Anomalous paleomagnetism of the Crowsnest Formation of the Rocky Mountains

1986 ◽  
Vol 23 (5) ◽  
pp. 591-598 ◽  
Author(s):  
E. Irving ◽  
P. J. Wynne ◽  
M. E. Evans ◽  
W. Gough
Keyword(s):  
North America ◽  
Early Cretaceous ◽  
Rocky Mountains ◽  
Remanent Magnetization ◽  
Rocky Mountain ◽  
Thrust Belt ◽  
Present Position ◽  
Paleosecular Variation ◽  
The Third ◽  
Fold And Thrust Belt

The volcanic Crowsnest Formation of Albian age (late Early Cretaceous) from the Rocky Mountain fold and thrust belt of Alberta has a stable remanent magnetization with a mean direction of 349°, 59 °(α95 = 5°) and paleopole at 78°N, 108°E(dm = 7°, dp = 5°). The inclination is lower than, and the declination clockwise of, the expected mid-Cretaceous paleogeomagnetic field for cratonic North America. Taken at face value the result indicates that the Crowsnest Formation and the thrust sheet in which it occurs have been transported from the south relative to cratonic North America by 17 ± 6 °(about 1800 km) and rotated 24 ± 10° clockwise. It is also possible that flattening of inclination is caused by magnetic anistropy, but tests show this to be unlikely. A third possibility is that the magnetization is secondary and of latest Cretaceous age, but there are good reasons for believing this is not so. Lastly, it is possible that the unit could have been formed close to its present position relative to the craton but was deposited so quickly that the paleosecular variation was not adequately sampled, and the result is only a "spot" reading of the paleofield. The last is our preferred interpretation of the flattened inclination, but the clockwise deflection of the declination could reflect rotation. Other paleomagnetic data from the fold and thrust belt are generally consistent with the third interpretation.

The early Silurian pentamerid brachiopod Costistricklandia canadensis (Billings, 1859) and its biostratigraphic and paleobiogeographic significance

2002 ◽  
Vol 76 (4) ◽  
pp. 638-647 ◽  
Author(s):  
Jisuo Jin
Keyword(s):  
North America ◽  
Rocky Mountains ◽  
Baltic Region ◽  
Northern Rocky Mountains ◽  
The Third ◽  
Niagara Escarpment ◽  
The Common ◽  
Anticosti Island ◽  
The Baltic ◽  
Common Association

Costistricklandia is a common, easily recognizable pentamerid brachiopod in upper Llandovery to lowest Wenlock rocks of eastern Laurentia, Avalonia and Baltica. In this paper, the poorly known Costistricklandia canadensis (Billings) is re-described from the upper Telychian Rockway Dolomite of the Niagara Escarpment, Ontario. Compared to the relatively complete record of the Stricklandia-Costistricklandia evolution in the Welsh Borderland and the Baltic region, true representatives of the Stricklandia lens lineage are sporadic in North America, including those from the Merrimack Formation of Anticosti Island, the Red Mountain Formation of Alabama, the Hopkinton Formation of Iowa, and the Nonda Formation of the northern Rocky Mountains. Although the exact mode of speciation in the Stricklandia-Costistricklandia and the Pentamerus-Pentameroides transitions remains debatable, the common association of Costistricklandia and Pentameroides make them a useful concurrent biozone for correlating middle to upper Telychian rocks of North America and Europe. Paleobiogeographically, the Pentameroides-Costistricklandia Fauna marks the third major pulse of pentamerid faunal migration between Laurentia and its adjacent paleo-plates during the Early Silurian, following the limited intercontinental dispersal of the early Llandovery Virgiana Fauna and the quasi-cosmopolitan dispersal of the middle Llandovery Pentamerus Fauna.

A SEISMIC STRUCTURAL OVERVIEW OF LIARD BASIN, NORTHEAST BRITISH COLUMBIA, CANADA

2021 ◽  
pp. 1-53
Author(s):  
Jennifer Leslie-Panek ◽  
Margot McMechan
Keyword(s):  
British Columbia ◽  
Rocky Mountain ◽  
Structural Features ◽  
Boundary Structure ◽  
Thrust Belt ◽  
Western Canada Sedimentary Basin ◽  
Large Structures ◽  
Fold And Thrust Belt ◽  
High Level ◽  
Extensional Structures

The Liard Basin is an important sub-basin of the Western Canada Sedimentary Basin located in Northeast British Columbia along the eastern margin of the Canadian Cordillera. It contains significant potential unconventional gas resources but is largely underrepresented in public literature. Using available-for-purchase 2D seismic data, a regional structural interpretation of the basin was completed providing the first seismically controlled, high-level overview of the structural features of the basin and its surrounding area. The shape of the Liard Basin largely reflects the orientation of older Paleozoic and Proterozoic extensional structures that localized structures formed during Cretaceous - Tertiary compressive deformation. The eastern boundary of the basin is marked by the well-documented Bovie Structure. The Liard Anticline and the Liard River Anticline found near 60o N latitude are the only large structures located within the Liard Basin proper. Inversion of the herein named Liard Basin Boundary Structure, a west-side-down fault zone of Early Paleozoic age, localized the northwest boundary of the basin with the Liard Fold and Thrust Belt. A triangle zone bounds the Rocky Mountain Foothills and the Liard Basin to the southwest. Reflectors in the Proterozoic strata below the Liard Basin were deformed by compressive and then extensional structures prior to the deposition of Paleozoic strata. Proterozoic strata are involved in all the major structures of the adjacent Liard Fold and Thrust Belt, the Rocky Mountain Foothills and the Bovie Structure. These structures controlled the location of the Liard Basin.

Zebra dolomitization as a result of focused fluid flow in the Rocky Mountains Fold and Thrust Belt, Canada

Sedimentology ◽  
2005 ◽  
Vol 52 (5) ◽  
pp. 1067-1095 ◽  
Author(s):  
VEERLE VANDEGINSTE ◽  
RUDY SWENNEN ◽  
SARAH A. GLEESON ◽  
ROB M. ELLAM ◽  
KIRK OSADETZ ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Rocky Mountains ◽  
Thrust Belt ◽  
Fold And Thrust Belt

Paleomagnetism of some Grenville Province Rocks

1973 ◽  
Vol 10 (8) ◽  
pp. 1175-1190 ◽  
Author(s):  
H. C. Palmer ◽  
C. M. Carmichael
Keyword(s):  
North America ◽  
Remanent Magnetization ◽  
Present Position ◽  
Grenville Province ◽  
Paleomagnetic Pole ◽  
The Pacific

Anorthositic rocks 20 to 30 km south of the Grenville Front in the Grenville Province of Ontario have a stable remanent magnetization which yields a paleomagnetic pole at 161 °E, 8 °N. This pole is close to other poles from the Precambrian of North America of 1050 m.y. age. Paleomagnetic results have also been obtained from two rock units in the southern part of the Grenville Province of Ontario. These are a pyroxenite exposed near Wilberforce and the Tudor Gabbro exposed near Madoc. The directions of remanent magnetization yield pole positions as follows: Wilberforce pyroxenite—148 °E, 14.5 °S; Tudor Gabbro—137 °E, 17 °N. These pole positions, together with others from the literature, which have been derived from rock units 200 km or more south of the Grenville Front, plot farther west in the Pacific than do poles of inferred similar age from other regions of North America. A possible interpretation of these results is that the southern part of the Grenville province was formed some 30° SE of its present position.

Palaeomagnetic, rock-magnetic and mineralogical investigations of the Lower Triassic Vardebukta Formation from the southern part of the West Spitsbergen Fold and Thrust Belt

2018 ◽  
Vol 156 (4) ◽  
pp. 620-638 ◽  
Author(s):  
KATARZYNA DUDZISZ ◽  
KRZYSZTOF MICHALSKI ◽  
RAFAŁ SZANIAWSKI ◽  
KRZYSZTOF NEJBERT ◽  
GEOFFREY MANBY
Keyword(s):  
Remanent Magnetization ◽  
Vitrinite Reflectance ◽  
Lower Triassic ◽  
Natural Remanent Magnetization ◽  
The Other ◽  
Thrust Belt ◽  
The West ◽  
Fold And Thrust Belt ◽  
Oriented Samples ◽  
West Spitsbergen

AbstractMagnetic, petrological and mineralogical data from 13 sites (99 independently oriented samples) of the Lower Triassic rocks located in the SW segment of the West Spitsbergen Fold and Thrust Belt (WSFTB) are presented in order to identify the ferrimagnetic carriers and establish the origin of the natural remanent magnetization (NRM). Volcanic lithoclasts and other detrital resistive grains in which the primary magnetization might endure are present in some samples. On the other hand, petrological studies indicate that sulphide remineralization could have had an important influence on the remagnetization of these rocks. The dominant ferrimagnetic carriers are titanomagnetite and magnetite. While the titanomagnetite may preserve the primary magnetization, the magnetite is a more likely potential carrier of secondary overprints. The complex NRM patterns found in most of the samples may be explained by the coexistence and partial overlapping of components representing different stages of magnetization. Components of both polarities were identified in the investigated material. The reversal test performed on the most stable components that demagnetized above 300°C proved to be negative at the 95% confidence level at any stage of unfolding. They are better grouped, however, after 100% tectonic corrections and the most stable components are clustered in high inclinations (c. 70–80°). This suggests that at least part of the measured palaeomagnetic vectors represent a secondary prefolding magnetic overprint that originated in post-Jurassic time before the WSFTB event. Vitrinite reflectance studies show these rocks have not been subjected to any strong heating (<200°C).

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