts that supplied mainly ca. 230-215 Ma zir-cons eroded from the plutonic roots of the Stuhini arc. Lesser components include late Paleozoic (ca. 350- 330 Ma) zircons from Stikinia's basement and penecontemporaneous (ca. 205-172 Ma) zir-cons from Hazelton volcanic/subvolcanic sources. Reexamination of the four main volcanic fields that make up the lower Hazelton Group suggests that the main Hazelton volcanic belt formed a southward- convex magmatic arc from eastern Stikinia across the Skeena arch, including the Toodoggone and Telkwa belts, with the Spatsizi and Stewart- Iskut regions of northwestern British Columbia in its back-arc. The Whitehorse trough and Hazelton belt represent a collision zone to active arc pair. Southward advance of the arc and counterclockwise rotation of the Stikinia micro-plate contributed to closure against the Quesnellia arc and assembly of the inner Canadian Cordilleran terrane collage