In central British Columbia, north-trending dextral strike-slip faults that cut Late Eocene granite also truncate northwesttrending dextral strike-slip faults. The northwest-trending strike-slip faults bound the Wolverine Metamorphic Complex (Wolverine Complex), which has been uplifted primarily by northwest-southeast Eocene crustal extension and somewhat by Late Eocene northerly extension. The crustal extension is indicated by shallow-dipping extensions faults, dyke complexes, and stretching lineations. The Wolverine Complex and its bounding faults define a crustal pull-apart in an en echelon dextral transform. The northwest-and north-trending dextral strike-slip faults in central British Columbia are the continuations of faults that transect the interior of the North American Cordillera, and they represent at least two distinct plate boundaries intermittently active during the Early to Middle Eocene, and the Late Eocene to Early Oligocene. Each of these systems consists of en echelon strike-slip faults linked by extensional pull-aparts, locally represented by metamorphic core complexes. These two plate-boundary systems represent two distinct plate-motion configurations between the North American and Kula-Pacific plates. The older plate boundary is truncated and disrupted by the younger one. These two systems may in turn be disrupted by a younger and different plate-motion configuration represented by the transverse Basin and Range extension complex and its northern and southern transform boundary faults.Les failles coulissantes dextres, de direction nord, dans le centre de la Colombie-Britannique, qui coupent les massifs de granite d'bge Cockne tardif, tronquent aussi les failles coulissantes dextres qui sont orientkes nord-ouest. Les failles coulissantes de direction nord-ouest encadrent le Complexe mktamorphique de Wolverine (Complexe de Wolverine), principalement souleve A 1'Eocbne par une extension crustale nord-ouest -sud-est, et partiellement A 1'Eocbne tardif par une extension vers le nord. Les failles de dktachement, les complexes filoniens et les lineations d'ktirement sont les tCmoins de I'extension crustale. Le Complexe de Wolverine et ses failles bordikres definissent un bassin transtension crustal, dCveloppC dans une faille transformante dextre en tchelons. Dans le centre de la Colombie-Britannique, les failles coulissantes dextres de direction nord-ouest et nord representent le prolongement des failles qui transectent I'intCrieur de la Cordillbre de 1'AmCrigue du Nord, et elles indique~t au moins deux bordures distinctes de plaques qui furent Lpisodiquement actives durant 1'Eockne moyen i precoce, et 1'Eockne tardif i I'Oligockne precoce. Chacun de ces systkmes comprend de failles coulissantes en CcheIons relites par des bassins de transtension extensifs, et localement ils correspondent h des noyaux de massifs mktamorphiques. Ces deux systbmes de bordures de plaques reprtsentent deux modes distincts de mouvements entre les plaques de 1'AmCrique du Nord et de Kula -Pacifique. La plus ancienne des b...

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Conodonts, radiolarians, foraminiferids, and corals provide constraints on the geology and tectonics of the Nechako region. They also support the notion that the Cache Creek Terrane is allochthonous with respect to the North American craton. The 177 conodont collections, assigned to 20 faunas, range in age from Bashkirian (Late Carboniferous) to Norian (Late Triassic); 70 radiolarian collections representing 12 zones range from Gzhelian (Late Carboniferous) to Toarcian (Early Jurassic); 335 collections assigned to 11 fusulinacean assemblages (with associated foram-algal associations) range from Bashkirian to Wordian (Middle Permian); and two coral faunas are of Bashkirian and Wordian age. The fossils document a long but sporadic history of sedimentary events within the Cache Creek Complex that included two major carbonate buildups in the Late Carboniferous (Pope limestone) and Middle Permian (Copley limestone), punctuated by intervening Early Permian deepening; basaltic eruptions during the mid Carboniferous and mid Permian; the onset of oceanic chert sedimentation close to the Carboniferous–Permian boundary and its persistence through the Late Triassic (Sowchea succession); latest Permian and Early Triassic mixed clastics and volcanics (Kloch Lake succession); Middle and Late Triassic reworking of carbonates (Whitefish limestone), including cavity fill in older limestones (Necoslie breccia), and fine-grained clastic sedimentation extending into the Early Jurassic (Tezzeron succession). Tethyan, eastern Pacific, and (or) low-latitude biogeographic attributes of the faunas are noted in the Gzhelian (fusulines), Artinskian (conodonts, fusulines), Wordian (fusulines, corals, conodonts), and Ladinian (conodonts, radiolarians). The Cache Creek Terrane lay far to the west of the North American continent during these times.

Upper Paleozoic to Lower Jurassic oceanic rocks of the Cache Creek Terrane near Fort St. James, in central British Columbia, form a stack of thrust sheets cut by steeply dipping strike-slip faults. Paleontologically dated upper Paleozoic strata include bioclastic shallow-water limestone and ribbon chert. Isotopically dated Permian rocks consist of tonalite sills and stocks and rhyolite flows intercalated with basalt flows. Paleontologically dated lower Mesozoic rocks include greywacke, sandstone, siltstone, argillite, ribbon chert, conglomerate, limestone, and basalt tuff. Trembleur Ultramafite unit of the Cache Creek Complex, in places part of an ophiolite suite, forms thrust sheets and klippen that overlie lower Mesozoic sedimentary rocks. Sedimentological, lithochemical, paleontological, petrological, and textural comparisons with other areas and established models demonstrate that Cache Creek Terrane is an accretionary complex, a structurally stacked assemblage of rocks that originated in diverse and disparate oceanic paleoenvironments. These environments include spreading ridge, oceanic plateau, atoll, trench fill, and possibly arc. Internal imbrication of the terrane is as young as Early Jurassic, as determined from fossil evidence, and the minimum age of obduction of the thrust stack westward onto Stikine Terrane is Middle Jurassic, as determined from dating of a crosscutting pluton. Triassic blueschist and eclogite of Cache Creek Terrane are interpreted to have been primarily uplifted to upper crustal levels during Triassic subduction. Cache Creek Terrane, as a remnant of that subduction process, and caught in the collision between Stikine and Quesnel terranes, marks the position of a lithosphere-scale suture zone, the Pinchi Suture.

Three tectonostratigraphic successions are established from remapping of the area near Barkerville and Cariboo River. The first, of Late Proterozoic to Cambrian sediments, was deposited on the shallow to moderately deep platformal shelf west of and derived from the exposed North American craton. The second is an unconformably overlying Ordovician to Permian sequence of sedimentary and volcanic rocks representing a basinal environment with periodic highs. These packages of sediments were deposited on the North American craton and its western transitional extensions. The third succession, composed of oceanic chert and basalt of the Permo-Pennsylvanian Antler Formation, was thrust eastward over the other two during the early Mesozoic. The three successions were folded, faulted, and metamorphosed during the mid-Mesozoic Columbian Orogeny. The DevonoMississippian Cariboo Orogeny, which was thought to have affected all of the first sequence and part of the second, could not be documented in its type locality. The geology of the Barkerville -Cariboo River area has many similarities with that of Selwyn Basin and Cassiar platform of northern British Columbia and Yukon.Trois successions tectonostratigraphiques sont Ctablies suite a une reprise de la cartographie de la region pr&s de Barkerville et de la riviere Cariboo. La premibre est composCe de sCdiments du ProtCrozoi'que supkrieur a Cambrien et fut dCposCe sur la plateforme peu h modCrCment profonde du plateau continental a l'ouest du craton nord amkricain expos6 et lequel a fourni les sCdiments. La deuxieme est une sCquence discordante sus-jacente ordovicienne B permienne de roches ~Cdimentaires et volcaniques qui reprksentent un environnement de bassin avec des points culminants pkriodiques. Ces ensembles de sCdiments furent dCposks sur le craton nord amkricain et sur les zones de transition se prolongeant vers l'ouest. La troisibme succession est composCe de chert ocCanique et de basalte de la formation Antler d'lge Permo-Pennsylvanien qui a chevauchC vers l'est au-dessus des deux autres durant le MCsozoique infkrieur. Les trois successions ont Ct C plisstes, faillCes et mCtamorphisCes pendant I'orogCnie colombienne au MCsozoi'que rnoyen. L'orogenie Cariboo d'lge DCvono-Mississipien, laquelle semble avoir affect6 la totalit6 de la premikre sCquence et une partie de la deuxibme, ne fournit aucun renseignement reliC B la localit6 type. La gtologie de la rkgion Barkerville -riviere Cariboo prksente plusieurs similitudes avec celle du bassin Selwyn et de la plateforme Cassiar du nord de la Colombie Britannique et au Yukon.