scholarly journals Diabase dyke swarms as structural controls for kimberlite pipes under the James Bay and Hudson Bay lowlands, Ontario

2007 ◽  
Vol 44 (5) ◽  
pp. 643-664 ◽  
Author(s):  
Kenneth L Buchan ◽  
Jean Goutier ◽  
Michael A Hamilton ◽  
Richard E Ernst ◽  
William A Matthews

An extensive set of north- to northwest-trending diabase dykes, termed the Lac Esprit swarm, is identified in the Superior Province east of James Bay based on geological mapping and a distinctive paleomagnetic pole (61.7°N, 169.1°E, dm = 7.7°, dp = 5.5°). The Lac Esprit swarm yields a U–Pb baddeleyite age of 2069 ± 1 Ma similar to that of the 2076+5–4 Ma Fort Frances swarm of the western Superior Province. Their paleomagnetic declinations differ by 23° ± 12° after correction to a common reference locality. The difference is likely due mainly to counterclockwise rotation about a vertical axis of the Fort Frances area relative to the Lac Esprit area. Differential rotation of 10°–20° has been proposed more locally across the Kapuskasing Structural Zone separating the eastern and western Superior Province in earlier paleomagnetic studies of ca. 2450 Ma Matachewan and 2170 Ma Biscotasing dyke swarms. Thus, relative rotation may have involved the entire eastern and western Superior Province, perhaps in response to collisional events associated with the Trans-Hudson Orogen to the north or the Penokean orogen to the south, or in response to rifting beneath Hudson Bay. Other dykes in the study area are interpreted from a combination of paleomagnetism, trend, and geochemistry to belong to the Senneterre, Matachewan, and Mistassini swarms. The 2216 Ma Senneterre dykes form part of a giant swarm that fans across the eastern Superior Province. Paleomagnetic directions and geometry of this swarm rule out substantial block rotations within the eastern Superior Province since dyke emplacement.


2012 ◽  
Vol 7 ◽  
pp. 37-47 ◽  
Author(s):  
G. Allard ◽  
M. Roy ◽  
B. Ghaleb ◽  
P.J.H. Richard ◽  
A.C. Larouche ◽  
...  

1987 ◽  
Vol 65 (7) ◽  
pp. 1410-1419 ◽  
Author(s):  
S. L. Wolff ◽  
R. L. Jefferies

Morphological and electrophoretic variation has been documented within and among populations of Salicornia europaea L. (s.l.) in northeastern North America. Univariate and multivariate analyses (discriminant analyses) of measurements of floral and vegetative characters delimited three morphologically distinct groups of populations: Atlantic coast tetraploids (2n = 36), Hudson Bay diploids, and Atlantic coast and James Bay diploids (2n = 18). The two diploid groups were morphologically distinct from the midwestern diploid, S. rubra Nels., based on anther length, width of the scarious border of the fertile segment, and the overall width of the fertile segment. Electrophoretic evidence supported the delimitation of the three distinct morphological groups of populations of S. europaea with the exception of the population from James Bay, which had electrophoretic patterns identical with those of plants from Hudson Bay but resembled the Atlantic coast diploids morphologically. Most enzyme systems assayed were monomorphic. Only homozygous banding patterns were detected in diploid plants and electrophoretic variation was not observed within populations of S. europaea or S. rubra but was detected between groups of populations. Four multilocus phenotypes were evident; these corresponded to the major groups recognized on the basis of ploidy level and morphology. Reasons that may account for the paucity of isozymic variation are discussed.


2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Rodney W. Brook ◽  
Lisa A. Pollock ◽  
Kenneth F. Abraham ◽  
Glen S. Brown

2018 ◽  
Vol 492 ◽  
pp. 50-63 ◽  
Author(s):  
April S. Dalton ◽  
Sarah A. Finkelstein ◽  
Peter J. Barnett ◽  
Minna Väliranta ◽  
Steven L. Forman

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