REMANENT MAGNETIZATION FROM COMPARISON OF GRAVITY AND MAGNETIC ANOMALIES

Geophysics ◽  
1976 ◽  
Vol 41 (1) ◽  
pp. 56-61 ◽  
Author(s):  
D. H. Shurbet ◽  
G. R. Keller ◽  
J. P. Friess
Keyword(s):  
Remanent Magnetization ◽  
Spatial Relationship ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
The Body ◽  
Gravity And Magnetic

Gravity and magnetic anomalies caused by deeply buried rock bodies in northwest Texas are compared. Interpretation of the gravity anomalies by modeling is used to locate and define the geometry of the body in a way analogous to the use of bathymetry in studies concerned with magnetization of seamounts. The direction of magnetization is then determined from the spatial relationship between the gravity and magnetic anomalies. This procedure amounts to an in‐situ determination of direction of magnetization of the body. In one example direction of magnetization indicates the time of intrusion and in another it indicates regional heating since intrusion.

IN‐SITU DETERMINATION OF THE REMANENT MAGNETIC VECTOR OF TWO‐DIMENSIONAL TABULAR BODIES

Geophysics ◽  
1966 ◽  
Vol 31 (5) ◽  
pp. 949-962 ◽  
Author(s):  
H. P. Ross ◽  
P. M. Lavin
Keyword(s):  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Potential Fields ◽  
Small Samples ◽  
Magnetic Survey ◽  
Two Dimensional ◽  
Magnetic Vector ◽  
Gravity And Magnetic

Recent studies have shown that many rocks of the earth’s crust have a substantial component of remanent magnetization. Extensive sampling is required to determine adequately the remanent vector from small samples. A field technique has been developed (and tested on model data) for the in‐situ determination of the resultant (induced+remanent) magnetic vector of bulk volumes of rock, using a combined analysis of the gravity and magnetic fields of a disturbing body (Poisson’s Theorem). The potential fields are sampled adequately at a limited expenditure of time and effort in the field by utilizing the geometry of two‐dimensional bodies. The major limitation to the analysis is the removal of regional gradients and the estimation of the base levels of anomalies. Combined gravity and magnetic surveys were conducted over six diabase bodies in the Triassic Basin of Pennsylvania. The results of these surveys indicate a resultant direction of magnetization given approximately by: declination 2° W, inclination 41 degrees below the horizon. The corresponding direction of natural remanent magnetization has a declination of 1° W and an inclination of 28 degrees. The ratio of remanent to induced magnetization for the diabase is approximately two. These results have been used to provide a better interpretation of magnetic survey data over a magnetite deposit in the Triassic Basin.

A DIRECT COMPUTATION OF GRAVITY AND MAGNETIC ANOMALIES CAUSED BY 2- AND 3-DIMENSIONAL BODIES OF ARBITRARY SHAPE AND ARBITRARY MAGNETIC POLARIZATION BY EQUIVALENT‐POINT METHOD AND A SIMPLIFIED CUBIC SPLINE

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 610-622 ◽  
Author(s):  
Chao C. Ku
Keyword(s):  
Arbitrary Shape ◽  
Gaussian Quadrature ◽  
Magnetic Anomalies ◽  
Cubic Spline ◽  
The Body ◽  
Point Method ◽  
Magnetic Polarization ◽  
3 Dimensional ◽  
Equivalent Point ◽  
Gravity And Magnetic

A computational method, which combines the Gaussian quadrature formula for numerical integration and a cubic spline for interpolation in evaluating the limits of integration, is employed to compute directly the gravity and magnetic anomalies caused by 2-dimensional and 3-dimensional bodies of arbitrary shape and arbitrary magnetic polarization. The mathematics involved in this method is indeed old and well known. Furthermore, the physical concept of the Gaussian quadrature integration leads us back to the old concept of equivalent point masses or equivalent magnetic point dipoles: namely, the gravity or magnetic anomaly due to a body can be evaluated simply by a number of equivalent points which are distributed in the “Gaussian way” within the body. As an illustration, explicit formulas are given for dikes and prisms using 2 × 2 and 2 × 2 × 2 point Gaussian quadrature formulas. The basic limitation in the equivalent‐point method is that the distance between the point of observation and the equivalent points must be larger than the distance between the equivalent points within the body. By using a reasonable number of equivalent points or dividing the body into a number of smaller subbodies, the method might provide a useful alternative for computing in gravity and magnetic methods. The use of a simplified cubic spline enables us to compute the gravity and magnetic anomalies due to bodies of arbitrary shape and arbitrary magnetic polarization with ease and a certain degree of accuracy. This method also appears to be quite attractive for terrain corrections in gravity and possibly in magnetic surveys.

THE DETERMINATION OF AN INFINITE INCLINED DIKE FROM THE RESULTS OF GRAVITY AND MAGNETIC SURVEYS

Geophysics ◽  
1948 ◽  
Vol 13 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Laszlo Egyed
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Anomaly ◽  
The Body ◽  
Gravitational Gradient ◽  
Ore Bodies ◽  
Gravity And Magnetic ◽  
Anomalous Density

The equations are given for the gravitational gradient and curvature, and for the horizontal and vertical components of the magnetic anomaly for ore bodies of the Kursk type. It is then shown how from these equations the depth, width of crest, angle of dip, anomalous density and magnetic susceptibility of the body may be determined.

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 Determination of Very Low Concentration of Bisphenol A in Toys and Baby Pacifiers Using Dispersive Liquid–Liquid Microextraction by In Situ Ionic Liquid Formation and High-Performance Liquid Chromatography

2020 ◽  
Vol 13 (10) ◽  
pp. 301
Author(s):  
Yesica Vicente-Martínez ◽  
Manuel Caravaca ◽  
Antonio Soto-Meca
Keyword(s):  
Ionic Liquid ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
The Body ◽  
Dispersive Liquid Liquid Microextraction ◽  
Liquid Microextraction ◽  
Total Extraction

Bisphenol A (BPA) is a chemical compound used in the manufacturing of plastics and resins whose presence in the body in low concentrations can cause serious health problems. Due to this, there is a growing interest in the scientific community to develop analytical methods that allow quantifying trace concentrations of BPA in different types of samples. The determination of this compound in toys made of plastics that can be manipulated by children leads to an extra concern, because it is possible for BPA to enter the body by introducing these toys into the mouth. This work presents a novel procedure to the quickly and easily quantification of trace levels of BPA in samples of toys and pacifiers according to the current demanding regulations. The determination of very low levels of BPA was carried out by ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) followed by high-performance liquid chromatography (HPLC). The formation in situ of the ionic liquid (IL) 1-octyl-3-methylimidazolium bis((trifluoromethane)sulfonyl)imide ([C8MIm] [NTf2]), was achieved by mixing 1-octyl-3-methylimidazolium chloride ([C8MIm]Cl) and lithium bis(trifluoromethanesulfonyl)imide ([NTf2]Li) aqueous solutions, reaching an instant dispersion whose cloud of microdrops allows the total extraction of BPA in the IL from aqueous solutions. After centrifugation, BPA concentration in the sedimented phase was determined by HPLC. The optimal experimental conditions for the microextraction and determination of BPA in the IL were studied. The total extraction was achieved at pH 4, heating the sample at 30 °C for 5 min, using 100 µL of IL precursor volume, and spinning after the formation of dispersion at 3000 rpm for 10 min. The enrichment factor (EF) and detection limit (LOD) reached with the procedure were 299 and 0.19 µg L−1, respectively. The relative standard deviation for ten replications at the 0.5 µg L−1 level was 5.2%. Recovery studies showed a mean value for BPA recovery percentage in the samples of 99%. Additionally, a hybrid model was applied to characterize the extraction kinetics. This simple, low cost and fast method simplifies traditional microextraction techniques, representing an outstanding alternative.

A GEOLOGICAL AND GEOPHYSICAL STUDY OF PILOT KNOB (SOUTH), TRAVIS COUNTY, TEXAS

Geophysics ◽  
1954 ◽  
Vol 19 (3) ◽  
pp. 438-454 ◽  
Author(s):  
Frederick Romberg ◽  
Virgil E. Barnes
Keyword(s):  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Complete Picture ◽  
Magnetic Data ◽  
Strong Gravity ◽  
Local Setting ◽  
Gravity And Magnetic ◽  
Geophysical Study ◽  
Gravity And Magnetic Data ◽  
First Time

Pilot Knob is an exhumed volcano of Cretaceous age, composed of “serpentinized” pyroclastics and minor amounts of basalt in both intrusive and extrusive masses. The geology of Pilot Knob was re‐examined, and gravity and magnetic observations made and interpreted, in order to present a complete picture of the feature itself, its history, its relation to the region and area surrounding it, and the resemblances between it and the serpentine plugs in the neighborhood, to which it is geologically related. Some of these plugs have been discovered by geophysical means, and some so discovered have produced oil; the application of gravity and magnetic data to such discoveries is analyzed. The extrusive masses are here reported for the first time, and other evidence is given for the age and volcanic nature of Pilot Knob. The observations reveal 1) strong gravity and magnetic anomalies over the central basalt mass, 2) a pattern of weaker anomalies probably caused by flows and dikes and suggesting that Pilot Knob is situated near the intersection of two sets of fractures, and 3) evidence that “serpentinized” pyroclastics show weak magnetic anomalies and (in the local setting) no visible gravity anomalies.

Use of Gait-Kinematics in Sensor-Based Gait Monitoring: A Feasibility Study

2013 ◽  
Vol 81 (4) ◽  
Author(s):  
Yohannes Ketema ◽  
Demoz Gebre-Egziabher ◽  
Michael Schwartz ◽  
Chris Matthews ◽  
Ryan Kirker
Keyword(s):  
Kinematic Model ◽  
Human Locomotion ◽  
The Body ◽  
Step Size ◽  
Gait Patterns ◽  
Gait Kinematics ◽  
Key Points ◽  
Gait Monitoring

A concept for fusing information from the kinematics describing human locomotion with body-fixed sensors for the purpose of in situ gait monitoring is studied. This is done by using an individual's gait patterns (as captured by a simplified kinematic model) with acceleration measurements made at key points on the body. The gait patterns are expressed as nominal relations between shank, thigh, and stance leg angles during normal walking. It is shown how the use of known gait patterns reduces the required number of sensors attached to the body that are required for a sensor-based monitoring of gait. The feasibility of the approach is demonstrated using a single acceleration measurement at the ankle to estimate limb angles and step size in situ. Such gait monitoring may be used for the evaluations of a subject's overall quality of gait through the determination of flexions at the knees and hip. In addition, step sizes, distance walked, and speed can be estimated. Apart from gait analysis, the method can be used for remotely monitoring the safety of individuals to the extent this can be done through consideration of the state of gait.

A MECHANICAL INTEGRATOR FOR THE COMPUTATION OF GRAVITY ANOMALIES

Geophysics ◽  
1942 ◽  
Vol 7 (4) ◽  
pp. 354-366 ◽  
Author(s):  
Arnold J. F. Siegert
Keyword(s):  
Gravity Anomaly ◽  
Indirect Method ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Closed Curve ◽  
The Body ◽  
Line Integral ◽  
Contour Lines ◽  
Terrain Corrections ◽  
Finite Body

With the instrument here described the gravity anomaly caused by an arbitrarily given finite body can be computed. The integrator is operated by tracing the contour lines representing the body in a manner similar to the operation of a planimeter. The instrument is useful mainly in the indirect method of interpretation of observed gravity anomalies, in the computation of terrain corrections, and in the evaluation of magnetic anomalies. Its design is based on a formula which expresses the gravity anomaly caused by an infinitely thin slab, bounded by a closed curve, as a line integral over this curve.

Correlation Analysis Method and its Application to Interpretation of Regional Gravity and Magnetic Anomalies in Eastern Xinjiang, China

2012 ◽  
Vol 546-547 ◽  
pp. 628-633
Author(s):  
Chun Guan Zhang ◽  
Bing Qiang Yuan ◽  
Yu Hong Li
Keyword(s):  
Correlation Analysis ◽  
Junggar Basin ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Analysis Method ◽  
Contributing Factors ◽  
Gravity And Magnetic ◽  
Metamorphic Basement ◽  
Correlation Analysis Method ◽  
Regional Gravity

Based on detailed analysis of Bouguer gravity anomaly and magnetic anomaly by reduced to the pole, this paper uses correlation analysis method to analyze regional gravity and magnetic anomalies of different filter scales, including filter scales of 50km, 90km, and 130km, and then discusses the contributing factors of local gravity and magnetic anomalies in eastern Xinjiang. The results show that regional gravity and magnetic anomalies are cogenetic anomalies in some areas, such as Hangou, and northern Lamamiao, Jingrquan, and western Qijiaojing, gravity and magnetic anomalies are allogenic anomalies in other areas. The study reveals that regional negative gravity anomalies are chiefly caused by Cenozoic – Mesozoic with larger thickness and lower density, and regional positive magnetic anomalies are mainly caused by Precambrian metamorphic basement with stronger magnetic property uplifting in Turpan – Hami and Santanghu basin. Mantle substances uplifting mainly cause regional positive gravity and magnetic anomalies in Junggar basin. Regional positive gravity anomalies are mainly caused by Pre-Mesozoic with higher density uplifting, and regional negative magnetic anomalies are chiefly caused by sedimentary formation and intermediate acidity rock with larger thickness and weaker magnetism and Precambrian metamorphic basement.

Magnetic and gravity anomaly patterns related to hydrocarbon fields in northern West Siberia

Geophysics ◽  
1997 ◽  
Vol 62 (3) ◽  
pp. 831-841 ◽  
Author(s):  
Alexey L. Piskarev ◽  
Mikhail Yu Tchernyshev
Keyword(s):  
Potential Field ◽  
Oil And Gas ◽  
Spatial Relationship ◽  
Gravity Anomalies ◽  
West Siberia ◽  
Gas Reservoirs ◽  
Gravity And Magnetic ◽  
High Gradients ◽  
Hydrocarbon Fields ◽  
Hydrocarbon Deposits

A study of the features of gravity and magnetic fields in the vicinity of oil and gas reservoirs in West Siberia demonstrated a spatial relationship with the hydrocarbon deposits. The relevant magnetic and gravity anomalies cover approximately [Formula: see text] in northern West Siberia. Amplitude and frequency were investigated initially using double Fourier spectrum (DFS) analysis. This was followed by (1) application of transformations, filtering, and “moving windows” analysis; (2) compilation of maps of regional and local anomalies, and potential field derivatives; and (3) investigation of the distribution of parameters in areas of known deposits. Hydrocarbon deposits are located mostly at the slopes of positive regional gravity and magnetic anomalies which are interpreted as relating to deep riftogenic structures. At the same time, it is established that the location of hydrocarbon depositions coincides commonly with local gravity and magnetic minima generated by lows in basement density and magnetization. All known hydrocarbon deposits in northern West Siberia are in areas characterized by comparatively high gradients of constituent of gravity anomalies with a wavelength of about 90–100 km. These newly revealed links between reservoirs and potential field parameters may be a means to predict new discoveries in poorly explored territories and seas, primarily in Russia's Arctic shelf.

Sign in / Sign up

Export Citation Format

Share Document