scholarly journals Gravity and magnetic models of the Iron Mask Batholith, south-central Canadian Cordillera, British Columbia

2019 ◽  
Author(s):  
M D Thomas
Keyword(s):  
British Columbia ◽  
Canadian Cordillera ◽  
South Central ◽  
Gravity And Magnetic

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.

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.

scholarly journals Conservation Evaluation of Lemmon's Holly Fern, Polystichum lemmonii, a Threatened Fern in Canada

2004 ◽  
Vol 118 (2) ◽  
pp. 164
Author(s):  
George W. Douglas
Keyword(s):  
British Columbia ◽  
Road Construction ◽  
Montane Forest ◽  
Mountain Area ◽  
Forest Road ◽  
South Central ◽  
Northern Idaho ◽  
Mining Exploration ◽  
Conservation Evaluation ◽  
Forest Road Construction

In Canada, Lemmon's Holly Fern, Polystichum lemmonii, is restricted to the Baldy Mountain area on the eastern side of the Okanagan River valley in south-central British Columbia. This population represents the northern limits of the species which ranges south through northern Idaho, Washington and Oregon to northern California. In British Columbia, P. lemmonii is associated with ultramafic rocky ridges within a montane forest at an elevation of 1900 m. The population in the Baldy Mountain area is relatively small, unprotected and potentially imperilled by mining exploration, forest road construction or wildfires.

scholarly journals Conservation Evaluation of the Pacific Population of Dwarf Woollyheads, Psilocarphus brevissimus var. brevissimus, in Canada

2006 ◽  
Vol 120 (2) ◽  
pp. 163
Author(s):  
George W. Douglas ◽  
Jenifer L. Penny ◽  
Ksenia Barton
Keyword(s):  
British Columbia ◽  
Coalbed Methane ◽  
Groundwater Levels ◽  
Gas Drilling ◽  
Pacific Population ◽  
South Central ◽  
The Pacific ◽  
Recreational Vehicles ◽  
Forest Openings ◽  
Conservation Evaluation

In Canada, Dwarf Woolly-heads, Psilocarphus brevissimus var. brevissimus, is restricted to the Similkameen River valley, south of Princeton in southwestern British Columbia and the extreme southeast and southwest corners of Alberta and Saskatchewan, respectively. This paper deals with the three British Columbia populations which represent the northwestern limit of the species which ranges from south-central British Columbia, southward in the western United States to Montana, Idaho, Washington, Oregon, Nevada, Utah, Wyoming, California and Baja California, Mexico. In British Columbia, P. brevissimus is associated with calcareous vernal pools and ephemeral pond edges in large forest openings. This habitat is rare in the area the few existing populations could easily be extirpated or degraded through slight changes in groundwater levels, coalbed methane gas drilling, housing development or recreational vehicles.

Trap response of cutworm moths (Abagrotis orbis) to a sex-attractant lure in grape vineyards

2010 ◽  
Vol 142 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Peter J. Landolt ◽  
D. Thomas Lowery ◽  
Lawrence C. Wright ◽  
Constance Smithhisler ◽  
Christelle Gúedot ◽  
...  
Keyword(s):  
British Columbia ◽  
Vitis Vinifera ◽  
Field Experiments ◽  
Sex Attractant ◽  
Early Spring ◽  
South Central ◽  
Tetradecenyl Acetate ◽  
Feltia Jaculifera ◽  
Multiple Field ◽  
Lepidoptera Noctuidae

AbstractLarvae of Abagrotis orbis (Grote) (Lepidoptera: Noctuidae) are climbing cutworms and can damage grapevines, Vitis vinifera L. (Vitaceae), in early spring by consuming expanding buds. A sex attractant would be useful for monitoring this insect in commercial vineyards. (Z)-7-Tetradecenyl acetate and (Z)-11-hexadecenyl acetate were found in extracts of female abdominal tips. In multiple field experiments, male A. orbis were captured in traps baited with a combination of these two chemicals but not in traps baited with either chemical alone. Males were trapped from mid-September to early October in south-central Washington and south-central British Columbia. Other noctuid moths (Mamestra configurata Walker, Xestia c-nigrum (L.), and Feltia jaculifera (Guenée)) were also captured in traps baited with the A. orbis pheromone and may complicate the use of this lure to monitor A. orbis. Abagrotis discoidalis (Grote) was captured in traps baited with (Z)-7-tetradecenyl acetate but not in traps baited with the two chemicals together.

Status of the Jurassic in the Canadian Cordillera of British Columbia, Alberta, and southern Yukon

1970 ◽  
Vol 7 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Hans Frebold ◽  
H. W. Tipper
Keyword(s):  
British Columbia ◽  
Fossil Record ◽  
Canadian Cordillera ◽  
Tectonic Events ◽  
Source Of Information

Jurassic index fossils of the Canadian Cordillera indicate the presence of some zones of most Jurassic stages. In this report the more important localities are listed, the source of information, published and unpublished, is indicated, and an up-dated correlation chart is presented. The importance of tectonic events and their effect on the completeness of the Jurassic fossil record and on the Jurassic paleogeography are stressed.

scholarly journals Identifying and Characterizing Important Trembling Aspen Competitors with Juvenile Lodgepole Pine in Three South-Central British Columbia Ecosystems

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Teresa A. Newsome ◽  
Jean L. Heineman ◽  
Amanda F. Linnell Nemec
Keyword(s):  
British Columbia ◽  
Lodgepole Pine ◽  
Geographic Range ◽  
Regression Analyses ◽  
Relative Height ◽  
Trembling Aspen ◽  
Ecosystem Productivity ◽  
Height Ratio ◽  
Critical Height ◽  
South Central

Critical height ratios for predicting competition between trembling aspen and lodgepole pine were identified in six juvenile stands in three south-central British Columbia ecosystems. We used a series of regression analyses predicting pine stem diameter from the density of neighbouring aspen in successively shorter relative height classes to identify the aspen-pine height ratio that maximizedR2. Critical height ratios varied widely among sites when stands were 8–12 years old but, by age 14–19, had converged at 1.25–1.5. MaximumR2values at age 14–19 ranged from 13.4% to 69.8%, demonstrating that the importance of aspen competition varied widely across a relatively small geographic range. Logistic regression also indicated that the risk of poor pine vigour in the presence of aspen varied between sites. Generally, the degree of competition, risk to pine vigour, and size of individual aspen contributing to the models declined along a gradient of decreasing ecosystem productivity.

Shackanite and related analcite-bearing lavas in British Columbia

1978 ◽  
Vol 15 (10) ◽  
pp. 1669-1672 ◽  
Author(s):  
B.N. Church
Keyword(s):  
British Columbia ◽  
Great Depth ◽  
Bulk Rock ◽  
Rock Composition ◽  
Bulk Rock Composition ◽  
South Central ◽  
Early Tertiary ◽  
Broad Field ◽  
New Localities

New localities of shackanite and related analcite-bearing lavas have been discovered in a broad field of early Tertiary phonolite and mafic phonolite in south-central British Columbia. The development of primary and secondary analcite in these rocks is probably the result of cooling lava during and shortly after extrusion.The possibility of leucite to analcite transformation in Daly's shackanite is unlikely because of lack of petrographic evidence and a preponderance of Na2O over K2O in bulk rock composition. It is also unlikely that analcite, and particularly groundmass analcite, crystallized at great depth and was transported to surface during eruption.

Paleomagnetism of the Triassic Nikolai Greenstone, McCarthy Quadrangle, Alaska

1977 ◽  
Vol 14 (11) ◽  
pp. 2578-2592 ◽  
Author(s):  
J. W. Hillhouse
Keyword(s):  
British Columbia ◽  
High Temperature ◽  
North America ◽  
Vertical Axis ◽  
Upper Triassic ◽  
Present Position ◽  
Stable Component ◽  
South Central ◽  
Early Mesozoic ◽  
Lamellar Texture

Paleomagnetic evidence indicates that the extensive early Mesozoic basalt field near McCarthy, south-central Alaska, originated far south of its present position relative to North America. Results obtained from the Middle and (or) Upper Triassic Nikolai Greenstone suggest that those basalts originated within 15° of the paleoequator. This position is at least 27° (3000 km) south of the Upper Triassic latitude predicted for McCarthy on the basis of paleomagnetic data from continental North America. The Nikolai pole, as determined from 50 flows sampled at 5 sites, is at 2.2° N, 146.1° E (α95 = 4.8°). The polarity of the pole is ambiguous, because the corresponding magnetic direction has a low inclination and a westerly declination. Therefore, the Nikolai may have originated near 15° N latitude or, alternatively, as far south as 15° S latitude. In addition to being displaced northward, the Nikolai block has been rotated roughly 90° about the vertical axis. A measure of the reliability of this pole is provided by favorable results from the following tests: (1) Within one stratigraphic section, normal and reversed directions from consecutive flows are antipolar. (2) Consistent directions were obtained from sites 30 km apart. (3) Application of the fold test indicated the magnetization was acquired before the rocks were folded. (4) The magnetizations of several pilot specimens are thermally stable up to 550 °C. The stable component is probably carried by magnetite with lamellar texture, a primary feature commonly acquired by a basalt at high temperature during initial cooling of the magma. Geologic and paleomagnetic evidence indicates that the Nikolai is allochthonous to Alaska and that, together with associated formations in southern Alaska and British Columbia, it is part of a now disrupted equatorial terrane.

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