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.

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.

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

1976 ◽  
Vol 13 (4) ◽  
pp. 563-578 ◽  
Author(s):  
D. K. Bingham ◽  
M. E. Evans
Keyword(s):  
Northwest Territories ◽  
North American ◽  
Geomagnetic Field ◽  
Pole Position ◽  
The West ◽  
Stratigraphic Sequence ◽  
Polar Wander ◽  
Early Proterozoic ◽  
The North ◽  
Polarity Reversals

Paleomagnetic results from 55 sampling sites throughout the Stark Formation are reported. The known stratigraphic sequence of these sites enables the behaviour of the geomagnetic field in these remote times (1750 m.y.) to be elucidated. Two polarity reversals are identified and these represent potentially useful correlative features in strata devoid of index fossils. One of these is investigated in detail and indicates that behaviour of the geomagnetic field during polarity reversals was essentially the same in the early Proterozoic as it has been over the last few million years. The pole position (145°W, 15°S, dp = 3.5, dm = 6.9) lies far to the west of that anticipated from earlier results, implying further complexity of the North American polar wander curve. Possible alternatives to this added complexity are discussed.

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.

Late Hadrynian and Helikian pole positions from the Spokane Formation, Montana

1977 ◽  
Vol 14 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Icaro Vitorello ◽  
Rob Van der Voo
Keyword(s):  
Heat Flow ◽  
Geomagnetic Field ◽  
Pole Position ◽  
The Other ◽  
Low Grade ◽  
Thermal Event ◽  
Thermal Demagnetization ◽  
Grade Metamorphism ◽  
Laramide Orogeny ◽  
Good Agreement

The natural remanent magnetizations of Beltian argillites from the Spokane Formation (formerly Grinnell Formation) have been analyzed with alternating field and thermal demagnetization techniques. Two groups of magnetic directions have been observed. One is assumed to be the primary magnetization, representative of the Helikian (approx. 1300 Ma) geomagnetic field: D = 201.5°; I = +40°; k = 61; and α95 = 5.1° for N = 14 sites (51 samples), yielding a pole position at 15.5 °S. 134.5 °W, dp = 3.7°, dm = 6.2°. Comparisons with contemporaneous pole positions reveal good agreement. The other direction of magnetization corresponds to a Late Hadrynian age (approx. 600 to 750 Ma) and resulted from low-grade metamorphism. It is speculated that this thermal event resulted from enhanced heat flow during continental breakup in the Late Hadrynian. This direction (D = 267.5°; I = +17; k = 10; α95 = 9.1° for N = 28 specimens) yields a pole position at 5°N, 163.5°E, with dp = 4.9°, dm = 9.4°. Both groups of directions of magnetization are pre-folding, which occurred during the Laramide orogeny. Laramide deformation was only moderate, however, and the eastward thrusting of the Beltian sediments over the Lewis thrust was probably not accompanied by significant structural rotation.

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.

scholarly journals Neutron Imaging Using a Fine-Grained Nuclear Emulsion

2021 ◽  
Vol 7 (1) ◽  
pp. 4
Author(s):  
Katsuya Hirota ◽  
Tomoko Ariga ◽  
Masahiro Hino ◽  
Go Ichikawa ◽  
Shinsuke Kawasaki ◽  
...  
Keyword(s):  
Image Analysis ◽  
High Resolution ◽  
Neutron Detector ◽  
Nuclear Emulsion ◽  
Neutron Imaging ◽  
The Other ◽  
Crystal Oscillator ◽  
Fine Grained ◽  
Cold Neutrons ◽  
Track Analysis

A neutron detector using a fine-grained nuclear emulsion has a sub-micron spatial resolution and thus has potential to be applied as high-resolution neutron imaging. In this paper, we present two approaches to applying the emulsion detectors for neutron imaging. One is using a track analysis to derive the reaction points for high resolution. From an image obtained with a 9 μm pitch Gd grating with cold neutrons, periodic peak with a standard deviation of 1.3 μm was observed. The other is an approach without a track analysis for high-density irradiation. An internal structure of a crystal oscillator chip, with a scale of approximately 30 μm, was able to be observed after an image analysis.

scholarly journals Global-Local Enhancement Network for NMF-Aware Sign Language Recognition

2021 ◽  
Vol 17 (3) ◽  
pp. 1-19
Author(s):  
Hezhen Hu ◽  
Wengang Zhou ◽  
Junfu Pu ◽  
Houqiang Li
Keyword(s):  
Sign Language ◽  
Daily Life ◽  
The Other ◽  
Challenging Problem ◽  
Language Recognition ◽  
Local Enhancement ◽  
Sign Language Recognition ◽  
Vocabulary Size ◽  
Hand Gestures ◽  
Fine Grained

Sign language recognition (SLR) is a challenging problem, involving complex manual features (i.e., hand gestures) and fine-grained non-manual features (NMFs) (i.e., facial expression, mouth shapes, etc .). Although manual features are dominant, non-manual features also play an important role in the expression of a sign word. Specifically, many sign words convey different meanings due to non-manual features, even though they share the same hand gestures. This ambiguity introduces great challenges in the recognition of sign words. To tackle the above issue, we propose a simple yet effective architecture called Global-Local Enhancement Network (GLE-Net), including two mutually promoted streams toward different crucial aspects of SLR. Of the two streams, one captures the global contextual relationship, while the other stream captures the discriminative fine-grained cues. Moreover, due to the lack of datasets explicitly focusing on this kind of feature, we introduce the first non-manual-feature-aware isolated Chinese sign language dataset (NMFs-CSL) with a total vocabulary size of 1,067 sign words in daily life. Extensive experiments on NMFs-CSL and SLR500 datasets demonstrate the effectiveness of our method.

scholarly journals Eurasian and North American phylogeny of Turolian hipparionine horses (Perissodactyla, Mammalia) in China

1992 ◽  
Vol 6 ◽  
pp. 305-305
Author(s):  
Mahito Watabe
Keyword(s):  
North America ◽  
North American ◽  
Northern China ◽  
Sensu Stricto ◽  
The Other ◽  
Dental Morphology ◽  
Facial Morphology ◽  
Open Land ◽  
Specialized Form ◽  
Eastern Half

The late Miocene Chinese hipparions are morphologically diversified showing similarity to both western Old World's and North American forms. Two Chinese taxa that are phylogenetically related to western Old World's forms are Hipparion fossatum (= H. forstende) from Baode (Shanxi) and H. hippidiodus from Qingyang (Gansu) and Baode. The former is related to H. mediterraneum and the latter to H. urmiense - platygenys from the Turolian localities in the western Old World. H. fossatum and H. hippidiodus are associated with the “dorcadoides” (open-land) and “mixed” faunas in northern China. Hipparion fossatum that is characterized by POF located close to the orbit co-occurs with large and morphologically specialized form, H. dermatorhinum in Baode (Loc.30). H. hippidiodus with reduced POF is discovered with smaller H. coelophyes in Loc. 43, 44 (Baode) and Loc. 115 (Gansu).The hipparions associated with the “gaudryi” (forest) fauna are characterized by well defined and small POF located far from the orbit. Those forms are: H. platyodus from Loc. 70; H. ptychodus from Loc. 73; H. tylodus from Hsi-Liang in Yushe - Wuxiang basins; and H. sefvei from Loc. 12 at Xin-an in Henan province. H. coelophyes from Baode (Loc.43 & 44) and Qingyang (Loc. 115) also show similar facial morphology to the these forms, although it has small size and shallow POF. Those forms are similar in facial and dental morphology to Hipparion sensu stricto and some species of Cormohipparion in North America.The assemblages of Chinese hipparions are composed of two groups whose members are phylogenetically similar to the forms from both western part of Eurasia and North America. The “gaudryi” fauna is considered younger than the other two on the basis of faunal analyses. The similarity in hipparionine taxonomy between northern China and North America in the latest Miocene is an evidences for possible faunal interchange(s) occurred during that period, as suggested by taxonomic analyses on carnivores and proboscideans in eastern half of Eurasia and North America.

scholarly journals I.—Microscopic Structure of Irish Granites. No. 2. Granite of Aillemore, Co. Mayo

1874 ◽  
Vol 1 (1) ◽  
pp. 1-2
Author(s):  
Edward Hull
Keyword(s):  
The Other ◽  
Microscopic Structure ◽  
South Side ◽  
North West ◽  
Fine Grained ◽  
Lower Silurian ◽  
The North ◽  
Geological Map ◽  
Vertical Walls ◽  
Dark Green

This granite forms an isolated mass, rising into two eminences a few miles south of Louisburg, called Corvock Brack (1287 feet) and Knockaskeheen (1288 feet). It is a greyish granite—generally fine—grained—consisting of quartz, two felspars,—one orthoclase, the other triclinic, probably oligoclase—and dark green mica. In some places there are patches in which the felspar assumes the appearance of “graphic granite.” Numerous boulders of this granite are strewn over the district to the north-west, and on the south side of Knockaskeheen; the rock is traversed by regular joints ranging N. 10 W., along which it splits off into nearly vertical walls. The position of the granite is shown on Griffith's Geological Map of Ireland, and it is surrounded by schistose beds, generally metamorphosed, and probably of Lower Silurian age. The granite itself is of older date than the Upper Llandovery beds, which lie to the southward.

Conditional Belief and the Ramsey Test

2002 ◽  
Vol 51 ◽  
pp. 215-232
Author(s):  
Scott Sturgeon
Keyword(s):  
Everyday Life ◽  
Common Sense ◽  
The Other ◽  
Coarse Grained ◽  
Degrees Of Belief ◽  
Conditional Belief ◽  
Ramsey Test ◽  
Fine Grained

Consider the frameS believes that—.Fill it with a conditional, sayIf you eat an Apple, you'll drink a Coke.what makes the result true? More generally, what facts are marked by instances ofS believes (A→C)?In a sense the answer is obious: beliefs are so marked. Yet that bromide leads directly to competing schools of thought. And the reason is simple.Common-sense thinks of belief two ways. Sometimes it sees it as a three-part affair. When so viewed either you believe, disbelieve, or suspend judgment. This take on belief is coarse-grained. It says belief has three flavours: acceptance, rejection, neither. But it's not the only way common-sense thinks of belief. Sometimes it's more subtle: ‘How strong is your faith?’ can be apposite between believers. That signals an important fact. Ordinary practice also treats belief as a fine-grained affair. It speaks of levels of confidence. It admits degrees of belief. It contains a fine-grained take as well. There are two ways belief is seen in everyday life. One is coarse-grained. The other is fine-grained.

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