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.

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.

Viscosité magnétique potentielle, aimantation détritique et viscosité réelle d'un sédiment lacustre quaternaire

1987 ◽  
Vol 24 (9) ◽  
pp. 1903-1912 ◽  
Author(s):  
Daniel Biquand ◽  
François Sémah
Keyword(s):  
Remanent Magnetization ◽  
Rock Magnetism ◽  
Viscosity Index ◽  
Natural Remanent Magnetization ◽  
Blocking Temperature ◽  
Magnetic Viscosity ◽  
Paleomagnetic Study ◽  
Temperature Spectra

The magnetic viscosity of sediments, as indicated by thermal demagnetization of natural remanent magnetization (NRM), depends on two main parameters: (i) the specific magnetic viscosity of the material and (ii) the efficiency of the primary magnetization process. In an attempt to determine the relative importance of these two variables, we studied a Lower Pleistocene lacustrine sequence bearing a primary reversed detrital remanent magnetization (DRM).Using natural samples and small cores made of crushed sediment, our study is based on the thermodynamic theory of rock magnetism developed by L. Néel, who established an equivalence between time and temperature, that is, between viscous remanent (VRM) and thermoremanent (TRM) magnetization processes. The determination of the blocking temperature spectra from 20 to 152 °C allows us to calculate the maximum theoretical VRM acquired in situ at each horizon, while the detailed thermal study of the NRM permits an appraisal of the DRM quality. This leads us to define a geological viscosity index, which accounts, in a rather convincing manner, for the behaviour of the samples observed during the classical paleomagnetic study. For the section studied, it appears that the variations of this index are closely correlated with the efficiency of the DRM acquisition process.

Direct determination of the natural remanent magnetization effect in a hole drilled in layered ground from magnetic field and susceptibility logs

Geophysics ◽  
1992 ◽  
Vol 57 (7) ◽  
pp. 872-884 ◽  
Author(s):  
Guy Desvignes ◽  
Véronique Barthes ◽  
Alain Tabbagh
Keyword(s):  
Magnetic Field ◽  
Remanent Magnetization ◽  
Direct Determination ◽  
Theoretical Models ◽  
Natural Remanent Magnetization ◽  
Case Examples ◽  
Joint Interpretation ◽  
The Fourier Transform ◽  
Layered Ground

A new method as presented, allows the joint interpretation of both electromagnetic (EM) and magnetic logs in layered ground, based on the fact that the susceptibility responses for these two measurements are linear. Thus we can make use of the classical properties of the Fourier transform to extract from these two signals the magnetic field due to remanent magnetization. Theoretical models show that for a sufficient sample step this remanent magnetization can be recovered, even if the Koenigsberger ratio is of the order of 0.2 and if the thickness of the magnetized layer is of the order of 1 m. The results for two case examples in a sedimentary context are also shown. Despite the difficulties due to experimental procedures, we show that the amplitude of the extracted information is significant in these two cases, even if its variations are somewhat structureless and cannot be easily explained by the geology.

Direct growth of two-dimensional phthalocyanine-based COF on Cu-MOF to construct a photoelectrochemical-electrochemical dual-mode biosensing platform for high-efficiency determination of Cr(iii)

2021 ◽  
Author(s):  
Shuai Zhang ◽  
Kun Chen ◽  
Lei Zhu ◽  
Miaoran Xu ◽  
Yingpan Song ◽  
...  
Keyword(s):  
High Efficiency ◽  
Two Dimensional ◽  
Dual Mode ◽  
Direct Growth ◽  
Efficiency Determination

A two-dimensional phthalocyanine-based COF (CoPc-PT-COF) was in situ grown on a Cu-MOF substrate to construct a COF@MOF heterostructure as a biosensing platform.

Determination of Material Acoustic Features Using Small Samples

2014 ◽  
Vol 606 ◽  
pp. 111-114
Author(s):  
Jan Holub ◽  
Bastien Desbos ◽  
Vítězslav Vacek ◽  
Jiří Kolísko
Keyword(s):  
Signal Processing ◽  
New Method ◽  
Small Samples ◽  
Acoustic Absorption ◽  
Practical Consideration ◽  
Acoustic Features

A new method to determine acoustic absorption in-situ is described in this paper. For practical consideration, this measurement can be performed on small samples (square of 60x60cm). This paper describes all the steps needed to obtain results: device setup, recording, signal processing.

The measurement of the hydraulic permeability of saturated soil in situ . II

1953 ◽  
Vol 216 (1124) ◽  
pp. 72-89 ◽  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Potential Distribution ◽  
Hydraulic Permeability ◽  
Two Dimensional ◽  
Capillary Fringe ◽  
Isotropic Media ◽  
Two Dimensional Flow

After a brief description of a new sand-tank laboratory and equipment for studying problems of the flow of fluids in porous materials, the remainder of the paper is devoted to an account of the application of a part of this equipment to a study of the flow of water between a pair of wells, such as is required for the determination of the permeability of the sand by the method described in part I. The potential distribution about the wells is found to conform sufficiently well with theory to justify the application of the analysis of part I, the interference due to the confining walls being satisfactorily negligible. The perturbation of the water table inseparable from the imposition of a potential difference between the wells is found not to invalidate the results based on an assumption of two-dimensional flow, while the corrections on account of the presence of a capillary fringe and a surface of seepage are satisfactorily made by adding to the measured depth of water in the well an increment equal to about half the thickness of the capillary fringe. The end correction for non-penetrating wells is also sufficiently well made by an addition to the measured depth of water; the magnitude of the correction is given for isotropic media for a well system of the dimensions used here, and the method of applying it to anisotropic media is indicated. The two-well method is used to estimate the permeability of the sand, which is then discussed in relation to the pore-size distribution. The elucidation of the permeability profile in a succession of strata is then discussed. Finally, techniques suited to work in the field are described, and a few preliminary fields results are quoted.

Rock magnetism as a tool for investigating the use of archaeological artefacts from baked clay

2021 ◽  
Author(s):  
Evdokia Tema ◽  
Enzo Ferrara ◽  
Lorenzo Zamboni ◽  
Marica Venturino ◽  
Margherita Reboldi ◽  
...  
Keyword(s):  
Iron Age ◽  
Remanent Magnetization ◽  
Rock Magnetism ◽  
Magnetic Behavior ◽  
Archaeological Site ◽  
Natural Remanent Magnetization ◽  
Rock Magnetic Properties ◽  
Ring Shape ◽  
Magnetic Analysis

<p>Even though multidisciplinary approaches applied to the investigation of archaeological findings are widely used, the use of rock magnetic properties is still poorly exploited in the determination of the use of ancient artefacts. In this study, we present the results of a combined archaeological, morphological and magnetic analyses applied on the ring-shape clay artefacts found at the archaeological site of Villa del Foro, in Northern Italy. The materials studied are dated between the sixth and the first half of fifth century BC and are found in large quantities in different trenches of the archaeological excavation. To investigate their thermal history and to exploit their possible use as kiln supports, cooking stands, or loom weights, we have investigated their natural remanent magnetization (NRM) and the magnetic mineralogy changes occurred during laboratory heating. Magnetic analysis used for the determination of the firing temperatures show thermal stability up to 500-600 <sup>o </sup>C, while further laboratory heating at 700 <sup>o </sup>C introduces magnetic alteration. Thermal demagnetization of the samples generally shows a strong and stable thermal remanent magnetization. In few cases, a clear secondary component is present, suggesting partial re-heating or displacement at temperatures ranging from 200 <sup>o</sup>C to 450 °C. Such secondary magnetic component can be indicative of a secondary heating or of a displacement of the rings from their initial firing position while still hot. Even though the studied rings belong to casually different morphological typologies, no connection among type and magnetic behavior was observed, suggesting that the ring’s morphology does not define neither their production conditions nor the final use of the artefacts. The estimated firing temperatures of around 600-700 <sup>o</sup>C are compatible with the heating of the rings during their manufacture rather than related to cooking activities. In combination with the archaeological evidence and the morphological analysis it is thus suggested that the rings were used as weight looms and baked only during their production procedures. Such a pilot study can be used as reference for the identification of similar objects found in Italy and Europe during the Iron Age and confirms the great potential of rock magnetic analysis in the investigation of the technology and use of ancient baked clays.</p>

scholarly journals ARCHAEOMAGNETIC STUDIES IN KILNS FROM N. GREECE

2017 ◽  
Vol 43 (4) ◽  
pp. 1888 ◽  
Author(s):  
E. Aidona ◽  
D. Kondopoulou ◽  
M. Alexandrou ◽  
N. Ioannidis
Keyword(s):  
Magnetic Field ◽  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Archaeological Sites ◽  
Isothermal Remanent Magnetization ◽  
Thermomagnetic Analysis ◽  
Intensity Measurements ◽  
Magnetic Carriers ◽  
Characteristic Component

Archaeomagnetism combines the magnetic properties of baked materials with Archaeology. The archaeomagnetic method can be applied to any kind of permanent - in situ or displaced- burnt structures, such as kilns, ovens, hearths, burnt floors, tiles, bricks and pottery fragments, the latter for intensity measurements only. In this study we present the latest archaeomagnetic results from archaeological sites which are distributed in N. Greece (Polymylos, Sani, Thesssaloniki). The Natural Remanent Magnetization (NRM) and the magnetic susceptibility of the samples have been initially measured. The samples have been subjected to magnetic cleaning (AF and Thermal demagnetizations) and this procedure revealed the characteristic component of the ancient magnetic field. Rock magnetic experiments such as acquisition of the Isothermal Remanent Magnetization (IRM) and thermomagnetic analysis have been performed in pilot samples in order to identify the main magnetic carriers. Finally the secular variation curves for Greece and the SCHA.DIF.3K model were used in order to date these archaeological structures. This dating improved or modified the estimated archaeological ages.

DETERMINATION OF VOLCANIC THICKNESS AND UNDERLYING STRUCTURES FROM AEROMAGNETIC MAPS IN THE SILET AREA OF ALGERIA

Geophysics ◽  
1975 ◽  
Vol 40 (1) ◽  
pp. 79-90 ◽  
Author(s):  
C. E. Curtis ◽  
S. Jain
Keyword(s):  
Spectral Analysis ◽  
Dimensional Analysis ◽  
Magnetic Survey ◽  
Average Thickness ◽  
Two Dimensional ◽  
One Dimensional

In the course of the interpretation of an aero‐magnetic survey of Algeria, techniques based on spectral analysis were found to be quite useful in the determination of volcanic thicknesses and the resolution of underlying structural trends in a mineralized region near Silet. One‐dimensional analysis, applied to a series, of traverses crossing the area, indicates the average thickness of volcanics to be about 100 m. Two‐dimensional spectra were used to design appropriate filters for attenuating anomalies from shallow sources thereby enhancing the responses of the underlying regional structures.

The Mid-Atlantic Ridge near 45° N. XIII. Magnetic properties of basalt bore-core

1970 ◽  
Vol 7 (6) ◽  
pp. 1515-1527 ◽  
Author(s):  
J. Brooke ◽  
E. Irving ◽  
J. K. Park
Keyword(s):  
Magnetic Properties ◽  
Coercive Force ◽  
Physical Properties ◽  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
The Core ◽  
Mid Atlantic Ridge ◽  
Technical Interest

Three bore-cores containing basalts have been obtained from the Mid-Atlantic Ridge at 45° N. The material is fresh and ideal for the study of physical properties. The drilling record and the nature of the core itself suggest that much of the basalt is from detached boulders, although one core may be in situ. In one core, variations in coercivity by a factor 2 occur within a distance of 5 cm. The coercive force spectra of anhysteretic and natural remanent magnetization are similar, but there are small differences due to secondary components which are used to predict correctly the polarity of 11 out of 12 specimens studied. This result may be of technical interest only since there is no guarantee that the material is in situ.

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