Upper paleozoic rocks of the Atlin Terrane, northwestern British Columbia and south-central Yukon

1975 ◽  
Author(s):  
J W H Monger
Keyword(s):  
British Columbia ◽  
South Central ◽  
Upper Paleozoic ◽  
Paleozoic Rocks

Geological and geochemical evidence for variable magmatism and tectonics in the southern Canadian Cordillera: Paleozoic to Jurassic suites, Greenwood, southern British Columbia

2001 ◽  
Vol 38 (1) ◽  
pp. 75-90 ◽  
Author(s):  
J Dostal ◽  
B N Church ◽  
T Hoy
Keyword(s):  
British Columbia ◽  
Middle Triassic ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Deep Ocean ◽  
Island Arc ◽  
Canadian Cordillera ◽  
South Central ◽  
Upper Paleozoic ◽  
Paleozoic Rocks

The Paleozoic and early Mesozoic rocks of the Greenwood mining camp in southern British Columbia are a part of the Quesnel terrane in the eastern part of the Intermontane Belt of the Canadian Cordillera. Upper Paleozoic rocks include the Knob Hill Group composed of oceanic tholeiitic basalts (with (La/Yb)n [Formula: see text] 0.4–1.2), associated with deep ocean sedimentary rocks and serpentinites; the Attwood Group that comprises island-arc tholeiites (with (La/Yb)n [Formula: see text] 1–4 and positive εNd values), clastic sedimentary rocks and limestones; and a unit of oceanic gabbros with (La/Yb)n < 0.5. These lithologically defined units occur as tectonically emplaced slivers of oceanic crust probably produced during the closure of the Slide Mountain basin during the Permian. They are unconformably overlain by Middle Triassic calc-alkaline volcanic and sedimentary rocks of the Brooklyn Group. The Brooklyn Group volcanic rocks have characteristics of mature island-arc rocks, including (La/Yb)n [Formula: see text] 2.5–4.5 and positive εNd values. The Paleozoic rocks are crosscut by a 200 million years old granodioritic intrusion containing zircon with an Early Proterozoic inheritance age (~2.4 Ga). By inference, southern Quesnellia may have been well offshore from the ancestral North American margin in the Mississippian, in close proximity to the margin by the Middle Triassic, and contiguous with it by the Early Jurassic. It is suggested that the complex tectonic history of extension and contraction of the southern Canadian Cordillera during the post Middle Jurassic can be extended in south-central British Columbia as far back as the upper Paleozoic.

The Blind Creek Limestone, Keremeos, British Columbia: Structure and Regional Tectonic Significance

1975 ◽  
Vol 12 (11) ◽  
pp. 1929-1933
Author(s):  
W. C. Barnes ◽  
J. V. Ross
Keyword(s):  
British Columbia ◽  
Compressive Stress ◽  
Ductile Deformation ◽  
Large Block ◽  
Stress Direction ◽  
Upper Paleozoic ◽  
Tectonic Significance ◽  
Regional Tectonic ◽  
Similar Body ◽  
Paleozoic Rocks

A large block of Upper Paleozoic limestone at Blind Creek near Keremeos, B.C. was emplaced by dry gravity sliding, probably associated with uplift related to nearby Eocene volcanism. The block is a nearly flat tabular unit, exposed over an area of 650 m by 1300 m, and is separated from underlying chaotic breccias derived from adjacent Paleozoic rocks and from Eocene volcanic flow rocks by a sole fault. The block comprises two lithologically and tectonically distinct units, a lower imbricated unit consisting of several slices repeating the same sequence of strata, separated from an upper unit of massive limestone by a low-angle fault. Within the imbricated unit, early faults emanate from lenticular masses of breccia along the sole, become increasingly steeper upward, and are truncated above by the upper low angle fault. Associated minor folds and fractures have a clockwise sense of rotation. Later fractures and associated minor folds have the opposite dip and sense of rotation. These two subsets comprise a conjugate set whose inferred compressive stress direction coincides with the present overall dip direction of the entire mass.The northwesterly adjacent autochthonous Olalla limestone, or a similar body now buried by younger units, is a likely source for the Blind Creek allochthon.Absence of any structures within the limestone indicative of ductile deformation contrasts markedly with those of the highly deformed rocks of the Old Tom and Shoemaker Formations, the Kobau Group, and the nearby gneisses of the western Shuswap Complex.

Upper Paleozoic rocks of the western Canadian Cordillera and their bearing on Cordilleran evolution

1977 ◽  
Vol 14 (8) ◽  
pp. 1832-1859 ◽  
Author(s):  
J. W. H. Monger
Keyword(s):  
British Columbia ◽  
Pacific Ocean ◽  
Sedimentary Rocks ◽  
Ocean Floor ◽  
Canadian Cordillera ◽  
Island Arcs ◽  
South Central ◽  
Early Mesozoic ◽  
Basic Volcanics ◽  
Paleozoic Rocks

Volcanic and sedimentary successions of late Paleozoic and locally Mesozoic age in the Canadian Cordillera form six assemblages, based mainly on lithological association and similar stratigraphy. From east to west these assemblages are: (1) Eastern assemblage, located along the Omineca Crystalline Belt and consisting of Mississippian to Permian largely sedimentary rocks overlain by mainly Permian basic volcanics and ultramafics; (2) poorly known rocks in south-central British Columbia characterized by abundant volcaniclastics of Pennsylvanian and Permian ages; (3) Cache Creek – Bridge River assemblage of the Intermontane Bell, ranging from Lower Mississippian to Middle Jurassic and composed of chert, argillite, carbonate, basic volcanics, and ultramafics: (4) Stikine assemblage of northwestern and north-central British Columbia of Mississippian and Permian age, with basic to acidic volcanics, argillite, and carbonate; (5) Chilliwack Group on the west side of the Cascade Mountains, of Pennsylvanian and Permian age, with basic to acidic volcanics overlying a carbonate and clastic succession: and (6) Sicker–Skolai assemblage of Vancouver Island and the Saint Elias Mountains with basic to acidic volcanics overlain by sedimentary rocks. Coeval faunas in several of these assemblages differ. The assemblages may be largely unrelated to one another and came together in the Mesozoic, Their present distribution, with rocks typical of ocean basins (assemblages 1, 3) east of rocks that probably represent island arcs (assemblages, 2, 4, 5, 6) presents major problems. Two hypotheses attempt to explain this distribution. (1) The oceanic assemblages represent Paleozoic and early Mesozoic Pacific Ocean floor obducted over a broad arc terrane in the Jurassic, or (2) they are Paleozoic and early Mesozoic Pacific Ocean floor, trapped east of allochthonous arc terranes (assemblages 4, 5, 6) emplaced in the Mesozoic.

Magmatic composition and tectonic setting of altered, volcanic rocks of the Fennell Formation, British Columbia

1984 ◽  
Vol 21 (7) ◽  
pp. 743-752 ◽  
Author(s):  
Pradeep K. Aggarwal ◽  
Toshitsugu Fujii ◽  
Bruce E. Nesbitt
Keyword(s):  
British Columbia ◽  
Marine Sediments ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Tholeiitic Basalt ◽  
Oceanic Islands ◽  
Mineral Deposit ◽  
South Central ◽  
Ti Oxides ◽  
Upper Paleozoic

The upper Paleozoic Fennell Formation in south-central British Columbia consists of basalts and associated marine sediments metamorphosed at low greenschist facies conditions. Although the microphenocrysts of plagioclase and Fe–Ti oxides are almost completely altered, those of augite and amphibole have survived this metamorphism. In the vicinity of the Chu Chua mineral deposit, relict augite microphenocrysts, which constitute a major proportion of the microphenocryst assemblage, are enriched in Al and Ti and are similar in composition to those from alkalic and transitional basalts. Relict amphiboles are also enriched in Ti (4.5–5.9% TiO2) and are classified as kaersutites. The occurrence of kaersutite and the chemistry of relict augites indicate that in this area the Fennell Formation basalts were originally alkalic and transitional in composition. On conventional Ti–(Zr/P2O5) and (Nb/Y)–(Zr/P2O5) immobile-element discrimination diagrams, both the kaersutite-bearing and kaersutite-free rocks plot in the tholeiitic basalt field. Accordingly, it is suggested that these diagrams may not provide clear evidence for the magmatic composition of altered volcanic rocks.Based on the lead isotopic compositions, petrographic features, and alkalic character of the Fennell Formation basalts, it is interpreted that these basalts were formed in a tectonic setting similar to that of present-day oceanic islands or seamounts.

Upper Paleozoic Rocks of Northeast British Columbia

1967 ◽  
Author(s):  
E W Bamber ◽  
R M Procter ◽  
G C Taylor
Keyword(s):  
British Columbia ◽  
Upper Paleozoic ◽  
Paleozoic Rocks

Upper Paleozoic Ostracodes of the Harper Ranch Beds (South-Central British Columbia, Canada)

1994 ◽  
Vol 40 (3) ◽  
pp. 242 ◽  
Author(s):  
Sylvie Crasquin-Soleau ◽  
Mike J. Orchard
Keyword(s):  
British Columbia ◽  
South Central ◽  
Upper Paleozoic
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