Preliminary account of the trilobite biostratigraphy of the survey Peak and Outram formations [Late Cambrian, Early Ordovician] At Wilcox Pass, southern Canadian Rocky Mountains, Alberta

1978 ◽  
Author(s):  
W T Dean
Keyword(s):  
Rocky Mountains ◽  
Canadian Rocky Mountains ◽  
Early Ordovician ◽  
Late Cambrian ◽  
Preliminary Account

Conodont biostratigraphy of the latest Cambrian - Early Ordovician upper McKay Group, southeastern British Columbia

2007 ◽  
Vol 44 (12) ◽  
pp. 1713-1740 ◽  
Author(s):  
Leanne J Pyle ◽  
Christopher R Barnes ◽  
Lee McKenzie McAnally
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Canadian Rocky Mountains ◽  
Conodont Biostratigraphy ◽  
Northern Rocky Mountains ◽  
Early Ordovician ◽  
Low Diversity ◽  
History Of ◽  
Conodont Fauna ◽  
Thermal Subsidence

The age of the upper McKay Group based on conodont biostratigraphy is latest Cambrian (Cordylodus proavus Zone) to late Early Ordovician (middle Floian; Oepikodus communis Zone). A collection of 12 940 conodont elements was recovered from 306 samples of upper McKay Group strata exposed in the Western Main Ranges of the southern Canadian Rocky Mountains, southeastern British Columbia. The conodont fauna is assigned to 53 species representing 30 genera. Twelve zones are recognized, two of which are cosmopolitan: Cordylodus proavus Zone and Iapetognathus Zone. Seven Midcontinent Realm zones, in ascending order, include Polycostatus falsioneotensis, Rossodus tenuis, Rossodus manitouensis, low diversity interval, Scolopodus subrex, and Acodus kechikaensis zones, and Tropodus sweeti Subzone (of the Oepikodus communis Zone). Three Atlantic Realm zones, in ascending order, include Cordylodus angulatus, Acodus deltatus, and Paroistodus proteus zones. The zonation for the upper McKay Group establishes correlation with the Survey Peak Formation and lower Outram Formation of the Bow Platform, and with the Kechika Formation and lower Skoki Formation of the Macdonald Platform and Kechika Trough in the northern Rocky Mountains. The McKay Group represents deposition during post-rift thermal subsidence of the margin, although its thickness, abrupt transition to black shale of the overlying Glenogle Formation, and intercalation of volcanogenic rocks imply a history of differential subsidence similar to that of the northern Cordillera, probably related to periodic extension.

Early Ordovician alkali-ultramafic Zhilandy complex (Central Kazakhstan): structure and age of formation

2019 ◽  
Vol 484 (1) ◽  
pp. 61-65
Author(s):  
R. M. Antonuk ◽  
A. A. Tretyakov ◽  
K. E. Degtyarev ◽  
A. B. Kotov
Keyword(s):  
Complex Formation ◽  
Central Asian Orogenic Belt ◽  
Early Cambrian ◽  
Early Ordovician ◽  
Late Cambrian ◽  
Central Asian ◽  
Geochronological Study ◽  
Three Stages ◽  
Late Neoproterozoic ◽  
Quartz Monzodiorites

U–Pb geochronological study of amphibole-bearing quartz monzodiorites of the alkali-ultramafic Zhilandy complex in Central Kazakhstan, whose formation is deduced at the Early Ordovician era (479 ± 3 Ma). The obtained data indicate three stages of intra-plate magmatism in the western part of the Central Asian Orogenic Belt: Late Neoproterozoic stage of alkali syenites of the Karsakpay complex intrusion, Early Cambrian stage of ultramafic-gabbroid plutons of the Ulutau complex formation, and Late Cambrian–Early Ordovician stage of formation of the Zhilandy complex and Krasnomay complex intrusions.

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.

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