Inversion of scalar magnetic anomalies to magnetic susceptibility anomalies

1984 ◽  
Author(s):  
J. Arkani‐Hamed ◽  
D. W. Strangway
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomalies

Analysis of Magnetic Anomaly Characteristics of Underground Non-Coplanar Cross-buried Iron Pipelines

2020 ◽  
Vol 25 (2) ◽  
pp. 223-233
Author(s):  
Pan Wu ◽  
Minghui Wei
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
Magnetic Dipole ◽  
Geomagnetic Field ◽  
Magnetic Anomalies ◽  
Buried Pipelines ◽  
Magnetic Declination ◽  
Magnetic Inclination ◽  
Basic Characteristics ◽  
Geomagnetic Intensity

The non-coplanar cross-buried pipelines are a common way of pipeline wiring. In order to investigate the magnetic anomaly characteristics of the non-coplanar cross-buried pipelines and guide the site operation, the influences of a series of factors on the magnetic anomaly of the non-coplanar cross-buried pipelines are analyzed. Based on the principle of magnetic dipole construction, a forward model is established for the magnetic anomaly characteristics of the subsurface non-coplanar cross-buried pipelines. The basic characteristics of magnetic anomaly for the non-coplanar cross-buried pipelines are defined. The influences of geomagnetic parameters (geomagnetic intensity, geomagnetic inclination, and geomagnetic declination), pipeline parameters (thickness, magnetic susceptibility), and cross angle of pipelines on the characteristics of magnetic anomalies are analyzed. The results show that the shape of the total magnetic anomaly is mainly affected by the magnetic inclination, and the curve of magnetic anomaly at ± I site shows some symmetry. The amplitude is approximately linearly affected by the total geomagnetic field, magnetic declination, pipeline thickness, material magnetic susceptibility, and pipeline cross angle. There is a periodic change of the amplitude with the increase of geomagnetic inclination (−90°–>90°). The crest-trough distance is mainly affected by geomagnetic inclination, magnetic declination, thickness, magnetic susceptibility, and pipeline cross angle. A more accurate measurement can be achieved if the direction of the pipelines is roughly measured and then the number of measurement points is augmented near the intersection of pipelines and the measurement lines. Present work obtains the equivalent magnetic dipole units by segmenting pipelines. The magnetic anomaly characteristics of non-coplanar crossed iron pipelines are successfully simulated. The numerical results are in accordance with the experimental analysis.

LIMITING VALUES OF GRAVITATIONAL AND MAGNETIC ANOMALIES DUE TO A SUBTERRANEAN STRUCTURE BOUNDED BY A SINGLE DIFFERENTIAL SURFACE

Geophysics ◽  
1941 ◽  
Vol 6 (1) ◽  
pp. 1-12 ◽  
Author(s):  
J. W. Fisher
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Magnetic Anomalies ◽  
Effective Thickness ◽  
Earth’S Magnetic Field ◽  
Magnetic Effects ◽  
Earth's Magnetic Field ◽  
Survey Results ◽  
Limiting Values

Calculations are made of gravitational and magnetic anomalies supposed due to local variations in the form of a single differential surface separating an overlying rock from an underlying one, the effective thickness of the latter being infinite. Both layers are homogeneous in density or magnetic susceptibility and only those magnetic effects are considered which are due to induction in the earth’s magnetic field. The maximum possible values of these anomalies and of their first and second horizontal derivatives are calculated under these simplified conditions, and it is pointed out that the numerical readings of these quantities, provided by survey results, may lead to useful estimates of the extreme depth and proportions of the structure responsible.

scholarly journals Magnetic anomalies in the spin-chain compoundSr3CuRhO6: Griffiths-phase-like behavior of magnetic susceptibility

2007 ◽  
Vol 75 (5) ◽  
Author(s):  
E. V. Sampathkumaran ◽  
Niharika Mohapatra ◽  
Sudhindra Rayaprol ◽  
Kartik K. Iyer
Keyword(s):  
Magnetic Susceptibility ◽  
Spin Chain ◽  
Magnetic Anomalies ◽  
Griffiths Phase

scholarly journals Petrophysical Properties (Density and Magnetization) of Rocks from the Suhbaatar-Ulaanbaatar-Dalandzadgad Geophysical Profile in Mongolia and Their Implications

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Tao Yang ◽  
Jintian Gao ◽  
Zuowen Gu ◽  
Baatarkhuu Dagva ◽  
Batsaikhan Tserenpil
Keyword(s):  
Magnetic Susceptibility ◽  
Remanent Magnetization ◽  
Ground Surface ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Natural Remanent Magnetization ◽  
Petrophysical Properties ◽  
Geological History ◽  
Essential Information ◽  
Variable Gravity

Petrophysical properties of 585 rock samples from the Suhbaatar-Ulaanbaatar-Dalandzadgad geophysical profile in Mongolia are presented. Based on the rock classifications and tectonic units, petrophysical parameters (bulk density, magnetic susceptibility, intensity of natural remanent magnetization, and Köenigsberger ratio) of these rocks are summarized. Results indicate that (1) significant density contrast of different rocks would result in variable gravity anomalies along the profile; (2) magnetic susceptibility and natural remanent magnetization of all rocks are variable, covering 5-6 orders of magnitude, which would make a variable induced magnetization and further links to complex magnetic anomalies in ground surface; (3) the distribution of rocks with different lithologies controls the pattern of lithospheric magnetic anomaly along the profile. The petrophysical database thus provides not only one of the keys to understand the geological history and structure of the profile, but also essential information for analysis and interpretation of the geophysical (e.g., magnetic and gravity) survey data.

scholarly journals Two Dimensional Modeling of Basaltic Rocks Intrusion Based on The Local Magnetic Anomalies Data in Jatilawang District Banyumas Regency

2020 ◽  
Vol 10 (2) ◽  
pp. 171
Author(s):  
Sehah Sehah ◽  
Sukmaji Anom Raharjo ◽  
Urip Nurwijayanto Prabowo
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomalies ◽  
Basaltic Rock ◽  
Research Area ◽  
Magnetic Data ◽  
Two Dimensional ◽  
Basaltic Rocks ◽  
Dimensional Modeling ◽  
Susceptibility Contrast ◽  
Lateral Length

Two dimensional modeling to basaltic rocks intrusion in Pekuncen and Karanglewas Villages Jatilawang District, Banyumas Regency, Central Java based on the local magnetic anomalies data has been carried out in March – June 2020. The amount of magnetic data obtained from the acquisition in the field was 239 data stretching in position of 109.107222° – 109.134944°E and 7.561361° – 7.577306°S, with the local magnetic anomalies values ranging of -2,961.11 – 1,516.31 nT. To model anomalous sources in the subsurface in two dimensions, then the local magnetic anomalies data is transformed into pseudogravity anomalies data, so that anomalous value can be obtained as -27.815 – 41.087 mGal. Based on the pseudogravity anomalous map, the basaltic rock intrusion is interpreted to be located in the eastern part of the research area, so modeling of anomalous sources is conducted in this area. The results of 2D-modeling to local magnetic anomalies data indicate the presence of anomalous object interpreted as basaltic rock intrusion with magnetic susceptibility contrast value of 0.0223 cgs, located at depth of 52.61 – 505.97 m and a lateral length of 1777.94 m. This rock intrudes sediment rock from the Halang Formation and is connected to other basaltic rock near the surface with magnetic susceptibility contrast value of 0.0165 cgs, located at depth of 1.94 – 80.90 m and lateral length of 751.83 m. The results of lithological interpretation are in accordance with the geological information of the research area.

Archaeomagnetism and magnetic anomalies in the American Southwest

Geophysics ◽  
1987 ◽  
Vol 52 (3) ◽  
pp. 368-371 ◽  
Author(s):  
Robert S. Sternberg
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Induction ◽  
Remanent Magnetization ◽  
Magnetic Anomalies ◽  
American Southwest ◽  
Archaeological Sites ◽  
Thermoremanent Magnetization ◽  
Disturbed Soil ◽  
Magnetic Remanence ◽  
Geophysical Technique

Magnetic surveying is probably the most widely used geophysical technique at archaeological sites (Weymouth and Huggins, 1985). It is useful for locating features in which the magnetic susceptibility contrasts with the magnetic susceptibility of the surroundings because of induced and/or remanent magnetization. A contrast in magnetic induction can arise, for example, when the disturbed soil fill inside a formerly occupied room has a different magnetic susceptibility from the subsoil outside the room (Tite and Mullins, 1971). A contrast in magnetic remanence most commonly occurs when a baked clay artifact or feature such as a hearth has acquired a thermoremanent magnetization after being heated to several hundred degrees Celsius.

A geophysical interpretation of the geology of Conception Bay, Newfoundland

1983 ◽  
Vol 20 (9) ◽  
pp. 1421-1433 ◽  
Author(s):  
H. G. Miller
Keyword(s):  
Magnetic Susceptibility ◽  
Volcanic Rocks ◽  
Magnetic Anomalies ◽  
Vertical Movement ◽  
Geophysical Data ◽  
Two Dimensional ◽  
Geophysical Interpretation ◽  
Gravity And Magnetic ◽  
Conception Bay ◽  
Avalon Peninsula

Geophysical data from Conception Bay and the adjacent peninsulas of the Avalon Peninsula, Newfoundland are presented and quantitatively interpreted using two-dimensional models to interpret the geology beneath the bay. The portion of the bay underlain by mafic volcanic rocks is determined and the maximum extent of the Cambro-Ordovician rocks containing the Wabana hematite deposit is delineated. All gravity and magnetic anomalies in the area are explained in terms of density and magnetic susceptibility variations confined to the upper 12 km of the crust. The geophysical models indicate that mafic volcanics underlie a significant portion of the study area and are more extensive than indicated by the surface outcrop on land. The models also indicate significant vertical movement on the Topsail Fault and on the extension of a fault passing out into the bay near Holyrood. The Cambro-Ordovician sediments are confined to the southern portion of the block bounded by these faults. The geophysical data are unable to detect the presence of the mafic volcanics east of the Topsail Fault in the study area.

Regional magnetic anomalies, magnetic units, and crustal structure in the Kenora District of Ontario

1968 ◽  
Vol 5 (5) ◽  
pp. 1277-1296 ◽  
Author(s):  
Donald H. Hall
Keyword(s):  
Magnetic Susceptibility ◽  
Crustal Structure ◽  
Continuous Distribution ◽  
Magnetic Anomalies ◽  
Canadian Shield ◽  
Superior Province ◽  
Quantitative Interpretation ◽  
Variable Intensity ◽  
Depth Determination ◽  
Greenstone Belts

Regional magnetic anomalies were smoothed from aeromagnetic maps in a part of the Superior Province of the Canadian Shield (latitudes 48°45′ to 50°00′ N; longitudes 93°30′ to 95°00′ W). It was found that anomaly lows lie over Keewatin greenstone belts, and highs over adjacent granitic areas.Surface mapping of magnetic susceptibility and NRM was combined with quantitative interpretation of the regional magnetic anomalies. It was found that, when considered regionally, magnetization lies primarily in the granitic bodies, with a continuous distribution from the surface down to the Intermediate (Conrad) discontinuity. Intensity of magnetization increases with depth, and is directed nearly along the direction of the present-day geomagnetic field.As an aid to the interpretation, a method of depth determination for deep crustal magnetic units with sloping sides is introduced, and one for variable intensity of magnetization with depth.

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