Magnetic properties of serpentinized peridotites from the Dongbo ophiolite, SW Tibet: Implications for suture-zone magnetic anomalies

2017 ◽  
Vol 122 (7) ◽  
pp. 4814-4830 ◽  
Author(s):  
Zhiyong Li ◽  
Jianping Zheng ◽  
B. M. Moskowitz ◽  
Qingsheng Liu ◽  
Qing Xiong ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anomalies ◽  
Suture Zone

Magnetic anomalies, chemical and magnetic properties at wide temperature range (15–1000 K) in LiSrxFe5-xO8 (x = 0, 0.025, 0.05)

2021 ◽  
Vol 859 ◽  
pp. 158290
Author(s):  
S. Udhayakumar ◽  
G. Jagadish Kumar ◽  
E. Senthil Kumar ◽  
M. Navaneethan ◽  
K. Kamala Bharathi
Keyword(s):  
Magnetic Properties ◽  
Wide Temperature Range ◽  
Magnetic Anomalies ◽  
Temperature Range

The sub-surface shape of part of the Loch Ailsh Intrusion, Assynt, as deduced from magnetic anomalies across the contact, with a note on traverses across the Loch Borralan Complex

1965 ◽  
Vol 102 (1) ◽  
pp. 46-58 ◽  
Author(s):  
Ian Parsons
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anomalies ◽  
Surface Shape ◽  
Large Magnitude ◽  
Southern Margin

AbstractLocal magnetic anomalies of large magnitude are found over the marginal ultrabasic rocks of the Loch Ailsh intrusion. An intrepretation of these anomalies based on the measured magnetic properties of the pyroxenites shows that they are not reconcilable with a low-angle structure as required by the hypothesis that the intrusion is a stratified laccolite, and suggests that they form a steeply dipping sheet at the syenite-limestone contact. Similar anomalies occur along the southern margin of the Loch Borralan complex, suggesting steeply dipping marginal ultrabasic rocks.

scholarly journals Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

Geosciences ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 225
Author(s):  
Pierre Rochette ◽  
Natalia S. Bezaeva ◽  
Andrei Kosterov ◽  
Jérôme Gattacceca ◽  
Victor L. Masaitis ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Oxidation State ◽  
Redox State ◽  
Magnetic Anomalies ◽  
Formation Processes ◽  
X Ray ◽  
Ferromagnetic Component ◽  
High Velocity Impacts ◽  
Superparamagnetic State

High velocity impacts produce melts that solidify as ejected or in-situ glasses. We provide a review of their peculiar magnetic properties, as well as a new detailed study of four glasses from Siberia: El’gygytgyn, Popigai, urengoites, and South-Ural glass (on a total of 24 different craters or strewn-fields). Two types of behavior appear: 1) purely paramagnetic with ferromagnetic impurities at most of the order of 10 ppm; this corresponds to the five tektite strewn-fields (including the new one from Belize), urengoites, and Darwin glass. Oxidation state, based in particular on X-ray spectroscopy, is mostly restricted to Fe2+; 2) variable and up to strong ferromagnetic component, up to the 1 wt % range, mostly due to substituted magnetite often in superparamagnetic state. Accordingly, bulk oxidation state is intermediate between Fe2+ and Fe3+, although metallic iron, hematite, and pyrrhotite are sometimes encountered. Various applications of these magnetic properties are reviewed in the field of paleomagnetism, magnetic anomalies, recognition of glass origin, and formation processes.

Magnetic properties of unrusted steel drums from laboratory and field‐magnetic measurements

Geophysics ◽  
1996 ◽  
Vol 61 (5) ◽  
pp. 1325-1335 ◽  
Author(s):  
Dhananjay Ravat
Keyword(s):  
Magnetic Properties ◽  
Magnetic Measurements ◽  
Magnetic Anomalies ◽  
Point Of View ◽  
Small Samples ◽  
Environmental Investigation ◽  
Bulk Magnetization ◽  
Steel Drums ◽  
Study Laboratory ◽  
Better Than

Laboratory‐derived magnetic properties from samples of steel drums appear to be lower than bulk magnetic properties required to produce observed magnetic anomalies over the same drums. The origin of this discrepancy is perhaps in the shape demagnetization experienced by samples used in the laboratory study. Laboratory observations of magnetic susceptibility in different directions suggest that the demagnetization mechanism may have significantly attenuated the laboratory‐derived magnetization values from small samples of drums. Field observations and computer modeling indicate that even though the effect of demagnetization is important for drum‐shaped objects, demagnetization is less pronounced in the shape of the drum than in the samples cut for laboratory measurements. Therefore, laboratory‐derived magnetizations from samples of steel drums cannot be used to model magnetic anomalies of steel drums. If laboratory‐derived magnetizations were used to model steel drums, the models would underestimate the resulting magnetic anomalies considerably and, in turn, would overestimate the number of buried drums at an environmental investigation site. Apparent bulk magnetization values for unrusted vertically oriented 55 and 30 gallon drums have been calculated (i.e., the values corrected for the effect of shape demagnetization of the drums). These range from ∼90 to ∼125 SI units (∼7 to ∼10 cgs units) for volume susceptibility and from ∼325 to ∼2750 A/m (∼0.325 to [Formula: see text]) for remanent magnetization (based on eight 55 gallon and four 30 gallon drums). Further deviations in these values could arise from the type and thickness of the steel and variations in manufacturing conditions affecting magnetizations. From the point of view of modeling the drums, at most source‐to‐observation distances applicable to environmental investigations, the equivalent source method is able to approximate the observed anomalies of steel drums better than the 3-D modeling method. With two years of rusting, magnetic anomalies of some of the drums have reduced, while in other drums, they have slightly increased. The overall magnetic changes caused by rusting appear to be more complex than anticipated, at least in the initial phase of rusting.

APPLICATION OF THE MAGNETIC ANOMALIES IN IDENTIFICATION THE STRUCTURE OF THE CRYSTALLINE BASEMENT OF THE SOUTH–EASTERN POLAND

2017 ◽  
pp. 17-48
Author(s):  
Teresa GRABOWSKA ◽  
Grzegorz BOJDYS ◽  
Zdzislaw PETECKI
Keyword(s):  
Magnetic Properties ◽  
Western Europe ◽  
Three Dimensional ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Geological Structure ◽  
Crystalline Basement ◽  
East European Craton ◽  
East European ◽  
South Eastern

South-eastern Poland is situated between the East European Craton (EEC), the Paleozoic and Mezosoic of Western Europe and the Carpathians. Complex geological structure of the area is reflected on the maps of potential fields anomalies. The analyses of the total magnetic intensity anomaly map ∆T and the vertical derivatives of these anomalies in relation to geological data provide many information concerning the structure and magnetic properties of rocks of the crystalline basement. These analyses indirectly reveal the degree of the petrologic diversification and the tectonics of the basement in comparison with the adjoining blocks of the Paleozoic and Variscan orogens and their basement as well as those located in the area of the Trans–European Suture Zone (TESZ). Two dimensional (2D) magnetic models of the basement along the seismic profiles (CEL 01, CEL 05) and corresponding three dimensional (3D) model have been constructed. This interpretation is based on spectral analysis of the magnetic anomalies and their quantitative interpretation which includes data from the CELEBRATION 2000 project, as well as information concerning the magnetic properties of rocks made available through drilling. The comparative analysis of maps showing magnetic and gravity anomalies have revealed the architecture of the crystalline basement in the area where the East European Craton (EEC) is in contact with the Paleozoic and Mezosoic of Western Europe, as well as its impact on the image of residual gravity anomalies within the area of the craton.

SPECTRAL ANALYSIS OF TOTAL MAGNETIC ANOMALIES OF STEP MODEL

Geophysics ◽  
1978 ◽  
Vol 43 (3) ◽  
pp. 634-636 ◽  
Author(s):  
M. V. Ramanaiah Chowdary
Keyword(s):  
Magnetic Properties ◽  
Spectral Analysis ◽  
Frequency Analysis ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
Model Parameters ◽  
Considerable Success ◽  
Step Model ◽  
Gravity And Magnetic ◽  
Gravity And Magnetic Data

A great deal of interest has been shown in the frequency analysis of gravity and magnetic data originally suggested by Dean (1958). The application of this method for potential field problems has met with considerable success. The purpose of this note is to show that the interpretation of total magnetic anomalies due to a sloping step model, which represents a contact between zones having different magnetic properties in terms of model parameters, is less complicated in the frequency domain than in the spatial domain.

The Mid-Atlantic ridge near 45° N. VII. Magnetic properties and opaque mineralogy of dredged samples

1970 ◽  
Vol 7 (2) ◽  
pp. 239-256 ◽  
Author(s):  
C. M. Carmichael
Keyword(s):  
Magnetic Properties ◽  
Remanent Magnetization ◽  
Complex Structure ◽  
Magnetic Anomalies ◽  
Natural Remanent Magnetization ◽  
Coarse Grained ◽  
X Ray Diffraction ◽  
Field Polarity ◽  
Fine Grained ◽  
Mid Atlantic Ridge

Measurements of the magnetic properties, paleomagnetic field intensity, and the inferred paleomagnetic field polarity have been made using fine grained basalt and coarser grained rock samples dredged from the mid-Atlantic ridge near 45° N and supplied by the Geological Survey of Canada. The opaque mineralogy of the samples was studied by microscope, Curie point, and X-ray diffraction techniques. The natural remanent magnetization of the basalt is of the order of 5 to 10 × 10−3 e.m.u./cm3 with some values from the center of the median valley reaching 10−1 e.m.u./cm3. Magnetic anomalies over the ridge can be accounted for by the remanent magnetization of a few hundred meters of this basalt. The coarse grained rocks were relatively weakly magnetized, and while they contribute little to the magnetic anomalies, their diverse character suggests that the major portion of the oceanic crust, below a thin veneer of fine grained basalt, has differentiated into a complex structure.

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