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TitleGeological relationships in ophiolitic rocks of the northern Cache Creek terrane: GEM 2 Cordillera
AuthorZagorevski, AORCID logo; Mihalynuk, M G; Joyce, N; McGoldrick, S; Bédard, J H; Canil, D; Corriveau, A -S
SourcePoster session abstracts: AME Roundup; 2017 p. 52-53 Open Access logo Open Access
LinksOnline - En ligne (complete volume - volume complet, PDF, 2.33 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20190389
PublisherAssociation for Mineral Exploration
MeetingAME Roundup 2017; Vancouver, BC; CA; January 23-26, 2017
Mediaon-line; digital
File formatpdf
ProvinceBritish Columbia
AreaKing Mountain
Subjectsstructural geology; Science and Technology; Nature and Environment; Cache Creek Terrane; Canadian Cordillera
ProgramGEM2: Geo-mapping for Energy and Minerals Western Cordillera, Cache Creek Terrane
Released2017 01 01
AbstractStructurally dismembered, Penrose-style ophiolite components are well exposed in the King Mountain area where they exhibit boninitic chemistry. Nakina Formation basalt and related hypabyssal rocks, the upper crustal component of the ophiolite, are predominantly exposed further to the northwest, such as in the Nahlin Mountain-Nakina Atlin and Teslin areas immediately above Nahlin suite ultramafic rocks. This lack of lower and middle ophiolitic crust distribution suggests removal by structural excision along an intra-oceanic detachment zone, well known in intra?oceanic core complexes. Ophiolitic spreading appears to have been accommodated magmatically in the southeast and tectonically in the northwest . Such a relationship may result from progressive rifting of a supra-subduction zone ophiolite, with initial rifting accommodated magmatically in the King Mountain area ac ca. 255 Ma and tectonically in Atlin-Jakes Corner area at ca. 245 Ma. Re?evaluation of tectonic relationships indicate that the Cache Creek terrane contains at least two terranes. In the Mt. Nimbus area, ophiolitic rocks are thrust over Mississippian limestone that is interbedded with ocean island basalt. Even though it may have been reactivated, this thrust demarcates the suture between upper plate arc rocks (ophiolite) and subducting plate (limestone platform). In the Jubilee Mountain area, the same juxtaposition is preserved: an isolated klippe of ultramafic rocks intruded by gabbro structurally overlies Horsefeed Formation limestone. Identification of such suture localities is critical for unravelling the tectonostratigraphy of the northern Cache Creek terrane as it is the primary contact in the thrust stack that was later reworked by D2 folds and thrusts and younger strike slip faults.

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