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TitleLate Cretaceous magmatism in the Atlin-Tagish area, Northern British Columbia (104M, 104N)
AuthorZagorevski, A; Mihalynuk, M G; Joyce, N; Anderson, R G
SourceBritish Columbia Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork no. 2017-1, 2016 p. 133-152 (Open Access)
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20160314
PublisherBritish Columbia Ministry of Energy and Mines
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS104M; 104N
AreaAtlin; Tagish
Lat/Long WENS-134.2500 -133.7500 59.7500 59.5000
Subjectsmagmatism; ophiolites; intrusive rocks; uranium lead dates; zircon dates; Windy-Table suite; Peninsula Mountain suite; Surprise Lake batholith; Graham Inlet suite; Cretaceous
Illustrationslocation maps; geological sketch maps; stratigraphic charts; stratigraphic correlations; tables; photographs; Concordia diagrams; graphs
ProgramWestern Cordillera, Cache Creek Terrane, GEM2: Geo-mapping for Energy and Minerals
AbstractThe Cache Creek and Stikine terranes in northern British Columbia are unconformably overlain by Upper Cretaceous volcanic, hypabyssal, and sedimentary rocks of the Montana Mountain complex and Windy-Table suite and cut by intrusive rocks of the Surprise Lake plutonic suite. Although these rocks are commonly spatially and temporally associated with mineral prospects, their regional distribution and inter-relationships are not well understood. Herein we present three new U-Pb zircon ages for Upper Cretaceous volcanic and plutonic rocks and new geochemical data. A sample of Peninsula Mountain rhyolite yielded a 85.0 ± 1.6 Ma age indicating that it forms part of the Windy-Table suite. Mafic volcanic rocks previously assigned to Peninsula Mountain suite have the same geochemical characteristics as ophiolitic rocks of the Graham Inlet suite (Cache Creek terrane). These data indicate that the stratigraphy of the area requires significant revision. Ages from the Surprise Lake batholith of 79.70 ± 0.15 Ma and from a granite near Tutshi Lake of 76.5 ± 1.3 Ma are slightly younger than the Windy-Table suite volcanism. The age of these volcanic and plutonic rocks overlaps the age of magmatism and prolific mineralization in northern British Columbia and Yukon.
Summary(Plain Language Summary, not published)
This report presents preliminary results and models developed through GEM2 program on volcanic and plutonic rocks in British Columbia. It details the age and characteristics of magmatic rocks and associated mineralization on the basis of field and laboratory analyses. The results presented herein help progress GEM2 model to ultimately redefine the regional tectonic models of the Cordillera.