scholarly journals Stratigraphy, tectonic evolution and structural analysis of the Halfway River map area (94B), northern Rocky Mountains, British Columbia

1989 ◽  
Author(s):  
R I Thompson
Keyword(s):  
British Columbia ◽  
Structural Analysis ◽  
Rocky Mountains ◽  
Tectonic Evolution ◽  
Northern Rocky Mountains

Late Holocene glacier expansion in the Cariboo and northern Rocky Mountains, British Columbia, Canada

2012 ◽  
Vol 51 ◽  
pp. 71-80 ◽  
Author(s):  
Malyssa K. Maurer ◽  
Brian Menounos ◽  
Brian H. Luckman ◽  
Gerald Osborn ◽  
John J. Clague ◽  
...  
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Late Holocene ◽  
Northern Rocky Mountains

Geochemistry, geochronology, and tectonic implications of two quartz monzonite intrusions, Purcell Mountains, southeastern British Columbia

1988 ◽  
Vol 25 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Trygve Höy ◽  
P. van der Heyden
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Tectonic Evolution ◽  
Rocky Mountain ◽  
Normal Fault ◽  
Thrust Faults ◽  
Quartz Monzonite ◽  
Reverse Thrust ◽  
Early Late ◽  
Middle Proterozoic

The Reade Lake and Kiakho stocks are posttectonic mesozonal quartz monzonite porphyries that intrude dominantly Middle Proterozoic Purcell Supergroup rocks in southeastern British Columbia. K–Ar dates of hornblende from the Reade Lake stock range from 103 to 143 Ma. However, a U–Pb date of 94 Ma from zircon concentrates is interpreted to be the age of emplacement of the stock, suggesting the range and older K–Ar dates are due to excess 40Ar. A K–Ar date of 122 Ma for the hornblende from the Kiakho stock is believed to be a more reliable intrusive age.Both stocks cut across and apparently seal two faults that have played roles in the tectonic evolution of the Purcell anticlinorium and Rocky Mountain thrust belt. The Reade Lake stock cuts the St. Mary fault, an east-trending reverse thrust that crosses the Rocky Mountain trench and links with thrusts in the Rocky Mountains; the Kiakho stock cuts the Cranbrook fault, an older east-trending normal fault. Hence, the 94 Ma date on the Reade Lake stock constrains the latest movement on the St. Mary fault to early Late Cretaceous; and the 122 Ma date on the Kiakho stock appears to limit latest movement on the Cranbrook fault to Early Cretaceous. These faults and the intrusions are part of an allochthonous package, displaced eastward by underlying thrust faults during formation of the Purcell anticlinorium and more eastern thrusts in the Rocky Mountains.

A structural interpretation across part of the northern Rocky Mountains, British Columbia, Canada

1979 ◽  
Vol 16 (6) ◽  
pp. 1228-1241 ◽  
Author(s):  
Robert I. Thompson
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Lateral Displacement ◽  
Rocky Mountain ◽  
Thrust Faults ◽  
Northern Rocky Mountains ◽  
Eastern Margin ◽  
The North ◽  
Structural Style ◽  
Mountain Front

The northern Canadian Rocky Mountains, as exemplified by the Halfway River map-area (94B) in British Columbia, consists of a rugged and mountainous structurally complex Foothills subprovince of large amplitude box and chevron-style folds in rocks of late Paleozoic and Mesozoic age, and a structurally diverse Rocky Mountain subprovince with open folds and apparently inconspicuous thrust faults in upper Precambrian to upper Paleozoic rocks; separating them is a narrow topographically subdued and heavily vegetated 'transition interval' comprising more penetratively folded and faulted shales and thin-bedded carbonate rocks of late Devonian and Mississippian age.Flat thrust faults, with displacements in the order of 10 km, which occur under the eastern margin of the Rocky Mountain subprovince (mountain front) extend across the 'transition interval' and beneath the western margin of the Foothills subprovince. These faults terminate within a décollement along the Devonian and Mississippian Besa River shale, as the displacement on them is transformed into disharmonic kink-type box and chevron folds in overlying units and into tectonic thickening within the Besa River shale. Because most of the major thrust faults along the Rocky Mountains are 'blind' and cannot be traced to surface exposures, one is left with the erroneous impression that very little lateral displacement (foreshortening) has occurred in the northern Canadian Rocky Mountains.The basic change from a well organized thrust-fault terrane in the southern Rockies to a more diverse fold terrane with few large mappable thrusts in the north is consistent with changes in the stratigraphic character of the rock prism that was deformed: the proportion of thick incompetent shale units increases northward, and major lateral carbonate to shale facies transitions traverse the eastern margin of the Rocky Mountain subprovince.Despite the differences in structural style from south to north, strain patterns within the northern Rocky Mountains are consistent with the lateral eastward movement of a detached prism of sedimentary rocks, and support the basic tenets of thin-skinned tectonics.

Early establishment of conifer recruits in the northern Rocky Mountains as a function of postfire duff depth

2009 ◽  
Vol 39 (11) ◽  
pp. 2059-2064 ◽  
Author(s):  
M. Hesketh ◽  
D. F. Greene ◽  
E. Pounden
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Additional Data ◽  
Mineral Soil ◽  
Data Sets ◽  
Hypocotyl Length ◽  
Northern Rocky Mountains ◽  
Early Establishment

Well-combusted duff (<3 cm depth) is generally considered the best seedbed for small-seeded species on upland sites, but we ask here, What is the optimal, postfire residual duff thickness? We hypothesize that a duff thickness equal to (but not greater than) the length of the germinant will offer the best conditions, because at this thickness, the duff layer will not prohibit radicle penetration into the mineral soil, and yet it will serve as a water-conserving mulch. Data from a recent fire in the Rocky mountains of British Columbia were used to show that for three species of Pinus and Picea, (1) duff depths <3 cm were far more clement substrates than thicker duff, and (2) there was a peak in relative survivorship at about 1–2 cm, somewhat shallower than the typical hypocotyl length for these species. Additional data sets from studies previously conducted at boreal and northern cordilleran sites in Alberta, Saskatchewan, Yukon, and Quebec (a combined 21 fires) bolstered these results.

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