scholarly journals Walcott's lower cambrian olenellid trilobite collection 61k, Mount Robson area, Canadian Rocky Mountains

1992 ◽  
Author(s):  
W H Fritz
Keyword(s):  
Rocky Mountains ◽  
Lower Cambrian ◽  
Canadian Rocky Mountains

Palynology of uppermost Proterozoic and lowermost Cambrian formations, central Mackenzie Mountains, northwestern Canada

1989 ◽  
Vol 26 (1) ◽  
pp. 129-148 ◽  
Author(s):  
D. Baudet ◽  
J. D. Aitken ◽  
M. Vanguestaine
Keyword(s):  
Rocky Mountains ◽  
Lower Cambrian ◽  
Russian Platform ◽  
Blue Flower ◽  
Flower Formation ◽  
Early Cambrian ◽  
Canadian Rocky Mountains ◽  
Structural Units ◽  
Upper Proterozoic ◽  
Lithostratigraphic Correlation

The acritarch assemblages of strata from the base of the Upper Proterozoic Sheepbed Formation to the base of the Lower Cambrian (Atdabanian) Sekwi Formation are described. The sections sampled are in southwestern (internal) structural units where erosion beneath the "sub-Cambrian"(?) unconformity is least evident. Problems of lithostratigraphic correlation of post-Sheepbed, pre-Backbone Ranges formations remain. Acritarchs indicate the age of the Sheepbed Formation and the Blue-flower Formation above it is latest Proterozoic (Vendian), whereas that of the Vampire Formation is Early Cambrian (Atdabanian). The Backbone Ranges Formation has not yielded datable acritarchs, but it is for the most part Cambrian in age, based on other fossil evidence. Comparisons are made with the Russian Platform and southern Canadian Rocky Mountains successions. The total number of acritarch genera increases markedly across the Precambrian–Cambrian transition.

Gold mineralization in Lower Cambrian McNaughton Formation, Athabasca Pass, Canadian Rocky Mountains: structural, mineralogical, and temporal relationships

1990 ◽  
Vol 27 (4) ◽  
pp. 477-493 ◽  
Author(s):  
Robert P. Shaw ◽  
Roger D. Morton
Keyword(s):  
Rocky Mountains ◽  
Lower Cambrian ◽  
Gold Mineralization ◽  
White Mica ◽  
Gold Deposits ◽  
Process Models ◽  
Gold Deposition ◽  
Canadian Rocky Mountains ◽  
Gold Stage ◽  
Gold Bearing

Gold-bearing quartz veins were recently discovered in archimetamorphic quartzite–rudite and quartzite–pelite sequences of the Lower Cambrian McNaughton Formation in the main ranges of the central Canadian Rocky Mountains. There are two distinct vein types: an early syntectonic, syn- to postmetamorphic, auriferous, bedding-parallel type, generated during repeated northeast-directed compressive tectonism; and a late, postpenetrative deformational discordant type, which contains only minor gold (<500 ppb Au). Gold emplacement and discordant veining were confined to the onset of late compression leading to development of the Chatter Creek Fault.The spatial distribution and dimensions of the veins attest to mechanically founded lithologic anisotropy. Bedding-parallel veins are confined to less competent, volumetrically minor pelitic rock types. Discordant veins are confined to competent quartzitic units.Bedding-parallel vein filling took place in two paragenetic stages: a protracted, pre-gold stage (quartz ± minor white mica and pyrite) depositing over 90% of vein material; and a late gold-bearing–post-gold stage (quartz–pyrite–gold–galena ± white mica and Fe carbonate). Gold usually occurs in association with brecciated pelites and penecontemporaneous sulfides. Discordant veins (quartz ± minor pyrite) record a single stage of vein filling broadly coeval with gold deposition. Minor hydrothermal alteration (pyrite ± white mica ± carbonate) of adjacent wall rocks accompanied gold emplacement and is mineralogically congruent with the regional archimetamorphic and bedding-parallel vein assemblages.In terms of their setting and morphology, the Athabasca Pass gold lodes are viewed as a siliciclastic-hosted analogue of the turbidite-hosted class of gold deposits. Principle geochemical differences from published process models for turbidite-hosted gold deposits are a function of the mineralogical maturity of the siliciclastic host strata in the Athabasca Pass.

New Lower Cambrian olenelloid trilobite genera Cirquella and Geraldinella from southwestern Canada

1993 ◽  
Vol 67 (5) ◽  
pp. 856-868 ◽  
Author(s):  
W. H. Fritz
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Lower Cambrian ◽  
Type Species ◽  
Canadian Rocky Mountains

The genus Cirquella is erected for small, smooth nevadiid trilobites that lack genal spines. The type species, C. nummularia, is associated with taxa in the Dogtooth Mountains, British Columbia, that belong to the Nevadella Zone. A second species, C. espinata, is described from the southern Canadian Rocky Mountains, where it is associated with the new archaeaspid genus Geraldinella. Strata in the latter locality can be physically correlated to documented strata of the Nevadella Zone. The same zone in Nevada contains C. nummularia?.

Wildfires in the southern Canadian Rocky Mountains and their relationship to mid-tropospheric anomalies

1993 ◽  
Vol 23 (6) ◽  
pp. 1213-1222 ◽  
Author(s):  
E.A. Johnson ◽  
D.R. Wowchuk
Keyword(s):  
North America ◽  
Rocky Mountains ◽  
Large Scale ◽  
Fire Frequency ◽  
Fuel Moisture ◽  
Large Fire ◽  
Canadian Rocky Mountains ◽  
Area Burned ◽  
Upper Level ◽  
Moisture Conditions

In this paper we present evidence for a large-scale (synoptic-scale) meteorological mechanism controlling the fire frequency in the southern Canadian Rocky Mountains. This large-scale control may explain the similarity in average fire frequencies and timing of change in average fire frequencies for the southern Canadian Rocky Mountains. Over the last 86 years the size distribution of fires (annual area burned) in the southern Canadian Rockies was distinctly bimodal, with a separation between small- and large-fire years at approximately 10–25 ha annual area burned. During the last 35 years, large-fire years had significantly lower fuel moisture conditions and many mid-tropospheric surface-blocking events (high-pressure upper level ridges) during July and August (the period of greatest fire activity). Small-fire years in this period exhibited significantly higher fuel moisture conditions and fewer persistent mid-tropospheric surface-blocking events during July and August. Mid-tropospheric surface-blocking events during large-fire years were teleconnected (spatially and temporally correlated in 50 kPa heights) to upper level troughs in the North Pacific and eastern North America. This relationship takes the form of the positive mode of the Pacific North America pattern.

Canadian Rocky Mountains

1903 ◽  
Vol 21 (6) ◽  
pp. 685
Author(s):  
J. Norman Collie
Keyword(s):  
Rocky Mountains ◽  
Canadian Rocky Mountains

Spatial and temporal variations of fire regimes in the Canadian Rocky Mountains and Foothills of southern Alberta

2016 ◽  
Vol 25 (11) ◽  
pp. 1117 ◽  
Author(s):  
Marie-Pierre Rogeau ◽  
Mike D. Flannigan ◽  
Brad C. Hawkes ◽  
Marc-André Parisien ◽  
Rick Arthur
Keyword(s):  
Rocky Mountains ◽  
Fire History ◽  
Fire Severity ◽  
Ecological Integrity ◽  
Fire Regimes ◽  
Temporal Variations ◽  
Fire Season ◽  
Canadian Rocky Mountains ◽  
Southern Alberta ◽  
Fire Exclusion

Like many fire-adapted ecosystems, decades of fire exclusion policy in the Rocky Mountains and Foothills natural regions of southern Alberta, Canada are raising concern over the loss of ecological integrity. Departure from historical conditions is evaluated using median fire return intervals (MdFRI) based on fire history data from the Subalpine (SUB), Montane (MT) and Upper Foothills (UF) natural subregions. Fire severity, seasonality and cause are also documented. Pre-1948 MdFRI ranged between 65 and 85 years in SUB, between 26 and 35 years in MT and was 39 years in UF. The fire exclusion era resulted in a critical departure of 197–223% in MT (MdFRI = 84–104 years). The departure in UF was 170% (MdFRI = 104 years), while regions of continuous fuels in SUB were departed by 129% (MdFRI = 149 years). The most rugged region of SUB is within its historical range of variation with a departure of 42% (MdFRI = 121 years). More mixed-severity burning took place in MT and UF. SUB and MT are in a lightning shadow pointing to a predominance of anthropogenic burning. A summer fire season prevails in SUB, but occurs from spring to fall elsewhere. These findings will assist in developing fire and forest management policies and adaptive strategies in the future.

New Lower Jurassic ammonite faunas from the Fernie Formation, southern Canadian Rocky Mountains

1987 ◽  
Vol 24 (8) ◽  
pp. 1688-1704 ◽  
Author(s):  
Russell L. Hall
Keyword(s):  
British Columbia ◽  
North American ◽  
Rocky Mountains ◽  
Red Deer ◽  
First Record ◽  
Lower Jurassic ◽  
Canadian Rocky Mountains ◽  
Poker Chip

New ammonite faunas are described from sections along Bighorn and Scalp creeks in central-western Alberta where Lower Jurassic parts of the Fernie Formation are exposed. The first record of the upper Sinemurian Obtusum Zone from the Fernie is based on the occurrence of Asteroceras cf. stellare and Epophioceras cf. breoni in the basal pebbly coquina on Bighorn Creek. The overlying Red Deer Member has yielded Amaltheus cf. stokesi, representing the upper Pliensbachian Margaritatus Zone; in immediately superjacent strata the first North American examples of ?Amauroceras occur together with Protogrammoceras and ?Aveyroniceras. In the basal parts of the overlying Poker Chip Shale a fauna including Harpoceras cf. falciferum, Harpoceratoides, Polyplectus cf. subplanatus, Hildaites cf. serpentiniformis, and Dactylioceras cf. athleticum is correlated with the lower Toarcian Falciferum Zone.The upper parts of the Poker Chip Shale on Fording River in southeastern British Columbia contain a fauna representing some part of the upper Toarcian, but owing to poor preservation, generic identifications are only tentatively made.

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