Paleomagnetism of the Lac St-Jean anorthosite and related rocks, Grenville Province, Quebec

1983 ◽  
Vol 20 (2) ◽  
pp. 246-258 ◽  
Author(s):  
K. L. Buchan ◽  
W. F. Fahrig ◽  
G. N. Freda ◽  
R. A. Frith
Keyword(s):  
North American ◽  
Regional Metamorphism ◽  
The Other ◽  
Central Portion ◽  
Grenville Province ◽  
Polar Wander ◽  
Thermal Demagnetization ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Normal Polarity

Alternating field and thermal demagnetization study of the Lac St-Jean anorthosite and related rock units in the central portion of the exposed Grenville Province reveals two components of magnetization, one of reversed and the other of normal polarity. Both components are thought to have been acquired during the last regional metamorphism, which was sufficiently intense in this area (mostly amphibolite grade) to reset any earlier magnetization. Corresponding paleopoles at 193°W, 8°S (dm = 7.3°, dp = 4.6°) and 213°W, 19°S (dm = 10.5°, dp = 8.5°) lie along the 950–900 Ma segment of the recently calibrated Grenville track of the North American apparent polar wander path, a track that has thus far been defined largely by results from rock units of the western Grenville.

Implications of Early Devonian poles from the Canadian Arctic Archipelago for the North American apparent polar wander path

1982 ◽  
Vol 19 (9) ◽  
pp. 1802-1809 ◽  
Author(s):  
Peter Dankers
Keyword(s):  
North American ◽  
Canadian Arctic ◽  
Canadian Arctic Archipelago ◽  
Early Devonian ◽  
Polar Wander ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Late Cambrian ◽  
Normal Polarity ◽  
North American Craton

Lower Devonian red beds from the upper member of the Peel Sound Formation at Prince of Wales Island (Canadian arctic) yield two different paleopoles at 25N 099E and at 01N 091E, the first one being older than the second one. The magnetic directions from which the poles are calculated are derived from vector analysis of thermal, chemical, and alternating magnetic field demagnetization results. Normal and reversed polarities are recorded for the northerly pole, whereas the pole at the equator reveals mainly a normal polarity. The position of the pole close to the equator has significant implications for the early Paleozoic apparent polar wander path of the North American craton. It appears that from the Late Cambrian to Early Devonian the craton moved continuously in a counter-clockwise direction that ended abruptly in the Early Devonian when the direction of the motion of the continent was reversed in a very similar manner to what occurred in Late Cambrian times.

Paleomagnetism of the Lawrenceton Formation volcanic rocks, Silurian Botwood Group, Change Islands, Newfoundland

1989 ◽  
Vol 26 (2) ◽  
pp. 296-304 ◽  
Author(s):  
Julie E. Gales ◽  
Ben A. van der Pluijm ◽  
Rob Van der Voo
Keyword(s):  
North American ◽  
Volcanic Rocks ◽  
Mobile Belt ◽  
Structural Mapping ◽  
Polar Wander ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
North American Craton

Paleomagnetic sampling of the Lawrenceton Formation of the Silurian Botwood Group in northeastern Newfoundland was combined with detailed structural mapping of the area in order to determine the deformation history and make adequate structural corrections to the paleomagnetic data.Structural analysis indicates that the Lawrenceton Formation experienced at least two folding events: (i) a regional northeast–southwest-trending, Siluro-Devonian folding episode that produced a well-developed axial-plane cleavage; and (ii) an episode of local north-trending folding. Bedding – regional cleavage relationships indicate that the latter event is older than the regional folding.Thermal demagnetization of the Lawrenceton Formation yielded univectorial southerly and shallow directions (in situ). A fold test on an early mesoscale fold indicates that the magnetization of the Botwood postdates this folding event. However, our results, combined with an earlier paleomagnetic study of nearby Lawrenceton Formation rocks, demonstrate that the magnetization predates the regional folding. Therefore, we conclude that the magnetization occurred subsequent to the local folding but prior to the period of regional folding.While a tectonic origin for local folding cannot be entirely excluded, the subaerial nature of these volcanics, the isolated occurrence of these folds, and the absence of similar north-trending folds in other areas of eastern Notre Dame Bay suggest a syndepositional origin. Consequently, the magnetization may be nearly primary. Our study yields a characteristic direction of D = 175°, I = +43°, with a paleopole (16°N, 131 °E) that plots near the mid-Silurian track of the North American apparent polar wander path. This result is consistent with an early origin for the magnetization and supports the notion that the Central Mobile Belt of Newfoundland was adjacent to the North American craton, in its present-day position, since the Silurian.

Paleomagnetism of the komatiitic basalts of the Ottawa Islands, N.W.T.

1985 ◽  
Vol 22 (4) ◽  
pp. 553-566 ◽  
Author(s):  
K. L. Buchan ◽  
W. R. A. Baragar
Keyword(s):  
North American ◽  
Hudson Bay ◽  
The West ◽  
Magnetization Direction ◽  
Polar Wander ◽  
The North ◽  
Dominant Component ◽  
Apparent Polar Wander Path

The komatiitic basalts of the Ottawa Islands in eastern Hudson Bay are on strike with and believed to form a continuation of similar units of the Cape Smith Belt 150 km to the northeast. Units sampled in the Ottawa Islands all dip gently to the west and hence are not suitable for an internal fold test of their age of magnetization. However, before correcting for the tilt of the lavas, the dominant magnetization direction (D = 207.6°, I = 61.9°, k = 168, α95 = 3.7°) does not differ significantly from the uncorrected magnetization direction reported from the steeply dipping, northwest-facing units at Cape Smith (D = 218°, I = 60°, k = 47, α95 = 4°). This negative fold test suggests that the remanence at both locations was acquired after folding. Comparison with the North American Precambrian apparent polar wander path implies that overprinting is related to the Hudsonian Orogeny.A second stable magnetization directed to the west with a shallow inclination is superimposed on the dominant component at a number of sampling sites. Its direction is poorly defined and no fold test is possible. However, magnetic evidence suggests that this component was probably acquired as an overprint after the dominant magnetization, perhaps during a mild reheating associated with the Elsonian Orogeny.

Paleomagnetism of the Moenkopi and Chinle Formations in central New Mexico: Implications for the North American Apparent Polar Wander Path and Triassic magnetostratigraphy

1991 ◽  
Vol 96 (B9) ◽  
pp. 14239-14262 ◽  
Author(s):  
Roberto S. Molina-Garza ◽  
John W. Geissman ◽  
Rob Van der Voo ◽  
Spencer G. Lucas ◽  
Steve N. Hayden
Keyword(s):  
New Mexico ◽  
North American ◽  
Polar Wander ◽  
The North ◽  
Apparent Polar Wander Path

Comments and Reply on "Age estimation of the Deccan Traps from the North American apparent polar wander path"

Geology ◽  
1989 ◽  
Vol 17 (1) ◽  
pp. 88 ◽  
Author(s):  
Jean Besse ◽  
Vincent Courtillot ◽  
Didier Vandamme ◽  
A. K. Baksi ◽  
Paul R. Stoddard ◽  
...  
Keyword(s):  
North American ◽  
Age Estimation ◽  
Deccan Traps ◽  
Polar Wander ◽  
The North ◽  
Apparent Polar Wander Path

Paleomagnetism of pre-Grenvillian mafic intrusions from the Grenville Province, southeast Labrador

1989 ◽  
Vol 26 (12) ◽  
pp. 2541-2555 ◽  
Author(s):  
G. Murthy ◽  
C. F. Gower ◽  
M. Tubrett ◽  
R. Pätzold
Keyword(s):  
Layered Intrusions ◽  
Characteristic Direction ◽  
Heating Pulse ◽  
Grenville Province ◽  
Polar Wander ◽  
Mafic Intrusions ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Layered Mafic Intrusion ◽  
Middle Proterozoic

Paleomagnetic results are reported for Middle Proterozoic layered intrusions and dykes from within the Grenville Province of coastal southeastern Labrador. Rock units studied include the Little Grady Island layered norite intrusion, crosscutting mafic dykes from Little Grady Island, the dated Michael Gabbro from Double Island, and other miscellaneous mafic intrusions. On the basis of mineralogy and composition, it is concluded that the Little Grady Island layered mafic intrusion, the crosscutting dykes from Little Grady Island, and the miscellaneous mafic intrusions belong to the same period of magmatism (ca. 1650 Ma), in contrast with the Michael Gabbro, which belongs to a later event (ca. 1426 Ma).All rock units (except two dykes from the Hawke River Terrane) yield similar directions of magnetization. The remanence is extremely stable and has a characteristic direction of declination (D) = 321.7 °and inclination (I) = −49.3 °(N = 20, k = 24.1, α95 = 6.8°), with corresponding paleopole at 0.1°N, 155.1°E. This paleopole is interpreted as being representative of Grenvillian remagnetization. Based on an earlier age-calibrated Grenville track of the North American apparent polar wander path, this magnetization is correlated with a 900 Ma event, probably a (heating) pulse superposed on the general Grenvillian cooling. In contrast with this regional behaviour, two dykes from the Hawke River Terrane (Earl Island) yield a characteristic remanence of D = 285.7 °and I = 6.6°, with corresponding pole at 12°N, 158°W, interpreted as acquired during pre-Grenvillian, probably Elsonian, resetting.

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