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.

scholarly journals Acritarchs from the Upper Proterozoic and Lower Cambrian of East Greenland

1979 ◽  
Vol 134 ◽  
pp. 1-40
Author(s):  
G Vidal
Keyword(s):  
Lower Cambrian ◽  
Russian Platform ◽  
The State ◽  
Tectonic Deformation ◽  
Early Cambrian ◽  
Thermal Alteration ◽  
Island Formation ◽  
East Greenland ◽  
Upper Proterozoic

Acritarchs are described from rocks of the Upper Proterozoic Eleonore Bay Group and Tillite Group and from the Lower Cambrian Bastion Formation and Ella Island Formation. Twenty-four previously described acritarch taxa have been identified. The state of preservation is variable perhaps depending on variable thermal alteration due to thickness of overburden, tectonic deformation and metamorphism. Palaeoenvironmental aspects of some acritarchs are discussed. The acritarchs of the Ella Island Formation and Upper Bastion Formation indicate a late Early Cambrian age in agreement with the age indicated by shelly faunas. A Vendian age is ascribed to the Tillite Group. The upper part of the Eleonore Bay Group is regarded as Late Riphean. Correlations of these units with Lower Cambrian and Upper Proterozoic sequences in the Russian Platform, Scandinavia and elsewhere are presented.

Precambrian—Cambrian boundary and correlation from southwestern and central part of Spain

1984 ◽  
Vol 121 (3) ◽  
pp. 221-228 ◽  
Author(s):  
E. Liñán ◽  
T. Palacios ◽  
A. Perejón
Keyword(s):  
Iberian Peninsula ◽  
Lower Cambrian ◽  
First Record ◽  
Trace Fossils ◽  
Middle Part ◽  
Early Cambrian ◽  
Upper Proterozoic ◽  
Upper Vendian ◽  
General Series ◽  
Calcareous Microfossils

AbstractThis paper comprises the first palaeontological correlation between the Upper Proterozoic–Lower Cambrian Series of Ossa-Morena, Luso-Oriental-Alcúdica and Galaico-Castellana Zones of the Iberian Peninsula.The authors show the palaeontological events on acritarchs, stromatolites, cyanophyta, soft-bodied metazoa, trilobites, archaeocyathans and skeletal microfossils from three representative sequences of the above mentioned zones and discuss the position of the Precambrian–Cambrian boundary in the sequences. The Sierra de Córdoba general Series (Ossa-Morena Zone) has an erosive discontinuity between the rocks with the first record of Cambrian metazoan activity (Skolithos sp., Monomorphichnus sp., Phycodes pedum and Rusophycus sp.) and the rocks with a palynological association (Bavlinella faveolata, Protosphaeridium flexosum, Trachisphaeridium sp., aff. Octoedryxium truncatum, Phycomicetes? sp. and cf. Ooidium sp.) which suggests a Lower–Middle Vendian age. For this reason we suggest that the Precambrian–Cambrian boundary be placed at this unconformity.The upper part of the Sierra de Guadalupe Series (Luso-Oriental-Alcúdica Zone) includes detrital beds with Phycodes pedum, Planolites sp. and Treptichnus sp. which are also the first record of Cambrian metazoan activity. In the middle part of the sequences, acritarchs attributed to the genus Micrhystridium are found at the top of the Calcareous Beds. This is taken to indicate an early Cambrian age. Vendotaenids and Bavlinella faveolata are found in abundance, thus indicating a Late Vendian age for the middle part of this unit. Thus, we propose the Precambrian–Cambrian boundary be located in the upper part of the Calcareous Beds.In the Rio Uso Series (Galaico-Castellana Zone), the Azorejo Sandstones contain Rusophycus gr. radwanskii, Planolites sp. and Gordia sp. Trace fossils produced by trilobite-like arthropoda (Monomorphichnus) have been cited in the upper part of the underlying Pusa Shales. Moreover, Octoedryxium truncatum and Bavlinella faveolata are found in the lower part of this unit which suggest that the Precambrian–Cambrian boundary could be situated in the Pusa Shales.Calcareous microfossils related to annelid polychaetes are found associated with Upper Vendian acritarchs in the Calcareous Beds of Sierra de Guadalupe. They are the oldest record of skeletal metazoa in the Spanish Series.The medusoids found are associated with a Vendian flora and they are also the oldest non-skeletal metazoa record known in the Iberian Peninsula.

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.

Lower Cambrian acritarchs from Scotland, Norway, Greenland and Canada

1982 ◽  
Vol 72 (4) ◽  
pp. 257-285 ◽  
Author(s):  
C. Downie
Keyword(s):  
New Species ◽  
Rocky Mountains ◽  
Lower Cambrian ◽  
National Park ◽  
Russian Platform ◽  
New Genera ◽  
East Greenland ◽  
Banff National Park

ABSTRACTAssemblages of acritarchs are described from the Fucoid Beds of Skiag Bridge, Knockan Cliff and Skye in NW Scotland, and Holmia Shales of the Mjøsen area of Norway, the Bastion Formation of Ella Ø in East Greenland, the Lower Cambrian of the Burin Peninsula in Newfoundland and from the Gog Formation of the Rocky Mountains of Banff National Park, Alberta. These are shown to be correctable on the basis of acritarchs and with the Lower Cambrian successions of the Russian Platform. Twenty-one genera and fifty-three species of acritarchs and one tasmanitid are described. These include the new genera Skiagia and Volkovia, and thirteen new species, Acrum cylindiferum, Micrhystridium coniferum, M. ellaensis, M. ellipticum, M. flexispinosum, M. gogensis, M. minutum, M. ordensis, Multiplicisphaeridium ? waltoni, Skiagia brevispinosa, S. scottica, Revinotesta ordensis and Evittia irregulare. A number of recombinations have also been made.

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.

Sign in / Sign up

Export Citation Format

Share Document