Metamorphism of the northern Selkirk Mountains, British Columbia

1978 ◽  
Author(s):  
R L Brown ◽  
R W Leatherbarrow
Keyword(s):  
British Columbia ◽  
Selkirk Mountains

Stratigraphy and deformational history of the Scrip Nappe, Monashee Mountains, British Columbia

1983 ◽  
Vol 20 (4) ◽  
pp. 639-650 ◽  
Author(s):  
Robert P. Raeside ◽  
Philip S. Simony
Keyword(s):  
British Columbia ◽  
Lower Limb ◽  
Rocky Mountains ◽  
Metamorphic Grade ◽  
Deformational History ◽  
Crenulation Cleavage ◽  
Deformation Phase ◽  
Nappe Complex ◽  
Selkirk Mountains ◽  
History Of

The Scrip Nappe, a large recumbent anticline that occupies the northern Selkirk and northern Monashee Mountains, has an inverted lower limb, some 50 km in length across strike, and comprises stratigraphic divisions of the Hadrynian Horsethief Creek Group, which can be traced southward with decreasing metamorphic grade through the Selkirk Mountains to the northern Purcell Mountains. The Scrip Nappe has a southwesterly vergence and it formed that way during the first folding phase of the Mesozoic Columbian Orogeny. Metamorphism no greater than biotite zone accompanied that first deformation. The nappe was subsequently refolded into tight northeast verging folds. Metamorphism rose to upper amphibolite facies late in the second deformation phase. After the metamorphic climax, northeast verging buckle folds and associated crenulation cleavage formed locally during a third folding episode. The entire nappe complex was then carried northeastward, on the Purcell thrust, over the folds and thrusts of the western Rocky Mountains.

Early-winter diet of woodland caribou in relation to snow accumulation, Selkirk Mountains, British Columbia, Canada

1990 ◽  
Vol 68 (12) ◽  
pp. 2691-2694 ◽  
Author(s):  
Eric M. Rominger ◽  
John L. Oldemeyer
Keyword(s):  
British Columbia ◽  
Rangifer Tarandus ◽  
Transition Period ◽  
Management Strategies ◽  
Snow Accumulation ◽  
Late Winter ◽  
Early Winter ◽  
Accumulation Rates ◽  
Woodland Caribou ◽  
Selkirk Mountains

Woodland caribou (Rangifer tarandus caribou) in the southern Selkirk Mountains of British Columbia shift from a diet of primarily vascular taxa during snow-free months to an arboreal lichen – conifer diet during late winter. We present evidence that caribou diets, during the early-winter transition period, are influenced by snow accumulation rates. Caribou shift to an arboreal lichen – conifer diet earlier during winters of rapid snow accumulation and forage extensively on myrtle boxwood (Pachistima myrsinites), an evergreen shrub, and other vascular plants during years of slower snow accumulation. The role of coniferous forage in early-winter food habits is examined. Forest management strategies can be developed to provide habitat that will enable caribou to forage in response to varying snow accumulation rates.

Stratigraphy, sedimentology, and regional correlation of the Horsethief Creek Group (Hadrynian, Late Precambrian) in the northern Purcell and Selkirk Mountains, British Columbia

1980 ◽  
Vol 17 (12) ◽  
pp. 1708-1724 ◽  
Author(s):  
T. P. Poulton ◽  
P. S. Simony
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Submarine Fan ◽  
Source Areas ◽  
Late Precambrian ◽  
Coarse Sediment ◽  
Regional Correlation ◽  
Selkirk Mountains ◽  
Igneous Activity ◽  
Thickness Variations

The Hadrynian Horsethief Creek Group in the northernmost Purcell Mountains and adjacent Selkirk Mountains is subdivisible regionally into grit, slate, carbonate, and upper clastic divisions in upward succession. The grit division represents a submarine fan assemblage and the slate division hemipelagic muds probably deposited in intermediate depths. The carbonate division comprises an interval of discontinuous lenses representing "bahamian" carbonate bank and off-bank assemblages, and the upper clastic division is a heterogeneous clastic wedge, which shows some evidence of northerly and westerly increasing depositional depths. Feldspathic quartz pebble conglomerate beds intercalated with the carbonates in both bank and off-bank facies indicate tectonic activation of granitic source areas like those from which similar rocks in the upper part of the Miette Group of the Rocky Mountains were derived.The upper part of the slate division, which can be differentiated in western localities as a distinct semipelite–amphibolite unit, and the upper clastic division each expand in thickness northwestward to dominate the Horsethief Creek outcrops in the Selkirk Mountains. These thickness variations, the increase of amphibolite northward in the semipelite–amphibolite unit, and the loss of grit beds northward in the slate division suggest deposition in a depocentre that received coarse sediment from southerly and easterly directions, and that became the site of mafic igneous activity.

Stratigraphy and sedimentology of the Hamill Group in the northern Selkirk Mountains, British Columbia: evidence for latest Proterozoic – Early Cambrian extensional tectonism

1989 ◽  
Vol 26 (3) ◽  
pp. 515-533 ◽  
Author(s):  
William J. Devlin
Keyword(s):  
British Columbia ◽  
Fault Scarp ◽  
Gravity Flow ◽  
Tectonic Activity ◽  
Turbidity Currents ◽  
Early Cambrian ◽  
Shallow Marine ◽  
Sedimentary Characteristics ◽  
Sediment Gravity Flow ◽  
Selkirk Mountains

Three informal stratigraphic divisions are recognized in the uppermost Proterozoic – Lower Cambrian Hamill Group in the northern Selkirk Mountains of British Columbia. These informal divisions include a lower sandstone unit, a greenstone–graded-sandstone unit, and an upper sandstone unit. Both the lower and upper sandstone units display sedimentary characteristics that are uniform along strike and indicate a shallow-marine environment of deposition. As is typical of other exposures of the Hamil Group in southeastern British Columbia, the lower sandstone unit is coarser grained and more poorly sorted than the mature quartz arenites of the upper sandstone unit.The greenstone–graded-sandstone unit is a complex assemblage of mafic metavolcanic rocks and associated sandstone facies. This unit is highly variable along strike but essentially consists of a thick succession of subaqueous extrusive rocks overlain by a variety of sediment gravity-flow deposits. These latter deposits include resedimented conglomerates, debris-flow deposits, and trubidites (deposited from both high- and low-density turbidity currents). Stratigraphic sections of this unit are described in detail from three different localities and are examined in terms of their transport and depositional mechanisms.The stratigraphic succession of the Hamill Group indicates that deposition of the shallow-marine sands of the lower sandstone unit was abruptly interrupted by a period of volcanism, the creation of a paleoslope, and the deposition of a large volume of sediment gravity-flow deposits of the greenstone–graded-sandstone unit. These relations are attributed to an episode of syndepositional normal faulting. The inferred fault(s) could have served as the conduit for the extrusion of the volcanics. Offset along the fault(s), the tilting of fault blocks, and the consequent formation of an unstable slope adjacent to a fault scarp created an environment favorable for deposition of the sediment gravity flows. In general, deposition of proximal, base-of-slope deposits was followed by an aggradational basin-fill phase of sedimentation. With the waning of tectonic activity and the filling of the fault-bounded basin, depositon of shallow-marine sands resumed (the upper sandstone unit). The stratigraphic relations of the Hamill Group in the northern Selkirk Mountains are considered direct evidence for an episode of latest Proterozoic – Early Cambrian extensional tectonism. The evidence for an episode of rift-related tectonism in the northern Selkirk Mountains supports inferences concerning the timing of this event as derived from tectonic subsidence analyses of post-rift strata of the Cordilleran miogeocline.

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