Paleomagnetism of the Middle Proterozoic Mount Nelson Formation: evidence for a regional remagnetization event in the Late Precambrian of the Cordillera

1983 ◽  
Vol 20 (4) ◽  
pp. 561-567 ◽  
Author(s):  
W. A. Morris ◽  
M. E. McMechan
Keyword(s):  
British Columbia ◽  
National Park ◽  
Acid Leaching ◽  
Pole Position ◽  
Glacier National Park ◽  
Geological Process ◽  
Thermal Demagnetization ◽  
Fine Grained ◽  
Late Precambrian ◽  
Middle Proterozoic

Chemical and thermal demagnetization of 92 specimens from the Mount Nelson Formation (uppermost Purcell Supergroup) in the Purcell Mountains of southeastern British Columbia yields two distinct directional groups. MN-A, found by thermal and chemical demagnetization, has a mean direction of D = 274°, I = 19° (α95 = 10°, tilt corrected), which corresponds to a pole position at 156 °E, 10 °N, MN-A resides in fine-grained hematite and is similar to other overprint directions reported from middle and upper Belt–Purcell strata in the Glacier National Park – Clark Range area. Genesis of this overprint is related to some regional geological process, most probably the Goat River Orogeny [Formula: see text]. Direction MN-B, which is found after acid leaching of more than 250 h, has a mean direction of D = 331°, I = 47°(α95 = +4°, tilt corrected), corresponding to a pole at 119 °E, 59 °N. The MN-B pole is significantly different from all poles previously reported from the Belt–Purcell Supergroup (ca. 210 °E, 20 °S). As the age of the MN-B pole is unconstrained the significance of this marked discrepancy is at present uncertain.

Paleomagnetism of the Great Slave Supergroup, Northwest Territories, Canada: the Tochatwi Formation

1976 ◽  
Vol 13 (4) ◽  
pp. 555-562 ◽  
Author(s):  
M. E. Evans ◽  
D. K. Bingham
Keyword(s):  
Northwest Territories ◽  
North American ◽  
Pole Position ◽  
The Other ◽  
Thermal Demagnetization ◽  
Fine Grained ◽  
I 11 ◽  
Two Phases ◽  
Geological Work ◽  
Magnetic Vectors

The Tochatwi Formation comprises some 800 m of fine-grained red to buff sandstone in the upper part of the Great Slave Supergroup. Recent geological work indicates an age of 1700 m.y., but this is not yet known with certainty. Results from 29 sampling sites stratigraphically covering the Tochatwi Formation are presented. Standard paleomagnetic techniques indicate that post-folding remagnetization is common, and this is confirmed by analysis of the magnetic vectors removed as partial thermal demagnetization proceeds. Two phases of remagnetization are recognized, one of which can be attributed to nearby Mackenzie-age intrusions. The other phase is equivalent to a remagnetization observed by other workers in Kahochella Group strata at localities 70 km away. As yet, the source of this remagnetization event cannot be identified. Eight sampling sites have escaped total remagnetization and an earlier, pre-folding remanence has been isolated from these (D = 030, I = −11, k = 14, α95 = 15°). The corresponding pole position (144W, 18S) is remote from those deduced from North American rocks of similar age, and possible explanations of this problem are discussed.

Bats of Kootenay, Glacier, and Mount Revelstoke national parks in Canada: identification by echolocation calls, distribution, and biology

1983 ◽  
Vol 61 (11) ◽  
pp. 2503-2508 ◽  
Author(s):  
M. B. Fenton ◽  
H. G. Merriam ◽  
G. L. Holroyd
Keyword(s):  
British Columbia ◽  
National Parks ◽  
National Park ◽  
Myotis Lucifugus ◽  
Glacier National Park ◽  
Lasiurus Cinereus ◽  
Echolocation Calls ◽  
Bat Activity ◽  
Lasionycteris Noctivagans ◽  
The Town

We studied the behaviour, echolocation calls, and distribution of bats in Kootenay, Glacier, and Mount Revelstoke national parks in British Columbia, Canada. Presented here are keys for identification of nine species of bats by their echolocation calls as rendered by two different bat-detecting systems. The species involved include Myotis lucifugus, M. evotis, M. volans, M. septentrionalis, M. californicus, Lasionycteris noctivagans, Eptesicus fuscus, Lasiurus cinereus, and L. borealis. The distribution of these species within the three parks was assessed by capturing bats in traps and mist nets and by monitoring of their echolocation calls. Most of the species exploited concentrations of insects around spotlights, providing convenient foci of activity for assessing distribution. Although most species of Myotis were commonly encountered away from the lights, Lasiurus cinereus in Kootenay National Park was only regularly encountered feeding on insects at lights. This species was not detected in Glacier National Park, and although we regularly encountered it in the town of Revelstoke, it was rarely encountered in Mount Revelstoke National Park. Another focus of bat activity was small pools in cedar forest in Mount Revelstoke National Park. This involved high levels of Myotis spp. activity at dusk as the bats came to the pools to drink.

Paleomagnetism of the Sutton Lake Proterozoic inlier, Ontario, Canada

1982 ◽  
Vol 19 (6) ◽  
pp. 1330-1332
Author(s):  
E. J. Schwarz ◽  
K. R. Clark ◽  
Y. Fujiwara
Keyword(s):  
Pole Position ◽  
North Pole ◽  
The Other ◽  
Stratigraphic Correlation ◽  
Red Beds ◽  
End Points ◽  
Thermal Demagnetization ◽  
Fine Grained ◽  
Dark Layer ◽  
Volcanic Suite

Thirty-eight cores were collected from eight sites in the Sutton Lake Proterozoic inlier, which is thought to be an extension of the Circum-Ungava Belt. Six sites from a 100 m thick diabase sill yielded essentially single-component magnetization averaging D = 35°, I = −54°, k = 39,α95 = 11°. The diabase dips north at 4° and shows only minor alteration (epidote and chlorite). The other two sites were in a fine-grained dark layer within the sill and in a dike. No end points were observed for these sites upon alternating field and thermal demagnetization. The six diabase sites yielded a north pole at 67°E, 3°S, dm = 15, dp = 11. This pole position is similar to that obtained for the youngest volcanic suite (Flaherty Formation) of the Belcher Islands and to that obtained for red beds of the La Grande 4 outlier, suggesting a time-stratigraphic correlation between these units.

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