Post-Aphebian uplift deduced from remanent magnetization, Yellowknife area of Slave Province

1985 ◽  
Vol 22 (12) ◽  
pp. 1793-1802 ◽  
Author(s):  
Erik J. Schwarz ◽  
Kenneth L. Buchan ◽  
Alain Cazavant
Keyword(s):  
Host Rock ◽  
Remanent Magnetization ◽  
Probable Error ◽  
Slave Province ◽  
Rock Temperature ◽  
Individual Specimen ◽  
Depth Of Burial ◽  
Paleogeothermal Gradient ◽  
Structural Zones ◽  
Erosion Surface

Remanent magnetization in five Indin, three Dogrib, two Archean, and one Mackenzie dyke contact zone(s) from the Yellowknife area of the Canadian Precambrian Shield has been studied in order to establish the ambient temperature of the host rock and the depth of burial of the present erosion surface at the time of intrusion. A positive baked-contact test for an Aphebian Indin dyke demonstrates the primary nature of the dyke magnetization. From this contact, eight individual specimen determinations of the ambient host-rock temperature at the time of intrusion yield an average of 211 °C, with a standard deviation of 18 °C and probable error of ± 36 °C. Assuming a paleogeothermal gradient of 44 °C/km (± 30%) the estimated depth of burial of the present erosion surface is [Formula: see text]. None of the remaining contacts yield estimates of the depth of burial. However, the results from the three Dogrib contacts illustrate complications such as chemical overprinting that must be considered when analysis is made of magnetization in igneous contact zones. Thus, only one spot reading of the depth of burial of the area has been obtained. Correlation of the Indin result with a result from the Matheson area of Ontario and with stratigraphic indicators is uncertain because of large intervening distances and the occurrence of younger structural zones.

Uplift estimated from remanent magnetization: Munro area of Superior Province since 2150 Ma ago

1981 ◽  
Vol 18 (7) ◽  
pp. 1164-1173 ◽  
Author(s):  
Kenneth L. Buchan ◽  
Erik J. Schwarz
Keyword(s):  
Remanent Magnetization ◽  
Country Rock ◽  
Canadian Shield ◽  
Magnetic Component ◽  
Superior Province ◽  
Ambient Temperatures ◽  
Different Ages ◽  
Depth Of Burial ◽  
Erosion Surface

A method for determining depth of burial from remanent magnetization was applied to three igneous contacts of two different ages in Munro Township of the Superior Province of the Canadian Shield. Sampling profiles perpendicular to the contact of a 2150 Ma diabase dike, one collected in an older (2690 Ma) diabase dike and a second in gabbro country rock, yielded ambient temperatures for the present erosion surface at the time of dike emplacement of 219 ± 23 and 181 ± 7 °C, respectively. A third sampling profile perpendicular to a 2690 Ma dike failed to provide a usable magnetic contact zone.A secondary magnetic component with shallow inclination and easterly declination was detected in individual samples collected from both dikes as well as from the surrounding country rock. Converging remagnetization circles indicate that this component, acquired some time after emplacement of the younger (2150 Ma) dike, has the direction D = 70°, I = −39° and corresponding paleopole 39°E, 4°S.

A paleomagnetic study of the layered mafic intrusion at Sept-Îles, Quebec

1987 ◽  
Vol 24 (7) ◽  
pp. 1431-1438 ◽  
Author(s):  
E. I. Tanczyk ◽  
P. Lapointe ◽  
W. A. Morris ◽  
P. W. Schmidt
Keyword(s):  
North America ◽  
Excellent Agreement ◽  
Host Rock ◽  
Remanent Magnetization ◽  
Mafic Intrusion ◽  
Paleomagnetic Study ◽  
Local Host ◽  
Layered Mafic Intrusion ◽  
The One

A paleomagnetic study of gabbroic and anorthositic members of the Sept-Îles layered mafic intrusion has isolated a remanence with direction D = 333°, I = −29 °(remanence A) and a corresponding pole of 141 °E, 20°N. The rocks are cut by numerous diabase dykes of unknown age. The remanence carried by the dykes has direction D = 188°, I = −85 °(remanence B), with a corresponding pole of 116°E, 59°S. Another remanence, statistically identical to B (D = 186°, I = −85°), is found at dyke contacts and in the local host rock; its associated pole, 115°E, 61°S, is identical to the one derived from the dykes. This overprint is significantly different from remanence A, and is obviously related to dyke emplacement. The location of the pole derived from remanence A is in excellent agreement with many other Cambrian poles from a variety of locations throughout cratonic North America. The rocks at Sept-Îles have been previously dated radiometrically at 540 Ma. Thus, all evidence indicates that remanence A is an original thermochemical remanent magnetization, acquired during initial cooling of the intrusion in the Cambrian and prior to the emplacement of the dykes.

scholarly journals Temperature conditions in the ventilation shaft lining and the space behind lining when reversing the main ventilation unit in winter

2020 ◽  
Vol 192 ◽  
pp. 01018
Author(s):  
Aleksandr Kurilko ◽  
Dmitrii Solovev
Keyword(s):  
Rock Mass ◽  
Host Rock ◽  
Air Flow ◽  
Concrete Lining ◽  
Temperature Conditions ◽  
The North ◽  
Ventilation Shaft ◽  
Rock Temperature ◽  
Freezing Depth ◽  
Shaft Lining

Using mathematical modeling methods, the authors studied the temperature changes in the ventilation shaft lining and the space behind lining under an alternating thermal effect of the ventilation flow (reversing the main ventilation unit in winter). We established the pattern of the temperature conditions created in the ventilation shaft, the lining, and the host rock mass when reversing the main ventilation unit at mines in the North. Our studies have shown that, in case of emergency at the mine, which requires reversing the air flow in the coldest period of the year, it will result in a change in the temperature conditions in the ventilation shaft, the concrete lining, and the host rock mass. The extent of such effect depends on the reverse duration. Thus, at an ambient temperature of -45°C, during the first 24 hours after the reverse, we can observe complete freezing of the concrete lining at a ventilation flow rate of over 2 m/s. The rock temperature drops below 0°C and, at air flow rates of up to 10 m/s, the frozen area thickness around the shaft will be no more than 7 cm. 48 hours after the reverse, the maximum freezing depth of the rock will be 30 cm.

Paleomagnetism of the Tulemalu dykes, Northwest Territories, Canada

1984 ◽  
Vol 21 (5) ◽  
pp. 544-553 ◽  
Author(s):  
W. F. Fahrig ◽  
K. W. Christie ◽  
K. E. Eade ◽  
S. Tella
Keyword(s):  
Northwest Territories ◽  
Remanent Magnetization ◽  
Slave Province ◽  
Archean Rock ◽  
Great Slave Lake ◽  
Basic Rocks

Easterly trending Tulemalu diabase dykes that cut an area of predominantly Archean rock in southern Keewatin were magnetized more than 2200 Ma ago. Thirteen of the sampled sites (dykes) exhibit a southeast-down remanent magnetization and five sites give a more poorly grouped direction that is reversed to this. Their combined pole is at 122.4°E, 0.5°S, δm = 10.4°, δp = 6.0°. Six northeasterly trending Kazan dykes, which are probably correlatives of the Kaminak dykes, give a metamorphic pole at 94.2°W, 30.7°N, δm = 35°, δp = 31°. The age of their magnetization is thought to be between 1900 and 2000 Ma.The pole for the Tulemalu dykes lies within a group of poles of similar age derived from basic rocks of the Slave Province. It is about 30° away from the pole for the MacKay dykes, which occur north of Great Slave Lake and which have an easterly trend similar to that of the Tulemalu.Poles whose ages range between 1900 and 2200 Ma and that are derived from the Slave, western Churchill, and Superior provinces all suggest that during this period these three continental plates occupied approximately the same relative positions as they do today.

A succession of quartz veins in Archean metaturbidites, Yellowknife Bay, Slave Province

1987 ◽  
Vol 24 (4) ◽  
pp. 698-710 ◽  
Author(s):  
W. K. Fyson
Keyword(s):  
Hydraulic Fracturing ◽  
Host Rock ◽  
Early Stage ◽  
Shear Zones ◽  
Intermediate Stage ◽  
Quartz Veins ◽  
Slave Province

The style of extensional quartz veins changed during deformation and metamorphism of greywacke–mudstones near Yellowknife, with successive types of veins accompanying a progression from steeply plunging, predominantly macroscopic F1, and F2 folds to mesoscopic F3 folds and subvertical S3 axial planar cleavages. (A) Early-stage multiple bedding-parallel veins are confined to pelitic units. Some form saddle reefs around hinges of F1 and a few later folds, whereas others are unrelated to fold hinges. Emplacement of most bedding veins during or before F1 folding is suggested. (B) Echelon veins pre-dominantly lie stratabound within pelites. Folding about S3 cleavage indicates a pre-F3 or early F3 origin. (C) Foliation veins more commonly cross sandstones than pelites and follow S3 or F3 axial surfaces. Boudinage of the veins indicates emplacement before S3 was fully developed. (D) Sporadic veins, discordant to bedding and cleavage, vary from undeformed to folded about S3. Evidently these veins were emplaced towards the end or after F3 folding.The change from pelite as the preferred host rock for bedding and echelon veins to sandstone for foliation veins could reflect migration of loci of hydraulic fracturing as fluid was produced and lost during metamorphism. Bedding and foliation veins apparently followed weakness planes (bedding fissility and cleavage), whereas the echelon vein arrangement suggests that during an intermediate stage of deformation pelites acted as shear zones. All veins could have formed during variably directed, subhorizontal, tectonic compression.

Grain separation enhanced magnetic coercivity in Pt/Co multilayers.

1993 ◽  
Vol 51 ◽  
pp. 1038-1039 ◽  
Author(s):  
G.A. Bertero ◽  
R. Sinclair
Keyword(s):  
Remanent Magnetization ◽  
Strong Influence ◽  
Uniaxial Anisotropy ◽  
Magnetic Coupling ◽  
Recording Media ◽  
Magnetic Media ◽  
Signal To Noise ◽  
Out Of Plane ◽  
Longitudinal Recording ◽  
The Relationship

Pt/Co multilayers displaying perpendicular (out-of-plane) magnetic anisotropy and 100% perpendicular remanent magnetization are strong candidates as magnetic media for the next generation of magneto-optic recording devices. The magnetic coercivity, Hc, and uniaxial anisotropy energy, Ku, are two important materials parameters, among others, in the quest to achieving higher recording densities with acceptable signal to noise ratios (SNR). The relationship between Ku and Hc in these films is not a simple one since features such as grain boundaries, for example, can have a strong influence on Hc but affect Ku only in a secondary manner. In this regard grain boundary separation provides a way to minimize the grain-to-grain magnetic coupling which is known to result in larger coercivities and improved SNR as has been discussed extensively in the literature for conventional longitudinal recording media.We present here results from the deposition of two Pt/Co/Tb multilayers (A and B) which show significant differences in their coercive fields.

Propagation of Lightning Current Studied by Remanent Magnetization

2013 ◽  
Vol 133 (9) ◽  
pp. 694-699 ◽  
Author(s):  
Hideo Sakai ◽  
Kaname Yonezawa ◽  
Yoshihiro Kouno ◽  
Takatoshi Shindo
Keyword(s):  
Remanent Magnetization ◽  
Lightning Current

Optimal Density Determination of Bouguer Anomaly Using Fractal Analysis (Case of study: Charak area,IRAN)

2005 ◽  
Vol 1 (1) ◽  
pp. 21-24
Author(s):  
Hamid Reza Samadi
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Fractal Analysis ◽  
Fractal Geometry ◽  
Host Rock ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Density Difference ◽  
Optimal Density

In exploration geophysics the main and initial aim is to determine density of under-research goals which have certain density difference with the host rock. Therefore, we state a method in this paper to determine the density of bouguer plate, the so-called variogram method based on fractal geometry. This method is based on minimizing surface roughness of bouguer anomaly. The fractal dimension of surface has been used as surface roughness of bouguer anomaly. Using this method, the optimal density of Charak area insouth of Hormozgan province can be determined which is 2/7 g/cfor the under-research area. This determined density has been used to correct and investigate its results about the isostasy of the studied area and results well-coincided with the geology of the area and dug exploratory holes in the text area

Sign in / Sign up

Export Citation Format

Share Document