Stratigraphic evolution of the Paleozoic Stikine assemblage in the Stikine and Iskut rivers area, northwestern British Columbia

Abstract

The Stikine assemblage, the "basement" of Stikinia, extends 500 km along the western flank of the Intermontane Belt, east of younger Coast Belt plutons. Four different stratigraphic successions are characteristic of Lower to Middle Devonian, Carboniferous and Permian rocks in the Stikine and Iskut rivers area. West of Forrest Kerr Creek are penetratively deformed Lower to Middle Devonian island-arc volcaniclastic rocks, coralline limestone, and felsic tuff. Fringing carbonate buildups in an arc setting are best illustrated in the sequence at Round Lake where Lower Carboniferous mafic-dominated, bimodal submarine volcanic rocks grade upward into two distinctive coarse echinoderm limestone units and medial siliceous siltstone and limestone conglomerate. Conodont colour alteration indices for Lower Carboniferous rocks near Newmont Lake indicate an anomalously low-temperature thermal history. Upper Carboniferous -Permian polymictic volcanic conglomerate and Lower Permian limestone overlie these strata there. The Scud River sequence is distinguished by subgreenschist-to greenschist-grade Carboniferous(?) volcanic and sedimentary rocks overlain by a structurally thickened package (greater than 1000 m) of Lower Permian limestone. Local calcalkaline pyroclastic rocks interfinger with limestone near the top of the Scud River sequence. Basinal, shelf, and shallow-water carbonate facies developed in the Early Permian, giving way to calcalkaline volcanism in Late Permian followed by deposition of deep-water chert and argillite.The tectonic setting during the Devonian and Carboniferous is comparable with modem Pacific volcanic arcs and atolls, but there is no modem analogue for the shelf-carbonate accumulation during the Early Permian which characterizes the Stikine assemblage and permits Cordilleran-scale correlations. Permian fusulinid and coral species have very close affinity to those of the McCloud Limestone of the eastern Klamath Mountains, California. Other geologic events common to both Stikinia and the Eastern Klamath terrane are Devonian limestone breccia deposition, Lower Permian limestone accumulation with McCloud faunal affinity, Carboniferous and Permian calcalkaline volcanism, and Upper Permian tuffaceous limestone. Stratigraphic differences include the absence of quartz detritus in Devonian strata and lack of thick Upper Permian volcanic rocks in the Stikine River area. --Les roches de l'assemblage de Stikine, representant le << socle D du terrane de Stikinia, s'ktendent sur 500 krn le long du flanc occidental de la Zone Intermontane, a I'est des roches plus jeunes du Complexe plutonique cBtier. On reconnait quatre successions stratigraphiques diffkrentes caracteristiques formkes de roches du Dkvonien moyen et infkrieur, du Carbonifere et du Permien dans les rkgions des rivibres Stikine et Iskut. A l'ouest du ruisseau Forrest Kerr, affleurent des roches volcanoclastiques d'arc insulaire, profondkment dkformkes, d'lge dCvonien moyen a infkrieur, et des calcaires coralliens et des tufs felsitiques. Des complexes...

The odyssey of the Cache Creek terrane, Canadian Cordillera: Implications for accretionary orogens, tectonic setting of Panthalassa, the Pacific superwell, and break-up of Pangea

“…Devonian to Permian carbonate deposition and arc magmatism characterize the Stikinia-Quesnellia magmatic arc [9,[17][18][19][20]. A basal quartzose turbidite sequence suggests proximity to a continental domain in the Devonian [19,21].…”

“…A basal quartzose turbidite sequence suggests proximity to a continental domain in the Devonian [19,21]. A restricted, condensed sequence of argillite, chert and conglomerate characterizes the Upper Permian to Middle Triassic, deposition of which was followed in the Upper Triassic by arc magmatism and coral reef formation [18,22]. Stikinia-Quesnellia lack the distinctly Tethyan fauna that characterizes the Cache Creek terrane, and have considerably lower fusulinid species diversity.…”

Yukon-Tanana Terrane in the Scotia-Quaal Belt, Coast Plutonic Complex, central-western British Columbia

“…There, sections contain Lower to Middle Devonian arc-related mafic and felsic volcaniclastic rocks, thick bioclastic limestone and siltstone, and Carboniferous (and older?) arc-derived volcanic rocks, related sedimentary rocks, and thick carbonate units (Anderson, 1989;Brown et al, 1991). Late Devonian plutons locally cut the older strata (McClelland et al, 1993) and Late Mississippian to Pennsylvanian (310-330 Ma, U-Pb zircon) plutons are present in the Stikine terrane near Terrace (R. M. Friedman personal commun., 1997).…”

Age and tectonic setting of Early Jurassic episodic volcanism along the northeastern margin of the Hazelton Trough, northern British Columbia

“…However, none of the pre-Jurassic rocks exposed on Stikinia (Devonian to Triassic; Brown et al, 1991) have been recognized as sedimentary derivatives of Precambrian rock, and all have primitive isotopic signatures (Gabrielse et al, 1980;Armstrong, 1988;Samson et al, 1989). Whether the source of this contaminant was crystalline basement of Precambrian age, or a sedimentary or metasedimentary succession derived from the erosion of a Precambrian terrane, is unknown.…”

“…)Middle Triassic Stikine assemblage (Monger, 1977;Read and Psutka, 1990;Brown et al, 1991). )Middle Triassic Stikine assemblage (Monger, 1977;Read and Psutka, 1990;Brown et al, 1991).…”