McMurray Formation foraminifera within the lower Albian (Lower Cretaceous) Loon River shales of northern Alberta

2007 ◽  
Vol 44 (11) ◽  
pp. 1627-1651 ◽  
Author(s):  
C R Stelck ◽  
F H Trollope ◽  
A W Norris ◽  
S G Pemberton
Keyword(s):  
Lower Cretaceous ◽  
Isotopic Analysis ◽  
Radiometric Dating ◽  
Western Canada ◽  
Fort Mcmurray ◽  
Mcmurray Formation ◽  
Peace River ◽  
Clearwater Formation ◽  
Northeastern Alberta ◽  
Northern Alberta

Early Cretaceous paleogeography and biostratigraphy of western Canada are reviewed in light of a reassessment of foraminiferal and microfloral data from unpublished university theses on the early Albian Loon River shales of the lower Peace River area of northern Alberta (Norris 1951; Trollope 1951). The Loon River Formation, once considered to be an obsolete term, comprises numerous “zones” of foraminifera, radiolarian, and algal cysts, in ascending order Rectobolivina sp., lower Radiolarian zone, lower Leiosphaeridia zone, Haplophragmoides yukonensis, upper Radiolarian zone, upper Leiosphaeridia zone, Trochammina mcmurrayensis, Valvulineria loetterlei, Haplophragmoides topagorukensis, Marginulinopsis collinsi, and Haplophragmoides gigas minor. The upper part of the Loon River Formation, from the upper Radiolarian zone onwards, correlates with the McMurray, Wabiskaw, and Clearwater formations of the Fort McMurray area of northeastern Alberta. Molluscan data from various localities in western Canada indicates that the entire Loon River succession occurred within the early Albian. The presence of Inoceramus dowlingi and Cleoniceras sp. with the Marginulinopsis collinsi microfauna permits correlation of the type Clearwater Formation and type McMurray Formation with the Moosebar Formation of northeastern Bristish Columbia. An anomalous thick sequence of Leiosphaeridia (algal cysts) beds, bounded above and below by radiolarian-bearing strata, occurs in the mid part of the Loon River shales outcropping ~40 km along the lower Peace River. The Trochammina mcmurrayensis microfauna occurs 2–3 m below Inoceramus dowlingi and 30 m above Cleoniceras sp., and above the upper Leiosphaeridia zone. The radiolarian and Leiosphaeridia beds are considered to be the offshore neritic homotaxial equivalent of deltaic strata in the upper part of the McMurray Formation. The mid and lower Loon River shales are potential oil sources for the tar of the McMurray Formation, and this is supported by recent radiometric dating of the tar by Rhenium–Osmium isotopic analysis.

Uranium and thorium in the Precambrian basement of western Canada. I. Abundance and distribution

1976 ◽  
Vol 13 (2) ◽  
pp. 284-293 ◽  
Author(s):  
R. A. Burwash ◽  
G. L. Cumming
Keyword(s):  
Western Canada ◽  
Distribution Analysis ◽  
Metamorphic Belt ◽  
Mean Values ◽  
Western Canada Sedimentary Basin ◽  
Peace River ◽  
Peace River Arch ◽  
Abundance And Distribution ◽  
Canada Sedimentary Basin ◽  
Northern Alberta

Delayed neutron activation analyses of 182 core samples from the basement of the western Canada sedimentary basin give mean values of 4.13 ppm U and 21.1 ppm Th. These values are almost twice the published values for the Shield as a whole. Replicate analyses of a composite sample of all cores indicates an analytical precision of ±1% for uranium and ±7% for thorium.Histograms of number of samples vs. U and Th values indicate a negatively skewed frequency distribution. Analysis of composite samples prepared from a large number of hand specimens may tend to conceal this skewed nature. Mean abundance values will also be influenced by the form of the U and Th frequency distributions.Trend surface analysis, with smoothing to reduce the effect of high or low single sample values, indicates two 'highs' common to both U and Th. The helium-producing area around Swift Current, Saskatchewan is associated with a high U–Th plutonic complex. A linear belt trending northeast from Edmonton appears to be a Hudsonian metamorphic belt in which U and Th have been concentrated. Several local concentrations of U or Th are found in the Peace River Arch of northern Alberta.

Uranium and thorium in the Precambrian basement of western Canada. II. Petrologic and tectonic controls

1979 ◽  
Vol 16 (3) ◽  
pp. 472-483 ◽  
Author(s):  
R. A. Burwash
Keyword(s):  
Granulite Facies ◽  
Western Canada ◽  
Precambrian Basement ◽  
Granulite Facies Metamorphism ◽  
Frequency Distributions ◽  
Peace River ◽  
Quartz Monzonite ◽  
Facies Metamorphism ◽  
Northeastern Alberta ◽  
Two Populations

Analyses of 182 basement cores, when plotted as log U and log Th, show bimodal frequency distributions. Cumulative frequency plots indicate an approximate 35–65% split between the two populations. Histograms of numbers of samples in various rock classes vs. log U fail to explain the bimodal distribution.A plot of log K vs. log U provides easy visual separation of rocks with varying K/U ratios and U contents. K/U values greater than 3 × 104 are ascribed principally to granulite facies metamorphism. K/U values less than 5 × 103 represent U-enrichment either in granitic melts or K-metasomatized gneisses. Factor analysis indicates a strong correlation between U, Th. Rb, Pb, and K.The geographic distribution of samples with K/U values greater than 3 × 104 can be related to relict Kenoran granulite facies terranes in the subsurface of northeastern Alberta and west central Saskatchewan similar to those mapped on the exposed Shield in northwestern Saskatchewan. These relict granulites could account for most of the samples in the smaller of the two sample populations.The U-enriched rocks are concentrated in three areas: (1) the epizonal, porphyritic granitic plutons of southwestern Saskatchewan, (2) linear quartz monzonite batholiths along the Kasba Lake – Edmonton gravity low, and (3) K-rich gneisses in the Peace River High of northwestern Alberta. In none of these areas is assimilation of large volumes of Aphebian sedimentary rocks indicated.

A new Lower Cretaceous (lower Albian) ichthyosaur genus from the Clearwater Formation, Alberta, Canada

2010 ◽  
Vol 47 (8) ◽  
pp. 1037-1053 ◽  
Author(s):  
Patrick S. Druckenmiller ◽  
Erin E. Maxwell
Keyword(s):  
Lower Cretaceous ◽  
New Genus ◽  
Lateral View ◽  
Species Level ◽  
Pectoral Girdle ◽  
New Taxon ◽  
New Genus And Species ◽  
Fort Mcmurray ◽  
Clearwater Formation ◽  
The Right

A new, articulated skeleton of an ichthyosaur from the Lower Cretaceous (lower Albian) Wabiskaw Member of the Clearwater Formation near Fort McMurray, Alberta, is the most complete and stratigraphically oldest known ichthyosaur from the Cretaceous of North America and represents a new genus and species of ophthalmosaurian, Athabascasaurus bitumineus . The specimen consists of a nearly complete, dorsoventrally compressed skull, a complete and articulated presacral and partial caudal vertebral series, portions of the right pectoral girdle, and the right pelvic girdle and femur. The new taxon is characterized by the lack of a robust supranarial process of the premaxilla, an elongate maxilla that has its tallest point (in lateral view) posterior to the external naris, a wide postorbital region, the presence of a rectangular squamosal, an angular with greater lateral exposure on the posterior jaw ramus than the surangular, a dentition with extremely light enameled ridges, and a reduced presacral count of 42 vertebrae. The first species-level phylogenetic analysis of Ophthalmosauria reveals that Athabascasaurus is neither the sister taxon of, nor nests within Platypterygius , a geographically widespread, geologically long-lived, and taxonomically problematic genus. Athabascasaurus adds important new data on the morphology of Cretaceous ichthyosaurs and expands our knowledge of the palaeoecology and marine tetrapod diversity of the early Albian Boreal Sea.

Nearshore articulate crinoid from the Albian of Alberta, Canada (Early Cretaceous, Echinodermata)

2011 ◽  
Vol 48 (4) ◽  
pp. 719-727 ◽  
Author(s):  
William I. Ausich ◽  
Robin A. Buckley ◽  
A. Guy Plint
Keyword(s):  
British Columbia ◽  
Early Cretaceous ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Distal Portion ◽  
Peace River ◽  
The North ◽  
Facies Change ◽  
Northern Alberta ◽  
Facies Transition

During the middle Albian, a southward incursion of the Boreal Ocean flooded northern Alberta and adjacent British Columbia, forming a large embayment known as the Hulcross Sea. Marine mudstones of the Hulcross Formation and Harmon Member of the Peace River Formation record transgression, whereas sandstones of the Cadotte Member of the Peace River Formation record shoreline regression to the north. Abundant hummocky and swaley lamination in the Cadotte sandstone attest to the influence of storms on a shallow shelf. The Cadotte sandstone undergoes a lateral facies change from mud-free shoreface sandstone in the south to heterolithic offshore facies in the north. An articulated crinoid was found within a hummocky sandstone bed about 15 km seaward (north) of the shoreface-shelf facies transition. The articulated state of the crinoid indicates that it was buried very rapidly, and never exhumed. The arms through 20 mm of the column are preserved, but because the details of the aboral cup are not well preserved, this specimen must be left in open nomenclature. The elliptical columnals with a concave latus in the distal portion of the preserved column ally this specimen to the Bourgueticrinida, although with details of the aboral cup lacking and other characters atypical for Mesozoic bourgueticrinids, the Canadian specimen is placed in Bathycrinidae indeterminate. The oldest previously recorded bathycrinids were from the Upper Cretaceous (Maastrichtian), thus this report extends their range to the Lower Cretaceous (Albian).

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