scholarly journals Pliensbachian [lower jurassic] biostratigraphy and ammonite fauna of the Spatsizi area, north-central British Columbia

1992 ◽  
Author(s):  
R C Thomson ◽  
P L Smith
Keyword(s):  
British Columbia ◽  
Lower Jurassic ◽  
North Central ◽  
Area North

A Lower Jurassic heteroporid bryozoan and associated biota, Turnagain Lake, British Columbia

1981 ◽  
Vol 18 (3) ◽  
pp. 457-468 ◽  
Author(s):  
C. M. Henderson ◽  
D. G. Perry
Keyword(s):  
British Columbia ◽  
North America ◽  
Green Alga ◽  
Marine Environment ◽  
High Energy ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Associated Fauna ◽  
North Central ◽  
Commensal Relationship

Late Early Jurassic heteroporid bryozoa occur in arenaceous carbonates near Turnagain Lake, north-central British Columbia. The occurrence of Heteropora tipperi n. sp. marks the first documentation of Early Jurassic cyclostome bryozoa in North America. The associated fauna, comprising the ammonite Harpoceras, the foraminifer Reinholdella, and the pelecypod Weyla, establish the age as Early Toarcian. Other associated biota include an endolithic green alga(e), which is demonstrated to have a commensal relationship with H. tipperi n. sp. Sedimentologic and biotic data from the host strata point to a shallow, temperate, high-energy, normal marine environment.

Revised stratigraphy of the Takla Group, north-central British Columbia

1977 ◽  
Vol 14 (2) ◽  
pp. 318-326 ◽  
Author(s):  
J. W. H. Monger ◽  
B. N. Church
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Late Triassic ◽  
North Central ◽  
Volcaniclastic Rocks ◽  
Jurassic Rocks

The Takla Group of north-central British Columbia as originally defined contained volcanic and sedimentary rocks of Late Triassic and Jurassic ages. As redefined herein, it consists of three formations in the McConnell Creek map-area. Lowest is the Dewar Formation, composed of argillite and volcanic sandstone that is largely the distal equivalent of basic flows and coarse volcaniclastic rocks of the Savage Mountain Formation. These formations are overlain by the volcaniclastic, basic to intermediate Moosevale Formation. These rocks are Upper Triassic (upper Karnian and lower Norian). They are unconformably overlain by Lower Jurassic rocks of the Hazelton Group.

Lower to Middle Jurassic (Pliensbachian to Bajocian) stratigraphy of the northern Spatsizi area, north-central British Columbia

1986 ◽  
Vol 23 (12) ◽  
pp. 1963-1973 ◽  
Author(s):  
Robert C. Thomson ◽  
Paul L. Smith ◽  
Howard W. Tipper
Keyword(s):  
British Columbia ◽  
Grain Size ◽  
Middle Jurassic ◽  
Water Environment ◽  
Upper Jurassic ◽  
Calc Alkaline ◽  
Volcanic Arc ◽  
North Central ◽  
Area North ◽  
Southern Flank

The Lower to Middle Jurassic (Pliensbachian to lower Bajocian) Spatsizi Group in the northern Spatsizi area of north-central British Columbia is formally defined and subdivided into the Joan, Wolf Den, Melisson, Abou, and Quock formations. Each formation reflects deposition in a different, dominantly fine-clastic environment with a varying input of volcanic (epiclastic or pyroclastic) detritus. The Spatsizi Group represents the basinward sedimentary equivalent of the coeval Cold Fish Volcanics, a group of calc-alkaline flows and breccias that accumulated in a volcanic arc along the southern flank of the Stikine Arch. Arc-to basin-facies trends are best developed in the Joan and Wolf Den formations and are characterized by a decrease in the volcaniclastic component of the sediments, an overall reduction in grain size, and a progressively deeper water environment of deposition, as inferred from both sedimentological and faunal evidence.In the study area, the Spatsizi Group underlies with a slight angular discordance the Middle to Upper Jurassic Bowser Lake Group. Bowser lake sediments were deposited in the Bowser Basin, the largest Mesozoic successor basin in British Columbia. Based on evidence from the Spatsizi area and from other areas to the south at Diagonal Mountain and the Oweegee Mountains, the Spatsizi Group is interpreted as passing laterally into shales that underlie most of the Bowser Basin.

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